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8.5 Blending Transitions

When generating real-time or interactive imagery, often the application may switch between different representations of an object. A different representation may be chosen which provides more detail or less detail, takes less time to render, or for a variety of other reasons. The two representations may not be similar enough to generate the same pixels on the screen, so the transition may generate an objectionable ``pop'' on the screen. The apparent discontinuity can be reduced by fading the old representation in and the new representation over a number of frames using blending. The new representation is rendered with glBlendFuncGL_SRC_ALPHA, GL_ONE(GL_SRC_ALPHA, GL_ONE) and the old representation with glBlendFuncGL_ONE_MINUS_SRC_ALPHA, GL_ONE(GL_ONE_MINUS_SRC_ALPHA, GL_ONE), varying alpha from 0 to 1 over a few frames.



David Blythe
1999-08-06