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Atahualpa
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Hawthrone
Mar 1999
time: 06:30
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Bump mapping is a technique used to add relief to an object’s surface, without increasing the geometric complexity of the object. Bump mapping makes the surface of a smooth polygon appear irregular, or “bumpy.” Bump mapping can be used in games, visualization and simulation applications to represent relief all kinds of irregularities on floors, walls, water surfaces, and all kinds of objects. For example, an orange can be modeled by a smooth sphere with a bump map. The bump map is used to model all the small the creases in the orange’s skin, without increasing the geometric complexity of the model. Similarly, the surface of a lake can be modeled by a flat polygon and a dynamic bump map. In this case, the bump map is used to model the waves. Bump mapping is expected to have the same impact throughout the gaming world as the transition from pixelated point-filtered textures to smooth bilinear-filtered textures. Until very recently, the performance cost of bump mapping techniques was prohibitively expensive for games running on consumer-level hardware. Permedia3 makes bump mapping free in terms of performance (relative to simple bilinear mipmapped texturing) in Direct3D 6 games. This paper presents the basic idea behind bump mapping, Direct3D 6 and OpenGL bump mapping techniques, and Permedia3’s bump mapping capabilities. Principle Bump mapping consists of using variations in light intensity to simulate variations in height (“bumps”) at the surface of a smooth object. Basically, a brightly-lit point at the surface of the object will appear higher than a dimly-lit point. “True” bump mapping requires that lighting computations be performed individually for each pixel—a technique known as Phong shading. When that is the case, the way a point is lit is determined by the direction of the light source and by the surface normal at this point. Roughly speaking, the surface normal at a particular point is a vector perpendicular to the surface at this point. When lighting computations are performed on a per-pixel basis, bumps at the surface of a smooth object can be produced by adding small perturbations to the object’s surface normal. True per pixel lighting, or Phong shading, involves computing the true vertex normal and the true direction of the light for each point, and is not available in current implementations of Direct3D or OpenGL. Current Direct3D and OpenGL shaders perform “per vertex” lighting. In this model, lighting computations are performed for each vertex of each polygon. The results of these computations are then interpolated along the edges and across the face of each polygon. Because the current implementations of Direct3D and OpenGL do not support per-pixel lighting, Direct3D and OpenGL cannot be used to perform “true” bump mapping.
Source: http://www.3dlabs.com/product/techn...White_Paper.pdf
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dejon
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Just because I didn't play this one, doesn't mean I don't want to see the results!
(Bump)
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Soul Survivor
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UChicago
May 2003
time: 05:30
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great work JW! you're almost there!
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Soul Survivor
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UChicago
May 2003
time: 05:30
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its been nearly an hour since your last post???
final tally??
come on i need to know how low of a score i really got!
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07-08-2003 22:46
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