Shaded surface model images like computer graphics (CG) need to be displayed for practical 3-D computer-generated holograms (CGH). We developed a simple process that is used to obtain 3-D data for CGH from two CG images. The first image is a shaded CG image. The second one is a depth-cued image, i.e., the image intensity is modulated by the depth of the object. We have implemented our method on OpenGL to render these two images. OpenGL includes support for not only removing the hidden surface but also texture mapping, alpha-blending, etc. We demonstrate the effectiveness of the method in achieving texture mapping and alpha-blending on the computer-generated rainbow holograms.