/*
 * 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.
 *
*/

/*
 * $Logfile: /Freespace2/code/Graphics/GrOpenGLLight.cpp $
 * $Revision: 1.14 $
 * $Date: 2005-04-15 11:42:27 $
 * $Author: taylor $
 *
 * code to implement lighting in HT&L opengl
 *
 * $Log: not supported by cvs2svn $
 * Revision 1.13  2005/04/12 02:04:56  phreak
 * gr_set_ambient_light() function for the ambient light sliders in FRED
 *
 * Revision 1.12  2005/04/05 05:53:17  taylor
 * s/vector/vec3d/g, better support for different compilers (Jens Granseuer)
 *
 * Revision 1.11  2005/02/05 00:30:49  taylor
 * fix a few things post merge
 *
 * Revision 1.10  2005/02/04 23:29:31  taylor
 * merge with Linux/OSX tree - p0204-3
 *
 * Revision 1.9  2005/01/21 21:12:52  taylor
 * crap
 *
 * Revision 1.8  2005/01/21 08:29:04  taylor
 * add -rlm cmdline option to switch to local viewpoint lighting calculations (OGL only for now)
 *
 * Revision 1.7  2005/01/07 14:00:04  argv
 * Added missing #include.
 *
 * -- _argv[-1]
 *
 * Revision 1.6  2005/01/03 18:45:22  taylor
 * dynamic allocation of num supported OpenGL lights
 * add config option for more realistic light settings
 * don't render spec maps in nebula to address lighting issue
 *
 * Revision 1.5  2005/01/01 11:24:23  taylor
 * good OpenGL spec mapping
 * fix VBO crash with multitexture using same uv coord data
 * little speedup of opengl_tcache_frame()
 * error message to make sure hardware supports the minimum texture size
 * move OpenGL version check out of the extention printout code
 * disable 2d_poof with OpenGL
 *
 * Revision 1.4  2004/10/31 21:45:13  taylor
 * Linux tree merge, single array for VBOs/HTL
 *
 * Revision 1.3  2004/07/26 20:47:32  Kazan
 * remove MCD complete
 *
 * Revision 1.2  2004/07/12 16:32:48  Kazan
 * MCD - define _MCD_CHECK to use memory tracking
 *
 * Revision 1.1  2004/05/24 07:25:32  taylor
 * filename case change
 *
 * Revision 2.7  2004/05/13 00:17:20  taylor
 * disable COLOR_MATERIAL, for nvidia drivers
 *
 * Revision 2.6  2004/05/12 23:24:35  phreak
 * got rid of the color material call, nebulas should blind the player
 *
 * Revision 2.5  2004/05/11 19:39:29  phreak
 * fixed an array bounds error that was causing debug builds to crash when
 * rendering a ship
 *
 * Revision 2.4  2004/04/26 13:02:27  taylor
 * light setup changes, support cmdline ambient value
 *
 * Revision 2.3  2004/04/13 01:55:41  phreak
 * put in the correct fields for the CVS comments to register
 * fixed a glowmap problem that occured when rendering glowmapped and non-glowmapped ships
 *
 *
 * $NoKeywords: $
 */

#ifdef _WIN32
#include <windows.h>
#endif

#include "globalincs/pstypes.h"
#include "graphics/gropengl.h"
#include "graphics/gropenglextension.h"
#include "graphics/gropengllight.h"
#include "graphics/2d.h"
#include "render/3d.h"
#include "cmdline/cmdline.h"



// Variables
opengl_light opengl_lights[MAX_LIGHTS];
bool active_light_list[MAX_LIGHTS];
int *currently_enabled_lights = NULL;
bool lighting_is_enabled = true;
int active_gl_lights = 0;
int n_active_gl_lights = 0;
int GL_center_alpha = 0;

extern float static_point_factor;
extern float static_light_factor;
extern float static_tube_factor;
extern double specular_exponent_value;

extern int Cmdline_rlm;

int GL_max_lights = 0;

// OGL defaults
static const float GL_light_color[4] = { 0.8f, 0.8f, 0.8f, 1.0f };
static const float GL_light_spec[4] = { 1.0f, 1.0f, 1.0f, 1.0f };
static const float GL_light_zero[4] = { 0.0f, 0.0f, 0.0f, 1.0f };
static float GL_light_ambient_value = 0.47f;
static float GL_light_ambient[4] = { 0.47f, 0.47f, 0.47f, 1.0f };

void FSLight2GLLight(opengl_light *GLLight,light_data *FSLight) {

	GLLight->Diffuse.r = FSLight->r;// * FSLight->intensity;
	GLLight->Diffuse.g = FSLight->g;// * FSLight->intensity;
	GLLight->Diffuse.b = FSLight->b;// * FSLight->intensity;
	GLLight->Specular.r = FSLight->spec_r;// * FSLight->intensity;
	GLLight->Specular.g = FSLight->spec_g;// * FSLight->intensity;
	GLLight->Specular.b = FSLight->spec_b;// * FSLight->intensity;
	GLLight->Ambient.r = 0.0f;
	GLLight->Ambient.g = 0.0f;
	GLLight->Ambient.b = 0.0f;
	GLLight->Ambient.a = 1.0f;
	GLLight->Specular.a = 1.0f;
	GLLight->Diffuse.a = 1.0f;


	//If the light is a directional light
	if(FSLight->type == LT_DIRECTIONAL) {
		GLLight->Position.x = -FSLight->vec.xyz.x;
		GLLight->Position.y = -FSLight->vec.xyz.y;
		GLLight->Position.z = -FSLight->vec.xyz.z;
		GLLight->Position.w = 0.0f; //Directional lights in OpenGL have w set to 0 and the direction vector in the position field

		GLLight->Specular.r *= static_light_factor;
		GLLight->Specular.g *= static_light_factor;
		GLLight->Specular.b *= static_light_factor;
	}

	//If the light is a point or tube type
	if((FSLight->type == LT_POINT) || (FSLight->type == LT_TUBE)) {

		if(FSLight->type == LT_POINT){
			GLLight->Specular.r *= static_point_factor;
			GLLight->Specular.g *= static_point_factor;
			GLLight->Specular.b *= static_point_factor;
		}else{
			GLLight->Specular.r *= static_tube_factor;
			GLLight->Specular.g *= static_tube_factor;
			GLLight->Specular.b *= static_tube_factor;
		}

		GLLight->Position.x = FSLight->vec.xyz.x;
		GLLight->Position.y = FSLight->vec.xyz.y;
		GLLight->Position.z = FSLight->vec.xyz.z; //flipped axis for FS2
		GLLight->Position.w = 1.0f;		

		//They also have almost no radius...
//		GLLight->Range = FSLight->radb +FSLight->rada; //No range function in OpenGL that I'm aware of
		GLLight->ConstantAtten = 0.0f;
		GLLight->LinearAtten = 0.1f;
		GLLight->QuadraticAtten = 0.0f; 
	}

}

void set_opengl_light(int light_num, opengl_light *light)
{
	Assert(light_num < GL_max_lights);
	glLightfv(GL_LIGHT0+light_num, GL_POSITION, &light->Position.x);
	glLightfv(GL_LIGHT0+light_num, GL_AMBIENT, &light->Ambient.r);
	glLightfv(GL_LIGHT0+light_num, GL_DIFFUSE, &light->Diffuse.r);
	glLightfv(GL_LIGHT0+light_num, GL_SPECULAR, &light->Specular.r);
	glLightf(GL_LIGHT0+light_num, GL_CONSTANT_ATTENUATION, light->ConstantAtten);
	glLightf(GL_LIGHT0+light_num, GL_LINEAR_ATTENUATION, light->LinearAtten);
	glLightf(GL_LIGHT0+light_num, GL_QUADRATIC_ATTENUATION, light->QuadraticAtten);
}

//finds the first unocupyed light
void opengl_pre_render_init_lights(){
	for(int i = 0; i<GL_max_lights; i++){
		if(currently_enabled_lights[i] > -1) glDisable(GL_LIGHT0+i);
		currently_enabled_lights[i] = -1;
	}
}


void opengl_change_active_lights(int pos){
	int k = 0;
	int l = 0;
	if(!lighting_is_enabled)return;
	bool move = false;
	glMatrixMode(GL_MODELVIEW); 
	glPushMatrix();				
	glLoadIdentity();

//straight cut'n'paste out of gr_opengl_set_view_matrix, but I couldn't use that, since it messes up with the stack depth var
	vec3d fwd;
	vec3d *uvec=&Eye_matrix.vec.uvec;

	vm_vec_add(&fwd, &Eye_position, &Eye_matrix.vec.fvec);

	gluLookAt(Eye_position.xyz.x,Eye_position.xyz.y,-Eye_position.xyz.z,
	fwd.xyz.x,fwd.xyz.y,-fwd.xyz.z,
	uvec->xyz.x, uvec->xyz.y,-uvec->xyz.z);

	glScalef(1,1,-1);
	
	for(int i = 0; (i < GL_max_lights) && ((pos * GL_max_lights)+i < active_gl_lights); i++){
		glDisable(GL_LIGHT0+i);
		move = false;
		for(k=0; k<MAX_LIGHTS && !move; k++){
			int slot = (pos * GL_max_lights)+l;
			if(active_light_list[slot]){
				if(opengl_lights[slot].occupied){
					set_opengl_light(i,&opengl_lights[slot]);
					glEnable(GL_LIGHT0+i);
					currently_enabled_lights[i] = slot;
					move = true;
					l++;
				}
			}
		}
	}
	

	glPopMatrix();

}

int	gr_opengl_make_light(light_data* light, int idx, int priority)
{
//Stub
	return idx;
}

void gr_opengl_modify_light(light_data* light, int idx, int priority)
{
//Stub
}

void gr_opengl_destroy_light(int idx)
{
//Stub
}

void gr_opengl_set_light(light_data *light)
{
	//Init the light
	FSLight2GLLight(&opengl_lights[active_gl_lights],light);
	opengl_lights[active_gl_lights].occupied = true;
	active_light_list[active_gl_lights++] = true;
}

// this sets up a light to be pointinf from the eye to the object, 
// the point being to make the object ether center or edge alphaed with THL
// this effect is used mostly on shockwave models
// -1 == edge
// 1 == center
// 0 == none
// should be called after lighting has been set up, 
// currently not designed for use with lit models
void gr_opengl_center_alpha(int type)
{
	GL_center_alpha = type;
}

void gr_opengl_set_center_alpha(int type)
{	
}

void gr_opengl_reset_lighting()
{
	int i;

	for(i = 0; i<MAX_LIGHTS; i++){
		opengl_lights[i].occupied = false;
	}
	for(i=0; i<GL_max_lights; i++){
		glDisable(GL_LIGHT0+i);
		active_light_list[i] = false;
	}
	active_gl_lights =0;

	GL_center_alpha = 0;
}

static float clamp(float value, float min, float max)
{
	if (value < min) return min;
	if (value > max) return max;
	return value;
}

void opengl_calculate_ambient_factor()
{
	float amb_user = 0.0f;

	amb_user = (float)((Cmdline_ambient_factor * 2) - 255) / 255.0f;

	// set the ambient light
	GL_light_ambient[0] = clamp(GL_light_ambient[0] + amb_user, 0.02f, 1.0f);
	GL_light_ambient[1] = clamp(GL_light_ambient[1] + amb_user, 0.02f, 1.0f);
	GL_light_ambient[2] = clamp(GL_light_ambient[2] + amb_user, 0.02f, 1.0f);
	GL_light_ambient[3] = 1.0f;
}

void opengl_init_light()
{
	opengl_calculate_ambient_factor();

	// only on front, tends to be more believable
	glMaterialf(GL_FRONT, GL_SHININESS, 80.0f );

	// more realistic lighting model
	if (Cmdline_rlm)
		glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);

	glGetIntegerv(GL_MAX_LIGHTS, &GL_max_lights); // Get the max number of lights supported

	// allocate memory for enabled lights
	Verify(GL_max_lights > 0);
	currently_enabled_lights = (int*)malloc(GL_max_lights * sizeof(int));

	if (currently_enabled_lights == NULL)
		Error( LOCATION, "Unable to allocate memory for lights!\n");

	memset( currently_enabled_lights, -1, GL_max_lights * sizeof(int) );
}

void opengl_default_light_settings(int ambient = 1, int emission = 1, int specular = 1)
{
	if (!lighting_is_enabled)
		return;

	if (ambient) {
		glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, GL_light_color );
	} else {
		glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, GL_light_zero );
	}

	if (emission) {
		glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, GL_light_ambient );
	} else {
		glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, GL_light_zero );
	}

	if (specular) {
		// only on front, tends to be more believable
		glMaterialfv( GL_FRONT, GL_SPECULAR, GL_light_spec );
	} else {
		glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR, GL_light_zero );
	}
}

void gr_opengl_set_lighting(bool set, bool state)
{
	lighting_is_enabled = set;

	opengl_default_light_settings();

	if ( (gr_screen.current_alphablend_mode == GR_ALPHABLEND_FILTER) && !set ) {
		float amb[4] = { gr_screen.current_alpha, gr_screen.current_alpha, gr_screen.current_alpha, gr_screen.current_alpha };
		glLightModelfv( GL_LIGHT_MODEL_AMBIENT, amb );
	} else {
		glLightModelfv( GL_LIGHT_MODEL_AMBIENT, GL_light_ambient );
	}

	for(int i = 0; i<GL_max_lights; i++){
		if(currently_enabled_lights[i] > -1)glDisable(GL_LIGHT0+i);
		currently_enabled_lights[i] = -1;
	}

	if(state) {
		glEnable(GL_LIGHTING);
	} else {
		glDisable(GL_LIGHTING);
	}

}

void gr_opengl_set_ambient_light(int red, int green, int blue)
{
	GL_light_ambient[0] = i2fl(red)/255.0f;
	GL_light_ambient[1] = i2fl(green)/255.0f;
	GL_light_ambient[2] = i2fl(blue)/255.0f;
	GL_light_ambient[3] = 1.0f;
	opengl_calculate_ambient_factor();
}