Game Development Reference
In-Depth Information
Figure 1.9. Top view of the scene's cubemap setup (left) and the resulting rendition
(right). From top to bottom: corridor case from the SIGGRAPH talk, best case 1, and
best case 2.
1.3
Using Reflection Textures
1.3.1
Glossy Material Support
We saw how to generate a 2D reflection texture to approximate a reflected scene.
This texture is better suited for specular materials like perfect mirrors. In order
to support glossy material we store preconvolved versions of the base texture in
the mipmaps ( Figure 1.10 ). This is similar to a preconvolved cubemap [Kautz
et al. 00]. Each mipmap level maps to a different glossiness. A highly glossy re-
flection (more detailed) will look up a lower mipmap level, a less glossy reflection
(more blurred) will look up the average of a large number of pixels. We exper-
imented with two ways of generating the mipmaps: by rendering the reflected
scene for each mipmap, and by successively blurring base mipmaps.
Rendering the reflected scene in each mipmap. We first try to re-render the ap-
proximated reflected scene for each mipmap. For better results, we should use
both preconvolved cubemaps and preconvolved image proxies. At rendering time,
the current mipmap level to render is used to sample the current mipmap level
of the texture applied on the cubemap or image proxies. The diculty of this
 
 
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