32 lines
1.0 KiB
GLSL
32 lines
1.0 KiB
GLSL
#ifndef _LIGHT_COMMON_GLSL_
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#define _LIGHT_COMMON_GLSL_
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#ifdef _Spot
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float spotlightMask(const vec3 dir, const vec3 spotDir, const vec3 right, const vec2 scale, const float spotSize, const float spotBlend) {
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// Project the fragment's light dir to the z axis in the light's local space
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float localZ = dot(spotDir, dir);
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if (localZ < 0) {
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return 0.0; // Discard opposite cone
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}
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vec3 up = cross(spotDir, right);
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// Scale the incoming light direction to treat the spotlight's ellipse as if
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// it was 1 unit away from the light source, this way the smoothstep below
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// works independently of the distance
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vec3 scaledDir = dir.xyz / localZ;
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// Project to right and up vectors to apply axis scale
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float localX = dot(scaledDir, right) / scale.x;
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float localY = dot(scaledDir, up) / scale.y;
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// Inverse of length of vector from ellipse to light (scaledDir.z == 1.0)
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float ellipse = inversesqrt(localX * localX + localY * localY + 1.0);
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return smoothstep(0.0, 1.0, (ellipse - spotSize) / spotBlend);
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}
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#endif // _Spot
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#endif // _LIGHT_COMMON_GLSL_
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