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