Bump Mapped Objects

The GLE32V4 library provides the following bump-mapped objects: sphere, torus, cylinder, box, tetrahedron, octahedron, disk, partial disk, and quad. A base CgleBumpObject class implements the rendering algorithm, while the various descendant classes set up the inherited normal, vertex, texture coordinate and tangent vector information needed to draw each shape. The public interface for each object is surprisingly small, and nearly all of it is inherited from the base class.

The bump-mapping algorithm uses the GL_ARB_texture_env_dot3, GL_ARB_texture_env_combine and GL_ARB_texture_cube_map extensions to create and use a vector normalization cube map, and the GL_ARB_multitexture extension to simultaneously apply a base color texture and then modify it based on the per-pixel dot product of the light vector and the normal vector from a user-supplied normal map. The cube map is shared between all objects, and is created and destroyed with static functions declared in the base class. A complete explanation of the technique can be found at http://www.paulsprojects.net.

The common base class public interface is documented below, followed by the additions specific to each individual object. Each object has an Init method and a SetSize method, and a constructor which requires no parameters and initializes the object to a default size/state. The object must be re-initialized if tangents are inverted or under other conditions noted below, and they must be initialized before SetSize is called.