Fix brdf.rg may less than 0 (#2173)

zhuxudong · web-flow · commit b8850dc1c6b2 · 2024-07-15T10:51:57.000+08:00
* fix: brdf.xy may less than 0
diff --git a/packages/core/src/shaderlib/pbr/ibl_frag_define.glsl b/packages/core/src/shaderlib/pbr/ibl_frag_define.glsl
@@ -34,7 +34,8 @@ vec3 envBRDFApprox(vec3 specularColor,float roughness, float dotNV ) {
 
     vec2 AB = vec2( -1.04, 1.04 ) * a004 + r.zw;
 
-    return specularColor * AB.x + AB.y;
+    // AB may less than 0 at high roughness, ref: https://github.com/galacean/engine/pull/2173
+    return max(specularColor * AB.x + AB.y, 0.0);
 
 }
 

Original file line number	Diff line number	Diff line change
`@@ -34,7 +34,8 @@ vec3 envBRDFApprox(vec3 specularColor,float roughness, float dotNV ) {`
`34`	`34`
`35`	`35`	`vec2 AB = vec2( -1.04, 1.04 ) * a004 + r.zw;`
`36`	`36`
`37`		`- return specularColor * AB.x + AB.y;`
	`37`	`+ // AB may less than 0 at high roughness, ref: https://github.com/galacean/engine/pull/2173`
	`38`	`+ return max(specularColor * AB.x + AB.y, 0.0);`
`38`	`39`
`39`	`40`	`}`
`40`	`41`