@Override
    protected void generateUniforms(StringBuilder source, ShaderGenerationInfo info, ShaderType type) {
        generateCompatibilityDefines(source, type);
        super.generateUniforms(source, info, type);
    }
{@inheritDoc} in glsl 1.5 varying are prefixed with the "in" or "out"
keyword and not the "varying" keyword.

"in" is used for Fragment shader (maybe Geometry shader later) "out" is
used for Vertex shader (maybe Geometry shader later)
jme3-core/src/main/java/com/jme3/shader/Glsl150ShaderGenerator.java