ppsspp/UI/TiltEventProcessor.cpp

#define _USE_MATH_DEFINES

#include <cmath>

#include "Core/Config.h"
#include "Core/HLE/sceCtrl.h"
#include "UI/TiltEventProcessor.h"

using namespace TiltEventProcessor;

static u32 tiltButtonsDown = 0;
static bool tiltAnalogSet = false;

//deadzone is normalized - 0 to 1
//sensitivity controls how fast the deadzone reaches max value
inline float tiltInputCurve (float x, float deadzone, float sensitivity) {
	const float factor = sensitivity * 1.0f / (1.0f - deadzone);

	if (x > deadzone) {
		return (x - deadzone) * factor * factor + g_Config.fTiltDeadzoneSkip;
	} else if (x < -deadzone) {
		return (x + deadzone) * factor * factor - g_Config.fTiltDeadzoneSkip;
	} else {
		return 0.0f;
	}
}

//dampen the tilt according to the given deadzone amount.
inline Tilt dampTilt(const Tilt &tilt, float deadzone, float xSensitivity, float ySensitivity) {
	//multiply sensitivity by 2 so that "overshoot" is possible. I personally prefer a
	//sensitivity >1 for kingdom hearts and < 1 for Gods Eater. so yes, overshoot is nice
	//to have. 
	return Tilt(tiltInputCurve(tilt.x_, deadzone, 2.0f * xSensitivity), tiltInputCurve(tilt.y_, deadzone, 2.0f * ySensitivity));
}

inline float clamp(float f) {
	if (f > 1.0f) return 1.0f;
	if (f < -1.0f) return -1.0f;
	return f;
} 

Tilt TiltEventProcessor::NormalizeTilt(const Tilt &tilt){
	// Normalise the accelerometer manually per-platform, to 'g'
	#if defined(__ANDROID__)
		// Values are in metres per second. Divide by 9.8 to get 'g' value
		float maxX = 9.8f, maxY = 9.8f;
	#else
		float maxX = 1.0f, maxY = 1.0f;
	#endif

	return Tilt(tilt.x_ / maxX, tilt.y_ / maxY);

}

Tilt TiltEventProcessor::GenTilt(const Tilt &baseTilt, const Tilt &currentTilt, bool invertX, bool invertY, float deadzone, float xSensitivity, float ySensitivity) {
	//first convert to the correct coordinate system
	Tilt transformedTilt(currentTilt.x_ - baseTilt.x_, currentTilt.y_ - baseTilt.y_);

	//invert x and y axes if needed
	if (invertX) {
		transformedTilt.x_ *= -1.0f;
	}

	if (invertY) {
		transformedTilt.y_ *= -1.0f;
	}

	//next, normalize the tilt values
	transformedTilt = NormalizeTilt(transformedTilt);
	
	//finally, dampen the tilt according to our curve.
	return dampTilt(transformedTilt, deadzone, xSensitivity, ySensitivity);
}

void TiltEventProcessor::TranslateTiltToInput(const Tilt &tilt) {
	switch (g_Config.iTiltInputType) {
	case TILT_NULL:
		break;

	case TILT_ANALOG:
		GenerateAnalogStickEvent(tilt);
		break;

	case TILT_DPAD:
		GenerateDPadEvent(tilt);
		break;

	case TILT_ACTION_BUTTON:
		GenerateActionButtonEvent(tilt);
		break;

	case TILT_TRIGGER_BUTTON:
		GenerateTriggerButtonEvent(tilt);
		break;
	}
}

void TiltEventProcessor::GenerateAnalogStickEvent(const Tilt &tilt) {
	__CtrlSetAnalogXY(CTRL_STICK_LEFT, clamp(tilt.x_), clamp(tilt.y_));
	tiltAnalogSet = true;
}

void TiltEventProcessor::GenerateDPadEvent(const Tilt &tilt) {
	static const int dir[4] = {CTRL_RIGHT, CTRL_DOWN, CTRL_LEFT, CTRL_UP};

	if (tilt.x_ == 0) {
		__CtrlButtonUp(CTRL_RIGHT | CTRL_LEFT);
		tiltButtonsDown &= ~(CTRL_LEFT | CTRL_RIGHT);
	}

	if (tilt.y_ == 0) {
		__CtrlButtonUp(CTRL_UP | CTRL_DOWN);
		tiltButtonsDown &= ~(CTRL_UP | CTRL_DOWN);
	}

	if (tilt.x_ == 0 && tilt.y_ == 0) {
		return;
	}

	int ctrlMask = 0;
	int direction = (int)(floorf((atan2f(tilt.y_, tilt.x_) / (2.0f * (float)M_PI) * 8.0f) + 0.5f)) & 7;
	switch (direction) {
	case 0: ctrlMask |= CTRL_RIGHT; break;
	case 1: ctrlMask |= CTRL_RIGHT | CTRL_DOWN; break;
	case 2: ctrlMask |= CTRL_DOWN; break;
	case 3: ctrlMask |= CTRL_DOWN | CTRL_LEFT; break;
	case 4: ctrlMask |= CTRL_LEFT; break;
	case 5: ctrlMask |= CTRL_UP | CTRL_LEFT; break;
	case 6: ctrlMask |= CTRL_UP; break;
	case 7: ctrlMask |= CTRL_UP | CTRL_RIGHT; break;
	}

	__CtrlButtonDown(ctrlMask);
	tiltButtonsDown |= ctrlMask;
}

void TiltEventProcessor::GenerateActionButtonEvent(const Tilt &tilt) {
	static const int buttons[4] = {CTRL_CIRCLE, CTRL_CROSS, CTRL_SQUARE, CTRL_TRIANGLE};

	if (tilt.x_ == 0) {
		__CtrlButtonUp(CTRL_SQUARE | CTRL_CIRCLE);
		tiltButtonsDown &= ~(CTRL_SQUARE | CTRL_CIRCLE);
	}

	if (tilt.y_ == 0) {
		__CtrlButtonUp(CTRL_TRIANGLE | CTRL_CROSS);
		tiltButtonsDown &= ~(CTRL_TRIANGLE | CTRL_CROSS);
	}

	if (tilt.x_ == 0 && tilt.y_ == 0) {
		return;
	}

	int direction = (int)(floorf((atan2f(tilt.y_, tilt.x_) / (2.0f * (float)M_PI) * 4.0f) + 0.5f)) & 3;
	__CtrlButtonDown(buttons[direction]);
	tiltButtonsDown |= buttons[direction];
}

void TiltEventProcessor::GenerateTriggerButtonEvent(const Tilt &tilt) {
	u32 upButtons = 0;
	u32 downButtons = 0;
	// KISS, let's only look at X.  Expect deadzone to already be applied.
	if (tilt.x_ == 0.0f) {
		upButtons = CTRL_LTRIGGER | CTRL_RTRIGGER;
	} else if (tilt.x_ < 0.0f) {
		downButtons = CTRL_LTRIGGER;
		upButtons = CTRL_RTRIGGER;
	} else if (tilt.x_ > 0.0f) {
		downButtons = CTRL_RTRIGGER;
		upButtons = CTRL_LTRIGGER;
	}

	__CtrlButtonUp(upButtons);
	__CtrlButtonDown(downButtons);
	tiltButtonsDown = (tiltButtonsDown & ~upButtons) | downButtons;
}

void TiltEventProcessor::ResetTiltEvents() {
	// Reset the buttons we have marked pressed.
	__CtrlButtonUp(tiltButtonsDown);
	tiltButtonsDown = 0;

	if (tiltAnalogSet) {
		__CtrlSetAnalogXY(CTRL_STICK_LEFT, 0.0f, 0.0f);
		tiltAnalogSet = false;
	}
}