AnimationTreePlayer: blend value tracks (closes #2299)

Variant:
- zero() sets a Variant to the appropriate type of zero value
- blend() blends part of one Variant on top of another.

(cherry picked from commit 391ce81c5e)

core/variant.cpp

@@ -1115,6 +1115,21 @@ void Variant::reference(const Variant& p_variant) {
 	}		
 
 
+}
+void Variant::zero() {
+	switch(type) {
+		case NIL: break;
+		case BOOL: this->_data._bool = false; break;
+		case INT: this->_data._int = 0; break;
+		case REAL: this->_data._real = 0; break;
+		case VECTOR2: *reinterpret_cast<Vector2*>(this->_data._mem) = Vector2(); break;
+		case RECT2: *reinterpret_cast<Rect2*>(this->_data._mem) = Rect2(); break;
+		case VECTOR3: *reinterpret_cast<Vector3*>(this->_data._mem) = Vector3(); break;
+		case PLANE: *reinterpret_cast<Plane*>(this->_data._mem) = Plane(); break;
+		case QUAT: *reinterpret_cast<Quat*>(this->_data._mem) = Quat(); break;
+		case COLOR: *reinterpret_cast<Color*>(this->_data._mem) = Color(); break;
+		default: this->clear(); break;
+	}
 }
 void Variant::clear() {
 

core/variant.h

@@ -372,6 +372,8 @@ public:
 		return res;
 	}
 
+	void zero();
+	static void blend(const Variant& a, const Variant& b, float c,Variant &r_dst);
 	static void interpolate(const Variant& a, const Variant& b, float c,Variant &r_dst);
 
 	struct CallError {

core/variant_op.cpp

@@ -3431,6 +3431,59 @@ Variant Variant::iter_get(const Variant& r_iter,bool &r_valid) const {
 
 }
 
+void Variant::blend(const Variant& a, const Variant& b, float c, Variant &r_dst) {
+	if (a.type!=b.type) {
+		if(a.is_num() && b.is_num()) {
+			real_t va=a;
+			real_t vb=b;
+			r_dst=va + vb * c;
+		} else {
+			r_dst=a;
+		}
+		return;
+	}
+
+	switch(a.type) {
+		case NIL: { r_dst=Variant(); } return;
+		case INT:{
+			int va=a._data._int;
+			int vb=b._data._int;
+			r_dst=int(va + vb * c + 0.5);
+		} return;
+		case REAL:{
+			double ra=a._data._real;
+			double rb=b._data._real;
+			r_dst=ra + rb * c;
+		} return;
+		case VECTOR2:{ r_dst=*reinterpret_cast<const Vector2*>(a._data._mem)+*reinterpret_cast<const Vector2*>(b._data._mem)*c; } return;
+		case RECT2:{
+					   const Rect2 *ra = reinterpret_cast<const Rect2*>(a._data._mem);
+					   const Rect2 *rb = reinterpret_cast<const Rect2*>(b._data._mem);
+					   r_dst=Rect2(ra->pos + rb->pos * c, ra->size + rb->size * c);
+				   } return;
+		case VECTOR3:{ r_dst=*reinterpret_cast<const Vector2*>(a._data._mem)+*reinterpret_cast<const Vector2*>(b._data._mem)*c; } return;
+		case _AABB:{
+					   const AABB *ra = reinterpret_cast<const AABB*>(a._data._mem);
+					   const AABB *rb = reinterpret_cast<const AABB*>(b._data._mem);
+					   r_dst=AABB(ra->pos + rb->pos * c, ra->size + rb->size * c);
+				   } return;
+		case COLOR:{
+					   const Color *ca = reinterpret_cast<const Color*>(a._data._mem);
+					   const Color *cb = reinterpret_cast<const Color*>(b._data._mem);
+					   float r = ca->r + cb->r * c;
+					   float g = ca->g + cb->g * c;
+					   float b = ca->b + cb->b * c;
+					   float a = ca->a + cb->a * c;
+					   r = r > 1.0 ? 1.0 : r;
+					   g = g > 1.0 ? 1.0 : g;
+					   b = b > 1.0 ? 1.0 : b;
+					   a = a > 1.0 ? 1.0 : a;
+					   r_dst=Color(r, g, b, a);
+				   } return;
+		default:{ r_dst = c<0.5 ? a : b; } return;
+	}
+}
+
 void Variant::interpolate(const Variant& a, const Variant& b, float c,Variant &r_dst) {
 
 	if (a.type!=b.type) {

scene/animation/animation_tree_player.cpp

@@ -768,6 +768,10 @@ void AnimationTreePlayer::_process_animation(float p_delta) {
 		t.scale.x=0;
 		t.scale.y=0;
 		t.scale.z=0;
+
+		Variant value = t.node->get(t.property);
+		value.zero();
+		t.node->set(t.property, value);
 	}
 
 
@@ -777,11 +781,9 @@ void AnimationTreePlayer::_process_animation(float p_delta) {
 	Quat empty_rot;
 
 
-	int total = 0;
 	while(anim_list) {
 
 		if (!anim_list->animation.is_null() && !anim_list->skip) {
-			++total;
 			//check if animation is meaningful
 			Animation *a = anim_list->animation.operator->();
 
@@ -816,8 +818,9 @@ void AnimationTreePlayer::_process_animation(float p_delta) {
 					case Animation::TYPE_VALUE: { ///< Set a value in a property, can be interpolated.
 
 						if (a->value_track_is_continuous(tr.local_track)) {
-							Variant value = a->value_track_interpolate(tr.local_track,anim_list->time);
-							tr.track->node->set(tr.track->property,value);
+							Variant blended, value = a->value_track_interpolate(tr.local_track,anim_list->time);
+							Variant::blend(tr.track->node->get(tr.track->property),value,blend,blended);
+							tr.track->node->set(tr.track->property,blended);
 						} else {
 
 							List<int> indices;