From ed8cffbff8539bda975a8e55d7517ffd9693e8fa Mon Sep 17 00:00:00 2001
From: FMS-Cat <yutaka.obuchi@gmail.com>
Date: Sun, 14 Mar 2021 18:43:26 +0900
Subject: [PATCH] performance: improve PixelSorter performance

---
 src/entities/PixelSorter.ts         | 29 +++++++++++++++++------------
 src/shaders/pixel-sorter-index.frag |  9 ++++-----
 src/shaders/pixel-sorter.frag       | 11 +++++------
 3 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/src/entities/PixelSorter.ts b/src/entities/PixelSorter.ts
index b77c1e1..07233d1 100644
--- a/src/entities/PixelSorter.ts
+++ b/src/entities/PixelSorter.ts
@@ -39,17 +39,21 @@ export class PixelSorter {
       new BufferRenderTarget( {
         width: options.target.width,
         height: options.target.height,
-        numBuffers: 2,
         name: process.env.DEV && 'PixelSorter/swap0',
       } ),
       new BufferRenderTarget( {
         width: options.target.width,
         height: options.target.height,
-        numBuffers: 2,
         name: process.env.DEV && 'PixelSorter/swap1',
       } ),
     );
 
+    const bufferIndex = new BufferRenderTarget( {
+      width: options.target.width,
+      height: options.target.height,
+      name: process.env.DEV && 'PixelSorter/index',
+    } );
+
     // -- bypass -----------------------------------------------------------------------------------
     const materialReturn = new Material(
       quadVert,
@@ -70,7 +74,7 @@ export class PixelSorter {
     const indexMaterials: Material[] = [];
 
     while ( mul < options.target.width ) {
-      const isFirst = mul === 1;
+      const isLast = ( mul * 8 > options.target.width );
 
       const material = new Material(
         quadVert,
@@ -79,16 +83,16 @@ export class PixelSorter {
       material.addUniform( 'mul', '1f', mul );
       material.addUniformTexture(
         'sampler0',
-        isFirst ? options.input : this.swapBuffer.o.getTexture( gl.COLOR_ATTACHMENT0 ),
+        options.input,
       );
       material.addUniformTexture(
         'sampler1',
-        this.swapBuffer.o.getTexture( gl.COLOR_ATTACHMENT1 ),
+        this.swapBuffer.o.texture,
       );
       indexMaterials.push( material );
 
       entityMain.components.push( new Quad( {
-        target: this.swapBuffer.i,
+        target: isLast ? bufferIndex : this.swapBuffer.i,
         material,
         name: process.env.DEV && `PixelSorter/quadIndex-${ mul }`,
       } ) );
@@ -99,11 +103,12 @@ export class PixelSorter {
     }
 
     // -- sort -------------------------------------------------------------------------------------
-    let dir = 1.0 / 64.0;
-    let comp = 1.0 / 64.0;
+    let dir = 1.0 / 32.0;
+    let comp = 1.0 / 32.0;
 
     while ( dir < 1.0 ) {
-      const isLast = ( dir === 0.5 ) && ( comp === 1.0 / 64.0 );
+      const isFirst = dir === 1.0 / 32.0;
+      const isLast = ( dir === 0.5 ) && ( comp === 1.0 / 32.0 );
 
       const material = new Material(
         quadVert,
@@ -113,11 +118,11 @@ export class PixelSorter {
       material.addUniform( 'comp', '1f', comp );
       material.addUniformTexture(
         'sampler0',
-        this.swapBuffer.o.getTexture( gl.COLOR_ATTACHMENT0 ),
+        isFirst ? options.input : this.swapBuffer.o.texture,
       );
       material.addUniformTexture(
         'sampler1',
-        this.swapBuffer.o.getTexture( gl.COLOR_ATTACHMENT1 ),
+        bufferIndex.texture,
       );
 
       entityMain.components.push( new Quad( {
@@ -128,7 +133,7 @@ export class PixelSorter {
 
       this.swapBuffer.swap();
 
-      if ( comp === 1.0 / 64.0 ) {
+      if ( comp === 1.0 / 32.0 ) {
         dir *= 2.0;
         comp = dir;
       } else {
diff --git a/src/shaders/pixel-sorter-index.frag b/src/shaders/pixel-sorter-index.frag
index 49aab74..d4035a4 100644
--- a/src/shaders/pixel-sorter-index.frag
+++ b/src/shaders/pixel-sorter-index.frag
@@ -6,8 +6,7 @@ const vec3 RGB = vec3( 0.299, 0.587, 0.114 );
 
 in vec2 vUv;
 
-layout (location = 0) out vec4 fragColor;
-layout (location = 1) out vec4 fragClamp;
+out vec4 fragColor;
 
 uniform float threshold;
 uniform float mul;
@@ -26,12 +25,12 @@ vec2 getValue( vec2 uv ) {
 void main() {
   vec2 uv = vUv;
 
-  fragColor = vec4( texture( sampler0, uv ).xyz, 1.0 );
-  fragClamp = vec4( getValue( uv ), 0.0, 1.0 );
+  vec4 tex = vec4( texture( sampler0, uv ).xyz, 1.0 );
+  fragColor = vec4( getValue( uv ), 0.0, 1.0 );
 
   for ( int i = 1; i < 8; i ++ ) {
     vec2 uvc = uv - vec2( i, 0 ) / resolution * mul;
     vec2 texc = getValue( uvc );
-    fragClamp.xy = min( fragClamp.xy, texc + mul * float( i ) );
+    fragColor.xy = min( fragColor.xy, texc + mul * float( i ) );
   }
 }
diff --git a/src/shaders/pixel-sorter.frag b/src/shaders/pixel-sorter.frag
index 8015014..82493a1 100644
--- a/src/shaders/pixel-sorter.frag
+++ b/src/shaders/pixel-sorter.frag
@@ -8,8 +8,7 @@ const vec3 RGB = vec3( 0.299, 0.587, 0.114 );
 
 in vec2 vUv;
 
-layout (location = 0) out vec4 fragColor;
-layout (location = 1) out vec4 fragClamp;
+out vec4 fragColor;
 
 uniform float dir;
 uniform float comp;
@@ -25,14 +24,14 @@ void main() {
   vec2 uv = vUv;
 
   fragColor = texture( sampler0, uv );
-  fragClamp = texture( sampler1, uv );
+  vec4 texIndex = texture( sampler1, uv );
 
-  if ( fragClamp.x < 0.5 ) {
+  if ( texIndex.x < 0.5 ) {
     return;
   }
 
-  float index = fragClamp.x - 1.0;
-  float width = fragClamp.x + fragClamp.y - 1.0;
+  float index = texIndex.x - 1.0;
+  float width = texIndex.x + texIndex.y - 1.0;
 
   bool isCompRight = mod( index, 2.0 * comp * width ) < comp * width;
   float offset = floor( ( isCompRight ? comp : -comp ) * width + 0.5 );