OpenGL® Distilled

Chapter 5. Pixel Rectangles

The earliest framebuffers were simply mapped into host memory. To render, applications addressed the framebuffer like any normal block of memory and stored final color values at pixel locations within the framebuffer (Sproul 1979). As graphics hardware evolved, providing efficient direct access to the framebuffer became increasingly difficult, and many graphics hardware manufacturers stopped providing memory-mapped framebuffer access altogether. To support hardware that can’t be memory mapped, OpenGL allows reading, writing, and copying pixel rectangles in the framebuffer.

Chapter 6, “Texture Mapping,” describes a much more powerful use for pixel data than simply copying it to the framebuffer. This chapter serves as ...