fs2open.github.com/code/hud/hudlock.cpp

/*
 * Copyright (C) Volition, Inc. 1999.  All rights reserved.
 *
 * All source code herein is the property of Volition, Inc. You may not sell 
 * or otherwise commercially exploit the source or things you created based on the 
 * source.
 *
*/ 




#include "ai/ai.h"
#include "debugconsole/console.h"
#include "gamesequence/gamesequence.h"
#include "gamesnd/gamesnd.h"
#include "globalincs/linklist.h"
#include "hud/hudlock.h"
#include "iff_defs/iff_defs.h"
#include "io/timer.h"
#include "mission/missionparse.h"
#include "network/multi.h"
#include "object/object.h"
#include "playerman/player.h"
#include "render/3d.h"
#include "ship/ship.h"
#include "weapon/emp.h"
#include "weapon/weapon.h"


// Used for aspect locks. -MageKing17
#define VIRTUAL_FRAME_HALF_WIDTH	320.0f
#define VIRTUAL_FRAME_HALF_HEIGHT	240.0f


vec3d lock_world_pos;

static float Lock_start_dist;

sound_handle Missile_track_loop = sound_handle::invalid();
sound_handle Missile_lock_loop  = sound_handle::invalid();

int Lock_target_box_width[GR_NUM_RESOLUTIONS] = {
	19,
	30
};
int Lock_target_box_height[GR_NUM_RESOLUTIONS] = {
	19,
	30
};

// the locked triangles (that orbit lock indicator) dimensions
float Lock_triangle_base[GR_NUM_RESOLUTIONS] = {
	4.0f,
	6.5f
};
float Lock_triangle_height[GR_NUM_RESOLUTIONS] = {
	4.0f,
	6.5f
};

int Lock_gauge_half_w[NUM_HUD_RETICLE_STYLES][GR_NUM_RESOLUTIONS] = {
	{ 15, 24 },
	{ 17, 28 }
};
int Lock_gauge_half_h[GR_NUM_RESOLUTIONS] = {
	15, 
	25
};

#define LOCK_GAUGE_BLINK_RATE			5			// blinks/sec

int Lockspin_half_w[NUM_HUD_RETICLE_STYLES][GR_NUM_RESOLUTIONS] = {
	{ 16, 26 },
	{ 31, 50 }
};
int Lockspin_half_h[NUM_HUD_RETICLE_STYLES][GR_NUM_RESOLUTIONS] = {
	{ 16, 26 },
	{ 32, 52 }
};

char Lock_fname[NUM_HUD_RETICLE_STYLES][GR_NUM_RESOLUTIONS][MAX_FILENAME_LEN] =
{
	{ "lock1_fs1", "2_lock1_fs1" },
	{ "lock1", "2_lock1" }
};

char Lockspin_fname[NUM_HUD_RETICLE_STYLES][GR_NUM_RESOLUTIONS][MAX_FILENAME_LEN] =
{
	{ "lockspin_fs1", "2_lockspin_fs1" },
	{ "lockspin", "2_lockspin" }
};

void hud_lock_determine_lock_point(vec3d *lock_world_pos_out);
void hud_lock_determine_lock_point(lock_info *current_lock);

// hud_init_missile_lock() is called at the beginning of a mission
//
void hud_init_missile_lock()
{
	Players[Player_num].lock_indicator_start_x = -1;
	Players[Player_num].lock_indicator_start_y = -1;
	Players[Player_num].lock_indicator_visible = 0;
	Player_ai->current_target_is_locked = 0;

	Player_ai->last_secondary_index = -1;
}

HudGaugeLock::HudGaugeLock():
HudGauge3DAnchor(HUD_OBJECT_LOCK, HUD_LEAD_INDICATOR, false, false, VM_DEAD_VIEW, 255, 255, 255)
{
}

void HudGaugeLock::initGaugeHalfSize(int w, int h)
{
	Lock_gauge_half_w = w;
	Lock_gauge_half_h = h;
}

void HudGaugeLock::initSpinHalfSize(int w, int h)
{
	Lockspin_half_w = w;
	Lockspin_half_h = h;
}

void HudGaugeLock::initTriHeight(float h)
{
	Lock_triangle_height = h;
}

void HudGaugeLock::initTriBase(float length)
{
	Lock_triangle_base = length;
}

void HudGaugeLock::initTargetBoxSize(int w, int h)
{
	Lock_target_box_width = w;
	Lock_target_box_height = h;
}

void HudGaugeLock::initLoopLockedAnim(bool loop)
{
	loop_locked_anim = loop;
}

void HudGaugeLock::initBlinkLockedAnim(bool blink)
{
	blink_locked_anim = blink;
}

void HudGaugeLock::initBitmaps(char *lock_gauge_fname, char *lock_anim_fname)
{
	hud_anim_init(&Lock_gauge, 0, 0, lock_gauge_fname);
	hud_anim_load(&Lock_gauge);

	hud_anim_init(&Lock_anim, 0, 0, lock_anim_fname);
	hud_anim_load(&Lock_anim);
}

void HudGaugeLock::initialize()
{
	Lock_gauge_draw_stamp = -1;
	Lock_gauge_draw = 0;
	Rotate_time_id = 1;
	Last_lock_status = false;

	Lock_anim.time_elapsed = 0.0f;
	Lock_gauge.time_elapsed = 0.0f;

	HudGauge::initialize();
}

// hud_show_lock_indicator() will display the lock indicator for homing missiles.
// lock_point_pos should be the world coordinates of the target being locked. Assuming all the 
// necessary locking calculations are done for this frame, this function will compute 
// where the indicator should be relative to the player's viewpoint and will render accordingly.
void HudGaugeLock::renderOld(float frametime)
{
	int			target_objnum, sx, sy;
	object		*targetp;
	vertex lock_point;

	bool locked = Player_ai->current_target_is_locked ? true : false;
	bool reset_timers = false;

	if ( locked != Last_lock_status ) {
		// check if player lock status has changed since the last frame.
		reset_timers = true;
		Last_lock_status = locked;
	}

	if (Player_ai->target_objnum == -1) {
		return;
	}

	// 1 is the only value for which your target is actually dying
	if (Player->target_is_dying == 1) {
		return;
	}

	if (!Players[Player_num].lock_indicator_visible){
		return;
	}

	target_objnum = Player_ai->target_objnum;
	Assert(target_objnum != -1);
	targetp = &Objects[target_objnum];

	// check to see if there are any missile to fire.. we don't want to show the 
	// lock indicator if there are missiles to fire.
	if ( !ship_secondary_bank_has_ammo(Player_obj->instance) ) {
		return;
	}

	bool in_frame = g3_in_frame() > 0;
	if(!in_frame)
		g3_start_frame(0);
	gr_set_screen_scale(base_w, base_h);

	// Get the target's current position on the screen. If he's not on there,
	// we're not going to draw the lock indicator even if he's in front 
	// of our ship, so bail out. 
	g3_rotate_vertex(&lock_point, &lock_world_pos); 
	g3_project_vertex(&lock_point);
	if (lock_point.codes & PF_OVERFLOW) {
		gr_reset_screen_scale();

		if(!in_frame)
			g3_end_frame();

		return;
	}

	hud_set_iff_color(targetp);
//	nprintf(("Alan","lockx: %d, locky: %d TargetX: %d, TargetY: %d\n", Players[Player_num].lock_indicator_x, Players[Player_num].lock_indicator_y, Player->current_target_sx, Player->current_target_sy));

	// We have the coordinates of the lock indicator relative to the target in our "virtual frame" 
	// so, we calculate where it should be drawn based on the player's viewpoint.
	if (Player_ai->current_target_is_locked) {
		sx = fl2i(lock_point.screen.xyw.x); 
		sy = fl2i(lock_point.screen.xyw.y);
		gr_unsize_screen_pos(&sx, &sy);

		// show the rotating triangles if target is locked
		renderLockTriangles(sx, sy, frametime);

		if ( reset_timers ) {
			Lock_gauge.time_elapsed = 0.0f;
		}
	} else {
		const float scaling_factor = (gr_screen.clip_center_x < gr_screen.clip_center_y) ? (gr_screen.clip_center_x / VIRTUAL_FRAME_HALF_WIDTH) : (gr_screen.clip_center_y / VIRTUAL_FRAME_HALF_HEIGHT);
		sx = fl2i(lock_point.screen.xyw.x) - fl2i(i2fl(Player->current_target_sx - Players[Player_num].lock_indicator_x) * scaling_factor);
		sy = fl2i(lock_point.screen.xyw.y) - fl2i(i2fl(Player->current_target_sy - Players[Player_num].lock_indicator_y) * scaling_factor);
		gr_unsize_screen_pos(&sx, &sy);

		if ( reset_timers ) {
			Lock_gauge_draw_stamp = -1;
			Lock_gauge_draw = 0;
			Lock_anim.time_elapsed = 0.0f;
		}
	}

	// show locked indicator
	Lock_gauge.sx = sx - Lock_gauge_half_w;
	Lock_gauge.sy = sy - Lock_gauge_half_h;
	if (Player_ai->current_target_is_locked) {
		hud_anim_render(&Lock_gauge, 0.0f, 1);
	} else {
		hud_anim_render(&Lock_gauge, frametime, 1);
	}

	gr_reset_screen_scale();
	if(!in_frame)
		g3_end_frame();
}

// hud_show_lock_indicator() will display the lock indicator for homing missiles.
// lock_point_pos should be the world coordinates of the target being locked. Assuming all the 
// necessary locking calculations are done for this frame, this function will compute 
// where the indicator should be relative to the player's viewpoint and will render accordingly.
void HudGaugeLock::render(float frametime, bool config)
{
	float scale = 1.0;

	// This gauge does not accept config settings so we don't have to render it right now.
	// That may change in the future, in which case the code below can be restored.
	if (config) {
		// The coords don't really get converted here but we still get scale based on the screen size which we need
		/* int x = 0, y = 0;
		std::tie(x, y, scale) = hud_config_convert_coord_sys(position[0], position[1], base_w, base_h);

		int w;
		int h;
		// Will need actual coords for the below if we activate this gauge in config
		hud_config_set_mouse_coords(gauge_config_id, x, x + w, y, y + h);

		setGaugeColor(HUD_C_NONE, config);*/

		return;
	}

	// check to see if there are any missile to fire.. we don't want to show the 
	// lock indicator if there are missiles to fire.
	if ( !ship_secondary_bank_has_ammo(Player_obj->instance) ) {
		return;
	}

	bool in_frame = g3_in_frame() > 0;
	if(!in_frame)
		g3_start_frame(0);
	gr_set_screen_scale(base_w, base_h);

	// go through all present lock indicators
	for (auto& current_lock : Player_ship->missile_locks){

		if ( !current_lock.indicator_visible ) {
			continue;
		}

		// Get the target's current position on the screen. If he's not on there,
		// we're not going to draw the lock indicator even if he's in front 
		// of our ship, so bail out. 
		vertex lock_point;
		g3_rotate_vertex(&lock_point, &current_lock.world_pos); 
		g3_project_vertex(&lock_point);

		if (lock_point.codes & PF_OVERFLOW) {
			continue;
		}

		hud_set_iff_color(current_lock.obj);

		// We have the coordinates of the lock indicator relative to the target in our "virtual frame" 
		// so, we calculate where it should be drawn based on the player's viewpoint.
		int sx, sy;
		if ( current_lock.locked ) {
			sx = fl2i(lock_point.screen.xyw.x); 
			sy = fl2i(lock_point.screen.xyw.y);
			gr_unsize_screen_pos(&sx, &sy);

			// show the rotating triangles if target is locked
			renderLockTrianglesNew(sx, sy, frametime, &current_lock);
		} else {
			const float scaling_factor = (gr_screen.clip_center_x < gr_screen.clip_center_y)
											 ? (gr_screen.clip_center_x / VIRTUAL_FRAME_HALF_WIDTH)
											 : (gr_screen.clip_center_y / VIRTUAL_FRAME_HALF_HEIGHT);
			sx = fl2i(lock_point.screen.xyw.x) - fl2i(i2fl(current_lock.current_target_sx - current_lock.indicator_x) * scaling_factor);
			sy = fl2i(lock_point.screen.xyw.y) - fl2i(i2fl(current_lock.current_target_sy - current_lock.indicator_y) * scaling_factor);
			gr_unsize_screen_pos(&sx, &sy);
		}

		Lock_gauge.sx = sx - fl2i(Lock_gauge_half_w * scale);
		Lock_gauge.sy = sy - fl2i(Lock_gauge_half_h * scale);
		if( current_lock.locked ){
			current_lock.lock_gauge_time_elapsed = 0.0f;
			Lock_gauge.time_elapsed = current_lock.lock_gauge_time_elapsed;
			hud_anim_render(&Lock_gauge, 0.0f, 1, 1, 0, 0, GR_RESIZE_FULL, false, scale);
		} else {
			// manually track the animation time, since we may have more than one lock
			current_lock.lock_gauge_time_elapsed += frametime;
			if (current_lock.lock_gauge_time_elapsed > Lock_gauge.total_time) {
				current_lock.lock_gauge_time_elapsed = 0.0f;
			}
			Lock_gauge.time_elapsed = current_lock.lock_gauge_time_elapsed;

			hud_anim_render(&Lock_gauge, 0.0f, 1, 1, 0, 0, GR_RESIZE_FULL, false, scale);
		}
	}

	gr_reset_screen_scale();
	if(!in_frame)
		g3_end_frame();
}

// Reset data used for player lock indicator
void hud_lock_reset(float lock_time_scale)
{
	weapon_info	*wip;
	ship_weapon	*swp;

	swp = &Player_ship->weapons;
    
	if ((swp->current_secondary_bank >= 0) && (swp->secondary_bank_weapons[swp->current_secondary_bank] >= 0)) {
		Assert(swp->current_secondary_bank < MAX_SHIP_SECONDARY_BANKS);
		Assert(swp->secondary_bank_weapons[swp->current_secondary_bank] < weapon_info_size());
		wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];
		Player->lock_time_to_target = i2fl(wip->min_lock_time*lock_time_scale);
	} else {
		Player->lock_time_to_target = 0.0f;
	}

	Player_ai->current_target_is_locked = 0;
	Players[Player_num].lock_indicator_visible = 0;
	Player->target_in_lock_cone = 0;
	Player->current_target_sx = -1;
	Player->current_target_sy = -1;
	Player->locking_subsys=NULL;
	Player->locking_on_center=0;
	Player->locking_subsys_parent=-1;
	hud_stop_looped_locking_sounds();

	// reset the lock anim time elapsed
//	Lock_anim.time_elapsed = 0.0f;

	for ( auto & missile_locks : Player_ship->missile_locks) {
		ship_clear_lock(&missile_locks);
	}
}

// Determine if the locking code has a point to track
int hud_lock_has_homing_point()
{
	if ( Player_ai->targeted_subsys || Player->locking_subsys || Player->locking_on_center ) {
		return 1;
	}
	return 0;
}

int Nebula_sec_range = 0;
DCF_BOOL(nebula_sec_range, Nebula_sec_range);

// Determine if point to lock on is in range
int hud_lock_target_in_range()
{
	vec3d		target_world_pos;
	object		*targetp;

	if ( !hud_lock_has_homing_point() ) {
		return 0;
	}

	targetp = &Objects[Player_ai->target_objnum];

	if ( Player_ai->targeted_subsys != NULL ) {
		vm_vec_unrotate(&target_world_pos, &Player_ai->targeted_subsys->system_info->pnt, &targetp->orient);
		vm_vec_add2(&target_world_pos, &targetp->pos);
	} else {
		if ( Player->locking_subsys ) {
			vm_vec_unrotate(&target_world_pos, &Player->locking_subsys->system_info->pnt, &targetp->orient);
			vm_vec_add2(&target_world_pos, &targetp->pos);
		} else {
			Assert(Player->locking_on_center);
			target_world_pos = targetp->pos;
		}
	}
	ship_weapon* swp = &Player_ship->weapons;
	weapon_info* wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	return weapon_secondary_world_pos_in_range(Player_obj, wip, &target_world_pos);
}

int hud_abort_lock()
{
	int target_team;

	weapon_info	*wip;
	ship_weapon	*swp;

	if ( Player_ship->weapons.num_secondary_banks <= 0 ) {
		return 1;
	}

	if ( Player_ship->weapons.current_secondary_bank < 0 ) {
		return 1;
	}

	// check to see if there are any missile to fire.. we don't want to show the 
	// lock indicator if there are no missiles to fire.
	if ( !ship_secondary_bank_has_ammo(Player_obj->instance) ) {
		return 1;
	}

	if ( Player_ship->flags[Ship::Ship_Flags::No_secondary_lockon] ) {
		return 1;
	}

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	// if we're on the same team and the team doesn't attack itself, then don't lock!
	if ( (Player_ai->target_objnum >= 0) ) {
		target_team = obj_team(&Objects[Player_ai->target_objnum]);

		if ( ( Player_ship->team == target_team) && ( !iff_x_attacks_y(Player_ship->team, target_team) ) 
			&& !weapon_has_iff_restrictions(wip)) {
			// if we're in multiplayer dogfight, ignore this
			// remember to check if we're firing a missile that doesn't require a current target
			if(!MULTI_DOGFIGHT || wip->target_restrict == LR_ANY_TARGETS) {
				return 1;
			}
		}
	}

	// Reset locks on launch if this weapon allows it and if we've recently fired.
	if ( wip->launch_reset_locks && !timestamp_elapsed(swp->next_secondary_fire_stamp[swp->current_secondary_bank]) ) {
		return 1;
	}

	return 0;
}

// determine if the subsystem to lock on to has a direct line of sight
int hud_lock_on_subsys_ok()
{
	ship_subsys		*subsys;
	vec3d			subobj_pos;
	object			*target_objp;
	int				in_sight=0;
	
	Assert(Player_ai->target_objnum >= 0);
	target_objp	= &Objects[Player_ai->target_objnum];

	subsys = Player_ai->targeted_subsys;
	if ( !subsys ) {
		return 0;
	}

	vm_vec_unrotate(&subobj_pos, &subsys->system_info->pnt, &target_objp->orient);
	vm_vec_add2(&subobj_pos, &target_objp->pos);

	if ( Player->subsys_in_view < 0 ) {
		in_sight = ship_subsystem_in_sight(target_objp, subsys, &View_position, &subobj_pos) ? 1 : 0;
	} else {
		in_sight = Player->subsys_in_view;
	}

	return in_sight;
}

// Determine if locking point is in the locking cone
void hud_lock_check_if_target_in_lock_cone()
{
	float	dot;
	vec3d	vec_to_target;

	vm_vec_normalized_dir(&vec_to_target, &lock_world_pos, &Player_obj->pos);
	dot = vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_target);

	if ( dot > 0.85) {
		Player->target_in_lock_cone = 1;
	} else {
		Player->target_in_lock_cone = 0;
	}
}

void hud_lock_check_if_target_in_lock_cone(lock_info *current_lock, weapon_info *wip)
{
	float	dot;
	vec3d	vec_to_target;

	vm_vec_normalized_dir(&vec_to_target, &current_lock->world_pos, &Player_obj->pos);
	dot = vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_target);

	current_lock->target_in_lock_cone = dot > wip->lock_fov;
}

// return 1 if current secondary weapon is different than previous secondary weapon
int hud_lock_secondary_weapon_changed(ship_weapon *swp)
{

	if ( swp->current_secondary_bank != Player_ai->last_secondary_index ) {
		return 1;
	}

	return 0;
/*
	int last_wi_index = -1;
	int current_wi_index = -1;


	// do a quick out if same bank is selected
	if ( swp->current_secondary_bank == Player_ai->last_secondary_index ) {
		return 0;
	}

	// bank has changed, but it still may be the same weapon type
	if ( swp->current_secondary_bank >= 0 ) {
		current_wi_index = swp->secondary_bank_weapons[swp->current_secondary_bank];
	}

	if ( Player_ai->last_secondary_index >= 0 ) {
		last_wi_index = swp->secondary_bank_weapons[Player_ai->last_secondary_index];
	}

	if ( current_wi_index != last_wi_index ) {
		return 1;
	}

	return 0;
*/

}

// hud_do_lock_indicator() manages missle locking, both the non-rendering calculations and the 2D HUD rendering
void hud_do_lock_indicator(float frametime)
{
	ship_weapon *swp;
	weapon_info	*wip;

	// if i'm a multiplayer observer, bail here
	if((Game_mode & GM_MULTIPLAYER) && ((Net_player->flags & NETINFO_FLAG_OBSERVER) || (Player_obj->type == OBJ_OBSERVER)) ){
		return;
	}

	Assert(Player_ai->target_objnum >= 0);

	// be sure to unset this flag, then possibly set later in this function so that
	// threat indicators work properly.
	Player_ai->ai_flags.remove(AI::AI_Flags::Seek_lock);

	if ( hud_abort_lock() ) {
		hud_lock_reset();
		return;
	}

	// if there is an EMP effect active, never update lock
	if(emp_active_local()){
		hud_lock_reset();
		return;
	}

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	Lock_start_dist = wip->min_lock_time * wip->lock_pixels_per_sec;

	// if secondary weapons change, reset the lock
	if ( hud_lock_secondary_weapon_changed(swp) ) {
		hud_lock_reset();
	}
		
	Player_ai->last_secondary_index = swp->current_secondary_bank;

	object *tobjp = &Objects[Player_ai->target_objnum];
	vec3d dir_to_target;
	vm_vec_normalized_dir(&dir_to_target, &tobjp->pos, &Player_obj->pos);

	if ( !(wip->is_locked_homing()) ) {
		hud_lock_reset();
		return;		
	}

	// Allow locking on ships and bombs (only targeted weapon allowed is a bomb, so don't bother checking flags)
	if ( (Objects[Player_ai->target_objnum].type != OBJ_SHIP) && (Objects[Player_ai->target_objnum].type != OBJ_WEAPON) ) {	
		hud_lock_reset();
		return;
	}

	// Javelins must lock on engines if locking on a ship and those must be in sight
	if (wip->wi_flags[Weapon::Info_Flags::Homing_javelin] && 
		tobjp->type == OBJ_SHIP &&
		Player->locking_subsys != NULL) {
			vec3d subobj_pos;
			vm_vec_unrotate(&subobj_pos, &Player->locking_subsys->system_info->pnt, &tobjp->orient);
			vm_vec_add2(&subobj_pos, &tobjp->pos);
			bool target_subsys_in_sight = ship_subsystem_in_sight(tobjp, Player->locking_subsys, &Player_obj->pos, &subobj_pos);

			if (!target_subsys_in_sight || Player->locking_subsys->system_info->type != SUBSYSTEM_ENGINE) {
				Player->locking_subsys =
					ship_get_closest_subsys_in_sight(&Ships[tobjp->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);
			}
	}

	if (wip->wi_flags[Weapon::Info_Flags::Homing_javelin] && 
		tobjp->type == OBJ_SHIP &&
		Player->locking_subsys == NULL) {
			Player->locking_subsys =
				ship_get_closest_subsys_in_sight(&Ships[tobjp->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);

			if (Player->locking_subsys == NULL) {
				hud_lock_reset();
				return;
			}
	}

	hud_lock_determine_lock_point(&lock_world_pos);

	if ( !hud_lock_has_homing_point() ) {
		Player->target_in_lock_cone=0;
	}

	hud_lock_check_if_target_in_lock_cone();

	// check if the target is within range of the current secondary weapon.  If it is not,
	// a lock will not be detected
	if ( !hud_lock_target_in_range() ) {
		Player->target_in_lock_cone = 0;
	}

	// If locking on a subsystem, and not in sight... can't lock
	//	Changed by MK on 4/3/98.  It was confusing me that my hornets would not lock on my target.
	//	It will now be confusing that they lock, but don't home on your subsystem, but I think that's preferable.
	//	Often you really care about destroying the target, not just the subsystem.
	/*if ( Player_ai->targeted_subsys ) {
		if ( !hud_lock_on_subsys_ok() ) {
			Player->target_in_lock_cone=0;
		}
	}*/

	if ( !Player->target_in_lock_cone ) {
		Player->locking_on_center=0;
		Player->locking_subsys_parent=-1;
		Player->locking_subsys=NULL;
	}
		
	hud_calculate_lock_position(frametime);

	if (!Players[Player_num].lock_indicator_visible)
		return;

	if (Player_ai->current_target_is_locked) {
		if (Missile_track_loop.isValid()) {
			snd_stop(Missile_track_loop);
			Missile_track_loop = sound_handle::invalid();

			if (wip->hud_locked_snd.isValid())
			{
				Missile_lock_loop = snd_play(gamesnd_get_game_sound(wip->hud_locked_snd));
			}
			else
			{
				Missile_lock_loop = snd_play(gamesnd_get_game_sound(ship_get_sound(Player_obj, GameSounds::MISSILE_LOCK)));
			}
		}
	}
	else {
		Player_ai->ai_flags.set(AI::AI_Flags::Seek_lock);		// set this flag so multiplayer's properly track lock on other ships
		if (Missile_lock_loop.isValid() && snd_is_playing(Missile_lock_loop)) {
			snd_stop(Missile_lock_loop);
			Missile_lock_loop = sound_handle::invalid();
		}
	}
}

void hud_lock_acquire_current_target(object *target_objp, ship_subsys *target_subsys)
{
	ship			*target_shipp=nullptr;
	int			lock_in_range=0;
	float			best_lock_dot=-1.0f, lock_dot=-1.0f;
	ship_subsys	*ss;
	vec3d		subsys_world_pos, vec_to_lock;

	if ( target_objp->type == OBJ_SHIP ) {
		target_shipp = &Ships[target_objp->instance];
	}

	ship_weapon* swp = &Player_ship->weapons;
	weapon_info* wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	// Reset target subsys in case it isn't needed
	if (target_subsys != nullptr) target_subsys = nullptr;

	// if a large ship, lock to pos closest to center and within range
	if ( (target_shipp) && (Ship_info[target_shipp->ship_info_index].is_big_or_huge()) ) {
		// check all the subsystems and the center of the ship

		// assume best lock pos is the center of the ship
		lock_in_range = weapon_secondary_world_pos_in_range(Player_obj, wip, &target_objp->pos);
		vm_vec_normalized_dir(&vec_to_lock, &target_objp->pos, &Player_obj->pos);
		if ( lock_in_range ) {
			best_lock_dot=vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_lock);
		} 
		// take center if reasonable dot
		if ( best_lock_dot > 0.95 ) {
			return;
		}

		// iterate through subsystems to see if we can get a better choice
		ss = GET_FIRST(&target_shipp->subsys_list);
		while ( ss != END_OF_LIST( &target_shipp->subsys_list ) ) {

			// get world pos of subsystem
			get_subsystem_world_pos(target_objp, ss, &subsys_world_pos);

			if ( weapon_secondary_world_pos_in_range(Player_obj, wip, &subsys_world_pos) ) {
				vm_vec_normalized_dir(&vec_to_lock, &subsys_world_pos, &Player_obj->pos);
				lock_dot=vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_lock);
				if ( lock_dot > best_lock_dot ) {
					best_lock_dot=lock_dot;
					target_subsys = ss;
				}
			}
			ss = GET_NEXT( ss );
		}
	}

}

void hud_lock_acquire_uncaged_subsystem(weapon_info *wip, lock_info *lock, float *best_dot, int *least_num_locks)
{
	Assert( lock->obj->type == OBJ_SHIP );

	ship *sp = &Ships[lock->obj->instance];

	float ss_dot;

	int current_num_locks = 0;

	if ( Ship_info[sp->ship_info_index].is_big_or_huge() ) {
		for (ship_subsys* ss = GET_FIRST(&sp->subsys_list); ss != END_OF_LIST(&sp->subsys_list); ss = GET_NEXT(ss) ) {

			if (!weapon_multilock_can_lock_on_subsys(Player_obj, lock->obj, ss, wip, &ss_dot))
				continue;

			// check for existing locks
			current_num_locks = 0;
			bool actively_locking = false;

			for ( auto & missile_lock : Player_ship->missile_locks) {
				if (missile_lock.obj != nullptr && OBJ_INDEX(missile_lock.obj) == OBJ_INDEX(lock->obj) ) {
					if (missile_lock.subsys != nullptr && missile_lock.subsys == ss ) {
						if ( !missile_lock.locked ) {
							// we're already currently locking on this subsystem so let's not throw another aspect lock on it.
							actively_locking = true;
							continue;
						}

						++current_num_locks;
					}
				}
			}

			if ( !actively_locking 
				&& current_num_locks < wip->max_seekers_per_target
				&& current_num_locks <= *least_num_locks
				&& ss_dot > *best_dot ) {
					lock->subsys = ss;
					*best_dot = ss_dot;
					*least_num_locks = current_num_locks;
			}
		}
	}
}

void hud_lock_acquire_uncaged_target(lock_info *current_lock, weapon_info *wip)
{
	object *A;
	float dot;

	size_t i = 0;

	object* best_obj = nullptr;
	ship_subsys *best_subsys = nullptr;

	float best_dot = 0.0f;

	int current_num_locks = 0;
	int least_num_locks = INT_MAX;
	bool actively_locking = false;

	for ( A = GET_FIRST(&obj_used_list); A !=END_OF_LIST(&obj_used_list); A = GET_NEXT(A) ) {
		if (A->flags[Object::Object_Flags::Should_be_dead])
			continue;

		if (!weapon_multilock_can_lock_on_target(Player_obj, A, wip, &dot))
			continue;

		bool in_range = weapon_secondary_world_pos_in_range(Player_obj, wip, &A->pos);

		if ( A->type == OBJ_SHIP && Ship_info[Ships[A->instance].ship_info_index].is_big_or_huge() ) {
			lock_info temp_lock;

			temp_lock.obj = A;
			temp_lock.subsys = nullptr;

			float ss_dot = 0.0f;
			int ss_num_locks = INT_MAX;

			hud_lock_acquire_uncaged_subsystem(wip, &temp_lock, &ss_dot, &ss_num_locks);

			if ( temp_lock.subsys != nullptr && ss_num_locks < wip->max_seekers_per_target && ss_num_locks <= least_num_locks && ss_dot > best_dot ) {
				best_subsys = temp_lock.subsys;
				best_obj = A;
				best_dot = ss_dot;
				least_num_locks = ss_num_locks;
			}
		} else {
			if ( !in_range ) {
				continue;
			}

			if ( dot < wip->lock_fov ) {
				continue;
			}

			current_num_locks = 0;
			actively_locking = false;

			for ( i = 0; i < Player_ship->missile_locks.size(); ++i ) {
				if ( Player_ship->missile_locks[i].obj != nullptr && OBJ_INDEX(Player_ship->missile_locks[i].obj) == OBJ_INDEX(A) && Player_ship->missile_locks[i].subsys == nullptr) {
					if ( !Player_ship->missile_locks[i].locked ) {
						// we're already currently locking on this subsystem so let's not throw another aspect lock on it.
						actively_locking = true;
						continue;
					}

					current_num_locks++;
				}
			}

			if ( !actively_locking 
				&& current_num_locks < wip->max_seekers_per_target
				&& current_num_locks <= least_num_locks
				&& dot > best_dot ) {
					best_subsys = nullptr;
					best_obj = A;
					best_dot = dot;
					least_num_locks = current_num_locks;
			}
		}
	}

	current_lock->obj = best_obj;
	current_lock->subsys = best_subsys;
}

void hud_lock_acquire_uncaged_target_weapon(lock_info* current_lock, weapon_info* wip)
{
	object* A;
	float dot;

	size_t i = 0;

	object* best_obj = nullptr;
	ship_subsys* best_subsys = nullptr;

	float best_dot = 0.0f;

	int current_num_locks = 0;
	int least_num_locks = INT_MAX;
	bool actively_locking = false;

	for (A = GET_FIRST(&obj_used_list); A != END_OF_LIST(&obj_used_list); A = GET_NEXT(A)) {
		if (A->flags[Object::Object_Flags::Should_be_dead])
			continue;

		if (!weapon_multilock_can_lock_on_target(Player_obj, A, wip, &dot, true))
			continue;

		bool in_range = weapon_secondary_world_pos_in_range(Player_obj, wip, &A->pos);

		if (!in_range) {
			continue;
		}

		if (dot < wip->lock_fov) {
			continue;
		}

		current_num_locks = 0;
		actively_locking = false;

		for (i = 0; i < Player_ship->missile_locks.size(); ++i) {
			if (Player_ship->missile_locks[i].obj != nullptr && OBJ_INDEX(Player_ship->missile_locks[i].obj) == OBJ_INDEX(A) && Player_ship->missile_locks[i].subsys == nullptr) {
				if (!Player_ship->missile_locks[i].locked) {
					// we're already currently locking on this subsystem so let's not throw another aspect lock on it.
					actively_locking = true;
					continue;
				}

				current_num_locks++;
			}
		}

		if (!actively_locking
			&& current_num_locks < wip->max_seekers_per_target
			&& current_num_locks <= least_num_locks
			&& dot > best_dot) {
			best_subsys = nullptr;
			best_obj = A;
			best_dot = dot;
			least_num_locks = current_num_locks;
		}
	}

	current_lock->obj = best_obj;
	current_lock->subsys = best_subsys;
}

void hud_lock_determine_lock_target(lock_info *lock_slot, weapon_info *wip)
{
	if ( lock_slot->obj != nullptr) {
		return;
	}

	if (wip->target_restrict == LR_ANY_TARGETS) {
		// if this weapon is uncaged, grab the best possible target within the player's lock cone and weapon distance
		vec3d vec_to_target;
		vec3d target_pos;
		object *objp;
		float dot;

		if ( lock_slot->obj != nullptr) {

			// lock slot occupied; do a check to see if this is a valid lock
			objp = lock_slot->obj;

			if ( lock_slot->subsys ) {
				vm_vec_unrotate(&target_pos, &Player->locking_subsys->system_info->pnt, &objp->orient);
				vm_vec_add2(&target_pos, &objp->pos);
			} else {
				target_pos = objp->pos;
			}

			vm_vec_normalized_dir(&vec_to_target, &target_pos, &Eye_position);
			dot = vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_target);

			if (!weapon_secondary_world_pos_in_range(Player_obj, wip, &lock_slot->obj->pos) || dot < wip->lock_fov) {
				// set this lock slot to empty
				ship_clear_lock(lock_slot);
				if (wip->target_restrict_objecttypes == LR_Objecttypes::LRO_SHIPS)
					hud_lock_acquire_uncaged_target(lock_slot, wip);
				else
					hud_lock_acquire_uncaged_target_weapon(lock_slot, wip);
			}
		} else {
			// not using an else because the previous block may have 
			// invalidated the target that was previously in this lock slot
			ship_clear_lock(lock_slot);
			if (wip->target_restrict_objecttypes == LR_Objecttypes::LRO_SHIPS)
				hud_lock_acquire_uncaged_target(lock_slot, wip);
			else
				hud_lock_acquire_uncaged_target_weapon(lock_slot, wip);
		}
	} else if ( wip->target_restrict == LR_CURRENT_TARGET_SUBSYS ) {
		if ( lock_slot->obj != nullptr) {
			return;
		}

		if ( Player_ai->target_objnum < 0 ) {
			ship_clear_lock(lock_slot);
			return;
		}

		lock_slot->obj = &Objects[Player_ai->target_objnum];

		// Allow locking on ships and bombs (only targeted weapon allowed is a bomb, so don't bother checking flags)
		if ( lock_slot->obj->type != OBJ_SHIP && lock_slot->obj->type != OBJ_WEAPON ) {
			ship_clear_lock(lock_slot);
			return;
		}

		if ( !weapon_target_satisfies_lock_restrictions(wip, lock_slot->obj) ) {
			ship_clear_lock(lock_slot);
			return;
		}

		if ( lock_slot->obj->type == OBJ_SHIP && Ship_info[Ships[lock_slot->obj->instance].ship_info_index].is_big_or_huge() ) {
			float dot = 0.0f;
			int num_locks = INT_MAX;
			lock_info temp_lock;

			temp_lock.obj = lock_slot->obj;
			temp_lock.subsys = nullptr;

			hud_lock_acquire_uncaged_subsystem(wip, &temp_lock, &dot, &num_locks);

			ship_clear_lock(lock_slot);

			if ( temp_lock.subsys != nullptr) {
				lock_slot->obj = temp_lock.obj;
				lock_slot->subsys = temp_lock.subsys;
			}
		} else {
			// If subsystem is targeted, we must try to lock on that
			if ( Player_ai->targeted_subsys && !(wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) ) {
				lock_slot->subsys = Player_ai->targeted_subsys;
			} else if ( wip->wi_flags[Weapon::Info_Flags::Homing_javelin] && lock_slot->obj->type == OBJ_SHIP) {
				if ( Player_ai->targeted_subsys ) {
					vec3d subobj_pos;

					vm_vec_unrotate(&subobj_pos, &Player->locking_subsys->system_info->pnt, &lock_slot->obj->orient);
					vm_vec_add2(&subobj_pos, &lock_slot->obj->pos);

					bool target_subsys_in_sight = ship_subsystem_in_sight(lock_slot->obj, Player_ai->targeted_subsys, &Player_obj->pos, &subobj_pos);

					if ( !target_subsys_in_sight || Player->locking_subsys->system_info->type != SUBSYSTEM_ENGINE ) {
						lock_slot->subsys = ship_get_closest_subsys_in_sight(&Ships[lock_slot->obj->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);
					}
				} else {
					lock_slot->subsys = ship_get_closest_subsys_in_sight(&Ships[lock_slot->obj->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);

					if (lock_slot->subsys == nullptr) {
						lock_slot->obj = nullptr;
						return;
					}
				}
			} else {
				hud_lock_acquire_current_target(lock_slot->obj, lock_slot->subsys);
			}
		}
	} else {
		if ( lock_slot->obj != nullptr) {
			return;
		}

		if ( Player_ai->target_objnum < 0 ) {
			ship_clear_lock(lock_slot);
			return;
		}

		// if caged, we're locking on the current target
		lock_slot->obj = &Objects[Player_ai->target_objnum];

		// Allow locking on ships and bombs (only targeted weapon allowed is a bomb, so don't bother checking flags)
		if ( lock_slot->obj->type != OBJ_SHIP && lock_slot->obj->type != OBJ_WEAPON ) {
			ship_clear_lock(lock_slot);
			return;
		}

		if ( !weapon_target_satisfies_lock_restrictions(wip, lock_slot->obj) ) {
			ship_clear_lock(lock_slot);
			return;
		}

		// If subsystem is targeted, we must try to lock on that
		if ( Player_ai->targeted_subsys && !(wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) ) {
			lock_slot->subsys = Player_ai->targeted_subsys;
		} else if ( wip->wi_flags[Weapon::Info_Flags::Homing_javelin] && lock_slot->obj->type == OBJ_SHIP) {
			if ( Player_ai->targeted_subsys ) {
				vec3d subobj_pos;

				vm_vec_unrotate(&subobj_pos, &Player_ai->targeted_subsys->system_info->pnt, &lock_slot->obj->orient);
				vm_vec_add2(&subobj_pos, &lock_slot->obj->pos);

				bool target_subsys_in_sight = ship_subsystem_in_sight(lock_slot->obj, Player_ai->targeted_subsys, &Player_obj->pos, &subobj_pos);

				if ( !target_subsys_in_sight || Player_ai->targeted_subsys->system_info->type != SUBSYSTEM_ENGINE ) {
					lock_slot->subsys = ship_get_closest_subsys_in_sight(&Ships[lock_slot->obj->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);
				}
			} else {
				lock_slot->subsys = ship_get_closest_subsys_in_sight(&Ships[lock_slot->obj->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);

				if (lock_slot->subsys == nullptr) {
					lock_slot->obj = nullptr;
					return;
				}
			}
		} else {
			hud_lock_acquire_current_target(lock_slot->obj, lock_slot->subsys);
		}
	}
}

// Decide which point lock should be homing on
void hud_lock_determine_lock_point(lock_info *current_lock)
{
	vec3d vec_to_lock_pos;
	vec3d lock_local_pos;

	Assert(current_lock->obj != nullptr);

	current_lock->current_target_sx = -1;
	current_lock->current_target_sy = -1;

	if ( current_lock->subsys ) {
		get_subsystem_world_pos(current_lock->obj, current_lock->subsys, &current_lock->world_pos);
	} else {
		current_lock->world_pos = current_lock->obj->pos;
	}

	vm_vec_sub(&vec_to_lock_pos,&current_lock->world_pos,&Player_obj->pos);
	vm_vec_rotate(&lock_local_pos,&vec_to_lock_pos,&Player_obj->orient);

	if ( lock_local_pos.xyz.z > 0.0f ) {
		// Get the location of our target in the "virtual frame" where the locking computation will be done
		float w = 1.0f / lock_local_pos.xyz.z;
		// Let's force our "virtual frame" to be 640x480. -MageKing17
		float sx = gr_screen.clip_center_x + (lock_local_pos.xyz.x * VIRTUAL_FRAME_HALF_WIDTH * w);
		float sy = gr_screen.clip_center_y - (lock_local_pos.xyz.y * VIRTUAL_FRAME_HALF_HEIGHT * w);

		current_lock->current_target_sx = (int)sx;
		current_lock->current_target_sy = (int)sy;
	}
}

void hud_calculate_lock_start_pos(lock_info *current_lock)
{
	double hypotenuse;
	double delta_y;
	double delta_x;
	double target_mag, target_x, target_y;

	delta_x = static_cast<double>(current_lock->current_target_sx) - gr_screen.clip_center_x;
	delta_y = static_cast<double>(current_lock->current_target_sy) - gr_screen.clip_center_y;

	if ( (delta_x == 0.0) && (delta_y == 0.0) ) {
		current_lock->indicator_start_x = fl2i(gr_screen.clip_center_x + Lock_start_dist);
		current_lock->indicator_start_y = fl2i(gr_screen.clip_center_y);
		return;
	}

	hypotenuse = _hypot(delta_y, delta_x);

	if (hypotenuse >= Lock_start_dist) {
		current_lock->indicator_start_x = fl2i(gr_screen.clip_center_x);
		current_lock->indicator_start_y = fl2i(gr_screen.clip_center_y);
		return;
	}

	target_mag = Lock_start_dist - hypotenuse;
	target_x = target_mag * (delta_x / hypotenuse);
	target_y = target_mag * (delta_y / hypotenuse);

	current_lock->indicator_start_x = fl2i(gr_screen.clip_center_x - target_x);
	current_lock->indicator_start_y = fl2i(gr_screen.clip_center_y - target_y);

	CLAMP(current_lock->indicator_start_x, gr_screen.clip_left, gr_screen.clip_right);
	CLAMP(current_lock->indicator_start_y, gr_screen.clip_top, gr_screen.clip_bottom);
}

void hud_calculate_lock_slot_time(lock_info *current_lock, weapon_info *wip, float frametime)
{
	if ( current_lock->target_in_lock_cone ) {
		if ( !current_lock->indicator_visible ) {
			hud_calculate_lock_start_pos(current_lock);
			current_lock->last_dist_to_target = 0;

			current_lock->indicator_x = current_lock->indicator_start_x;
			current_lock->indicator_y = current_lock->indicator_start_y;
			current_lock->indicator_visible = true;

			current_lock->accumulated_x_pixels = 0.0f;
			current_lock->accumulated_y_pixels = 0.0f;

			current_lock->time_to_lock = i2fl(wip->min_lock_time);
			current_lock->catching_up = 0;
		}

		current_lock->need_new_start_pos = true;

		if ( current_lock->locked ) {
			current_lock->indicator_x = current_lock->current_target_sx;
			current_lock->indicator_y = current_lock->current_target_sy;
			return;
		}

		current_lock->time_to_lock -= frametime;
	} else {
		current_lock->time_to_lock += frametime;
	}
}

void hud_calculate_lock_slot_position(lock_info *current_lock, float frametime)
{
	ship_weapon *swp;
	weapon_info	*wip;

	float pixels_moved_while_locking;
	float pixels_moved_while_degrading;
	//static int Need_new_start_pos = 0;

	//static double accumulated_x_pixels, accumulated_y_pixels;
	double int_portion;

	//static float last_dist_to_target;

	//static int catching_up;

	//static int maintain_lock_count = 0;

	//static float catch_up_distance = 0.0f;

	double hypotenuse, delta_x, delta_y;

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	if ( current_lock->target_in_lock_cone ) {
		if ( !current_lock->indicator_visible ) {
			hud_calculate_lock_start_pos(current_lock);
			current_lock->last_dist_to_target = 0.0f;

			current_lock->indicator_x = current_lock->indicator_start_x;
			current_lock->indicator_y = current_lock->indicator_start_y;
			current_lock->indicator_visible = true;

			current_lock->time_to_lock = i2fl(wip->min_lock_time);
			current_lock->catching_up = 0;
			current_lock->maintain_lock_count = 0;
		}

		current_lock->need_new_start_pos = true;

		if ( current_lock->locked ) {
			current_lock->indicator_x = current_lock->current_target_sx;
			current_lock->indicator_y = current_lock->current_target_sy;
			return;
		}

		delta_x = (double)(current_lock->indicator_x - current_lock->current_target_sx);
		delta_y = (double)(current_lock->indicator_y - current_lock->current_target_sy);

		if (!delta_y && !delta_x) {
			hypotenuse = 0;
		}
		else {
			hypotenuse = (float)_hypot((double)delta_y, (double)delta_x);
		}

		current_lock->dist_to_lock = (float)hypotenuse;

		if ( current_lock->last_dist_to_target == 0) {
			current_lock->last_dist_to_target = current_lock->dist_to_lock;
		}

		//nprintf(("Alan","dist to target: %.2f\n",Players[Player_num].lock_dist_to_target));
		//nprintf(("Alan","last to target: %.2f\n\n",last_dist_to_target));

		if ( current_lock->catching_up ) {
			//nprintf(("Alan","IN CATCH UP MODE  catch_up_dist is %.2f\n",catch_up_distance));	
			if ( current_lock->dist_to_lock < current_lock->catch_up_distance )
				current_lock->catching_up = 0;
		}
		else {
			//nprintf(("Alan","IN NORMAL MODE\n"));
			if ( (current_lock->dist_to_lock - current_lock->last_dist_to_target) > 2.0f ) {
				current_lock->catching_up = 1;
				current_lock->catch_up_distance = current_lock->last_dist_to_target + wip->catchup_pixel_penalty;
			}
		}

		current_lock->last_dist_to_target = current_lock->dist_to_lock;

		if (!current_lock->catching_up) {
			current_lock->time_to_lock -= frametime;
			if ( current_lock->time_to_lock < 0.0f )
				current_lock->time_to_lock = 0.0f;
		}

		float lock_pixels_per_sec;
		if (current_lock->time_to_lock > 0) {
			lock_pixels_per_sec = current_lock->dist_to_lock / current_lock->time_to_lock;
		} else {
			lock_pixels_per_sec = i2fl(wip->lock_pixels_per_sec);
		}

		if (lock_pixels_per_sec > wip->lock_pixels_per_sec) {
			lock_pixels_per_sec = i2fl(wip->lock_pixels_per_sec);
		}

		if ( current_lock->catching_up ) {
			pixels_moved_while_locking = wip->catchup_pixels_per_sec * frametime;
		} else {
			pixels_moved_while_locking = lock_pixels_per_sec * frametime;
		}

		if ((delta_x != 0) && (hypotenuse != 0)) {
			current_lock->accumulated_x_pixels += pixels_moved_while_locking * delta_x/hypotenuse; 
		}

		if ((delta_y != 0) && (hypotenuse != 0)) {
			current_lock->accumulated_y_pixels += pixels_moved_while_locking * delta_y/hypotenuse; 
		}

		if (fl_abs((float)current_lock->accumulated_x_pixels) > 1.0f) {
			modf(current_lock->accumulated_x_pixels, &int_portion);

			current_lock->indicator_x -= (int)int_portion;

			if ( fl_abs((float)current_lock->indicator_x - (float)current_lock->current_target_sx) < fl_abs((float)int_portion) )
				current_lock->indicator_x = current_lock->current_target_sx;

			current_lock->accumulated_x_pixels -= int_portion;
		}

		if (fl_abs((float)current_lock->accumulated_y_pixels) > 1.0f) {
			modf(current_lock->accumulated_y_pixels, &int_portion);

			current_lock->indicator_y -= (int)int_portion;

			if ( fl_abs((float)current_lock->indicator_y - (float)current_lock->current_target_sy) < fl_abs((float)int_portion) )
				current_lock->indicator_y = current_lock->current_target_sy;

			current_lock->accumulated_y_pixels -= int_portion;
		}

		if (!current_lock->time_to_lock) {
			if ( (current_lock->indicator_x == current_lock->current_target_sx) && (current_lock->indicator_y == current_lock->current_target_sy) ) {
				if (current_lock->maintain_lock_count++ > 1) {
					current_lock->locked = true;
				}
			} else {
				current_lock->maintain_lock_count = 0;
			}
		}

	} else {
		current_lock->locked = false;

		if (!current_lock->indicator_visible) {
			return;
		}

		current_lock->catching_up = 0;
		current_lock->last_dist_to_target = 0.0f;

		if (current_lock->need_new_start_pos) {
			hud_calculate_lock_start_pos(current_lock);
			current_lock->need_new_start_pos = false;
			current_lock->accumulated_x_pixels = 0.0f;
			current_lock->accumulated_y_pixels = 0.0f;
			current_lock->maintain_lock_count = 0;
		}

		delta_x = i2fl(current_lock->indicator_x - current_lock->indicator_start_x);
		delta_y = i2fl(current_lock->indicator_y - current_lock->indicator_start_y);

		if (!delta_y && !delta_x) {
			hypotenuse = 0;
		}
		else {
			hypotenuse = _hypot(delta_y, delta_x);
		}

		current_lock->time_to_lock += frametime;

		if (current_lock->time_to_lock > wip->min_lock_time)
			current_lock->time_to_lock = i2fl(wip->min_lock_time);

		pixels_moved_while_degrading = 2.0f * wip->lock_pixels_per_sec * frametime;

		if ((delta_x != 0) && (hypotenuse != 0))
			current_lock->accumulated_x_pixels += pixels_moved_while_degrading * delta_x/hypotenuse; 

		if ((delta_y != 0) && (hypotenuse != 0))
			current_lock->accumulated_y_pixels += pixels_moved_while_degrading * delta_y/hypotenuse; 

		if (fl_abs((float)current_lock->accumulated_x_pixels) > 1.0f) {
			modf(current_lock->accumulated_x_pixels, &int_portion);

			current_lock->indicator_x -= (int)int_portion;

			if ( fl_abs((float)current_lock->indicator_x - (float)current_lock->indicator_start_x) < fl_abs((float)int_portion) )
				current_lock->indicator_x = current_lock->indicator_start_x;

			current_lock->accumulated_x_pixels -= int_portion;
		}

		if (fl_abs((float)current_lock->accumulated_y_pixels) > 1.0f) {
			modf(current_lock->accumulated_y_pixels, &int_portion);

			current_lock->indicator_y -= (int)int_portion;

			if ( fl_abs((float)current_lock->indicator_y - (float)current_lock->indicator_start_y) < fl_abs((float)int_portion) )
				current_lock->indicator_y = current_lock->indicator_start_y;

			current_lock->accumulated_y_pixels -= int_portion;
		}

		if ( (current_lock->indicator_x == current_lock->indicator_start_x) && (current_lock->indicator_y == current_lock->indicator_start_y) ) {
			current_lock->indicator_visible = false;
		}
	}
}

// Determine if point to lock on is in range
int hud_lock_target_in_range(lock_info *lock_slot)
{
	vec3d		target_world_pos;

	if ( lock_slot == nullptr || lock_slot->obj == nullptr) {
		return 0;
	}

	if ( lock_slot->subsys != nullptr) {
		vm_vec_unrotate(&target_world_pos, &lock_slot->subsys->system_info->pnt, &lock_slot->obj->orient);
		vm_vec_add2(&target_world_pos, &lock_slot->obj->pos);
	} else {
		if ( Player->locking_subsys ) {
			vm_vec_unrotate(&target_world_pos, &lock_slot->subsys->system_info->pnt, &lock_slot->obj->orient);
			vm_vec_add2(&target_world_pos, &lock_slot->obj->pos);
		} else {
			target_world_pos = lock_slot->obj->pos;
		}
	}
	ship_weapon* swp = &Player_ship->weapons;

	return weapon_secondary_world_pos_in_range(Player_obj, &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]], &target_world_pos);
}

void hud_do_lock_indicators(float frametime)
{
	ship_weapon *swp;
	weapon_info	*wip;

	// if i'm a multiplayer observer, bail here
 	if((Game_mode & GM_MULTIPLAYER) && ((Net_player->flags & NETINFO_FLAG_OBSERVER) || (Player_obj->type == OBJ_OBSERVER)) ){
		return;
	}

	// do not continue locking if the game is paused (viewer pause still has hud on)
	if (gameseq_get_state() == GS_STATE_GAME_PAUSED) {
		return;
	}

	// be sure to unset this flag, then possibly set later in this function so that
	// threat indicators work properly.
	Player_ai->ai_flags.remove(AI::AI_Flags::Seek_lock);

	if ( hud_abort_lock() ) {
		hud_lock_reset();
		return;
	}

	// if there is an EMP effect active, never update lock
	if(emp_active_local()){
		hud_lock_reset();
		return;
	}

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	if ( !(wip->is_locked_homing()) ) {
		hud_lock_reset();
		return;		
	}

	Lock_start_dist = wip->min_lock_time * wip->lock_pixels_per_sec;

	// if secondary weapons change, reset the lock
	if ( hud_lock_secondary_weapon_changed(swp) ) {
		hud_lock_reset();
	}
		
	Player_ai->last_secondary_index = swp->current_secondary_bank;

	int max_target_locks = weapon_get_max_missile_seekers(wip);

	// make sure ship has enough lock slots
	if ( (int)Player_ship->missile_locks.size() < max_target_locks) {
		lock_info new_slots;
		ship_clear_lock(&new_slots);

		Player_ship->missile_locks.resize(max_target_locks, new_slots);
	}

	lock_info *lock_slot;
	int num_active_seekers = 0;
	bool play_tracking_sound = false;
	bool player_has_lock = false;

	// go through all lock slots in play and do missile locks
	for ( int i = 0; i < max_target_locks; ++i ) {
		// need a check to see if we've exhausted our alloted simultaneous locks. if so, just check if already locked targets are valid.
		lock_slot = &Player_ship->missile_locks[i];

		hud_lock_determine_lock_target(lock_slot, wip);

		if ( lock_slot->obj == nullptr) {
			// reset this lock and continue
			ship_clear_lock(lock_slot);
			continue;
		}

		if ( lock_slot->obj->flags[Object::Object_Flags::Should_be_dead] ) {
			ship_clear_lock(lock_slot);
			continue;
		}

		if ( num_active_seekers >= wip->max_seeking ) {
			ship_clear_lock(lock_slot);
			continue;
		}

		if ( lock_slot->obj->type == OBJ_SHIP && Ships[lock_slot->obj->instance].flags[Ship::Ship_Flags::Dying] ) {
			ship_clear_lock(lock_slot);
			continue;
		}

		// Target ship is protected from Aspect Locks. Since this flag can be given mid mission, we need to cut short a lock attempt.
		if ( wip->is_locked_homing() && lock_slot->obj->type == OBJ_SHIP && Ships[lock_slot->obj->instance].flags[Ship::Ship_Flags::Aspect_immune] ) {
			ship_clear_lock(lock_slot);
			continue;
		}

		// unless they've flagged the weapon otherwise, discard locks on dead subsystems that aren't the primary target
		if ( !wip->wi_flags[Weapon::Info_Flags::Multilock_target_dead_subsys] && lock_slot->subsys != nullptr && Player_ai->targeted_subsys != lock_slot->subsys 
			&& lock_slot->subsys->current_hits <= 0.0f) {
			ship_clear_lock(lock_slot);
			continue;
		}

		hud_lock_determine_lock_point(lock_slot);

		hud_lock_check_if_target_in_lock_cone(lock_slot, wip);

		if ( !lock_slot->indicator_visible && !lock_slot->target_in_lock_cone ) {
			ship_clear_lock(lock_slot);
			continue;
		}

		// we can probably move this check into hud_lock_determine_lock_target
		if ( !hud_lock_target_in_range(lock_slot) ) {
			lock_slot->target_in_lock_cone = false;
		}

		if ( !lock_slot->locked && wip->trigger_lock && !(swp->flags[Ship::Weapon_Flags::Secondary_trigger_down]) ) {
			// only reset locks that are not locked if this is a trigger dependent weapon 
			// and player isn't holding down trigger
			ship_clear_lock(lock_slot);
			continue;
		}

		/*if ( wip->acquire_method == WLOCK_TIMER ) {
			hud_calculate_lock_slot_time(lock_slot, wip, frametime);
		} else {
			hud_calculate_lock_slot_position(lock_slot, frametime);
		}*/

		bool current_lock_status = lock_slot->locked;

		hud_calculate_lock_slot_position(lock_slot, frametime);

		if ( !lock_slot->locked ) {
			num_active_seekers++;
		} else {
			player_has_lock = true;
		}

		if ( !current_lock_status && lock_slot->locked ) {
			if (Missile_track_loop.isValid()) {
				snd_stop(Missile_track_loop);
				Missile_track_loop = sound_handle::invalid();

				if (wip->hud_locked_snd.isValid())
				{
					Missile_lock_loop = snd_play(gamesnd_get_game_sound(wip->hud_locked_snd));
				}
				else
				{
					Missile_lock_loop = snd_play(gamesnd_get_game_sound(ship_get_sound(Player_obj, GameSounds::MISSILE_LOCK)));
				}
			}

			lock_slot->lock_anim_time_elapsed = 0.0f;
		} else if ( !lock_slot->locked ) {
			if (Missile_lock_loop.isValid() && snd_is_playing(Missile_lock_loop)) {
				snd_stop(Missile_lock_loop);
				Missile_lock_loop = sound_handle::invalid();
			}
		}

		// if there's at least one lock_slot current locking, play the looping sound
		if ( lock_slot->indicator_visible && !lock_slot->locked ) {
			play_tracking_sound = true;
		}
	}

	if (player_has_lock) {
		Player_ai->ai_flags.remove(AI::AI_Flags::Seek_lock);		// set this flag so multiplayer's properly track lock on other ships
		Player_ai->current_target_is_locked = 1;
	} else {
		Player_ai->ai_flags.set(AI::AI_Flags::Seek_lock);		// set this flag so multiplayer's properly track lock on other ships
		Player_ai->current_target_is_locked = 0;
	}

	if ( play_tracking_sound ) {
		if ( !Missile_track_loop.isValid() ) {	
			Missile_track_loop = snd_play_looping(gamesnd_get_game_sound(ship_get_sound(Player_obj, GameSounds::MISSILE_TRACKING)), 0.0f, -1, -1);
		}
	} else {
		if ( Missile_track_loop.isValid() )	{
			snd_stop(Missile_track_loop);
			Missile_track_loop = sound_handle::invalid();
		}
	}
}

// hud_draw_lock_triangles() will draw the 4 rotating triangles around a lock indicator
// (This is done when a lock has been acquired)
#define ROTATE_DELAY 40
void HudGaugeLock::renderLockTrianglesOld(int center_x, int center_y, int radius)
{
	static float ang = 0.0f;

	float end_ang = ang + PI2;
	float x3,y3,x4,y4,xpos,ypos;

	if ( timestamp_elapsed(Rotate_time_id) ) {
		Rotate_time_id = timestamp(ROTATE_DELAY);
		ang += PI/12;
	}

	for (; ang <= end_ang; ang += PI_2) {

		// draw the orbiting triangles

		//ang = atan2(target_point.y,target_point.x);
		xpos = center_x + (float)cos(ang)*(radius + Lock_triangle_height + 2);
		ypos = center_y - (float)sin(ang)*(radius + Lock_triangle_height + 2);
			
		x3 = xpos - Lock_triangle_base * (float)sin(-ang);
		y3 = ypos + Lock_triangle_base * (float)cos(-ang);
		x4 = xpos + Lock_triangle_base * (float)sin(-ang);
		y4 = ypos - Lock_triangle_base * (float)cos(-ang);

		xpos = xpos - Lock_triangle_base * (float)cos(ang);
		ypos = ypos + Lock_triangle_base * (float)sin(ang);

		hud_tri(x3, y3, xpos, ypos, x4, y4);
	} // end for
}

// draw a frame of the rotating lock triangles animation
void HudGaugeLock::renderLockTriangles(int center_x, int center_y, float frametime)
{
	if ( Lock_anim.first_frame < 0 ) {
		renderLockTrianglesOld(center_x, center_y, Lock_target_box_width/2);
	} else {
		// render the anim
		Lock_anim.sx = center_x - Lockspin_half_w;
		Lock_anim.sy = center_y - Lockspin_half_h;
		
		// if it's still animating
		if(Lock_anim.time_elapsed < Lock_anim.total_time){
			if(loop_locked_anim) {
				hud_anim_render(&Lock_anim, frametime, 1, 1, 0);
			} else {
				hud_anim_render(&Lock_anim, frametime, 1, 0, 1);
			}
		} else {
			if(blink_locked_anim) {
				// if the timestamp is unset or expired
				if((Lock_gauge_draw_stamp < 0) || timestamp_elapsed(Lock_gauge_draw_stamp)){
					// reset timestamp
					Lock_gauge_draw_stamp = timestamp(1000 / (2 * LOCK_GAUGE_BLINK_RATE));

					// switch between draw and don't-draw
					Lock_gauge_draw = !Lock_gauge_draw;
				}
			}

			// maybe draw the anim
			Lock_gauge.time_elapsed = 0.0f;			
			if(Lock_gauge_draw || !blink_locked_anim){
				if(loop_locked_anim) {
					hud_anim_render(&Lock_anim, frametime, 1, 1, 0);
				} else {
					hud_anim_render(&Lock_anim, frametime, 1, 0, 1);
				}
			}
		}
	}
}

void HudGaugeLock::renderLockTrianglesNew(int center_x, int center_y, float frametime, lock_info *slot)
{
	if ( Lock_anim.first_frame < 0 ) {
		renderLockTrianglesOld(center_x, center_y, Lock_target_box_width/2);
	} else {
		// render the anim
		Lock_anim.sx = center_x - Lockspin_half_w;
		Lock_anim.sy = center_y - Lockspin_half_h;

		// if it's still animating
		if(slot->lock_anim_time_elapsed < Lock_anim.total_time){
			// manually track the animation time, since we may have more than one lock
			slot->lock_anim_time_elapsed += frametime;
			Lock_anim.time_elapsed = slot->lock_anim_time_elapsed;

			if(loop_locked_anim) {
				hud_anim_render(&Lock_anim, 0.0f, 1, 1, 0);
			} else {
				hud_anim_render(&Lock_anim, 0.0f, 1, 0, 1);
			}
		} else {
			if(blink_locked_anim) {
				// if the timestamp is unset or expired
				if((Lock_gauge_draw_stamp < 0) || timestamp_elapsed(Lock_gauge_draw_stamp)){
					// reset timestamp
					Lock_gauge_draw_stamp = timestamp(1000 / (2 * LOCK_GAUGE_BLINK_RATE));

					// switch between draw and don't-draw
					Lock_gauge_draw = !Lock_gauge_draw;
				}
			}

			// maybe draw the anim
			slot->lock_gauge_time_elapsed = 0.0f;			
			if(Lock_gauge_draw || !blink_locked_anim){
				// manually track the animation time, since we may have more than one lock
				slot->lock_anim_time_elapsed += frametime;
				Lock_anim.time_elapsed = slot->lock_anim_time_elapsed;

				if(loop_locked_anim) {
					hud_anim_render(&Lock_anim, 0.0f, 1, 1, 0);
				} else {
					hud_anim_render(&Lock_anim, 0.0f, 1, 0, 1);
				}
			}
		}
	}
}

// hud_calculate_lock_position()  will determine where on the screen to draw the lock 
// indicator, and will determine when a lock has occurred.  If the lock indicator is not
// on the screen yet, hud_calculate_lock_start_pos() is called to pick a starting location
void hud_calculate_lock_position(float frametime)
{
	ship_weapon *swp;
	weapon_info	*wip;

	static float pixels_moved_while_locking;
	static float pixels_moved_while_degrading;
	static int Need_new_start_pos = 0;

	static double accumulated_x_pixels, accumulated_y_pixels;
	double int_portion;

	static float last_dist_to_target;
	
	static int catching_up;

	static int maintain_lock_count = 0;

	static float catch_up_distance = 0.0f;

	double hypotenuse, delta_x, delta_y;

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	if (Player->target_in_lock_cone) {
		if (!Players[Player_num].lock_indicator_visible) {
			hud_calculate_lock_start_pos();
			last_dist_to_target = 0.0f;

			Players[Player_num].lock_indicator_x = Players[Player_num].lock_indicator_start_x;
			Players[Player_num].lock_indicator_y = Players[Player_num].lock_indicator_start_y;
			Players[Player_num].lock_indicator_visible = 1;

			Players[Player_num].lock_time_to_target = i2fl(wip->min_lock_time);
			catching_up = 0;
		}

		Need_new_start_pos = 1;

		if (Player_ai->current_target_is_locked) {
			Players[Player_num].lock_indicator_x = Player->current_target_sx;
			Players[Player_num].lock_indicator_y = Player->current_target_sy;
			return;
		}

		delta_x = Players[Player_num].lock_indicator_x - Player->current_target_sx;
		delta_y = Players[Player_num].lock_indicator_y - Player->current_target_sy;

		if (!delta_y && !delta_x) {
			hypotenuse = 0;
		}
		else {
			hypotenuse = _hypot(delta_y, delta_x);
		}

		Players[Player_num].lock_dist_to_target = (float)hypotenuse;

		if (last_dist_to_target == 0) {
			last_dist_to_target = Players[Player_num].lock_dist_to_target;
		}

		//nprintf(("Alan","dist to target: %.2f\n",Players[Player_num].lock_dist_to_target));
		//nprintf(("Alan","last to target: %.2f\n\n",last_dist_to_target));

		if (catching_up) {
			//nprintf(("Alan","IN CATCH UP MODE  catch_up_dist is %.2f\n",catch_up_distance));	
			if ( Players[Player_num].lock_dist_to_target < catch_up_distance )
				catching_up = 0;
		}
		else {
			//nprintf(("Alan","IN NORMAL MODE\n"));
			if ( (Players[Player_num].lock_dist_to_target - last_dist_to_target) > 2.0f ) {
				catching_up = 1;
				catch_up_distance = last_dist_to_target + wip->catchup_pixel_penalty;
			}
		}

		last_dist_to_target = Players[Player_num].lock_dist_to_target;

		if (!catching_up) {
			Players[Player_num].lock_time_to_target -= frametime;
			if (Players[Player_num].lock_time_to_target < 0.0f)
				Players[Player_num].lock_time_to_target = 0.0f;
		}

		float lock_pixels_per_sec;
		if (Players[Player_num].lock_time_to_target > 0) {
			lock_pixels_per_sec = Players[Player_num].lock_dist_to_target / Players[Player_num].lock_time_to_target;
		} else {
			lock_pixels_per_sec = i2fl(wip->lock_pixels_per_sec);
		}

		if (lock_pixels_per_sec > wip->lock_pixels_per_sec) {
			lock_pixels_per_sec = i2fl(wip->lock_pixels_per_sec);
		}
		
		if (catching_up) {
			pixels_moved_while_locking = wip->catchup_pixels_per_sec * frametime;
		} else {
			pixels_moved_while_locking = lock_pixels_per_sec * frametime;
		}
		
		if ((delta_x != 0) && (hypotenuse != 0)) {
			accumulated_x_pixels += pixels_moved_while_locking * delta_x/hypotenuse; 
		}

		if ((delta_y != 0) && (hypotenuse != 0)) {
			accumulated_y_pixels += pixels_moved_while_locking * delta_y/hypotenuse; 
		}

		if (fl_abs((float)accumulated_x_pixels) > 1.0f) {
			modf(accumulated_x_pixels, &int_portion);

			Players[Player_num].lock_indicator_x -= (int)int_portion;

			if ( fl_abs((float)Players[Player_num].lock_indicator_x - (float)Player->current_target_sx) < fl_abs((float)int_portion) )
				Players[Player_num].lock_indicator_x = Player->current_target_sx;

			accumulated_x_pixels -= int_portion;
		}

		if (fl_abs((float)accumulated_y_pixels) > 1.0f) {
			modf(accumulated_y_pixels, &int_portion);

			Players[Player_num].lock_indicator_y -= (int)int_portion;

			if ( fl_abs((float)Players[Player_num].lock_indicator_y - (float)Player->current_target_sy) < fl_abs((float)int_portion) )
				Players[Player_num].lock_indicator_y = Player->current_target_sy;

			accumulated_y_pixels -= int_portion;
		}

		if (!Missile_track_loop.isValid()) {
			if (wip->hud_tracking_snd.isValid())
			{
				Missile_track_loop = snd_play_looping( gamesnd_get_game_sound(wip->hud_tracking_snd), 0.0f , -1, -1);
			}
			else
			{
				Missile_track_loop = snd_play_looping( gamesnd_get_game_sound(ship_get_sound(Player_obj, GameSounds::MISSILE_TRACKING)), 0.0f , -1, -1);
			}
		}

		if (!Players[Player_num].lock_time_to_target) {
			if ( (Players[Player_num].lock_indicator_x == Player->current_target_sx) && (Players[Player_num].lock_indicator_y == Player->current_target_sy) ) {
				if (maintain_lock_count++ > 1) {
					Player_ai->current_target_is_locked = 1;
				}
			} else {
				maintain_lock_count = 0;
			}
		}

	} else {

		if (Missile_track_loop.isValid()) {
			snd_stop(Missile_track_loop);
			Missile_track_loop = sound_handle::invalid();
		}

		Player_ai->current_target_is_locked = 0;

		if (!Players[Player_num].lock_indicator_visible) {
			return;
		}

		catching_up = 0;
		last_dist_to_target = 0.0f;

		if (Need_new_start_pos) {
			hud_calculate_lock_start_pos();
			Need_new_start_pos = 0;
			accumulated_x_pixels = 0.0f;
			accumulated_y_pixels = 0.0f;
		}

		delta_x = Players[Player_num].lock_indicator_x - Players[Player_num].lock_indicator_start_x;
		delta_y = Players[Player_num].lock_indicator_y - Players[Player_num].lock_indicator_start_y;

		if (!delta_y && !delta_x) {
			hypotenuse = 0;
		}
		else {
			hypotenuse = _hypot(delta_y, delta_x);
		}

		Players[Player_num].lock_time_to_target += frametime;

		if (Players[Player_num].lock_time_to_target > wip->min_lock_time)
			Players[Player_num].lock_time_to_target = i2fl(wip->min_lock_time);

		pixels_moved_while_degrading = 2.0f * wip->lock_pixels_per_sec * frametime;

		if ((delta_x != 0) && (hypotenuse != 0))
			accumulated_x_pixels += pixels_moved_while_degrading * delta_x/hypotenuse; 

		if ((delta_y != 0) && (hypotenuse != 0))
			accumulated_y_pixels += pixels_moved_while_degrading * delta_y/hypotenuse; 

		if (fl_abs((float)accumulated_x_pixels) > 1.0f) {
			modf(accumulated_x_pixels, &int_portion);

			Players[Player_num].lock_indicator_x -= (int)int_portion;

			if ( fl_abs((float)Players[Player_num].lock_indicator_x - (float)Players[Player_num].lock_indicator_start_x) < fl_abs((float)int_portion) )
				Players[Player_num].lock_indicator_x = Players[Player_num].lock_indicator_start_x;

			accumulated_x_pixels -= int_portion;
		}

		if (fl_abs((float)accumulated_y_pixels) > 1.0f) {
			modf(accumulated_y_pixels, &int_portion);

			Players[Player_num].lock_indicator_y -= (int)int_portion;

			if ( fl_abs((float)Players[Player_num].lock_indicator_y - (float)Players[Player_num].lock_indicator_start_y) < fl_abs((float)int_portion) )
				Players[Player_num].lock_indicator_y = Players[Player_num].lock_indicator_start_y;

			accumulated_y_pixels -= int_portion;
		}

		if ( (Players[Player_num].lock_indicator_x == Players[Player_num].lock_indicator_start_x) && (Players[Player_num].lock_indicator_y == Players[Player_num].lock_indicator_start_y) ) {
			Players[Player_num].lock_indicator_visible = 0;
		}
	}
}

// hud_calculate_lock_start_pos() will determine where to draw the starting location of the lock
// indicator.  It does this by picking a location that is Lock_start_dist pixels away from the current
// target (in 2D).  This is accomplished by finding the endpoint of a line that passes through the 
// origin, and connects the target and lock indicator postion (and has a magnitude of Lock_start_dist)
void hud_calculate_lock_start_pos()
{
	double hypotenuse;
	double delta_y;
	double delta_x;
	double target_mag, target_x, target_y;

	delta_x = Player->current_target_sx - gr_screen.clip_center_x;
	delta_y = Player->current_target_sy - gr_screen.clip_center_y;

	if ( (delta_x == 0.0) && (delta_y == 0.0) ) {
		Players[Player_num].lock_indicator_start_x = fl2i(gr_screen.clip_center_x + Lock_start_dist);
		Players[Player_num].lock_indicator_start_y = fl2i(gr_screen.clip_center_y);
		return;
	}

	hypotenuse = _hypot(delta_y, delta_x);

	if (hypotenuse >= Lock_start_dist) {
		Players[Player_num].lock_indicator_start_x = fl2i(gr_screen.clip_center_x);
		Players[Player_num].lock_indicator_start_y = fl2i(gr_screen.clip_center_y);
		return;
	}

	target_mag = Lock_start_dist - hypotenuse;
	target_x = target_mag * (delta_x / hypotenuse);
	target_y = target_mag * (delta_y / hypotenuse);

	Players[Player_num].lock_indicator_start_x = fl2i(gr_screen.clip_center_x - target_x);
	Players[Player_num].lock_indicator_start_y = fl2i(gr_screen.clip_center_y - target_y);

	CLAMP(Players[Player_num].lock_indicator_start_x, gr_screen.clip_left, gr_screen.clip_right);
	CLAMP(Players[Player_num].lock_indicator_start_y, gr_screen.clip_top, gr_screen.clip_bottom);
}

// hud_stop_looped_locking_sounds() will terminate any hud related looping sounds that are playing
void hud_stop_looped_locking_sounds()
{
	if (Missile_track_loop.isValid()) {
		snd_stop(Missile_track_loop);
		Missile_track_loop = sound_handle::invalid();
	}
}

// Get a new world pos for the locking point
void hud_lock_update_lock_pos(object *target_objp)
{
	ship_weapon *swp = &Player_ship->weapons;
	weapon_info *wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	if ( Player_ai->targeted_subsys && !(wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) ) {
		get_subsystem_world_pos(target_objp, Player_ai->targeted_subsys, &lock_world_pos);
		return;
	}

	if ( Player->locking_on_center) {
		lock_world_pos = target_objp->pos;
	} else {
		Assert(Player->locking_subsys);
		get_subsystem_world_pos(target_objp, Player->locking_subsys, &lock_world_pos);
	}
}

// Try and find a new locking point
void hud_lock_get_new_lock_pos(object *target_objp)
{
	ship			*target_shipp=NULL;
	int			lock_in_range=0;
	float			best_lock_dot=-1.0f, lock_dot=-1.0f;
	ship_subsys	*ss;
	vec3d		subsys_world_pos, vec_to_lock;
	ship_weapon *swp;
	weapon_info *wip;

	if ( target_objp->type == OBJ_SHIP ) {
		target_shipp = &Ships[target_objp->instance];
	}

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	// if a large ship, lock to pos closest to center and within range
	if ( (target_shipp) && (Ship_info[target_shipp->ship_info_index].is_big_or_huge()) &&
		 !(wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) ) {
		// check all the subsystems and the center of the ship
		
		// assume best lock pos is the center of the ship
		lock_world_pos = target_objp->pos;
		Player->locking_on_center=1;
		Player->locking_subsys=NULL;
		Player->locking_subsys_parent=-1;
		lock_in_range = weapon_secondary_world_pos_in_range(Player_obj, wip, &lock_world_pos);
		vm_vec_normalized_dir(&vec_to_lock, &lock_world_pos, &Player_obj->pos);
		if ( lock_in_range ) {
			best_lock_dot=vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_lock);
		} 
		// take center if reasonable dot
		if ( best_lock_dot > 0.95 ) {
			return;
		}

		// iterate through subsystems to see if we can get a better choice
		ss = GET_FIRST(&target_shipp->subsys_list);
		while ( ss != END_OF_LIST( &target_shipp->subsys_list ) ) {

			// get world pos of subsystem
			get_subsystem_world_pos(target_objp, ss, &subsys_world_pos);

			if ( weapon_secondary_world_pos_in_range(Player_obj, wip, &subsys_world_pos) ) {
				vm_vec_normalized_dir(&vec_to_lock, &subsys_world_pos, &Player_obj->pos);
				lock_dot=vm_vec_dot(&Player_obj->orient.vec.fvec, &vec_to_lock);
				if ( lock_dot > best_lock_dot ) {
					best_lock_dot=lock_dot;
					Player->locking_on_center=0;
					Player->locking_subsys=ss;
					Player->locking_subsys_parent=Player_ai->target_objnum;
					lock_world_pos = subsys_world_pos;
				}
			}
			ss = GET_NEXT( ss );
		}
	} else if ( (target_shipp) && (wip->wi_flags[Weapon::Info_Flags::Homing_javelin])) {
		Player->locking_subsys = ship_get_closest_subsys_in_sight(target_shipp, SUBSYSTEM_ENGINE, &Player_obj->pos);
		if (Player->locking_subsys != NULL) {
			get_subsystem_world_pos(target_objp, Player->locking_subsys, &lock_world_pos);
			Player->locking_on_center=0;
			Player->locking_subsys_parent=Player_ai->target_objnum;
		} else {
			hud_lock_reset();
			return;
		}
	} else {
		// if small ship (or weapon), just go for the center
		lock_world_pos = target_objp->pos;
		Player->locking_on_center=1;
		Player->locking_subsys=NULL;
		Player->locking_subsys_parent=-1;
	}
}

// Decide which point lock should be homing on
void hud_lock_determine_lock_point(vec3d *lock_world_pos_out)
{
	object		*target_objp;
	ship_weapon	*swp;
	weapon_info	*wip;

	vec3d vec_to_lock_pos;
	vec3d lock_local_pos;

	Assert(Player_ai->target_objnum >= 0);
	target_objp = &Objects[Player_ai->target_objnum];

	Player->current_target_sx = -1;
	Player->current_target_sy = -1;

	swp = &Player_ship->weapons;
	wip = &Weapon_info[swp->secondary_bank_weapons[swp->current_secondary_bank]];

	// If subsystem is targeted, we must try to lock on that
	if ( Player_ai->targeted_subsys && !(wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) ) {
		hud_lock_update_lock_pos(target_objp);
		Player->locking_on_center=0;
		Player->locking_subsys=Player_ai->targeted_subsys;
		Player->locking_subsys_parent=Player_ai->target_objnum;
	} else if ( (wip->wi_flags[Weapon::Info_Flags::Homing_javelin]) && (target_objp->type == OBJ_SHIP)) {
		if (!Player->locking_subsys ||
			Player->locking_subsys->system_info->type != SUBSYSTEM_ENGINE) {
				Player->locking_subsys = ship_get_closest_subsys_in_sight(&Ships[target_objp->instance], SUBSYSTEM_ENGINE, &Player_obj->pos);
		}
		if (Player->locking_subsys != NULL) {
			get_subsystem_world_pos(target_objp, Player->locking_subsys, &lock_world_pos);
			Player->locking_on_center=0;
			Player->locking_subsys_parent=Player_ai->target_objnum;
		} else {
			hud_lock_reset();
			return;
		}
	} else {
		// See if we already have a successful locked point
		if ( hud_lock_has_homing_point() ) {
			hud_lock_update_lock_pos(target_objp);
		} else {
			hud_lock_get_new_lock_pos(target_objp);
		}
	}

	*lock_world_pos_out=lock_world_pos;

	vm_vec_sub(&vec_to_lock_pos,&lock_world_pos,&Player_obj->pos);
	vm_vec_rotate(&lock_local_pos,&vec_to_lock_pos,&Player_obj->orient);

	if ( lock_local_pos.xyz.z > 0.0f ) {
		// Get the location of our target in the "virtual frame" where the locking computation will be done
		float w = 1.0f / lock_local_pos.xyz.z;
		// Let's force our "virtual frame" to be 640x480. -MageKing17
		float sx = gr_screen.clip_center_x + (lock_local_pos.xyz.x * VIRTUAL_FRAME_HALF_WIDTH * w);
		float sy = gr_screen.clip_center_y - (lock_local_pos.xyz.y * VIRTUAL_FRAME_HALF_HEIGHT * w);

		Player->current_target_sx = (int)sx;
		Player->current_target_sy = (int)sy;
	}
}

void HudGaugeLock::pageIn()
{
	bm_page_in_aabitmap( Lock_gauge.first_frame, Lock_gauge.num_frames );
	bm_page_in_aabitmap( Lock_anim.first_frame, Lock_anim.num_frames );
}