95 lines
3.6 KiB
C++
95 lines
3.6 KiB
C++
// regcombine.cpp
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//
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// Copyright (C) 2001, Chris Laurel <claurel@shatters.net>
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//
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// Some functions for setting up the nVidia register combiners
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// extension for pretty rendering effects.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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#include "gl.h"
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#include "glext.h"
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#include "regcombine.h"
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void SetupCombinersBumpMap(CTexture& bumpTexture,
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CTexture& normalizationTexture,
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float* ambientColor)
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{
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glEnable(GL_REGISTER_COMBINERS_NV);
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glDisable(GL_LIGHTING);
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glActiveTextureARB(GL_TEXTURE1_ARB);
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glEnable(GL_TEXTURE_CUBE_MAP_EXT);
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glBindTexture(GL_TEXTURE_2D, normalizationTexture.getName());
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glActiveTextureARB(GL_TEXTURE0_ARB);
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glEnable(GL_TEXTURE_2D);
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glBindTexture(GL_TEXTURE_2D, bumpTexture.getName());
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// Just a single combiner stage required . . .
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glCombinerParameteriNV(GL_NUM_GENERAL_COMBINERS_NV, 1);
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glCombinerParameterfvNV(GL_CONSTANT_COLOR0_NV, ambientColor);
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// Compute N dot L in the RGB portion of combiner 0
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// Load register A with a normal N from the normal map
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glCombinerInputNV(GL_COMBINER0_NV, GL_RGB,
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GL_VARIABLE_A_NV, GL_TEXTURE0_ARB,
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GL_EXPAND_NORMAL_NV, GL_RGB);
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// Load register B with the normalized light direction L
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glCombinerInputNV(GL_COMBINER0_NV, GL_RGB,
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GL_VARIABLE_B_NV, GL_TEXTURE1_ARB,
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GL_EXPAND_NORMAL_NV, GL_RGB);
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// Compute N dot L
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glCombinerOutputNV(GL_COMBINER0_NV, GL_RGB,
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GL_SPARE0_NV, GL_DISCARD_NV, GL_DISCARD_NV,
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GL_NONE, GL_NONE, GL_TRUE, GL_FALSE, GL_FALSE);
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// Compute the self-shadowing term in the alpha portion of combiner 0
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// A = 1
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glCombinerInputNV(GL_COMBINER0_NV, GL_ALPHA, GL_VARIABLE_A_NV,
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GL_ZERO, GL_UNSIGNED_INVERT_NV, GL_ALPHA);
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// B = L.z
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glCombinerInputNV(GL_COMBINER0_NV, GL_ALPHA, GL_VARIABLE_B_NV,
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GL_TEXTURE1_ARB, GL_EXPAND_NORMAL_NV, GL_BLUE);
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// C = 1
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glCombinerInputNV(GL_COMBINER0_NV, GL_ALPHA, GL_VARIABLE_C_NV,
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GL_ZERO, GL_UNSIGNED_INVERT_NV, GL_ALPHA);
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// D = L.z
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glCombinerInputNV(GL_COMBINER0_NV, GL_ALPHA, GL_VARIABLE_D_NV,
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GL_TEXTURE1_ARB, GL_EXPAND_NORMAL_NV, GL_BLUE);
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// Create a steep ramp function for self-shadowing
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// SPARE0 = 4*(A*B+C*D) = 4*(1*L.z + 1*L.z) = 8 * L.z
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glCombinerOutputNV(GL_COMBINER0_NV, GL_ALPHA,
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GL_DISCARD_NV, GL_DISCARD_NV, GL_SPARE0_NV,
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GL_SCALE_BY_FOUR_NV, GL_NONE, GL_FALSE, GL_FALSE, GL_FALSE);
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// A = SPARE0_alpha = per-pixel self-shadowing term
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glFinalCombinerInputNV(GL_VARIABLE_A_NV,
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GL_SPARE0_NV, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);
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glFinalCombinerInputNV(GL_VARIABLE_B_NV,
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GL_SPARE0_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
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// D = ambient color
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glFinalCombinerInputNV(GL_VARIABLE_D_NV,
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GL_CONSTANT_COLOR0_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
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// G = diffuse illumination contribution = L dot N
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glFinalCombinerInputNV(GL_VARIABLE_G_NV,
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GL_SPARE0_NV, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);
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}
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void DisableCombiners()
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{
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glDisable(GL_REGISTER_COMBINERS_NV);
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glActiveTextureARB(GL_TEXTURE1_ARB);
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glDisable(GL_TEXTURE_CUBE_MAP_EXT);
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glActiveTextureARB(GL_TEXTURE0_ARB);
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}
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