GL2 gl = drawable.getGL().getGL2();
gl.glClear(GL_COLOR_BUFFER_BIT);
// draw julia set
gl.glRasterPos2i(0, 0);
gl.glDrawPixels(config.getWidth(), config.getHeight(), GL_RGB, GL_FLOAT, julia3d.getPixelBuffer());
// Draw Mu constant
int width = config.getWidth();