Dotproduct3 Bump Mapping with 3D Lightmapping on the Radeon®

The RadeonDotProduct3 sample uses EXT_texture_env_dot3, ATI_texture_mirror_once, ARB_texture_cube_map, EXT_texture3Dand to demonstrate per-pixel lighting effects possible in OpenGL®. It demonstrates DOT3 Bumpmapping, 3D Lightmap, and shows the difference when using a cube map for normalizing the vectors. For more on 3D light mapping as well as 3D texturing in general, check out the Radeon® 3D Texture Mapping Tutorial. Figure 1 shows the final result.

Figure 1 - Final Dot3 Bumps with 3D Lightmap

The process begins by taking the vector from each vertex to the light converting it into tangent space (the coordinate space of the base texture). This vector is packed into the color when a cube map is not used. When using a cube map for vector normalization the light vector is placed in the texture coordinates. These coordinates are used to reach into a pre-computed cube map in which each face of the cube contains a normalized vector pointing outward from the center of the cube. The results of these computations are shown in Figure 2

Figure 2 - Light Vector displayed as color

The dot product of this light vector and a pre-filtered height map (the normals in texture space, shown in Figure 3 as color) is computed using ATIX_texture_env_dot3 to produce the initial lighting. Figure 4 shows the results.

Figure 3 - Pre-Filtered Height displayed as color

Figure 4 - Light Vector DOT3ed with Pre-filtered height map

The results of this are modulated with the 3D lightmap (shown in Figure 5) and the base texture (shown in Figure 6) to produce the final image shown as Figure 1. The 3D lightmap is generated as one quadrant of a sphere and then mirrored using ATI_texture_mirror_once.

Figure 5 - Result of 3D lightmapping

Figure 6 - Base Texture

RadeonDot3Bump3DLight Controls M - Show stages of bump and lightmap process T - Cycle through the different textures V - Toggle display of light per-vertex vectors C - Toggle display of tangent space per-vertex coordinate systems W - Toggle display of wireframe [UP] - Move light further from object center [DOWN] - Move light closer to object center [LEFT MOUSE] + Mouse - Rotate Object [RIGHT MOUSE] + Mouse - Rotate Light [SPACE] - Stop light motion [ESC] - Quit

Downloads

Note: The source code and media should be unzipped into the following recommended directory structure to ensure you can easily compile and run the executable. Radeonxxxxxx.zip -> x:\atiddk\OpenGLmedia.zip -> x:\atiddk\mediaraw.zip -> x:\atiddk\media RadeonDotProduct3.zip media.zip Back to Samples Page