Fix lighting basis during RTT (playcanvas#3424)

slimbuck · web-flow · commit def256877ff0 · 2021-08-24T15:40:27.000+01:00
* add tbn multiplier

* move
diff --git a/src/graphics/program-lib/chunks/TBNderivative.frag b/src/graphics/program-lib/chunks/TBNderivative.frag
@@ -1,3 +1,5 @@
+uniform float tbnBasis;
+
 // http://www.thetenthplanet.de/archives/1180
 void getTBN() {
     vec2 uv = $UV;
@@ -16,6 +18,6 @@ void getTBN() {
 
     // construct a scale-invariant frame
     float denom = max( dot(T,T), dot(B,B) );
-    float invmax = (denom == 0.0) ? 0.0 : 1.0 / sqrt( denom );
-    dTBN = mat3( T * invmax, -B * invmax, dVertexNormalW );
+    float invmax = (denom == 0.0) ? 0.0 : tbnBasis / sqrt( denom );
+    dTBN = mat3(T * invmax, -B * invmax, dVertexNormalW );
 }
diff --git a/src/scene/renderer/forward-renderer.js b/src/scene/renderer/forward-renderer.js
@@ -130,6 +130,7 @@ class ForwardRenderer {
         this.nearClipId = scope.resolve('camera_near');
         this.farClipId = scope.resolve('camera_far');
         this.cameraParamsId = scope.resolve('camera_params');
+        this.tbnBasis = scope.resolve('tbnBasis');
 
         this.fogColorId = scope.resolve('fog_color');
         this.fogStartId = scope.resolve('fog_start');
@@ -456,6 +457,8 @@ class ForwardRenderer {
             camera.frustum.setFromMat4(viewProjMat);
         }
 
+        this.tbnBasis.setValue(target && target.flipY ? -1 : 1);
+
         // Near and far clip values
         this.nearClipId.setValue(camera._nearClip);
         this.farClipId.setValue(camera._farClip);
