47 lines
1.4 KiB
GLSL
47 lines
1.4 KiB
GLSL
out vec4 fragment;
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in vec4 gl_FragCoord;
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#include ":util/common.glsl"
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/*
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This averaging shader uses compile-time loop generation to ensure two things:
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- We can avoid requiring GL 4.3 features to dynamically index texture arrays
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- We ensure no branching occurs in this shader for optimial performance.
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The alternative is requiring the GLSL compiler to determine that a loop for
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texture array indexes (which must be determined at compile-time in 3.3) can be
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expanded if the bounds are constant. This is somewhat vendor-specific so GLava
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provides a special `#expand` macro to solve this problem in the preprocessing
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stage.
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*/
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#define SAMPLER(I) uniform sampler1D t##I;
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#expand SAMPLER _AVG_FRAMES
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#define WIN_FUNC window_frame
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void main() {
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float r = 0;
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/* Disable windowing for two frames (distorts results) */
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#if _AVG_FRAMES == 2
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#define _AVG_WINDOW 0
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#endif
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/* Use 'shallow' windowing for 3 frames to ensure the first & last
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frames have a reasonable amount of weight */
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#if _AVG_FRAMES == 3
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#define WIN_FUNC window_shallow
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#endif
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#if _AVG_WINDOW == 0
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#define F(I) r += texelFetch(t##I, int(gl_FragCoord.x), 0).r
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#else
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#define F(I) r += window(I, _AVG_FRAMES - 1) * texelFetch(t##I, int(gl_FragCoord.x), 0).r
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#endif
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#expand F _AVG_FRAMES
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fragment.r = r / _AVG_FRAMES;
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}
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