Last Updated January 11, 2012
There are two main approaches to the texture mapping problem. One technique is to map the texture to an object in world-coordinates and then to project each part of the object's surface onto a pixel, effectively 'stretching' the texture over the object. This approach is known as forward mapping. The main drawback with forward mapping is that the texel do not correspond to the pixel boundaries and will require fractional pixel calculations.
Forward Texture Mapping
The more natural approach to integrate with existing renderers is to find a correspondence between a polygon's pixel and a coordinate in texture space, this is inverse mapping.
The role of the renderer is to map a polygon's internal pixels to texture coordinates. This process is usually performed in parallel with an interpolative shading algorithm (e.g. Gouraud). Once the texel corresponding to a pixel is found, the colour information is used in a local lighting model to help compute the colouring for that pixel.
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