protected void fixInPositionType(ShaderNodeVariable var) {
        if(!var.getType().equals("vec3") || !var.getType().equals("vec4")){
            var.setType("vec3");
        }
    }
makes sure inPosition attribute is of type vec3 or vec4
@param var the inPosition attribute
jme3-core/src/main/java/com/jme3/shader/Glsl100ShaderGenerator.java