Added ParticleSystem:setLinearDamping and ParticleSystem:getLinearDamping (resolves issue #803.)

src/modules/graphics/opengl/ParticleSystem.cpp

@@ -86,6 +86,8 @@ ParticleSystem::ParticleSystem(Texture *texture, uint32 size)
 	, radialAccelerationMax(0)
 	, tangentialAccelerationMin(0)
 	, tangentialAccelerationMax(0)
+	, linearDampingMin(0.0f)
+	, linearDampingMax(0.0f)
 	, sizeVariation(0)
 	, rotationMin(0)
 	, rotationMax(0)
@@ -135,6 +137,8 @@ ParticleSystem::ParticleSystem(const ParticleSystem &p)
 	, radialAccelerationMax(p.radialAccelerationMax)
 	, tangentialAccelerationMin(p.tangentialAccelerationMin)
 	, tangentialAccelerationMax(p.tangentialAccelerationMax)
+	, linearDampingMin(p.linearDampingMin)
+	, linearDampingMax(p.linearDampingMax)
 	, sizes(p.sizes)
 	, sizeVariation(p.sizeVariation)
 	, rotationMin(p.rotationMin)
@@ -284,6 +288,10 @@ void ParticleSystem::initParticle(Particle *p, float t)
 	max = tangentialAccelerationMax;
 	p->tangentialAcceleration = (float) rng.random(min, max);
 
+	min = linearDampingMin;
+	max = linearDampingMax;
+	p->linearDamping = (float) rng.random(min, max);
+
 	p->sizeOffset       = (float) rng.random(sizeVariation); // time offset for size change
 	p->sizeIntervalSize = (1.0f - (float) rng.random(sizeVariation)) - p->sizeOffset;
 	p->size = sizes[(size_t)(p->sizeOffset - .5f) * (sizes.size() - 1)];
@@ -460,12 +468,10 @@ void ParticleSystem::setParticleLifetime(float min, float max)
 		particleLifeMax = max;
 }
 
-void ParticleSystem::getParticleLifetime(float *min, float *max) const
+void ParticleSystem::getParticleLifetime(float &min, float &max) const
 {
-	if (min)
-		*min = particleLifeMin;
-	if (max)
-		*max = particleLifeMax;
+	min = particleLifeMin;
+	max = particleLifeMax;
 }
 
 void ParticleSystem::setPosition(float x, float y)
@@ -531,12 +537,10 @@ void ParticleSystem::setSpeed(float min, float max)
 	speedMax = max;
 }
 
-void ParticleSystem::getSpeed(float *min, float *max) const
+void ParticleSystem::getSpeed(float &min, float &max) const
 {
-	if (min)
-		*min = speedMin;
-	if (max)
-		*max = speedMax;
+	min = speedMin;
+	max = speedMax;
 }
 
 void ParticleSystem::setLinearAcceleration(float x, float y)
@@ -551,12 +555,10 @@ void ParticleSystem::setLinearAcceleration(float xmin, float ymin, float xmax, f
 	linearAccelerationMax = love::Vector(xmax, ymax);
 }
 
-void ParticleSystem::getLinearAcceleration(love::Vector *min, love::Vector *max) const
+void ParticleSystem::getLinearAcceleration(love::Vector &min, love::Vector &max) const
 {
-	if (min)
-		*min = linearAccelerationMin;
-	if (max)
-		*max = linearAccelerationMax;
+	min = linearAccelerationMin;
+	max = linearAccelerationMax;
 }
 
 void ParticleSystem::setRadialAcceleration(float acceleration)
@@ -570,12 +572,10 @@ void ParticleSystem::setRadialAcceleration(float min, float max)
 	radialAccelerationMax = max;
 }
 
-void ParticleSystem::getRadialAcceleration(float *min, float *max) const
+void ParticleSystem::getRadialAcceleration(float &min, float &max) const
 {
-	if (min)
-		*min = radialAccelerationMin;
-	if (max)
-		*max = radialAccelerationMax;
+	min = radialAccelerationMin;
+	max = radialAccelerationMax;
 }
 
 void ParticleSystem::setTangentialAcceleration(float acceleration)
@@ -589,12 +589,22 @@ void ParticleSystem::setTangentialAcceleration(float min, float max)
 	tangentialAccelerationMax = max;
 }
 
-void ParticleSystem::getTangentialAcceleration(float *min, float *max) const
+void ParticleSystem::getTangentialAcceleration(float &min, float &max) const
+{
+	min = tangentialAccelerationMin;
+	max = tangentialAccelerationMax;
+}
+
+void ParticleSystem::setLinearDamping(float min, float max)
 {
-	if (min)
-		*min = tangentialAccelerationMin;
-	if (max)
-		*max = tangentialAccelerationMax;
+	linearDampingMin = min;
+	linearDampingMax = max;
+}
+
+void ParticleSystem::getLinearDamping(float &min, float &max) const
+{
+	min = linearDampingMin;
+	max = linearDampingMax;
 }
 
 void ParticleSystem::setSize(float size)
@@ -634,12 +644,10 @@ void ParticleSystem::setRotation(float min, float max)
 	rotationMax = max;
 }
 
-void ParticleSystem::getRotation(float *min, float *max) const
+void ParticleSystem::getRotation(float &min, float &max) const
 {
-	if (min)
-		*min = rotationMin;
-	if (max)
-		*max = rotationMax;
+	min = rotationMin;
+	max = rotationMax;
 }
 
 void ParticleSystem::setSpin(float spin)
@@ -654,12 +662,10 @@ void ParticleSystem::setSpin(float start, float end)
 	spinEnd = end;
 }
 
-void ParticleSystem::getSpin(float *start, float *end) const
+void ParticleSystem::getSpin(float &start, float &end) const
 {
-	if (start)
-		*start = spinStart;
-	if (end)
-		*end = spinEnd;
+	start = spinStart;
+	end = spinEnd;
 }
 
 void ParticleSystem::setSpinVariation(float variation)
@@ -931,6 +937,9 @@ void ParticleSystem::update(float dt)
 			// Update velocity.
 			p->velocity += (radial + tangential + p->linearAcceleration) * dt;
 
+			// Apply damping.
+			p->velocity *= 1.0f / (1.0f + p->linearDamping * dt);
+
 			// Modify position.
 			ppos += p->velocity * dt;
 

src/modules/graphics/opengl/ParticleSystem.h

@@ -162,7 +162,7 @@ public:
 	 * @param[out] min The minimum life.
 	 * @param[out] max The maximum life.
 	 **/
-	void getParticleLifetime(float *min, float *max) const;
+	void getParticleLifetime(float &min, float &max) const;
 
 	/**
 	 * Sets the position of the center of the emitter.
@@ -249,7 +249,7 @@ public:
 	 * @param[out] min The minimum speed.
 	 * @param[out] max The maximum speed.
 	 **/
-	void getSpeed(float *min, float *max) const;
+	void getSpeed(float &min, float &max) const;
 
 	/**
 	 * Sets the linear acceleration (the acceleration along the x and y axes).
@@ -272,7 +272,7 @@ public:
 	 * @param[out] min The minimum acceleration.
 	 * @param[out] max The maximum acceleration.
 	 **/
-	void getLinearAcceleration(love::Vector *min, love::Vector *max) const;
+	void getLinearAcceleration(love::Vector &min, love::Vector &max) const;
 
 	/**
 	 * Sets the radial acceleration (the acceleration towards the particle emitter).
@@ -292,7 +292,7 @@ public:
 	 * @param[out] min The minimum amount of radial acceleration.
 	 * @param[out] max The maximum amount of radial acceleration.
 	 **/
-	void getRadialAcceleration(float *min, float *max) const;
+	void getRadialAcceleration(float &min, float &max) const;
 
 	/**
 	 * Sets the tangential acceleration (the acceleration perpendicular to the particle's direction).
@@ -312,7 +312,18 @@ public:
 	 * @param[out] min The minimum tangential acceleration.
 	 * @param[out] max The maximum tangential acceleration.
 	 **/
-	void getTangentialAcceleration(float *min, float *max) const;
+	void getTangentialAcceleration(float &min, float &max) const;
+
+	/**
+	 * Sets the amount of linear damping. Damping reduces the velocity of
+	 * particles over time. A value of 0 corresponds to no damping.
+	 **/
+	void setLinearDamping(float min, float max);
+
+	/**
+	 * Gets the current amount of linear damping.
+	 **/
+	void getLinearDamping(float &min, float &max) const;
 
 	/**
 	 * Sets the size of the sprite (1.0 being the default size).
@@ -360,7 +371,7 @@ public:
 	 * @param[out] min The minimum initial rotation.
 	 * @param[out] max The maximum initial rotation.
 	 **/
-	void getRotation(float *min, float *max) const;
+	void getRotation(float &min, float &max) const;
 
 	/**
 	 * Sets the spin of the sprite.
@@ -380,7 +391,7 @@ public:
 	 * @param[out] start The initial spin, in radians / s.
 	 * @param[out] end The final spin, in radians / s.
 	 **/
-	void getSpin(float *start, float *end) const;
+	void getSpin(float &start, float &end) const;
 
 	/**
 	 * Sets the variation of the start spin (0 being no variation and 1 being a random spin between start and end).
@@ -533,6 +544,8 @@ protected:
 		float radialAcceleration;
 		float tangentialAcceleration;
 
+		float linearDamping;
+
 		float size;
 		float sizeOffset;
 		float sizeIntervalSize;
@@ -619,6 +632,9 @@ protected:
 	float tangentialAccelerationMin;
 	float tangentialAccelerationMax;
 
+	float linearDampingMin;
+	float linearDampingMax;
+
 	// Size.
 	std::vector<float> sizes;
 	float sizeVariation;

src/modules/graphics/opengl/wrap_ParticleSystem.cpp

@@ -164,7 +164,7 @@ int w_ParticleSystem_getParticleLifetime(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float min, max;
-	t->getParticleLifetime(&min, &max);
+	t->getParticleLifetime(min, max);
 	lua_pushnumber(L, min);
 	lua_pushnumber(L, max);
 	return 2;
@@ -278,7 +278,7 @@ int w_ParticleSystem_getSpeed(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float min, max;
-	t->getSpeed(&min, &max);
+	t->getSpeed(min, max);
 	lua_pushnumber(L, min);
 	lua_pushnumber(L, max);
 	return 2;
@@ -299,7 +299,7 @@ int w_ParticleSystem_getLinearAcceleration(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	love::Vector min, max;
-	t->getLinearAcceleration(&min, &max);
+	t->getLinearAcceleration(min, max);
 	lua_pushnumber(L, min.x);
 	lua_pushnumber(L, min.y);
 	lua_pushnumber(L, max.x);
@@ -320,7 +320,7 @@ int w_ParticleSystem_getRadialAcceleration(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float min, max;
-	t->getRadialAcceleration(&min, &max);
+	t->getRadialAcceleration(min, max);
 	lua_pushnumber(L, min);
 	lua_pushnumber(L, max);
 	return 2;
@@ -339,7 +339,26 @@ int w_ParticleSystem_getTangentialAcceleration(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float min, max;
-	t->getTangentialAcceleration(&min, &max);
+	t->getTangentialAcceleration(min, max);
+	lua_pushnumber(L, min);
+	lua_pushnumber(L, max);
+	return 2;
+}
+
+int w_ParticleSystem_setLinearDamping(lua_State *L)
+{
+	ParticleSystem *t = luax_checkparticlesystem(L, 1);
+	float arg1 = (float)luaL_checknumber(L, 2);
+	float arg2 = (float)luaL_optnumber(L, 3, arg1);
+	t->setLinearDamping(arg1, arg2);
+	return 0;
+}
+
+int w_ParticleSystem_getLinearDamping(lua_State *L)
+{
+	ParticleSystem *t = luax_checkparticlesystem(L, 1);
+	float min, max;
+	t->getLinearDamping(min, max);
 	lua_pushnumber(L, min);
 	lua_pushnumber(L, max);
 	return 2;
@@ -411,7 +430,7 @@ int w_ParticleSystem_getRotation(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float min, max;
-	t->getRotation(&min, &max);
+	t->getRotation(min, max);
 	lua_pushnumber(L, min);
 	lua_pushnumber(L, max);
 	return 2;
@@ -430,7 +449,7 @@ int w_ParticleSystem_getSpin(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 	float start, end;
-	t->getSpin(&start, &end);
+	t->getSpin(start, end);
 	lua_pushnumber(L, start);
 	lua_pushnumber(L, end);
 	return 2;
@@ -730,6 +749,8 @@ static const luaL_Reg functions[] =
 	{ "getRadialAcceleration", w_ParticleSystem_getRadialAcceleration },
 	{ "setTangentialAcceleration", w_ParticleSystem_setTangentialAcceleration },
 	{ "getTangentialAcceleration", w_ParticleSystem_getTangentialAcceleration },
+	{ "setLinearDamping", w_ParticleSystem_setLinearDamping },
+	{ "getLinearDamping", w_ParticleSystem_getLinearDamping },
 	{ "setSizes", w_ParticleSystem_setSizes },
 	{ "getSizes", w_ParticleSystem_getSizes },
 	{ "setSizeVariation", w_ParticleSystem_setSizeVariation },

src/modules/graphics/opengl/wrap_ParticleSystem.h

@@ -63,6 +63,8 @@ int w_ParticleSystem_setRadialAcceleration(lua_State *L);
 int w_ParticleSystem_getRadialAcceleration(lua_State *L);
 int w_ParticleSystem_setTangentialAcceleration(lua_State *L);
 int w_ParticleSystem_getTangentialAcceleration(lua_State *L);
+int w_ParticleSystem_setLinearDamping(lua_State *L);
+int w_ParticleSystem_getLinearDamping(lua_State *L);
 int w_ParticleSystem_setSizes(lua_State *L);
 int w_ParticleSystem_getSizes(lua_State *L);
 int w_ParticleSystem_setSizeVariation(lua_State *L);