Lighting Models in Computer Games

Lighting Effects in Computer Games
Act II
Ivan Viola
Institute of Computer Graphics & Algorithms
Vienna University of Technology
Vienna / Austria
Introduction






Ivan Viola
speed & quality trade-off
real-time rendering (>10 fps)
software based techniques
hardware acceleration
Quake
state of the art in HW acceleration techniques
2 / 13
Quake
 most important FPS game
 lighting of the world
 lighting of creatures, weapons, particles and
sprites
Ivan Viola
3 / 13
Quake - World Lighting Model (I)
 Gouraud shading
 angle variance (for n-gons; n>3)
 bad for big polygons (such as walls)
Ivan Viola
4 / 13
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
Ivan Viola
5 / 13
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
Ivan Viola
6 / 13
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
Ivan Viola
7 / 13
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!
Ivan Viola
8 / 13
Projective Textures
 projector simulation
 spotlight simulation
 shadow maps
Ivan Viola
9 / 13
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
Ivan Viola
10 / 13
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
Ivan Viola
11 / 13
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 <L·N> and <V·R>
 setup texture matrix for the dot product
 pass per-vertex tangent vector of surface or
fiber as texture coordinate using
glTexCoord3f(Tx,Ty,Tz)
Ivan Viola
12 / 13
Thank you
Ivan Viola
viola@cg.tuwien.ac.at

Download Report