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'''OpenGL extension APPLE.specular_vector
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This module customises the behaviour of the
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OpenGL.raw.GL.APPLE.specular_vector to provide a more
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Overview (from the spec)
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An alternative specular lighting model is enabled by passing
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the LIGHT_MODEL_SPECULAR_VECTOR token as the <pname> parameter
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to LightModel, and TRUE as the <param> parameter. The specular
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vector lighting model calculates the specular intensity as the
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dot product of the true reflection vector of the light source
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and the vector from the vertex to the viewpoint. This yields
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results that are visually similar to but often more realistic
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than the existing lighting model.
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Mathematically, the specular component s.n in the existing
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lighting model calculation is replaced with the following
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alternative calculation.
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Given three vectors, n, l, and p, where n is the unit normal
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vector at the vertex, l is the unit vector from the vertex to
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the light position, and p is the unit vector from the vertex
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to the viewpoint (or the vector {0,0,1} if
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LIGHT_MODEL_LOCAL_VIEWER is false), the specular component is
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(2 * cross(n, cross(n, l)) + l) . p
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All other lighting model and material parameters (shininess,
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spotlight, attenuation, local viewer, and direction/positional
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sources) operate normally. The specular vector lighting model
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affects both rgba and index modes.
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The official definition of this extension is available here:
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http://www.opengl.org/registry/specs/APPLE/specular_vector.txt
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from OpenGL import platform, constants, constant, arrays
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from OpenGL import extensions, wrapper
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from OpenGL.GL import glget
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from OpenGL.raw.GL.APPLE.specular_vector import *
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### END AUTOGENERATED SECTION
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from OpenGL.GL import glget
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glget.addGLGetConstant( GL_LIGHT_MODEL_SPECULAR_VECTOR_APPLE, (1,) ) # check size...
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GL/APPLE/specular_vector.py
