d27174028e
Use two-pass rendering for some shaders to reduce the cost of expensive shaders. Implement some material animations using a shader uniform. Eliminate use of gl_FrontFacing. It's too buggy on ATI/ Macintosh.
55 lines
2 KiB
GLSL
55 lines
2 KiB
GLSL
// -*-C++-*-
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// Shader that uses OpenGL state values to do per-pixel lighting
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//
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// The only light used is gl_LightSource[0], which is assumed to be
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// directional.
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//
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// Diffuse colors come from the gl_Color, ambient from the material. This is
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// equivalent to osg::Material::DIFFUSE.
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#define MODE_OFF 0
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#define MODE_DIFFUSE 1
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#define MODE_AMBIENT_AND_DIFFUSE 2
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// The ambient term of the lighting equation that doesn't depend on
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// the surface normal is passed in gl_{Front,Back}Color. The alpha
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// component is set to 1 for front, 0 for back in order to work around
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// bugs with gl_FrontFacing in the fragment shader.
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varying vec4 diffuse_term;
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varying vec3 normal;
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varying float fogCoord;
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uniform int colorMode;
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void main()
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{
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vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
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gl_Position = ftransform();
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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normal = gl_NormalMatrix * gl_Normal;
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vec4 ambient_color, diffuse_color;
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if (colorMode == MODE_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_FrontMaterial.ambient;
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} else if (colorMode == MODE_AMBIENT_AND_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_Color;
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} else {
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diffuse_color = gl_FrontMaterial.diffuse;
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ambient_color = gl_FrontMaterial.ambient;
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}
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diffuse_term = diffuse_color * gl_LightSource[0].diffuse;
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vec4 ambient_term = ambient_color * gl_LightSource[0].ambient;
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// Super hack: if diffuse material alpha is less than 1, assume a
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// transparency animation is at work
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if (gl_FrontMaterial.diffuse.a < 1.0)
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diffuse_term.a = gl_FrontMaterial.diffuse.a;
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else
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diffuse_term.a = gl_Color.a;
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// Another hack for supporting two-sided lighting without using
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// gl_FrontFacing in the fragment shader.
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gl_FrontColor.rgb = ambient_term.rgb; gl_FrontColor.a = 1.0;
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gl_BackColor.rgb = ambient_term.rgb; gl_FrontColor.a = 0.0;
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fogCoord = abs(ecPosition.z / ecPosition.w);
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}
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