GAMES101 Lecture 08 - Shading 2 (Shading, Pipeline and Texture Mapping)

GAMES101_Lecture_08.pdf

I. Shading

For the Blinn-Phong Reflectance Model, refer to Lecture07.md.

Shading Frequencies

• Flat Shading: Triangle face is flat.

  • One normal vector for each triangle

• Gouraud Shading: Interpolate colors from vertices across each triangle.

  • Each vertex has a normal vector

• Phong Shading: Interpolate normal vectors across each triangle.

  • Compute full shading model at each pixel.

Shading methods can be applied in different stages in pipeline. E.g., the Gouraud Shading method can be applied in Vertex Processing.

Defining Per-Vertex Normal Vectors

• Simple Scheme: average surrounding face normals. Possibly weighted.

  $$N_v=\frac{\sum _i{N}_i}{\Vert \sum _i{N}_i\Vert }$$

Defining Per-Pixel Normal Vectors

• Barycentric Interpolation:

II. Graphics Pipeline

Shader Programs

• Program vertex and fragment processing stages

• Describe operation on a single vertex (or fragment)

  • Vertex Shader

  • Fragment/Pixel Shader

• ShaderToy.com for testing shaders online

GPU: Heterogeneous, Multi-Core Processor

Specialized processors of executing graphics pipeline computations.

III. Texture Mapping

Refer to Lecture09.md.