16.9. Summary

With the fixed functionality in previous versions of OpenGL, animation effects were strictly in the domain of the application and had to be computed on the host CPU. With programmability, it has become easy to specify animation effects within a shader and let the graphics hardware do this work. Just about any aspect of a shaderposition, shape, color, texture coordinates, and lighting, to name just a fewcan be varied according to a global definition of current time.

When you develop a shader for an object that will be in motion, you should also consider how much of the animation effect you can encode within the shader. Encoding animation effects within a shader can offload the CPU and simplify the code in the application. This chapter described some simple ways for doing this. On and off, scrolling, and threshold effects are quite easy to do within a shader. Key-frame interpolation can be supported in a simple way through the power of programmability. Particles can be animated, including their position, color, velocity, and any other important attributes. Objects and textures can be made to oscillate, move, grow, or change based on mathematical expressions.

Animation is a powerful tool for conveying information, and the OpenGL Shading Language provides another avenue for expressing animation effects.