VertexShader vtxShader = new VertexShader() {
   public void main() {
      mat4 mat1 = new mat4();
      mat4 mat2 = new mat4();
      gl_Position = mat1.mult(mat2).mult((vec4)gl_Position);
   }
};
StringWriter writer = new StringWriter();
J2GLSLConverter glslConverter = new J2GLSLConverter();
//glslConverter.debugOpCodeStack = true;
glslConverter.compile( writer, vtxShader );
System.out.println( writer.toString() );

void main(  )
{
   mat4 mat1;
   mat4 mat2;
   gl_Position = mat1 * mat2 * gl_Position;
}