1 files changed, 47 insertions, 3 deletions

diff --git a/scene/resources/surface_tool.cpp b/scene/resources/surface_tool.cpp
index c0abee2030..3ba43006a3 100644
--- a/scene/resources/surface_tool.cpp
+++ b/scene/resources/surface_tool.cpp
@@ -108,8 +108,55 @@ void SurfaceTool::add_vertex(const Vector3 &p_vertex) {
 	vtx.bones = last_bones;
 	vtx.tangent = last_tangent.normal;
 	vtx.binormal = last_normal.cross(last_tangent.normal).normalized() * last_tangent.d;
+
+	const int expected_vertices = 4;
+
+	if ((format & Mesh::ARRAY_FORMAT_WEIGHTS || format & Mesh::ARRAY_FORMAT_BONES) && (vtx.weights.size() != expected_vertices || vtx.bones.size() != expected_vertices)) {
+		//ensure vertices are the expected amount
+		ERR_FAIL_COND(vtx.weights.size() != vtx.bones.size());
+		if (vtx.weights.size() < expected_vertices) {
+			//less than requred, fill
+			for (int i = vtx.weights.size(); i < expected_vertices; i++) {
+				vtx.weights.push_back(0);
+				vtx.bones.push_back(0);
+			}
+		} else if (vtx.weights.size() > expected_vertices) {
+			//more than required, sort, cap and normalize.
+			Vector<WeightSort> weights;
+			for (int i = 0; i < vtx.weights.size(); i++) {
+				WeightSort ws;
+				ws.index = vtx.bones[i];
+				ws.weight = vtx.weights[i];
+				weights.push_back(ws);
+			}
+
+			//sort
+			weights.sort();
+			//cap
+			weights.resize(expected_vertices);
+			//renormalize
+			float total = 0;
+			for (int i = 0; i < expected_vertices; i++) {
+				total += weights[i].weight;
+			}
+
+			vtx.weights.resize(expected_vertices);
+			vtx.bones.resize(expected_vertices);
+
+			for (int i = 0; i < expected_vertices; i++) {
+				if (total > 0) {
+					vtx.weights.write[i] = weights[i].weight / total;
+				} else {
+					vtx.weights.write[i] = 0;
+				}
+				vtx.bones.write[i] = weights[i].index;
+			}
+		}
+	}
+
 	vertex_array.push_back(vtx);
 	first = false;
+
 	format |= Mesh::ARRAY_FORMAT_VERTEX;
 }
 void SurfaceTool::add_color(Color p_color) {
@@ -161,7 +208,6 @@ void SurfaceTool::add_uv2(const Vector2 &p_uv2) {
 void SurfaceTool::add_bones(const Vector<int> &p_bones) {
 
 	ERR_FAIL_COND(!begun);
-	ERR_FAIL_COND(p_bones.size() != 4);
 	ERR_FAIL_COND(!first && !(format & Mesh::ARRAY_FORMAT_BONES));
 
 	format |= Mesh::ARRAY_FORMAT_BONES;
@@ -171,8 +217,6 @@ void SurfaceTool::add_bones(const Vector<int> &p_bones) {
 void SurfaceTool::add_weights(const Vector<float> &p_weights) {
 
 	ERR_FAIL_COND(!begun);
-
-	ERR_FAIL_COND(p_weights.size() != 4);
 	ERR_FAIL_COND(!first && !(format & Mesh::ARRAY_FORMAT_WEIGHTS));
 
 	format |= Mesh::ARRAY_FORMAT_WEIGHTS;