1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
vec2 mapping_octahedron(vec3 cubevec, vec2 texel_size)
{
/* projection onto octahedron */
cubevec /= dot( vec3(1), abs(cubevec) );
/* out-folding of the downward faces */
if ( cubevec.z < 0.0 ) {
cubevec.xy = (1.0 - abs(cubevec.yx)) * sign(cubevec.xy);
}
/* mapping to [0;1]ˆ2 texture space */
vec2 uvs = cubevec.xy * (0.5) + 0.5;
/* edge filtering fix */
uvs *= 1.0 - 2.0 * texel_size;
uvs += texel_size;
return uvs;
}
vec4 textureLod_octahedron(sampler2DArray tex, vec4 cubevec, float lod, float lod_max)
{
vec2 texelSize = 1.0 / vec2(textureSize(tex, int(lod_max)));
vec2 uvs = mapping_octahedron(cubevec.xyz, texelSize);
return textureLod(tex, vec3(uvs, cubevec.w), lod);
}
vec4 texture_octahedron(sampler2DArray tex, vec4 cubevec)
{
vec2 texelSize = 1.0 / vec2(textureSize(tex, 0));
vec2 uvs = mapping_octahedron(cubevec.xyz, texelSize);
return texture(tex, vec3(uvs, cubevec.w));
}
|
