Drawing Pixels Fast

The code fragment in Example 4-1 illustrates how to set OpenGL state so that subsequent calls to glDrawPixels() or glCopyPixels() will be fast.

Example 4-1 : Drawing Pixels Fast

        /*
         * Disable stuff that's likely to slow down 
         * glDrawPixels.(Omit as much of this as possible, 
         * when you know in advance that the OpenGL state is
         * already set correctly.)
         */
        glDisable(GL_ALPHA_TEST);
        glDisable(GL_BLEND);
        glDisable(GL_DEPTH_TEST);
        glDisable(GL_DITHER);
        glDisable(GL_FOG);
        glDisable(GL_LIGHTING);
        glDisable(GL_LOGIC_OP);
        glDisable(GL_STENCIL_TEST);
        glDisable(GL_TEXTURE_1D);
        glDisable(GL_TEXTURE_2D);
        glPixelTransferi(GL_MAP_COLOR, GL_FALSE);
        glPixelTransferi(GL_RED_SCALE, 1);
        glPixelTransferi(GL_RED_BIAS, 0);
        glPixelTransferi(GL_GREEN_SCALE, 1);
        glPixelTransferi(GL_GREEN_BIAS, 0);
        glPixelTransferi(GL_BLUE_SCALE, 1);
        glPixelTransferi(GL_BLUE_BIAS, 0);
        glPixelTransferi(GL_ALPHA_SCALE, 1);
        glPixelTransferi(GL_ALPHA_BIAS, 0);

        /*
         * Disable extensions that could slow down 
         * glDrawPixels.(Actually, you should check for the 
         * presence of the proper extension before making 
         * these calls.I omitted that code for simplicity.)
         */
        #if GL_SGI_index_func 
               (glDisable(GL_INDEX_TEST_SGI);
        #endif