mirror of
https://gitlab.com/skysthelimit.dev/selenite.git
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124 lines
3.2 KiB
GLSL
124 lines
3.2 KiB
GLSL
/*
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Author: rsn8887 (based on TheMaister)
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License: Public domain
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This is an integer prescale filter that should be combined
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with a bilinear hardware filtering (GL_BILINEAR filter or some such) to achieve
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a smooth scaling result with minimum blur. This is good for pixelgraphics
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that are scaled by non-integer factors.
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The prescale factor and texel coordinates are precalculated
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in the vertex shader for speed.
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*/
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#if defined(VERTEX)
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#if __VERSION__ >= 130
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#define COMPAT_VARYING out
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#define COMPAT_ATTRIBUTE in
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#define COMPAT_TEXTURE texture
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#else
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#define COMPAT_VARYING varying
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#define COMPAT_ATTRIBUTE attribute
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#define COMPAT_TEXTURE texture2D
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#endif
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#ifdef GL_ES
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#define COMPAT_PRECISION mediump
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#else
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#define COMPAT_PRECISION
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#endif
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COMPAT_ATTRIBUTE vec4 VertexCoord;
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COMPAT_ATTRIBUTE vec4 COLOR;
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COMPAT_ATTRIBUTE vec4 TexCoord;
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COMPAT_VARYING vec4 COL0;
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COMPAT_VARYING vec4 TEX0;
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uniform mat4 MVPMatrix;
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uniform COMPAT_PRECISION int FrameDirection;
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uniform COMPAT_PRECISION int FrameCount;
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uniform COMPAT_PRECISION vec2 OutputSize;
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uniform COMPAT_PRECISION vec2 TextureSize;
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uniform COMPAT_PRECISION vec2 InputSize;
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// vertex compatibility #defines
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#define vTexCoord TEX0.xy
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#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
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#define outsize vec4(OutputSize, 1.0 / OutputSize)
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COMPAT_VARYING vec2 precalc_texel;
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COMPAT_VARYING vec2 precalc_scale;
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void main()
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{
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gl_Position = MVPMatrix * VertexCoord;
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COL0 = COLOR;
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TEX0.xy = TexCoord.xy;
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precalc_texel = vTexCoord * SourceSize.xy;
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precalc_scale = max(floor(outsize.xy / InputSize.xy), vec2(1.0, 1.0));
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}
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#elif defined(FRAGMENT)
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#if __VERSION__ >= 130
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#define COMPAT_VARYING in
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#define COMPAT_TEXTURE texture
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out vec4 FragColor;
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#else
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#define COMPAT_VARYING varying
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#define FragColor gl_FragColor
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#define COMPAT_TEXTURE texture2D
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#endif
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#ifdef GL_ES
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#ifdef GL_FRAGMENT_PRECISION_HIGH
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precision highp float;
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#else
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precision mediump float;
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#endif
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#define COMPAT_PRECISION mediump
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#else
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#define COMPAT_PRECISION
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#endif
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uniform COMPAT_PRECISION int FrameDirection;
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uniform COMPAT_PRECISION int FrameCount;
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uniform COMPAT_PRECISION vec2 OutputSize;
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uniform COMPAT_PRECISION vec2 TextureSize;
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uniform COMPAT_PRECISION vec2 InputSize;
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uniform sampler2D Texture;
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COMPAT_VARYING vec4 TEX0;
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// fragment compatibility #defines
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#define Source Texture
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#define vTexCoord TEX0.xy
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#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
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#define outsize vec4(OutputSize, 1.0 / OutputSize)
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COMPAT_VARYING vec2 precalc_texel;
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COMPAT_VARYING vec2 precalc_scale;
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void main()
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{
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vec2 texel = precalc_texel;
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vec2 scale = precalc_scale;
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vec2 texel_floored = floor(texel);
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vec2 s = fract(texel);
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vec2 region_range = 0.5 - 0.5 / scale;
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// Figure out where in the texel to sample to get correct pre-scaled bilinear.
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// Uses the hardware bilinear interpolator to avoid having to sample 4 times manually.
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vec2 center_dist = s - 0.5;
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vec2 f = (center_dist - clamp(center_dist, -region_range, region_range)) * scale + 0.5;
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vec2 mod_texel = texel_floored + f;
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FragColor = vec4(COMPAT_TEXTURE(Source, mod_texel / SourceSize.xy).rgb, 1.0);
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}
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#endif
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