1. Lighting Effects in Computer Games Stefan Felkel

2. Talk Outline • Importance of lighting • Light Sources • Lighting Model • Material and OpenGL • Shading • Multipass Rendering • Multitexturing • Mapping Techniques • Radiosity • Examples and Screenshots Stefan Felkel

3. Importance of Lighting Stefan Felkel

4. Point Light • Spot Light Light Sources • Directional Light • Parameters: color, intensity • OpenGL: up to 8 light sources Stefan Felkel

5. Material • Parameters: • Ambient (color) • Diffuse (color) • Specular (color) • Shininess (specular exponent) • Emissive (color) • Color determined by these params + params of light source + lighting model Stefan Felkel

6. Lighting Model (1) • Good approximation to reality • Illumination calculated with LM • OpenGL LM • Ambient Lighting • Diffuse Lighting • Specular Lighting • Total lighting intensity: Stefan Felkel

7. Lighting Model • Ambient Lighting Stefan Felkel

8. Lighting Model • Diffuse Lighting • View & light-vector: no lighting >= 90° Stefan Felkel

9. Lighting Model • Specular Lighting Stefan Felkel

10. Shading • Flat Shading • Gouraud Shading • Phong Shading Stefan Felkel

11. Cube Environment Mapping 6 Textures  1 Cubemap Stefan Felkel

12. Multipass Rendering • Lighting calculations done in separate passes • Each successive pass modifies the result of the pass before • Quake III: up to 10 passes • Base textures • Lightmaps • Fog • ... Stefan Felkel

13. Multitexturing • In a single pass, multiple textures are accessed • Multiple stage model: output of each stage becomes input for next • Input for 1st stage is fragment color Stefan Felkel

14. Light Mapping (1) • Light maps: low resolution & precalculated • Introduced by Quake + = Lightmap + Texture = Combined Texture Stefan Felkel

15. Light Mapping (2) Multiple light maps packed into single texture Stefan Felkel

16. Gloss Mapping • Gloss map: • monochrome texture • stores specular intensity values  + = Gloss maptexture Diffuselighting Specularlighting Final combined result Stefan Felkel

17. Radiosity • Based on thermal heat transfer • Viewpoint independent • Radiosity = radiance exiting from a patch • Deals with area light sources • Radiosity is used for light map calculation Stefan Felkel

18. Radiosity Stefan Felkel

19. Meshing the Environment • Patch = surface, area, texel (light maps) • Every patch gets energy from surrounding patches Stefan Felkel

20. Examples • Wolfenstein 3D (1992) • Doom (1993) • GLQuake (1996) Stefan Felkel

21. Wolfenstein 3D (1992) Screenshot from Wolfenstein (“full-bright”) Stefan Felkel

22. Doom I (1993) Screenshot from Doom I (Depth Cueing) Stefan Felkel

23. GLQuake (1996) Screenshot from Quake II (Radiosity for light map calculation) Stefan Felkel

24. End Thanks for your attention!