Game Development Reference
In-Depth Information
7
II
Rasterized Voxel-Based
Dynamic Global Illumination
Hawar Doghramachi
7.1
Introduction
For modern games it becomes more and more important to offer a realistic envi-
ronment, where a convincing illumination plays a central role. Therefor, not only
direct illumination but also indirect illumination has to be taken into account. At
the same time modern games increasingly offer the player the possibility to inter-
act with the game world, i.e., move objects around, destroy buildings, or change
the lighting dynamically. This is where dynamic global illumination comes into
play; in contrast to static precalculated solutions, it does account for highly dy-
namic environments.
Rasterized voxel-based dynamic global illumination takes into consideration
that scenes, especially indoor, can contain a large number of light sources of
different types (e.g., point, spot, and directional lights). At the same time it
produces visually good and stable results while maintaining high interactive frame
rates.
7.2
Overview
This technique eciently utilizes features, which were introduced by DirectX 11
hardware, to accomplish the above stated results.
In the first step a voxel grid representation is created for the scene by using
the hardware rasterizer. Here the scene is rendered without depth testing into
a small 2D render-target, but instead of outputting the results into the bound
render-target, the rasterized pixels are written into a 3D read-write buffer by
using atomic functions. In this way the rasterizer is turned into a “voxelizer,”
creating eciently a highly populated 3D grid representation of the scene. This
voxel grid contains the diffuse albedo and normal information of the geometry
 
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