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/****************************************************************************
* MeshLab o o *
* An extendible mesh processor o o *
* _ O _ *
* Copyright(C) 2005, 2009 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
//
// Cook-Torrance reflectance model (per-pixel)
//
// by
// Massimiliano Corsini
// Visual Computing Lab (2006)
//
varying vec3 normal;
varying vec3 vpos;
// gaussian coefficient
uniform float C;
// index of refraction
uniform float ni;
void main()
{
// the material propertise are embedded in the shader (for now)
vec4 mat_ambient = vec4(1.0, 1.0, 1.0, 1.0);
vec4 mat_diffuse = gl_Color;//vec4(1.0, 1.0, 1.0, 1.0);
vec4 mat_specular= vec4(1.0, 1.0, 1.0, 1.0);
// normalize interpolated normal
vec3 N = normalize(normal);
// light vector
vec3 L = normalize(gl_LightSource[0].position.xyz - vpos);
// vertex-to-eye space (view vector)
vec3 V = normalize(-vpos);
// half-vector
vec3 H = normalize(vec3(gl_LightSource[0].halfVector));
float NdotH = max(0.0, dot(N, H));
float VdotH = dot(V, H);
float NdotV = dot(N, V);
float NdotL = dot(N, L);
// D term (gaussian)
float alpha = acos(NdotH);
float D = C * exp(- alpha * alpha * C);
// Geometric factor (G)
float G1 = 2.0 * NdotH * NdotV / VdotH;
float G2 = 2.0 * NdotH * NdotL / VdotH;
float G = min(1.0, min(G1, G2));
// Fresnel Refraction (F)
float k = pow(1.0 - NdotV, 5.0);
float F = 1.0 - k + ni * k;
// ambient
vec4 ambient = mat_ambient * gl_LightSource[0].ambient;
// diffuse color
vec4 kd = mat_diffuse * gl_LightSource[0].diffuse;
gl_FragColor = ambient + kd * (F * D * G) / NdotV;
}
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