Fix VP2 rendering of UsdPreviewSurface with opacityThreshold

lib/mayaUsd/render/vp2ShaderFragments/UsdPreviewSurfaceLightAPI2.xml

@@ -49,6 +49,7 @@ limitations under the License.
         <float name="roughness" ref="usdPreviewSurfaceLightingAPI2.specularRoughness"/>
         <float3 name="specularColor" ref="usdPreviewSurfaceLightingAPI2.specularColor"/>
         <float name="opacity" ref="opacityToTransparency.opacity"/>
+        <float name="opacityThreshold" ref="usdPreviewSurfaceLightingAPI2.opacityThreshold"/>
         <bool name="useSpecularWorkflow" ref="usdPreviewSurfaceLightingAPI2.useSpecularWorkflow"/>
 
         <!-- Maya Parameters for Lighting -->
@@ -86,6 +87,7 @@ limitations under the License.
         <float3 name="specularColor" value="0.0,0.0,0.0"/>
         <!-- The shader computes transparency from its "opacity" attribute. -->
         <float name="opacity" value="1.0"/>
+        <float name="opacityThreshold" value="0.0"/>
         <bool name="useSpecularWorkflow" value="false"/>
 
         <!-- Default values for Maya-provided parameters. -->

lib/mayaUsd/render/vp2ShaderFragments/UsdPreviewSurfaceLightAPI3.xml

@@ -49,6 +49,7 @@ limitations under the License.
         <float name="roughness" ref="usdPreviewSurfaceLightingAPI3.specularRoughness"/>
         <float3 name="specularColor" ref="usdPreviewSurfaceLightingAPI3.specularColor"/>
         <float name="opacity" ref="opacityToTransparency.opacity"/>
+        <float name="opacityThreshold" ref="usdPreviewSurfaceLightingAPI3.opacityThreshold"/>
         <bool name="useSpecularWorkflow" ref="usdPreviewSurfaceLightingAPI3.useSpecularWorkflow"/>
 
         <!-- Maya Parameters for Lighting -->
@@ -86,6 +87,7 @@ limitations under the License.
         <float3 name="specularColor" value="0.0,0.0,0.0"/>
         <!-- The shader computes transparency from its "opacity" attribute. -->
         <float name="opacity" value="1.0"/>
+        <float name="opacityThreshold" value="0.0"/>
         <bool name="useSpecularWorkflow" value="false"/>
 
         <!-- Default values for Maya-provided parameters. -->

lib/mayaUsd/render/vp2ShaderFragments/usdPreviewSurfaceLightingAPI2.xml

@@ -379,15 +379,24 @@ surfaceShader(vec3 Peye, vec3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
+    result.outGlowColor = vec3(0.0);
 
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        } 
+        result.outTransparency = vec3(0.0);
+        result.outMatteOpacity = vec3(1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = vec3(opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -406,12 +415,6 @@ surfaceShader(vec3 Peye, vec3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = vec3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = vec3(opacity);
-
     return result;
 }
 
@@ -733,15 +736,24 @@ surfaceShader(vec3 Peye, vec3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
+    result.outGlowColor = vec3(0.0);
 
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        }
+        result.outTransparency = vec3(0.0);
+        result.outMatteOpacity = vec3(1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = vec3(opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -760,12 +772,6 @@ surfaceShader(vec3 Peye, vec3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = vec3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = vec3(opacity);
-
     return result;
 }
 
@@ -1087,15 +1093,24 @@ surfaceShader(float3 Peye, float3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
+    result.outGlowColor = float3(0.0, 0.0, 0.0);
 
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        }
+        result.outTransparency = float3(0.0, 0.0, 0.0);
+        result.outMatteOpacity = float3(1.0, 1.0, 1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = float3(opacity, opacity, opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -1114,12 +1129,6 @@ surfaceShader(float3 Peye, float3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = float3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = float3(opacity, opacity, opacity);
-
     return result;
 }
 

lib/mayaUsd/render/vp2ShaderFragments/usdPreviewSurfaceLightingAPI3.xml

@@ -379,15 +379,24 @@ surfaceShader(vec3 Peye, vec3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
+    result.outGlowColor = vec3(0.0);
 
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        }
+        result.outTransparency = vec3(0.0);
+        result.outMatteOpacity = vec3(1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = vec3(opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -406,12 +415,6 @@ surfaceShader(vec3 Peye, vec3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = vec3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = vec3(opacity);
-
     return result;
 }
 
@@ -733,15 +736,24 @@ surfaceShader(vec3 Peye, vec3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
-
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    result.outGlowColor = vec3(0.0);
+
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        }
+        result.outTransparency = vec3(0.0);
+        result.outMatteOpacity = vec3(1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = vec3(opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -760,12 +772,6 @@ surfaceShader(vec3 Peye, vec3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = vec3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = vec3(opacity);
-
     return result;
 }
 
@@ -1087,15 +1093,24 @@ surfaceShader(float3 Peye, float3 Neye,
     float specularAmount
 )
 {
-    float opacity = 1.0 - transparency.r;
-    if (opacity < opacityThreshold) {
-        discard;
-    } 
-
     mayaSurfaceShaderOutput result;
-
-    // Pre-multiply diffuse color by opacity if not done so already
-    diffuseColor *= opacity;
+    result.outGlowColor = float3(0.0, 0.0, 0.0);
+
+    // Transparency and cutout.
+    float opacity = 1.0 - transparency.r;
+    if (opacityThreshold > 0.0) {
+        if (opacity < opacityThreshold) {
+            discard;
+        }
+        result.outTransparency = float3(0.0, 0.0, 0.0);
+        result.outMatteOpacity = float3(1.0, 1.0, 1.0);
+    } else {
+        result.outTransparency = transparency;
+        result.outMatteOpacity = float3(opacity, opacity, opacity);
+
+        // Pre-multiply diffuse color by opacity if not done so already
+        diffuseColor *= opacity;
+    }
 
     // Evaluate all lights.
     result.outColor = evaluateLights(
@@ -1114,12 +1129,6 @@ surfaceShader(float3 Peye, float3 Neye,
         Peye,
         Neye);
 
-    // Transparency
-    result.outTransparency = transparency;
-
-    result.outGlowColor = float3(0.0, 0.0, 0.0);
-    result.outMatteOpacity = float3(opacity, opacity, opacity);
-
     return result;
 }
 

lib/usd/pxrUsdPreviewSurface/usdPreviewSurface.cpp

@@ -393,6 +393,8 @@ MStatus PxrMayaUsdPreviewSurface::initialize()
 
     status = attributeAffects(opacityAttr, outTransparencyOnAttr);
     CHECK_MSTATUS_AND_RETURN_IT(status);
+    status = attributeAffects(opacityThresholdAttr, outTransparencyOnAttr);
+    CHECK_MSTATUS_AND_RETURN_IT(status);
 
     return status;
 }
@@ -444,8 +446,8 @@ MStatus PxrMayaUsdPreviewSurface::compute(const MPlug& plug, MDataBlock& dataBlo
         CHECK_MSTATUS(status);
         const float opacityThreshold = opacityThresholdData.asFloat();
 
-        if (opacity < opacityThreshold) {
-            opacity = 0.0f;
+        if (opacityThreshold > 0.0f) {
+            opacity = (opacity < opacityThreshold) ? 0.0f : 1.0f;
         }
 
         const float        transparency = 1.0f - opacity;
@@ -461,32 +463,44 @@ MStatus PxrMayaUsdPreviewSurface::compute(const MPlug& plug, MDataBlock& dataBlo
         // details. We don't use the user-visible "outTransparency" attribute for transparency test
         // because its value depends on upstream nodes and thus error-prone when the "opacity" plug
         // is connected to certain textures. In that case, we should enable transparency.
-        bool opacityConnected = false;
 
-        const MObject opacityAttr
-            = depNodeFn.attribute(PxrMayaUsdPreviewSurfaceTokens->OpacityAttrName.GetText());
-        const MPlug opacityPlug(thisMObject(), opacityAttr);
-        if (opacityPlug.isConnected()) {
-            const MPlug sourcePlug = opacityPlug.source(&status);
-            CHECK_MSTATUS(status);
-            const MObject sourceNode = sourcePlug.node(&status);
-            CHECK_MSTATUS(status);
-
-            // Anim curve output will be evaluated to determine if transparency should be enabled.
-            if (!sourceNode.hasFn(MFn::kAnimCurve)) {
-                opacityConnected = true;
-            }
-        }
+        MObject opacityThresholdAttr = depNodeFn.attribute(
+            PxrMayaUsdPreviewSurfaceTokens->OpacityThresholdAttrName.GetText());
+        const MDataHandle opacityThresholdData
+            = dataBlock.inputValue(opacityThresholdAttr, &status);
+        CHECK_MSTATUS(status);
 
         float transparencyOn = false;
-        if (opacityConnected) {
-            transparencyOn = true;
-        } else {
-            const MDataHandle opacityData = dataBlock.inputValue(opacityAttr, &status);
-            CHECK_MSTATUS(status);
-            const float opacity = opacityData.asFloat();
-            if (opacity < 1.0f - std::numeric_limits<float>::epsilon()) {
+
+        // For masked transparency, we want VP2 to treat the shader as opaque.
+        if (opacityThresholdData.asFloat() <= 0.0f) {
+            bool opacityConnected = false;
+
+            const MObject opacityAttr
+                = depNodeFn.attribute(PxrMayaUsdPreviewSurfaceTokens->OpacityAttrName.GetText());
+            const MPlug opacityPlug(thisMObject(), opacityAttr);
+            if (opacityPlug.isConnected()) {
+                const MPlug sourcePlug = opacityPlug.source(&status);
+                CHECK_MSTATUS(status);
+                const MObject sourceNode = sourcePlug.node(&status);
+                CHECK_MSTATUS(status);
+
+                // Anim curve output will be evaluated to determine if transparency should be
+                // enabled.
+                if (!sourceNode.hasFn(MFn::kAnimCurve)) {
+                    opacityConnected = true;
+                }
+            }
+
+            if (opacityConnected) {
                 transparencyOn = true;
+            } else {
+                const MDataHandle opacityData = dataBlock.inputValue(opacityAttr, &status);
+                CHECK_MSTATUS(status);
+                const float opacity = opacityData.asFloat();
+                if (opacity < 1.0f - std::numeric_limits<float>::epsilon()) {
+                    transparencyOn = true;
+                }
             }
         }