From 654666d272edac91b79ef2d600392f3037419f29 Mon Sep 17 00:00:00 2001
From: Garrett Johnson <garrett.kjohnson@gmail.com>
Date: Tue, 24 Dec 2024 14:44:00 +0900
Subject: [PATCH] Wrap the material with batched mesh uniforms

---
 src/plugins/three/fade/FadeMaterialManager.js |  73 +----------
 src/plugins/three/fade/wrapFadeMaterial.js    | 122 ++++++++++++++++++
 2 files changed, 125 insertions(+), 70 deletions(-)
 create mode 100644 src/plugins/three/fade/wrapFadeMaterial.js

diff --git a/src/plugins/three/fade/FadeMaterialManager.js b/src/plugins/three/fade/FadeMaterialManager.js
index 5eea03d4f..f6e432753 100644
--- a/src/plugins/three/fade/FadeMaterialManager.js
+++ b/src/plugins/three/fade/FadeMaterialManager.js
@@ -1,3 +1,5 @@
+import { wrapFadeMaterial } from './wrapFadeMaterial.js';
+
 export class FadeMaterialManager {
 
 	constructor() {
@@ -93,76 +95,7 @@ export class FadeMaterialManager {
 
 		}
 
-		const params = {
-			fadeIn: { value: 0 },
-			fadeOut: { value: 0 },
-		};
-
-		material.defines = {
-			FEATURE_FADE: 0,
-		};
-
-		material.onBeforeCompile = shader => {
-
-			shader.uniforms = {
-				...shader.uniforms,
-				...params,
-			};
-
-			shader.fragmentShader = shader.fragmentShader
-				.replace( /void main\(/, value => /* glsl */`
-					#if FEATURE_FADE
-
-					// adapted from https://www.shadertoy.com/view/Mlt3z8
-					float bayerDither2x2( vec2 v ) {
-
-						return mod( 3.0 * v.y + 2.0 * v.x, 4.0 );
-
-					}
-
-					float bayerDither4x4( vec2 v ) {
-
-						vec2 P1 = mod( v, 2.0 );
-						vec2 P2 = floor( 0.5 * mod( v, 4.0 ) );
-						return 4.0 * bayerDither2x2( P1 ) + bayerDither2x2( P2 );
-
-					}
-
-					uniform float fadeIn;
-					uniform float fadeOut;
-					#endif
-
-					${ value }
-				` )
-				.replace( /#include <dithering_fragment>/, value => /* glsl */`
-
-					${ value }
-
-					#if FEATURE_FADE
-
-					float bayerValue = bayerDither4x4( floor( mod( gl_FragCoord.xy, 4.0 ) ) );
-					float bayerBins = 16.0;
-					float dither = ( 0.5 + bayerValue ) / bayerBins;
-					if ( dither >= fadeIn ) {
-
-						discard;
-
-					}
-
-					if ( dither < fadeOut ) {
-
-						discard;
-
-					}
-
-					#endif
-
-				` );
-
-
-		};
-
-		fadeParams.set( material, params );
+		fadeParams.set( material, wrapFadeMaterial( material ) );
 
 	}
 
diff --git a/src/plugins/three/fade/wrapFadeMaterial.js b/src/plugins/three/fade/wrapFadeMaterial.js
new file mode 100644
index 000000000..f40f68c64
--- /dev/null
+++ b/src/plugins/three/fade/wrapFadeMaterial.js
@@ -0,0 +1,122 @@
+export function wrapFadeMaterial( material ) {
+
+	const params = {
+		fadeIn: { value: 0 },
+		fadeOut: { value: 0 },
+		fadeTexture: { value: null },
+	};
+
+	material.defines = {
+		FEATURE_FADE: 0,
+	};
+
+	material.onBeforeCompile = shader => {
+
+		shader.uniforms = {
+			...shader.uniforms,
+			...params,
+		};
+
+		shader.vertexShader = shader.vertexShader
+			.replace(
+				/void\s+main()\s+{/,
+				value => /* glsl */`
+					#ifdef USE_BATCHING
+
+					varying float vBatchId;
+
+					#endif
+
+					${ value }
+
+						#ifdef USE_BATCHING
+
+						// add 0.5 to the value to avoid floating error that may cause flickering
+						vBatchId = batchId + 0.5;
+
+						#endif
+				`
+			);
+
+		shader.fragmentShader = shader.fragmentShader
+			.replace( /void main\(/, value => /* glsl */`
+				#if FEATURE_FADE
+
+				// adapted from https://www.shadertoy.com/view/Mlt3z8
+				float bayerDither2x2( vec2 v ) {
+
+					return mod( 3.0 * v.y + 2.0 * v.x, 4.0 );
+
+				}
+
+				float bayerDither4x4( vec2 v ) {
+
+					vec2 P1 = mod( v, 2.0 );
+					vec2 P2 = floor( 0.5 * mod( v, 4.0 ) );
+					return 4.0 * bayerDither2x2( P1 ) + bayerDither2x2( P2 );
+
+				}
+
+				#ifdef USE_BATCHING
+
+				uniform sampler2D fadeTexture;
+				varying float vBatchId;
+				vec2 getFadeValues( const in float i ) {
+
+					int size = textureSize( fadeTexture, 0 ).x;
+					int j = int( i );
+					int x = j % size;
+					int y = j / size;
+					return texelFetch( fadeTexture, ivec2( x, y ), 0 ).rg;
+
+				}
+
+				#else
+
+				uniform float fadeIn;
+				uniform float fadeOut;
+
+				#endif
+
+				#endif
+
+				${ value }
+			` )
+			.replace( /#include <dithering_fragment>/, value => /* glsl */`
+
+				${ value }
+
+				#if FEATURE_FADE
+
+				#ifdef USE_BATCHING
+
+				vec2 fadeValues = getFadeValues( vBatchId );
+				float fadeIn = fadeValues.r;
+				float fadeOut = fadeValues.g;
+
+				#endif
+
+				float bayerValue = bayerDither4x4( floor( mod( gl_FragCoord.xy, 4.0 ) ) );
+				float bayerBins = 16.0;
+				float dither = ( 0.5 + bayerValue ) / bayerBins;
+				if ( dither >= fadeIn ) {
+
+					discard;
+
+				}
+
+				if ( dither < fadeOut ) {
+
+					discard;
+
+				}
+
+				#endif
+
+			` );
+
+	};
+
+	return params;
+
+}