Lighting Effects in Computer Games Act II Ivan Viola Institute of Computer Graphics & Algorithms Vienna University of Technology Vienna / Austria

2 / 13 Ivan ViolaIntroduction  speed & quality trade-off  real-time rendering (>10 fps)  software based techniques  hardware acceleration  Quake  state of the art in HW acceleration techniques

3 / 13 Ivan ViolaQuake  most important FPS game  lighting of the world  lighting of creatures, weapons, particles and sprites

4 / 13 Ivan Viola Quake - World Lighting Model (I)  Gouraud shading  angle variance (for n-gons; n>3)  bad for big polygons (such as walls)

5 / 13 Ivan Viola Quake - World Lighting Model (II)  Lightmaps  lighting is precalculated (using eg. radiosity)  stored in a 2D texture  easy to scale, translate to create various effects

6 / 13 Ivan Viola Quake - Lighting of Polygonal Objects  Gouraud shading  polygons are triangles  small enough  Subdivision rasterizer  division until the polygon is smaller than pixel and then draw

7 / 13 Ivan Viola Quake - Following Versions  Verite Quake  HW acceleration using Verite chip  GLQuake  downloadable upgrade that uses OpenGL HW acceleration  Quake II  OpenGL HW acceleration out-of-the-box

8 / 13 Ivan Viola State of the Art in FPS Games  Quake III Arena  curved surfaces  volumetric fog  shading languages  Doom III  unique style of lighting using HW acceleration  HW acceleration necessary!

9 / 13 Ivan Viola Projective Textures  projector simulation  spotlight simulation  shadow maps

10 / 13 Ivan Viola Environment Maps  cubic parameterization  implemented in most nowadays graphics chips  spherical parameterization  mapping is problematic  parabolic parameterization  solves problem of spherical parameterization  partly implemented in MESA

11 / 13 Ivan Viola BRDF-Based Lighting  BRDF is a 4D function  4D lookup table is needed  approximation of 4D lookup table through decomposition into two 2D lookup tables  efficient usage of the texture memory

12 / 13 Ivan Viola Anisotropic Lighting  examples of anisotropic surfaces  satin cloth, CD surface, brushed metal  setup and enable 2D texture that encodes lighting model as a function of and  setup and enable 2D texture that encodes lighting model as a function of and  setup texture matrix for the dot product  pass per-vertex tangent vector of surface or fiber as texture coordinate using glTexCoord3f(Tx,Ty,Tz)

Thank you Ivan Viola