MPO: clear param for null textures

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

@@ -788,6 +788,7 @@ public class Material implements CloneableSmartAsset, Cloneable, Savable {
     private void updateShaderMaterialParameters(Renderer renderer, Shader shader, List<MatParamOverride> overrides) {
         int unit = 0;
 
+        if (overrides != null) {
             for (MatParamOverride override : overrides) {
                 VarType type = override.getVarType();
 
@@ -797,6 +798,7 @@ public class Material implements CloneableSmartAsset, Cloneable, Savable {
                 }
 
                 Uniform uniform = shader.getUniform(override.getPrefixedName());
+                if (override.getValue() != null) {
                     if (type.isTextureType()) {
                         renderer.setTexture(unit, (Texture) override.getValue());
                         uniform.setValue(VarType.Int, unit);
@@ -804,6 +806,10 @@ public class Material implements CloneableSmartAsset, Cloneable, Savable {
                     } else {
                         uniform.setValue(type, override.getValue());
                     }
+                } else {
+                    uniform.clearValue();
+                }
+            }
         }
 
         for (int i = 0; i < paramValues.size(); i++) {