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View Full Version : What is difference between GL_SPHERE_MAP and GL_REFLECTION_MAP_NV (env.mapping)?



Optimizer
02-02-2002, 07:10 AM
I've just implemented enviroment mapping using GL_SPHERE_MAP (like described in Red Bood) and another version of env.mapping using GL_REFLECTION_MAP_NV (extension GL_NV_texgen_reflection or GL_EXT_texgen_reflection)

Implementation is exactly the same, but result is looking totally different.

Does anybody know how works GL_REFLECTION_MAP_NV?

davepermen
02-02-2002, 08:06 AM
reflection mapping is for cubemaps, sphere mapping for simple 2d-textures

JasonM [ATI]
02-03-2002, 07:51 PM
For more on the back ground of GL_NV_texgen_reflection have a look at View Independent and Environment maps (http://www.cs.ubc.ca/~heidrich/Papers/HWWS.98.pdf) and Realistic Hardware Accelerated Shading and Lighting (http://www.cs.ubc.ca/~heidrich/Papers/Siggraph.99.pdf) by Heidrich et al. In the first of these papers, Heidrich proposed what became the NV_texgen_reflection extension.

-JasonM

jwatte
02-04-2002, 08:14 AM
I suggest using the ARB_texture_cube_map extension which gives you the same thing without the vendor-specific name :-) It was folded into OpenGL 1.3 as a core feature, too.

mcraighead
02-04-2002, 12:11 PM
It was also in EXT_texture_cube_map. It's a feature with a long and distinguished history. http://www.opengl.org/discussion_boards/ubb/smile.gif

- Matt