Added acceleration

1 files changed, 67 insertions, 15 deletions

diff --git a/src/entity.c b/src/entity.c
index 0b6be9d..c88c767 100644
--- a/src/entity.c
+++ b/src/entity.c
@@ -6,6 +6,32 @@ const EntityTypeInfo entityTypeInfo[ENTITY_TYPE_COUNT] = {
 	(EntityTypeInfo){initAntifaShip, closeAntifaShip, updateAntifaShip, drawAntifaShip}
 };
 
+EntityVelocity entityVelocityIdentity() {
+	return (EntityVelocity){
+		.velocity = Vector3Zero(),
+		.angularVelocity = AxisAngleIdentity(),
+		.stick = Vector3Zero(),
+		.speed = 0
+	};
+}
+
+float accelerateValue(float value, float lastValue, float up, float down) {
+	if (value - lastValue >= up)
+		return lastValue + up;
+	if (lastValue - value >= down)
+		return lastValue - down;
+
+	return value;
+}
+
+Vector3 accelerateVector3(Vector3 value, Vector3 lastValue, Vector3 up, Vector3 down) {
+	return (Vector3){
+		accelerateValue(value.x, lastValue.x, up.x, down.x),
+		accelerateValue(value.y, lastValue.y, up.y, down.y),
+		accelerateValue(value.z, lastValue.z, up.z, down.z)
+	};
+}
+
 Entity createEntity(EntityType type) {
 	EntityTypeInfo info = entityTypeInfo[type];
 
@@ -13,10 +39,10 @@ Entity createEntity(EntityType type) {
 	Entity entity = (Entity){
 		.type = type,
 		.position = Vector3Zero(),
-		.angularVelocity = 0,
-		.rotationAxis = Vector3Zero(),
-		.velocity = Vector3Zero(),
 		.rotation = QuaternionIdentity(),
+		.velocity = entityVelocityIdentity(),
+		.lastVelocity = entityVelocityIdentity(),
+		.useAcceleration = false,
 		.updateCb = info.updateCb,
 		.drawCb = info.drawCb,
 		.data = NULL
@@ -48,9 +74,9 @@ void entityUpdatePosition(Entity * entity) {
 	float t = GetFrameTime();
 
 	Vector3 velocity = (Vector3){
-		entity->velocity.x * t,
-		entity->velocity.y * t,
-		entity->velocity.z * t
+		entity->velocity.velocity.x * t,
+		entity->velocity.velocity.y * t,
+		entity->velocity.velocity.z * t
 	};
 
 	entity->position = Vector3Add(entity->position, velocity);
@@ -60,27 +86,53 @@ void entityUpdateRotation(Entity * entity) {
 	float t = GetFrameTime();
 
     Quaternion angularRotation = QuaternionFromAxisAngle(
-		entity->rotationAxis, 
-		entity->angularVelocity * t
+		entity->velocity.angularVelocity.axis, 
+		entity->velocity.angularVelocity.angle * t
 	);
 
     entity->rotation = QuaternionMultiply(entity->rotation, angularRotation);
 }
 
 void entityJoystickControl(Entity * entity, Vector3 stick, float speed) {
+	float s = speed;
+	Vector3 st = stick;
+	float t = GetFrameTime();
+
+	// Handle acceleration.
+	if (entity->useAcceleration) {
+		s = accelerateValue(
+			speed,
+			entity->lastVelocity.speed,
+			entity->acceleration.speedUp * t,
+			entity->acceleration.speedDown * t
+		);
+
+		st = accelerateVector3(
+			stick,
+			entity->lastVelocity.stick,
+			Vector3Scale(entity->acceleration.rotationUp, t),
+			Vector3Scale(entity->acceleration.rotationDown, t)
+		);
+	}
+
+	entity->velocity.stick = st;
+	entity->velocity.speed = s;
+	entity->lastVelocity = entity->velocity;
+
 	// Set angular velocity.
-	Vector3 angularVelocity = Vector3Scale(stick, PI);
-	entity->angularVelocity = Vector3Length(angularVelocity);
-	entity->rotationAxis = stick;
+	Vector3 angularVelocity = Vector3Scale(st, PI);
+	entity->velocity.angularVelocity.angle = Vector3Length(angularVelocity);
+	entity->velocity.angularVelocity.axis = st;
+
 	entityUpdateRotation(entity);
 
 	// Set position.
 	Matrix m = QuaternionToMatrix(QuaternionInvert(entity->rotation));
 
-	entity->velocity = (Vector3){
-		m.m2 * speed,
-		m.m6 * speed,
-		m.m10 * speed,
+	entity->velocity.velocity = (Vector3){
+		m.m2 * s,
+		m.m6 * s,
+		m.m10 * s,
 	};
 
 	entityUpdatePosition(entity);