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6.4 Background geometry

Background geometry is assumed to be positioned at infinite distance, that is, no perspective calculations need to be performed. It is also assumed that it has been tessellated onto a unit sphere. In addition, a background color, an image, and the bounds within which the background is active can be specified. Background geometry is rendered after the background image has been drawn. See figures 6.8–6.10.


Figure 6.8 Sphere background geometry. A texture image was applied to the sphere and normal vectors generated such that the texture is visible when viewed from within the sphere


Figure 6.9 Sphere used as background geometry, rendered as a wireframe with an applied texture image


Figure 6.10 The texture image used to generate the “sunset” effect used in AvatarTest.java. Note that the texture coordinates set by the sphere primitive require that the sunset portion of the image be split in half and inverted


From AvatarTest.java