[FIX] Fixed double dereferencing of mesh (playcanvas#2027)

mvaligursky · web-flow · commit f89dffdde2ea · 2020-04-28T11:33:01.000+01:00
* [FIX] Mesh ref counting fix
diff --git a/src/scene/mesh-instance.js b/src/scene/mesh-instance.js
@@ -61,7 +61,7 @@ Object.assign(pc, function () {
 
         this.node = node;           // The node that defines the transform of the mesh instance
         this._mesh = mesh;           // The mesh that this instance renders
-        mesh._refCount++;
+        mesh.incReference();
         this.material = material;   // The material with which to render this instance
 
         this._shaderDefs = pc.MASK_DYNAMIC << 16; // 2 byte toggles, 2 bytes light mask; Default value is no toggles and mask = pc.MASK_DYNAMIC
@@ -118,9 +118,9 @@ Object.assign(pc, function () {
             return this._mesh;
         },
         set: function (mesh) {
-            if (this._mesh) this._mesh._refCount--;
+            if (this._mesh) this._mesh.decReference();
             this._mesh = mesh;
-            if (mesh) mesh._refCount++;
+            if (mesh) mesh.incReference();
         }
     });
 
diff --git a/src/scene/mesh.js b/src/scene/mesh.js
@@ -177,7 +177,22 @@ Object.assign(pc, function () {
         }
     });
 
+    Object.defineProperty(Mesh.prototype, 'refCount', {
+        get: function () {
+            return this._refCount;
+        }
+    });
+
     Object.assign(Mesh.prototype, {
+
+        incReference: function () {
+            this._refCount++;
+        },
+
+        decReference: function () {
+            this._refCount--;
+        },
+
         /**
          * @function
          * @name pc.Mesh#destroy
diff --git a/src/scene/model.js b/src/scene/model.js
@@ -171,12 +171,11 @@ Object.assign(pc, function () {
 
                 mesh = meshInstance.mesh;
                 if (mesh) {
-                    mesh._refCount--;
-                    if (mesh._refCount < 1) {
+                    meshInstance.mesh = null;   // this calls decReference on mesh
+                    if (mesh.refCount < 1) {
                         mesh.destroy();
                     }
                 }
-                meshInstance.mesh = null;
 
                 skin = meshInstance.skinInstance;
                 if (skin) {

Original file line number	Diff line number	Diff line change
`@@ -171,12 +171,11 @@ Object.assign(pc, function () {`
`171`	`171`
`172`	`172`	`mesh = meshInstance.mesh;`
`173`	`173`	`if (mesh) {`
`174`		`- mesh._refCount--;`
`175`		`- if (mesh._refCount < 1) {`
	`174`	`+ meshInstance.mesh = null; // this calls decReference on mesh`
	`175`	`+ if (mesh.refCount < 1) {`
`176`	`176`	`mesh.destroy();`
`177`	`177`	`}`
`178`	`178`	`}`
`179`		`- meshInstance.mesh = null;`
`180`	`179`
`181`	`180`	`skin = meshInstance.skinInstance;`
`182`	`181`	`if (skin) {`