And that’s all that there is. It is somewhat complicated when starting out, but the more you read about shadow maps, the more you’ll understand the basics involved in the various incarnations. GL_ARB_shadow is a very simple way of creating cheap shadows without finding inverses of matrices yourself.
Pingback by BitwiseOR » GL_ARB_shadow_funcs
January 10, 2006 @ 3:10 pm
[...] The GL_ARB_shadow_funcs extension requires GL_ARB_shadow and GL_ARB_depth_texture in order to have any effect. In the GL_ARB_shadow example on this site we use GL_LEQUAL when setting the GL_TEXTURE_COMPARE_FUNC_ARB texture parameter. GL_ARB_shadow allows this comparison function to be GL_GEQUAL as well, but not any of the other comparison functions. [...]
Pingback by » OpenGL Transforms and the Inverse Model View
August 14, 2006 @ 9:46 am
[...] It is important to realise that OpenGL’s Model View matrix is actually M * C, so, if we want to get the position of the vertex in world space, we will have to use the modelview matrix to go to camera space, then multiply by C-1 (the inverse of the camera matrix). This gives us V * M * C * C-1 = V * gl_ModelViewMatrix * C-1 = V * M. And world space is exactly what we need to do shadow mapping, refraction, reflectiona and a plethora of other things. OpenGL took care of this for us with the GL_ARB_Shadow extension. By using glTexGen, OpenGL computes the inverse camera matrix and applies it without us having to fuss with inverses. But, now we’ll need to do an inverse ourselves. [...]
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