SDL: Add ability to control gyro sensor with left analog stick (currently hardcoded)

src/platform/qt/InputController.cpp

@@ -66,6 +66,10 @@ InputController::~InputController() {
 	GBAInputMapDeinit(&m_inputMap);
 
 #ifdef BUILD_SDL
+	if (m_playerAttached) {
+		GBASDLDetachPlayer(&s_sdlEvents, &m_sdlPlayer);
+	}
+
 	--s_sdlInited;
 	if (s_sdlInited == 0) {
 		GBASDLDeinitEvents(&s_sdlEvents);

src/platform/sdl/main.c

@@ -134,6 +134,7 @@ int main(int argc, char** argv) {
 	GBAConfigFreeOpts(&opts);
 	GBAConfigDeinit(&config);
 	free(context.debugger);
+	GBASDLDetachPlayer(&renderer.events, &renderer.player);
 	GBAInputMapDeinit(&inputMap);
 
 	GBASDLDeinit(&renderer);

src/platform/sdl/sdl-events.c

@@ -20,9 +20,12 @@
 #define GUI_MOD KMOD_CTRL
 #endif
 
+#define GYRO_STEPS 100
+
 static void _GBASDLSetRumble(struct GBARumble* rumble, int enable);
 static int32_t _GBASDLReadTiltX(struct GBARotationSource* rumble);
 static int32_t _GBASDLReadTiltY(struct GBARotationSource* rumble);
+static int32_t _GBASDLReadGyroZ(struct GBARotationSource* rumble);
 static void _GBASDLRotationSample(struct GBARotationSource* source);
 
 bool GBASDLInitEvents(struct GBASDLEvents* context) {
@@ -151,10 +154,15 @@ bool GBASDLAttachPlayer(struct GBASDLEvents* events, struct GBASDLPlayer* player
 
 	player->rotation.d.readTiltX = _GBASDLReadTiltX;
 	player->rotation.d.readTiltY = _GBASDLReadTiltY;
-	player->rotation.d.readGyroZ = 0;
+	player->rotation.d.readGyroZ = _GBASDLReadGyroZ;
 	player->rotation.d.sample = _GBASDLRotationSample;
 	player->rotation.axisX = 2;
 	player->rotation.axisY = 3;
+	player->rotation.gyroSensitivity = 2.2e9f;
+	player->rotation.gyroX = 0;
+	player->rotation.gyroY = 1;
+	player->rotation.zDelta = 0;
+	CircleBufferInit(&player->rotation.zHistory, sizeof(float) * GYRO_STEPS);
 	player->rotation.p = player;
 
 	if (events->playersAttached >= MAX_PLAYERS) {
@@ -215,6 +223,11 @@ bool GBASDLAttachPlayer(struct GBASDLEvents* events, struct GBASDLPlayer* player
 	return true;
 }
 
+void GBASDLDetachPlayer(struct GBASDLEvents* events, struct GBASDLPlayer* player) {
+	events->joysticksClaimed[player->playerId] = SIZE_MAX;
+	CircleBufferDeinit(&player->rotation.zHistory);
+}
+
 void GBASDLPlayerLoadConfig(struct GBASDLPlayer* context, const struct Configuration* config) {
 	GBAInputMapLoad(context->bindings, SDL_BINDING_KEY, config);
 	if (context->joystick) {
@@ -472,7 +485,34 @@ static int32_t _GBASDLReadTiltY(struct GBARotationSource* source) {
 	struct GBASDLRotation* rotation = (struct GBASDLRotation*) source;
 	return _readTilt(rotation->p, rotation->axisY);
 }
-static void _GBASDLRotationSample(struct GBARotationSource* source) {
-	UNUSED(source);
-	SDL_JoystickUpdate();
+
+static int32_t _GBASDLReadGyroZ(struct GBARotationSource* source) {
+	struct GBASDLRotation* rotation = (struct GBASDLRotation*) source;
+	float z = rotation->zDelta;
+	return z * rotation->gyroSensitivity;
+}
+
+static void _GBASDLRotationSample(struct GBARotationSource* source) {
+	struct GBASDLRotation* rotation = (struct GBASDLRotation*) source;
+	SDL_JoystickUpdate();
+
+	int x = SDL_JoystickGetAxis(rotation->p->joystick, rotation->gyroX);
+	int y = SDL_JoystickGetAxis(rotation->p->joystick, rotation->gyroY);
+	float theta = atan2f(y, x) - atan2f(rotation->oldY, rotation->oldX);
+	if (isnan(theta)) {
+		theta = 0.0f;
+	} else if (theta > M_PI) {
+		theta -= 2.0f * M_PI;
+	} else if (theta < -M_PI) {
+		theta += 2.0f * M_PI;
+	}
+	rotation->oldX = x;
+	rotation->oldY = y;
+
+	float oldZ = 0;
+	if (CircleBufferSize(&rotation->zHistory) == GYRO_STEPS * sizeof(float)) {
+		CircleBufferRead32(&rotation->zHistory, (int32_t*) &oldZ);
+	}
+	CircleBufferWrite32(&rotation->zHistory, *(int32_t*) &theta);
+	rotation->zDelta += theta - oldZ;
 }

src/platform/sdl/sdl-events.h

@@ -7,6 +7,7 @@
 #define SDL_EVENTS_H
 
 #include "util/common.h"
+#include "util/circle-buffer.h"
 
 #include "gba/supervisor/thread.h"
 
@@ -51,8 +52,19 @@ struct GBASDLPlayer {
 	struct GBASDLRotation {
 		struct GBARotationSource d;
 		struct GBASDLPlayer* p;
+
+		// Tilt
 		int axisX;
 		int axisY;
+
+		// Gyro
+		int gyroX;
+		int gyroY;
+		float gyroSensitivity;
+		struct CircleBuffer zHistory;
+		int oldX;
+		int oldY;
+		float zDelta;
 	} rotation;
 };
 
@@ -60,6 +72,7 @@ bool GBASDLInitEvents(struct GBASDLEvents*);
 void GBASDLDeinitEvents(struct GBASDLEvents*);
 
 bool GBASDLAttachPlayer(struct GBASDLEvents*, struct GBASDLPlayer*);
+void GBASDLDetachPlayer(struct GBASDLEvents*, struct GBASDLPlayer*);
 void GBASDLEventsLoadConfig(struct GBASDLEvents*, const struct Configuration*);
 void GBASDLPlayerChangeJoystick(struct GBASDLEvents*, struct GBASDLPlayer*, size_t index);