OpenGL 4 Shading Language Cookbook - Third Edition

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This technique produces very nice-looking results and has relatively few drawbacks. However, it does have some issues with triangles that are large in screen space (extend outside the view volume). If the w coordinate is small or zero, the position in viewport space can approach infinity, producing some ugly artifacts.  This happens when the vertex is at or near the x-y plane in camera space.

However, it is a good example of how geometry shaders can be useful for tasks other than the modification of the actual geometry. In this case, we used the geometry shader simply to compute additional information about the primitive as it was being sent down the pipeline. This shader can be dropped in and applied to any mesh without ...