Fix models with negative scale

playcanvas · Jan 27, 2024 · 96dddd5 · 96dddd5
1 parent 931babb
commit 96dddd5
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Showing 5 changed files with 34 additions and 20 deletions.
diff --git a/examples/src/examples/graphics/normals-and-tangents.mjs b/examples/src/examples/graphics/normals-and-tangents.mjs
@@ -37,7 +37,7 @@ async function example({ canvas, deviceType, glslangPath, twgslPath, assetPath,
     app.init(createOptions);
 
     const assets = {
-        statue:  new pc.Asset('statue',            'container', { url: assetPath   + 'models/NormalTangentTest.glb' }),
+        model:   new pc.Asset('model',             'container', { url: assetPath   + 'models/NormalTangentTest.glb' }),
         script:  new pc.Asset('script',            'script',    { url: scriptsPath + 'camera/orbit-camera.js' }),
         helipad: new pc.Asset('helipad-env-atlas', 'texture',   { url: assetPath   + 'cubemaps/helipad-env-atlas.png' }, { type: pc.TEXTURETYPE_RGBP, mipmaps: false }),
     };
@@ -72,10 +72,17 @@ async function example({ canvas, deviceType, glslangPath, twgslPath, assetPath,
     app.scene.skyboxRotation = new pc.Quat().setFromEulerAngles(0, 70, 0);
     app.scene.skyboxIntensity = 1.5;
 
-    // Create an entity hierarchy representing the statue
-    const statueEntity = assets.statue.resource.instantiateRenderEntity();
-    statueEntity.setLocalEulerAngles(0, 90, 0);
-    app.root.addChild(statueEntity);
+    const leftEntity = assets.model.resource.instantiateRenderEntity();
+    leftEntity.setLocalEulerAngles(0, 90, 0);
+    leftEntity.setPosition(0, 0, 1);
+    leftEntity.setLocalScale(0.8, 0.8, 0.8);
+    app.root.addChild(leftEntity);
+
+    const rightEntity = assets.model.resource.instantiateRenderEntity();
+    rightEntity.setLocalEulerAngles(0, 90, 0);
+    rightEntity.setPosition(0, 0, -1);
+    rightEntity.setLocalScale(-0.8, -0.8, -0.8);
+    app.root.addChild(rightEntity);
 
     // Create a camera with an orbit camera script
     const camera = new pc.Entity();

diff --git a/src/scene/shader-lib/chunks/lit/frag/TBN.js b/src/scene/shader-lib/chunks/lit/frag/TBN.js
@@ -1,5 +1,13 @@
 export default /* glsl */`
 void getTBN(vec3 tangent, vec3 binormal, vec3 normal) {
-    dTBN = mat3(normalize(tangent), normalize(binormal), normalize(normal));
+    #ifdef TWO_SIDED_LIGHTING
+        dTBN = mat3(
+            normalize((gl_FrontFacing ? tangent  : -tangent ) * twoSidedLightingNegScaleFactor),
+            normalize((gl_FrontFacing ? binormal : -binormal) * twoSidedLightingNegScaleFactor),
+            normalize((gl_FrontFacing ? normal   : -normal  ) * twoSidedLightingNegScaleFactor)
+        );
+    #else
+        dTBN = mat3(normalize(tangent), normalize(binormal), normalize(normal));
+    #endif
 }
 `;
diff --git a/src/scene/shader-lib/chunks/lit/frag/TBNderivative.js b/src/scene/shader-lib/chunks/lit/frag/TBNderivative.js
@@ -22,7 +22,7 @@ void getTBN(vec3 tangent, vec3 binormal, vec3 normal) {
     float invmax = (denom == 0.0) ? 0.0 : tbnBasis / sqrt( denom );
 
     #ifdef TWO_SIDED_LIGHTING
-        dTBN = mat3(T * invmax, -B * invmax, gl_FrontFacing ? normal : -normal);
+        dTBN = mat3(T * invmax, -B * invmax, (gl_FrontFacing ? normal : -normal) * twoSidedLightingNegScaleFactor);
     #else
         dTBN = mat3(T * invmax, -B * invmax, normal);
     #endif

diff --git a/src/scene/shader-lib/chunks/lit/frag/TBNfast.js b/src/scene/shader-lib/chunks/lit/frag/TBNfast.js
@@ -1,5 +1,13 @@
 export default /* glsl */`
 void getTBN(vec3 tangent, vec3 binormal, vec3 normal) {
-    dTBN = mat3(tangent, binormal, normal);
+    #ifdef TWO_SIDED_LIGHTING
+        dTBN = mat3(
+            (gl_FrontFacing ? tangent  : -tangent ) * twoSidedLightingNegScaleFactor,
+            (gl_FrontFacing ? binormal : -binormal) * twoSidedLightingNegScaleFactor,
+            (gl_FrontFacing ? normal   : -normal  ) * twoSidedLightingNegScaleFactor
+        );
+    #else
+        dTBN = mat3(tangent, binormal, normal);
+    #endif
 }
 `;
diff --git a/src/scene/shader-lib/programs/lit-shader.js b/src/scene/shader-lib/programs/lit-shader.js
@@ -985,20 +985,11 @@ class LitShader {
         code.append(this._fsGetStartCode(code, device, chunks, options));
 
         if (this.needsNormal) {
-            if (options.twoSidedLighting) {
-                code.append("    dVertexNormalW = normalize(gl_FrontFacing ? vNormalW * twoSidedLightingNegScaleFactor : -vNormalW * twoSidedLightingNegScaleFactor);");
-            } else {
-                code.append("    dVertexNormalW = normalize(vNormalW);");
-            }
+            code.append("    dVertexNormalW = normalize(vNormalW);");
 
             if ((options.useHeights || options.useNormals) && options.hasTangents) {
-                if (options.twoSidedLighting) {
-                    code.append("    dTangentW = gl_FrontFacing ? vTangentW * twoSidedLightingNegScaleFactor : -vTangentW * twoSidedLightingNegScaleFactor;");
-                    code.append("    dBinormalW = gl_FrontFacing ? vBinormalW * twoSidedLightingNegScaleFactor : -vBinormalW * twoSidedLightingNegScaleFactor;");
-                } else {
-                    code.append("    dTangentW = vTangentW;");
-                    code.append("    dBinormalW = vBinormalW;");
-                }
+                code.append("    dTangentW = vTangentW;");
+                code.append("    dBinormalW = vBinormalW;");
             }
 
             code.append("    getViewDir();");