/* render to pBuffer */
JOGLTarget target = (bufferTarget == null)?
createJOGLTarget(gl, results, config) : bufferTarget;
target.renderPart(camera, projection,
xStart / (double)(x-1), xEnd / (double)(x-1),
yStart / (double)(y-1), yEnd / (double)(y-1));
if (target != bufferTarget) {
target.freeResources();