Jorg’s Graphics Lecture Notes – Discrete Graphics, Pixel shaders 1
Discrete Graphics, Pixel shaders
Better looking models
•curved surfaces (10),
•procedural detail (11),
•textures (9)
Bit maps: rgb, normal texture, displacement maps
geometry pipeline, pixel pipeline, ‘Vertex shader and Pixel shader’
Geometric
processing Rasterization DisplayVertices
Pixel
operations
Pixels
Texture maps
•Texture mapping types
–(2D) texture : pasting an image onto a surface (challenges: distortion
and aliasing)
–(3D) texture — generated random, x,y,z direct, discrete grid
–transfer texture from an intermediate object (sphere or cylinder) for
better parametrization; use the object normal.
–environment map:
place viewer at object center, cube map
transfer resulting image as texture (possibly via intermediate object)
•glTexCoord 9texgen.c 9checker.c
video texture
bump mapping: perturb normal nat point pas if phad been moved by
din the direction of the normal n:
pnew =p+dn.
Compute
∂pnew
∂u ×∂pnew
∂v =∂p
∂u +∂ d
∂u n+d∂n
∂u ×∂p
∂v +∂ d
∂v n+d∂n
∂v
=n+∂d
∂u n×∂p
∂v +∂ d
∂v n×∂p
∂u .+O(∂n
∂u ,∂n
∂v ).
The leading terms of the perturbation f the normal are therefore
∂d
∂u n×∂p
∂v +∂ d
∂v n×∂p
∂u .
