CPUParticles: Fix inconsistent tangential acceleration

The tangential acceleration for both CPUParticles2D and CPUParticles had been
badly converted from their GPU counterpart (ParticlesMaterial).
This fixes it and ensures that both GPU and CPU particles behave the same with
regard to tangential acceleration.

scene/2d/cpu_particles_2d.cpp

@@ -748,7 +748,7 @@ void CPUParticles2D::_particles_process(float p_delta) {
 			force += diff.length() > 0.0 ? diff.normalized() * (parameters[PARAM_RADIAL_ACCEL] + tex_radial_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_RADIAL_ACCEL]) : Vector2();
 			//apply tangential acceleration;
 			Vector2 yx = Vector2(diff.y, diff.x);
-			force += yx.length() > 0.0 ? (yx * Vector2(-1.0, 1.0)) * ((parameters[PARAM_TANGENTIAL_ACCEL] + tex_tangential_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_TANGENTIAL_ACCEL])) : Vector2();
+			force += yx.length() > 0.0 ? (yx * Vector2(-1.0, 1.0)).normalized() * ((parameters[PARAM_TANGENTIAL_ACCEL] + tex_tangential_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_TANGENTIAL_ACCEL])) : Vector2();
 			//apply attractor forces
 			p.velocity += force * local_delta;
 			//orbit velocity
@@ -1174,15 +1174,16 @@ void CPUParticles2D::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "emitting"), "set_emitting", "is_emitting");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "amount", PROPERTY_HINT_EXP_RANGE, "1,1000000,1"), "set_amount", "get_amount");
 	ADD_GROUP("Time", "");
-	ADD_PROPERTY(PropertyInfo(Variant::REAL, "lifetime", PROPERTY_HINT_EXP_RANGE, "0.01,600.0,0.01,or_greater"), "set_lifetime", "get_lifetime");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "lifetime", PROPERTY_HINT_RANGE, "0.01,600.0,0.01,or_greater"), "set_lifetime", "get_lifetime");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "one_shot"), "set_one_shot", "get_one_shot");
-	ADD_PROPERTY(PropertyInfo(Variant::REAL, "preprocess", PROPERTY_HINT_EXP_RANGE, "0.00,600.0,0.01"), "set_pre_process_time", "get_pre_process_time");
+	ADD_PROPERTY(PropertyInfo(Variant::REAL, "preprocess", PROPERTY_HINT_RANGE, "0.00,600.0,0.01"), "set_pre_process_time", "get_pre_process_time");
 	ADD_PROPERTY(PropertyInfo(Variant::REAL, "speed_scale", PROPERTY_HINT_RANGE, "0,64,0.01"), "set_speed_scale", "get_speed_scale");
 	ADD_PROPERTY(PropertyInfo(Variant::REAL, "explosiveness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_explosiveness_ratio", "get_explosiveness_ratio");
 	ADD_PROPERTY(PropertyInfo(Variant::REAL, "randomness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_randomness_ratio", "get_randomness_ratio");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "fixed_fps", PROPERTY_HINT_RANGE, "0,1000,1"), "set_fixed_fps", "get_fixed_fps");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "fract_delta"), "set_fractional_delta", "get_fractional_delta");
 	ADD_GROUP("Drawing", "");
+	// No visibility_rect property contrarily to Particles2D, it's updated automatically.
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "local_coords"), "set_use_local_coordinates", "get_use_local_coordinates");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "draw_order", PROPERTY_HINT_ENUM, "Index,Lifetime"), "set_draw_order", "get_draw_order");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "texture", PROPERTY_HINT_RESOURCE_TYPE, "Texture"), "set_texture", "get_texture");

scene/3d/cpu_particles.cpp

@@ -754,8 +754,9 @@ void CPUParticles::_particles_process(float p_delta) {
 			//apply tangential acceleration;
 			if (flags[FLAG_DISABLE_Z]) {
 
-				Vector3 yx = Vector3(diff.y, 0, diff.x);
-				force += yx.length() > 0.0 ? (yx * Vector3(-1.0, 0, 1.0)) * ((parameters[PARAM_TANGENTIAL_ACCEL] + tex_tangential_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_TANGENTIAL_ACCEL])) : Vector3();
+				Vector2 yx = Vector2(diff.y, diff.x);
+				Vector2 yx2 = (yx * Vector2(-1.0, 1.0)).normalized();
+				force += yx.length() > 0.0 ? Vector3(yx2.x, yx2.y, 0.0) * ((parameters[PARAM_TANGENTIAL_ACCEL] + tex_tangential_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_TANGENTIAL_ACCEL])) : Vector3();
 
 			} else {
 				Vector3 crossDiff = diff.normalized().cross(gravity.normalized());