Factor out common functions used in tile alpha shaders

resources/shaders/gl3/tile_alpha.fs.glsl

@@ -12,22 +12,54 @@
 
 
 
+#extension GL_GOOGLE_include_directive : enable
+
 precision highp float;
 
+out vec4 oFragColor;
+
+
+
+
+
+
+
+
+
+
+
+
 uniform sampler2D uStencilTexture;
 uniform sampler2D uPaintTexture;
+uniform sampler2D uDest;
 uniform vec2 uFramebufferSize;
 
 in vec2 vColorTexCoord;
 in vec2 vMaskTexCoord;
 
-out vec4 oFragColor;
 
-void main(){
+vec4 sampleSrcColor(){
     float coverage = texture(uStencilTexture, vMaskTexCoord). r;
-    vec4 color = texture(uPaintTexture, vColorTexCoord);
+    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
-    color . a *= coverage;
+    return vec4(srcRGBA . rgb, srcRGBA . a * coverage);
-    color . rgb *= color . a;
+}
-    oFragColor = color;
+
+vec4 sampleDestColor(){
+    vec2 destTexCoord = gl_FragCoord . xy / uFramebufferSize;
+    return texture(uDest, destTexCoord);
+}
+
+
+vec4 blendColors(vec4 destRGBA, vec4 srcRGBA, vec3 blendedRGB){
+    return vec4(srcRGBA . a *(1.0 - destRGBA . a)* srcRGBA . rgb +
+                srcRGBA . a * destRGBA . a * blendedRGB +
+                (1.0 - srcRGBA . a)* destRGBA . a * destRGBA . rgb,
+                1.0);
+}
+
+
+void main(){
+    vec4 srcRGBA = sampleSrcColor();
+    oFragColor = vec4(srcRGBA . rgb * srcRGBA . a, srcRGBA . a);
 }
 

resources/shaders/gl3/tile_alpha_hsl.fs.glsl

@@ -14,21 +14,54 @@
 
 #extension GL_GOOGLE_include_directive : enable
 
-
-
-
 precision highp float;
 
+uniform ivec3 uBlendHSL;
+
+out vec4 oFragColor;
+
+
+
+
+
+
+
+
+
+
+
+
 uniform sampler2D uStencilTexture;
 uniform sampler2D uPaintTexture;
 uniform sampler2D uDest;
-uniform ivec3 uBlendHSL;
 uniform vec2 uFramebufferSize;
 
 in vec2 vColorTexCoord;
 in vec2 vMaskTexCoord;
 
-out vec4 oFragColor;
+
+vec4 sampleSrcColor(){
+    float coverage = texture(uStencilTexture, vMaskTexCoord). r;
+    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
+    return vec4(srcRGBA . rgb, srcRGBA . a * coverage);
+}
+
+vec4 sampleDestColor(){
+    vec2 destTexCoord = gl_FragCoord . xy / uFramebufferSize;
+    return texture(uDest, destTexCoord);
+}
+
+
+vec4 blendColors(vec4 destRGBA, vec4 srcRGBA, vec3 blendedRGB){
+    return vec4(srcRGBA . a *(1.0 - destRGBA . a)* srcRGBA . rgb +
+                srcRGBA . a * destRGBA . a * blendedRGB +
+                (1.0 - srcRGBA . a)* destRGBA . a * destRGBA . rgb,
+                1.0);
+}
+
+
+
+
 
 
 
@@ -65,12 +98,8 @@ vec3 convertRGBToHSL(vec3 rgb){
 }
 
 void main(){
-    float coverage = texture(uStencilTexture, vMaskTexCoord). r;
+    vec4 srcRGBA = sampleSrcColor();
-    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
+    vec4 destRGBA = sampleDestColor();
-    srcRGBA . a *= coverage;
-
-    vec2 destTexCoord = gl_FragCoord . xy / uFramebufferSize;
-    vec4 destRGBA = texture(uDest, destTexCoord);
 
     vec3 destHSL = convertRGBToHSL(destRGBA . rgb);
     vec3 srcHSL = convertRGBToHSL(srcRGBA . rgb);
@@ -80,11 +109,6 @@ void main(){
                            blendDest . z ? destHSL . z : srcHSL . z);
     vec3 blendedRGB = convertHSLToRGB(blendedHSL);
 
-
+    oFragColor = blendColors(destRGBA, srcRGBA, blendedRGB);
-    vec4 color = vec4(srcRGBA . a *(1.0 - destRGBA . a)* srcRGBA . rgb +
-                      srcRGBA . a * destRGBA . a * blendedRGB +
-                      (1.0 - srcRGBA . a)* destRGBA . a * destRGBA . rgb,
-                      1.0);
-    oFragColor = color;
 }
 

resources/shaders/metal/tile_alpha.fs.metal

@@ -1,4 +1,6 @@
 // Automatically generated from files in pathfinder/shaders/. Do not edit!
+#pragma clang diagnostic ignored "-Wmissing-prototypes"
+
 #include <metal_stdlib>
 #include <simd/simd.h>
 
@@ -23,15 +25,18 @@ struct main0_in
     float2 vMaskTexCoord [[user(locn1)]];
 };
 
+float4 sampleSrcColor(thread texture2d<float> uStencilTexture, thread const sampler uStencilTextureSmplr, thread float2& vMaskTexCoord, thread texture2d<float> uPaintTexture, thread const sampler uPaintTextureSmplr, thread float2& vColorTexCoord)
+{
+    float coverage = uStencilTexture.sample(uStencilTextureSmplr, vMaskTexCoord).x;
+    float4 srcRGBA = uPaintTexture.sample(uPaintTextureSmplr, vColorTexCoord);
+    return float4(srcRGBA.xyz, srcRGBA.w * coverage);
+}
+
 fragment main0_out main0(main0_in in [[stage_in]], constant spvDescriptorSetBuffer0& spvDescriptorSet0 [[buffer(0)]])
 {
     main0_out out = {};
-    float coverage = spvDescriptorSet0.uStencilTexture.sample(spvDescriptorSet0.uStencilTextureSmplr, in.vMaskTexCoord).x;
+    float4 srcRGBA = sampleSrcColor(spvDescriptorSet0.uStencilTexture, spvDescriptorSet0.uStencilTextureSmplr, in.vMaskTexCoord, spvDescriptorSet0.uPaintTexture, spvDescriptorSet0.uPaintTextureSmplr, in.vColorTexCoord);
-    float4 color = spvDescriptorSet0.uPaintTexture.sample(spvDescriptorSet0.uPaintTextureSmplr, in.vColorTexCoord);
+    out.oFragColor = float4(srcRGBA.xyz * srcRGBA.w, srcRGBA.w);
-    color.w *= coverage;
-    float3 _41 = color.xyz * color.w;
-    color = float4(_41.x, _41.y, _41.z, color.w);
-    out.oFragColor = color;
     return out;
 }
 

resources/shaders/metal/tile_alpha_hsl.fs.metal

@@ -36,6 +36,19 @@ Tx mod(Tx x, Ty y)
     return x - y * floor(x / y);
 }
 
+float4 sampleSrcColor(thread texture2d<float> uStencilTexture, thread const sampler uStencilTextureSmplr, thread float2& vMaskTexCoord, thread texture2d<float> uPaintTexture, thread const sampler uPaintTextureSmplr, thread float2& vColorTexCoord)
+{
+    float coverage = uStencilTexture.sample(uStencilTextureSmplr, vMaskTexCoord).x;
+    float4 srcRGBA = uPaintTexture.sample(uPaintTextureSmplr, vColorTexCoord);
+    return float4(srcRGBA.xyz, srcRGBA.w * coverage);
+}
+
+float4 sampleDestColor(thread float4& gl_FragCoord, thread float2 uFramebufferSize, thread texture2d<float> uDest, thread const sampler uDestSmplr)
+{
+    float2 destTexCoord = gl_FragCoord.xy / uFramebufferSize;
+    return uDest.sample(uDestSmplr, destTexCoord);
+}
+
 float3 convertRGBToHSL(thread const float3& rgb)
 {
     float v = fast::max(rgb.y, rgb.z);
@@ -77,51 +90,55 @@ float3 convertHSLToRGB(thread const float3& hsl)
     return hsl.zzz - (fast::clamp(fast::min(ks - float3(3.0), float3(9.0) - ks), float3(-1.0), float3(1.0)) * a);
 }
 
+float4 blendColors(thread const float4& destRGBA, thread const float4& srcRGBA, thread const float3& blendedRGB)
+{
+    return float4(((srcRGBA.xyz * (srcRGBA.w * (1.0 - destRGBA.w))) + (blendedRGB * (srcRGBA.w * destRGBA.w))) + (destRGBA.xyz * ((1.0 - srcRGBA.w) * destRGBA.w)), 1.0);
+}
+
 fragment main0_out main0(main0_in in [[stage_in]], constant spvDescriptorSetBuffer0& spvDescriptorSet0 [[buffer(0)]], float4 gl_FragCoord [[position]])
 {
     main0_out out = {};
-    float coverage = spvDescriptorSet0.uStencilTexture.sample(spvDescriptorSet0.uStencilTextureSmplr, in.vMaskTexCoord).x;
+    float4 srcRGBA = sampleSrcColor(spvDescriptorSet0.uStencilTexture, spvDescriptorSet0.uStencilTextureSmplr, in.vMaskTexCoord, spvDescriptorSet0.uPaintTexture, spvDescriptorSet0.uPaintTextureSmplr, in.vColorTexCoord);
-    float4 srcRGBA = spvDescriptorSet0.uPaintTexture.sample(spvDescriptorSet0.uPaintTextureSmplr, in.vColorTexCoord);
+    float4 destRGBA = sampleDestColor(gl_FragCoord, (*spvDescriptorSet0.uFramebufferSize), spvDescriptorSet0.uDest, spvDescriptorSet0.uDestSmplr);
-    srcRGBA.w *= coverage;
-    float2 destTexCoord = gl_FragCoord.xy / (*spvDescriptorSet0.uFramebufferSize);
-    float4 destRGBA = spvDescriptorSet0.uDest.sample(spvDescriptorSet0.uDestSmplr, destTexCoord);
     float3 param = destRGBA.xyz;
     float3 destHSL = convertRGBToHSL(param);
     float3 param_1 = srcRGBA.xyz;
     float3 srcHSL = convertRGBToHSL(param_1);
     bool3 blendDest = (*spvDescriptorSet0.uBlendHSL) == int3(0);
-    float _225;
+    float _281;
     if (blendDest.x)
     {
-        _225 = destHSL.x;
+        _281 = destHSL.x;
     }
     else
     {
-        _225 = srcHSL.x;
+        _281 = srcHSL.x;
     }
-    float _236;
+    float _292;
     if (blendDest.y)
     {
-        _236 = destHSL.y;
+        _292 = destHSL.y;
     }
     else
     {
-        _236 = srcHSL.y;
+        _292 = srcHSL.y;
     }
-    float _247;
+    float _303;
     if (blendDest.z)
     {
-        _247 = destHSL.z;
+        _303 = destHSL.z;
     }
     else
     {
-        _247 = srcHSL.z;
+        _303 = srcHSL.z;
     }
-    float3 blendedHSL = float3(_225, _236, _247);
+    float3 blendedHSL = float3(_281, _292, _303);
     float3 param_2 = blendedHSL;
     float3 blendedRGB = convertHSLToRGB(param_2);
-    float4 color = float4(((srcRGBA.xyz * (srcRGBA.w * (1.0 - destRGBA.w))) + (blendedRGB * (srcRGBA.w * destRGBA.w))) + (destRGBA.xyz * ((1.0 - srcRGBA.w) * destRGBA.w)), 1.0);
+    float4 param_3 = destRGBA;
-    out.oFragColor = color;
+    float4 param_4 = srcRGBA;
+    float3 param_5 = blendedRGB;
+    out.oFragColor = blendColors(param_3, param_4, param_5);
     return out;
 }
 

shaders/Makefile

@@ -33,6 +33,7 @@ SHADERS=\
 INCLUDES=\
 	filter_text_convolve.inc.glsl \
 	filter_text_gamma_correct.inc.glsl \
+	tile_alpha_sample.inc.glsl \
 	$(EMPTY)
 
 OUT=\

shaders/tile_alpha.fs.glsl

@@ -10,21 +10,15 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#extension GL_GOOGLE_include_directive : enable
+
 precision highp float;
 
-uniform sampler2D uStencilTexture;
-uniform sampler2D uPaintTexture;
-uniform vec2 uFramebufferSize;
-
-in vec2 vColorTexCoord;
-in vec2 vMaskTexCoord;
-
 out vec4 oFragColor;
 
+#include "tile_alpha_sample.inc.glsl"
+
 void main() {
-    float coverage = texture(uStencilTexture, vMaskTexCoord).r;
+    vec4 srcRGBA = sampleSrcColor();
-    vec4 color = texture(uPaintTexture, vColorTexCoord);
+    oFragColor = vec4(srcRGBA.rgb * srcRGBA.a, srcRGBA.a);
-    color.a *= coverage;
-    color.rgb *= color.a;
-    oFragColor = color;
 }

shaders/tile_alpha_hsl.fs.glsl

@@ -12,26 +12,21 @@
 
 #extension GL_GOOGLE_include_directive : enable
 
-#define BLEND_TERM_DEST 0
-#define BLEND_TERM_SRC  1
-
 precision highp float;
 
-uniform sampler2D uStencilTexture;
-uniform sampler2D uPaintTexture;
-uniform sampler2D uDest;
 uniform ivec3 uBlendHSL;
-uniform vec2 uFramebufferSize;
-
-in vec2 vColorTexCoord;
-in vec2 vMaskTexCoord;
 
 out vec4 oFragColor;
 
+#include "tile_alpha_sample.inc.glsl"
+
 #define PI_2        6.283185307179586
 #define DEG_30_INV  1.9098593171027443
 #define DEG_60      1.0471975511965976
 
+#define BLEND_TERM_DEST 0
+#define BLEND_TERM_SRC  1
+
 // https://en.wikipedia.org/wiki/HSL_and_HSV#HSL_to_RGB_alternative
 vec3 convertHSLToRGB(vec3 hsl) {
     float a = hsl.y * min(hsl.z, 1.0 - hsl.z);
@@ -63,12 +58,8 @@ vec3 convertRGBToHSL(vec3 rgb) {
 }
 
 void main() {
-    float coverage = texture(uStencilTexture, vMaskTexCoord).r;
+    vec4 srcRGBA = sampleSrcColor();
-    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
+    vec4 destRGBA = sampleDestColor();
-    srcRGBA.a *= coverage;
-
-    vec2 destTexCoord = gl_FragCoord.xy / uFramebufferSize;
-    vec4 destRGBA = texture(uDest, destTexCoord);
 
     vec3 destHSL = convertRGBToHSL(destRGBA.rgb);
     vec3 srcHSL = convertRGBToHSL(srcRGBA.rgb);
@@ -78,10 +69,5 @@ void main() {
                            blendDest.z ? destHSL.z : srcHSL.z);
     vec3 blendedRGB = convertHSLToRGB(blendedHSL);
 
-    // FIXME(pcwalton): What should the output alpha be here?
+    oFragColor = blendColors(destRGBA, srcRGBA, blendedRGB);
-    vec4 color = vec4(srcRGBA.a * (1.0 - destRGBA.a) * srcRGBA.rgb +
-                      srcRGBA.a * destRGBA.a * blendedRGB +
-                      (1.0 - srcRGBA.a) * destRGBA.a * destRGBA.rgb,
-                      1.0);
-    oFragColor = color;
 }

shaders/tile_alpha_sample.inc.glsl

@@ -0,0 +1,37 @@
+// pathfinder/shaders/tile_alpha_sample.inc.glsl
+//
+// Copyright © 2020 The Pathfinder Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+uniform sampler2D uStencilTexture;
+uniform sampler2D uPaintTexture;
+uniform sampler2D uDest;
+uniform vec2 uFramebufferSize;
+
+in vec2 vColorTexCoord;
+in vec2 vMaskTexCoord;
+
+// NB: This does not premultiply.
+vec4 sampleSrcColor() {
+    float coverage = texture(uStencilTexture, vMaskTexCoord).r;
+    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
+    return vec4(srcRGBA.rgb, srcRGBA.a * coverage);
+}
+
+vec4 sampleDestColor() {
+    vec2 destTexCoord = gl_FragCoord.xy / uFramebufferSize;
+    return texture(uDest, destTexCoord);
+}
+
+// FIXME(pcwalton): What should the output alpha be here?
+vec4 blendColors(vec4 destRGBA, vec4 srcRGBA, vec3 blendedRGB) {
+    return vec4(srcRGBA.a * (1.0 - destRGBA.a) * srcRGBA.rgb +
+                srcRGBA.a * destRGBA.a * blendedRGB +
+                (1.0 - srcRGBA.a) * destRGBA.a * destRGBA.rgb,
+                1.0);
+}