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| Back to [[VTKShaders]]
| | You can download this file at [[Media:Phong.xml]]. |
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| <pre>
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| <?xml version="1.0" encoding="UTF-8"?>
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| <!--
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| This shader implements Phong shading. Phong shading is equivalent to
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| the Gouraud implemented by the standard OpenGL pipeline except that
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| instead of doing lighting caluclations on vertices and interpolating
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| colors, normals are interpolated and lighting is performed per fragment.
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| This can result in a much smoother surface.
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| Copyright 2006 Sandia Corporation.
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| Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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| license for use of this work by or on behalf of the
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| U.S. Government. Redistribution and use in source and binary forms, with
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| or without modification, are permitted provided that this Notice and any
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| statement of authorship are reproduced on all copies.
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| -->
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| <Material name="Phong"
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| number_of_properties="0"
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| number_of_vertex_shaders="1"
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| number_of_fragment_shaders="1">
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| <Shader scope="Vertex"
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| name="PhongVert"
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| location="Inline"
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| language="GLSL"
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| entry="main">
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| /* This is a vertex program for phong shading. Since the lighting is done
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| * in the fragment shader, it basically just transforms the vertices and
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| * passes the lighting parameters.
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| */
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| /*
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| * Copyright 2006 Sandia Corporation.
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| * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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| * license for use of this work by or on behalf of the
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| * U.S. Government. Redistribution and use in source and binary forms, with
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| * or without modification, are permitted provided that this Notice and any
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| * statement of authorship are reproduced on all copies.
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| */
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| varying vec3 Normal;
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| varying vec4 EyePosition;
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| void main(void)
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| {
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| gl_Position = ftransform();
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| /* Compute the position in eye coordinates. */
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| EyePosition = gl_ModelViewMatrix*gl_Vertex;
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| /* Transform the normal. */
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| Normal = normalize(gl_NormalMatrix*gl_Normal);
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| /* Pass lighting and coloring parameters. */
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| gl_FrontColor = gl_Color;
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| gl_BackColor = gl_Color;
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| gl_TexCoord[0] = gl_MultiTexCoord0;
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| }
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| </Shader>
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| <Shader scope="Fragment"
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| name="PhongFrag"
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| location="Inline"
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| language="GLSL"
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| entry="main">
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| <LightUniform name="NumLights" value="NumberOfLights"/>
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| /* This is a fragment program for phong shading.
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| *
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| * This shader performs 2 sided lighting, but assumes that all lights are
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| * directional (changing that would be pretty easy to fix).
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| *
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| * This shader supports up to 5 lights. The number 5 was picked because that is
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| * how many lights are created by light kit.
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| *
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| * This shader does not support mapping scalars to colors. You need to make
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| * custom variations of the shader to either do texture lookups or to
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| * replace the diffuse term with gl_Color.
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| */
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| /*
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| * Copyright 2006 Sandia Corporation.
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| * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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| * license for use of this work by or on behalf of the
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| * U.S. Government. Redistribution and use in source and binary forms, with
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| * or without modification, are permitted provided that this Notice and any
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| * statement of authorship are reproduced on all copies.
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| */
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| varying vec3 Normal;
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| varying vec4 EyePosition;
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| uniform int NumLights;
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| /* Compute the contribution from a particular light source. This basically
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| * comes straight out of the OpenGL orange book. */
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| void DirectionalLight(in int lightIndex,
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| in vec3 normal,
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| inout vec4 ambient,
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| inout vec4 diffuse,
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| inout vec4 specular)
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| {
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| /**** Compute ambient term. ****/
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| ambient += gl_LightSource[lightIndex].ambient;
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| /**** Compute diffuse term. ****/
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| /* normal dot light direction. Assume the light direction vector is already
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| normalized.*/
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| float nDotL = max(0.0, dot(normal,
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| normalize(vec3(gl_LightSource[lightIndex].position))));
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| diffuse += gl_LightSource[lightIndex].diffuse * nDotL;
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| /**** Compute specular term. ****/
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| /* normal dot halfway vector */
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| float nDotH = max(0.0, dot(normal,
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| vec3(gl_LightSource[lightIndex].halfVector)));
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| float pf; /* Power factor. */
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| if (nDotH <= 0.0)
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| {
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| pf = 0.0;
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| }
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| else
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| {
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| pf = pow(nDotH, gl_FrontMaterial.shininess);
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| }
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| specular += gl_LightSource[lightIndex].specular * pf;
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| }
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| void AllLights(in vec3 normal,
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| inout vec4 ambient,
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| inout vec4 diffuse,
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| inout vec4 specular)
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| {
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| DirectionalLight(0, normal, ambient, diffuse, specular);
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| if (NumLights > 1)
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| {
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| DirectionalLight(1, normal, ambient, diffuse, specular);
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| if (NumLights > 2)
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| {
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| DirectionalLight(2, normal, ambient, diffuse, specular);
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| if (NumLights > 3)
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| {
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| DirectionalLight(3, normal, ambient, diffuse, specular);
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| if (NumLights > 4)
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| {
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| DirectionalLight(4, normal, ambient, diffuse, specular);
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| }
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| }
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| }
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| }
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| }
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| void main(void)
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| {
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| /* If lighting the back of a polygon, flip normal.*/
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| vec3 normal = normalize(Normal);
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| /* Compute light contributions. */
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| vec4 ambient = vec4(0.0);
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| vec4 diffuse = vec4(0.0);
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| vec4 specular = vec4(0.0);
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| AllLights(normal, ambient, diffuse, specular);
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| gl_FragColor = ( ambient*gl_FrontMaterial.ambient
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| + diffuse*gl_FrontMaterial.diffuse
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| + specular*gl_FrontMaterial.specular);
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| }
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| </Shader>
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| </Material>
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| </pre>
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| Back to [[VTKShaders]]
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