38 lines
919 B
GLSL
38 lines
919 B
GLSL
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vec2 mapping_octahedron(vec3 cubevec, vec2 texel_size)
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{
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/* projection onto octahedron */
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cubevec /= dot( vec3(1), abs(cubevec) );
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/* out-folding of the downward faces */
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if ( cubevec.z < 0.0 ) {
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cubevec.xy = (1.0 - abs(cubevec.yx)) * sign(cubevec.xy);
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}
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/* mapping to [0;1]ˆ2 texture space */
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vec2 uvs = cubevec.xy * (0.5) + 0.5;
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/* edge filtering fix */
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uvs = (1.0 - 2.0 * texel_size) * uvs + texel_size;
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return uvs;
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}
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vec4 textureLod_octahedron(sampler2DArray tex, vec4 cubevec, float lod, float lod_max)
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{
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vec2 texelSize = 1.0 / vec2(textureSize(tex, int(lod_max)));
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vec2 uvs = mapping_octahedron(cubevec.xyz, texelSize);
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return textureLod(tex, vec3(uvs, cubevec.w), lod);
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}
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vec4 texture_octahedron(sampler2DArray tex, vec4 cubevec)
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{
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vec2 texelSize = 1.0 / vec2(textureSize(tex, 0));
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vec2 uvs = mapping_octahedron(cubevec.xyz, texelSize);
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return texture(tex, vec3(uvs, cubevec.w));
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}
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