GigaWalk: interactive walkthrough of complex environments
EGRW '02 Proceedings of the 13th Eurographics workshop on Rendering
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We propose a simple modification to the classical polygon rasterization pipeline that enables exact, efficient raycasting of bounded implicit surfaces without the use of a global spatial data structure bounding hierarchy. Our algorithm requires two descriptions for each object: a (possibly non-convex) polyhedral bounding volume, and an implicit equation (including, optionally, a number of clipping planes). Unlike conventional raycasters, the modified pipeline is unidirectional and operates in immediate mode, making hardware implementation feasible. We discuss an extension to the OpenGL state machine that enables immediate-mode raycasting while making no modification to OpenGL''s architecture for high-performance polygon rendering. A software simulation of our algorithm generates scenes of visual fidelity equal to those produced by a conventional raycaster, and superior to those produced by a polygon rasterizer, significantly faster than either existing method alone.