Renderer : fixed clear color buffer when color write is disabled

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@8192 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/lwjgl-ogl/com/jme3/renderer/lwjgl/LwjglRenderer.java

@@ -453,6 +453,11 @@ public class LwjglRenderer implements Renderer {
     public void clearBuffers(boolean color, boolean depth, boolean stencil) {
         int bits = 0;
         if (color) {
+            //See explanations of the depth below, we must enable color write to be able to clear the color buffer
+            if (context.colorWriteEnabled == false) {
+                glColorMask(true, true, true, true);
+                context.colorWriteEnabled = true;
+            }
             bits = GL_COLOR_BUFFER_BIT;
         }
         if (depth) {