41 lines
1.2 KiB
GLSL
41 lines
1.2 KiB
GLSL
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#version 330 core
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layout(location = 0) in vec4 pos;
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layout(location = 3) in vec4 multitexcoord0;
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out vec3 cubemap_coord;
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uniform mat4 osg_ModelViewProjectionMatrix;
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uniform int fg_CubemapFace;
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void main()
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{
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gl_Position = osg_ModelViewProjectionMatrix * pos;
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vec2 texcoord = multitexcoord0.xy * 2.0 - 1.0;
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// Map the quad texture coordinates to a direction vector to sample
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// the cubemap. This assumes that we are using the weird left-handed
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// orientations given by the OpenGL spec.
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// See https://www.khronos.org/opengl/wiki/Cubemap_Texture#Upload_and_orientation
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switch(fg_CubemapFace) {
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case 0: // +X
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cubemap_coord = vec3(1.0, -texcoord.y, -texcoord.x);
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break;
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case 1: // -X
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cubemap_coord = vec3(-1.0, -texcoord.y, texcoord.x);
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break;
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case 2: // +Y
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cubemap_coord = vec3(texcoord.x, 1.0, texcoord.y);
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break;
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case 3: // -Y
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cubemap_coord = vec3(texcoord.x, -1.0, -texcoord.y);
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break;
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case 4: // +Z
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cubemap_coord = vec3(texcoord.x, -texcoord.y, 1.0);
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break;
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case 5: // -Z
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cubemap_coord = vec3(-texcoord.x, -texcoord.y, -1.0);
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break;
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}
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}
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