Suppose that we have a normal which we wish to transform from object model coordinates to device coordinates.
Shadows are an important feature in modelling any scene.
Texture mapping is a process where an image is effectively pasted onto the surface of a polygon. This is a very commonly used technique for adding interesting surface detail to an otherwise bland polygon. The colour of scan-converted pixels in the polygon are determined by looking up point in the image. The figure below shows how texture mapping works. In order to generate the texture coordinates for other points within the polygon, binlinear interpolation is commonly used.