Fix algorithm + add comments

libraries/entities-renderer/src/RenderableModelEntityItem.cpp

@@ -416,34 +416,46 @@ void RenderableModelEntityItem::computeShapeInfo(ShapeInfo& info) {
 }
 
 bool RenderableModelEntityItem::contains(const glm::vec3& point) const {
-    bool result = EntityItem::contains(point);
+    if (EntityItem::contains(point) && _model && _model->getCollisionGeometry()) {
-    
-    if (result && _model && _model->getCollisionGeometry()) {
         const QSharedPointer<NetworkGeometry> collisionNetworkGeometry = _model->getCollisionGeometry();
         const FBXGeometry& collisionGeometry = collisionNetworkGeometry->getFBXGeometry();
         
         auto checkEachPrimitive = [=](FBXMesh& mesh, QVector<int> indices, int primitiveSize) -> bool {
+            // Check whether the point is "behind" all the primitives.
             for (unsigned int j = 0; j < indices.size(); j += primitiveSize) {
                 if (!isPointBehindTrianglesPlane(point,
                                                  mesh.vertices[indices[j]],
                                                  mesh.vertices[indices[j + 1]],
                                                  mesh.vertices[indices[j + 2]])) {
+                    // it's not behind at least one so we bail
                     return false;
                 }
             }
             return true;
         };
         
+        // Check that the point is contained in at least one convex mesh.
         for (auto mesh : collisionGeometry.meshes) {
+            bool insideMesh = true;
+            
+            // To be considered inside a convex mesh,
+            // the point needs to be "behind" all the primitives respective planes.
             for (auto part : mesh.parts) {
                 // run through all the triangles and quads
                 if (!checkEachPrimitive(mesh, part.triangleIndices, 3) ||
                     !checkEachPrimitive(mesh, part.quadIndices, 4)) {
-                    return false;
+                    // If not, the point is outside, bail for this mesh
+                    insideMesh = false;
+                    continue;
                 }
             }
+            if (insideMesh) {
+                // It's inside this mesh, return true.
+                return true;
+            }
         }
     }
 
-    return result;
+    // It wasn't in any mesh, return false.
+    return false;
 }