PV227 GPU Rendering
Marek Vinkler
Department of Computer Graphics and Design
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Textures
texture images,
diffuse texture,
dissolve effect,
cube map,
normal map.
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Diffuse Texture
texture for object apperance,
used to modulate the computed light,
should not be used for specular component.
Figure: Texture modulating ambient + diffuse color.
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Dissolve Effect
discard some of the fragments based on the texture value,
animation through changing the threshold.
Figure: Dissolve effect with t=0.5f.
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Cube Map
six textures mapped to sides of a cube,
accessed with a vector from the center of the cube in world
space.
Figure: Various methods of computing cube map vector.
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Cube Map Indexing
any access vector can be computed,
can be used as regular texture,
can be used to “follow” a modified light path.
Figure: D3D perspective. Taken from gpwiki.org
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Normal Map
modify the normal for lighting to increase details,
the normal map may be position dependent / independent.
Figure: Various methods of using the normal map.
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Normal Map Types
vector is stored per texel (only height for bump map),
Object/World normal map,
stores normals in object/world space,
predominantly green / yellow / red,
usefull only for fixed objects,
Tangent normal map,
stores normals in tangent space,
predominantly blue,
any object, any position / rotation.
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Normal Map Examples
Figure: Taken from crydev.net
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Tangent Normal Map
computations take place in tangent space,
light and eye must be transformed to this space,
conversion by a transform matrix,
n, t, b are in camera space.



t.x t.y t.z
b.x x.y b.z
n.x n.y n.z



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Tangent Space
Figure: Taken from txutxi.com
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