fix render states merging when additionalState is not set (#2208)

Author: riccardobl

jme3-core/src/main/java/com/jme3/material/Material.java

@@ -907,22 +907,23 @@ private BindUnits updateShaderMaterialParameters(Renderer renderer, Shader shade
 
 
     private void updateRenderState(Geometry geometry, RenderManager renderManager, Renderer renderer, TechniqueDef techniqueDef) {
+        RenderState finalRenderState;
         if (renderManager.getForcedRenderState() != null) {
-            mergedRenderState.copyFrom(renderManager.getForcedRenderState());
+            finalRenderState = mergedRenderState.copyFrom(renderManager.getForcedRenderState());
         } else if (techniqueDef.getRenderState() != null) {
-            mergedRenderState.copyFrom(RenderState.DEFAULT);
-            techniqueDef.getRenderState().copyMergedTo(additionalState, mergedRenderState);
+            finalRenderState = mergedRenderState.copyFrom(RenderState.DEFAULT);
+            finalRenderState = techniqueDef.getRenderState().copyMergedTo(additionalState, finalRenderState);
         } else {
-            mergedRenderState.copyFrom(RenderState.DEFAULT);
-            RenderState.DEFAULT.copyMergedTo(additionalState, mergedRenderState);
+            finalRenderState = mergedRenderState.copyFrom(RenderState.DEFAULT);
+            finalRenderState = RenderState.DEFAULT.copyMergedTo(additionalState, finalRenderState);
         }
         // test if the face cull mode should be flipped before render
-        if (mergedRenderState.isFaceCullFlippable() && isNormalsBackward(geometry.getWorldScale())) {
-            mergedRenderState.flipFaceCull();
+        if (finalRenderState.isFaceCullFlippable() && isNormalsBackward(geometry.getWorldScale())) {
+            finalRenderState.flipFaceCull();
         }
-        renderer.applyRenderState(mergedRenderState);
+        renderer.applyRenderState(finalRenderState);
     }
-    
+
     /**
      * Returns true if the geometry world scale indicates that normals will be backward.
      * @param scalar geometry world scale

jme3-core/src/main/java/com/jme3/material/RenderState.java

@@ -1692,7 +1692,7 @@ public void set(RenderState state) {
      * This method is more precise than {@link #set(com.jme3.material.RenderState)}.
      * @param state state to copy from
      */
-    public void copyFrom(RenderState state) {
+    public RenderState copyFrom(RenderState state) {
         this.applyBlendMode = state.applyBlendMode;
         this.applyColorWrite = state.applyColorWrite;
         this.applyCullMode = state.applyCullMode;
@@ -1734,6 +1734,7 @@ public void copyFrom(RenderState state) {
         this.sfactorRGB = state.sfactorRGB;
         this.stencilTest = state.stencilTest;
         this.wireframe = state.wireframe;
+        return this;
     }
 
     @Override