CSC418 - Notes
Topic 8: Texture Mapping

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Key concepts & Readings

• Texture mapping (Shirley: c. 10. Hill: p. 439-465. Foley & van Dam: p. 741-744)
• 2d texture mapping (Shirley: p. 198-199)
• 3d texture mapping or volumetric textures (Shirley: p. 192-198)
• Bump textures (Shirley: p. 204)
• Environment maps (Shirley: p. 205-206)

OpenGL

OpenGL has built-in support for 1D and 2D texture mapping.

2D Texture Mapping

• Enable texture mapping by calling
  glEnable(GL_TEXTURE_2D)
• Load a texture (either generate a texture on the fly or load one from an image)
• Setup OpenGL to use the texture by calling
  void glTexImage2D(GLenum target, GLint level, GLint components, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels)
  Example:
  glTexImage2D(GL_TEXTURE_2D, 0, 3, textureImageWidth, textureImage, 0, GL_RGB, GL_UNSIGNED_BYTE, &textureImage[0][0][0]);
• Setup wrapping and filtering options of the texture
  void glTexParameterf(GLenum target, GLenum pname, GLfloat param)
  void glTexParameteri(GLenum target, GLenum pname, GLint param)
• In the display function
• Setup the texture coordinates by calling
  glTexCoord*()
• Draw the scene

Notes

Texture Mapping

efficient way to add surface detail

• pastes an elastic photograph onto a surface
• used to modify colour, normals, ...
• requires prefiltering

Coordinate Systems

Shape of Filter Kernel

Fast Convolution for Texture Maps

• usually box filter
• quickly sum texels within filter kernel (preferably constant time)
• summed-area tables
• MIP maps

Bump Mapping

Bump Mapping: The surfaces appear to have bumps or gouges but that the silhouette of the object is still smooth. (Courtesy www.siggraph.org.)

• creates impression of small surface features
• wrinkles, dimples, etc. -- orange peel
• perturbs surface normal, affecting local illumination
• silhouette edges don't have bumps, no shadows from bumps

Volumetric Textures OR 3D Textures

• wood, marble
• colour = f(x,y,z)

Environment Mapping

to be written

Exercises