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Glow
Sunday, May 4, 2003 | Permalink

Executable
Source code
Glow.zip (399 KB)

Required:
GL_ARB_fragment_program
GL_ARB_vertex_program
WGL_ARB_render_texture/GLX_ATI_render_texture
This demo shows how to get glow into the scene. The idea is simple. Just render the object you want to be glowing into a texture, then apply a blur filter and add that on top of the scene in the final pass. Since we're blurring anyway the texture you render to doesn't need to be very large, in fact, I used 128x128 but even smaller would have been quite fine too. To get perfectly fine blurring I first apply a blur filter, then blur the blur, and for final perfection, blur the blurred blur. The last blurring pass can often be skipped, but I had fillrate to burn anyway. In order for the glow to be more visible I applied a simple trick that expanded the object slightly along its normals when I render it to the texture.

It should run on Radeon 9500+ and on GeForce FX.