Shading Languages

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Shading Languages

• By Markus Kummerer

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State of the Art Shading
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Overview

• RenderMan Interface
• Shape vs. Shading
• Types of Shaders
• Shading Language
• Examples
• Interactive Multi-Pass Shading

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RenderMan Interface

• Powerful set of primitive surface types
• Quadric surfaces
• Polygons
• Parametric surfaces
• Hierarchical modeling, geometry
• Constructive solid geometry
• Camera model
• Generalized shading model

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Shape vs. Shading

• Shape
• Geometric configuration of objects
• Shading
• Calculates the appearance of an object in a scene
  under a set of light sources
• Result defined by
• Colors of the surface and the light source(s)
• Position and orientation of the surface relative
  to the light
• Roughness of the surface

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Shading Pipeline

• Three basic parts of the shading process
• Emission at the light source
• Interaction of the light with the surface
• Atmospheric effects between the surface and the
  viewpoint

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Types of Shaders

• RenderMan Interface supports
• Light source shaders
• Surface shaders
• Volume shaders
• Transformation shaders
• Displacement shaders
• Imager shaders

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Light Source Shader

• Calculates the intensity and color of light sent
  by the light source to a point on a surface

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Surface Shader

• Determines the color of light reflecting from a
  point on a surface in a particular direction

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Volume Shader

• Generalizes the idea of atmosphere affecting
  light passing through space between a surface and
  the eye

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Shading Language

• Orthogonal definition
• Rendering environment
• Special data types
• Uniform and varying variables
• Integration constructs
• Filtered map access
• Function library

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Examples
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Example Surface Shader
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Example Surface Shader
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Example Displacement Shader
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Interactive Programmable Shading

• OpenGL acts as an assembly language for shader
  execution
• Compiler is introduced between the application
  and the graphics library

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Interactive Programmable Shading

• Results

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Conclusion

• Shading in software
• Common technique for production animation
• Offers generalized shading models
• Provides a highly flexible approach
• But is not interactive...
• Shading in hardware is needed for interactivity

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Hope you are delighted, too