Merge pull request #10703 from CesiumGS/points-back-face-culling

Add support for point cloud back face culling
CesiumGS · Aug 19, 2022 · 4b333bc · 4b333bc
2 parents 318bfae + 60694dd
commit 4b333bc
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Showing 12 changed files with 231 additions and 148 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -27,6 +27,7 @@
 ##### Additions :tada:
 
 - `Model` can now classify other assets with a given `classificationType`. [#10623](https://github.com/CesiumGS/cesium/pull/10623)
+- `Model` now supports back face culling for point clouds. [#10703](https://github.com/CesiumGS/cesium/pull/10703)
 
 ##### Fixes :wrench:
 

diff --git a/Source/Scene/Model/MaterialPipelineStage.js b/Source/Scene/Model/MaterialPipelineStage.js
@@ -128,7 +128,7 @@ MaterialPipelineStage.process = function (
     shaderBuilder.addDefine(
       "HAS_DOUBLE_SIDED_MATERIAL",
       undefined,
-      ShaderDestination.FRAGMENT
+      ShaderDestination.BOTH
     );
   }
 };

diff --git a/Source/Scene/Model/Model.js b/Source/Scene/Model/Model.js
@@ -314,6 +314,7 @@ function Model(options) {
   const pointCloudShading = new PointCloudShading(options.pointCloudShading);
   this._pointCloudShading = pointCloudShading;
   this._attenuation = pointCloudShading.attenuation;
+  this._pointCloudBackFaceCulling = pointCloudShading.backFaceCulling;
 
   // If the given clipping planes don't have an owner, make this model its owner.
   // Otherwise, the clipping planes are passed down from a tileset.
@@ -1674,7 +1675,7 @@ Model.prototype.update = function (frameState) {
     return;
   }
 
-  updatePointCloudAttenuation(this);
+  updatePointCloudShading(this);
   updateSilhouette(this, frameState);
   updateSkipLevelOfDetail(this, frameState);
   updateClippingPlanes(this, frameState);
@@ -1733,12 +1734,19 @@ function updateImageBasedLighting(model, frameState) {
   }
 }
 
-function updatePointCloudAttenuation(model) {
+function updatePointCloudShading(model) {
+  const pointCloudShading = model.pointCloudShading;
+
   // Check if the shader needs to be updated for point cloud attenuation
   // settings.
-  if (model.pointCloudShading.attenuation !== model._attenuation) {
+  if (pointCloudShading.attenuation !== model._attenuation) {
+    model.resetDrawCommands();
+    model._attenuation = pointCloudShading.attenuation;
+  }
+
+  if (pointCloudShading.backFaceCulling !== model._pointCloudBackFaceCulling) {
     model.resetDrawCommands();
-    model._attenuation = model.pointCloudShading.attenuation;
+    model._pointCloudBackFaceCulling = pointCloudShading.backFaceCulling;
   }
 }
 

diff --git a/Source/Scene/Model/ModelRuntimePrimitive.js b/Source/Scene/Model/ModelRuntimePrimitive.js
@@ -185,9 +185,11 @@ ModelRuntimePrimitive.prototype.configurePipeline = function (frameState) {
   const pointCloudShading = model.pointCloudShading;
   const hasAttenuation =
     defined(pointCloudShading) && pointCloudShading.attenuation;
+  const hasPointCloudBackFaceCulling =
+    defined(pointCloudShading) && pointCloudShading.backFaceCulling;
   const hasPointCloudStyle =
     primitive.primitiveType === PrimitiveType.POINTS &&
-    (defined(style) || hasAttenuation);
+    (defined(style) || hasAttenuation || hasPointCloudBackFaceCulling);
 
   const hasOutlines =
     model._enableShowOutline && defined(primitive.outlineCoordinates);

diff --git a/Source/Scene/Model/PointCloudStylingPipelineStage.js b/Source/Scene/Model/PointCloudStylingPipelineStage.js
@@ -117,14 +117,22 @@ PointCloudStylingPipelineStage.process = function (
   }
 
   const pointCloudShading = model.pointCloudShading;
-  if (model._attenuation) {
+  if (pointCloudShading.attenuation) {
     shaderBuilder.addDefine(
       "HAS_POINT_CLOUD_ATTENUATION",
       undefined,
       ShaderDestination.VERTEX
     );
   }
 
+  if (pointCloudShading.backFaceCulling) {
+    shaderBuilder.addDefine(
+      "HAS_POINT_CLOUD_BACK_FACE_CULLING",
+      undefined,
+      ShaderDestination.VERTEX
+    );
+  }
+
   let content;
   let is3DTiles;
   let usesAddRefinement;

diff --git a/Source/Shaders/Model/GeometryStageVS.glsl b/Source/Shaders/Model/GeometryStageVS.glsl
@@ -23,7 +23,7 @@ vec4 geometryStage(inout ProcessedAttributes attributes, mat4 modelView, mat3 no
     #endif
 
     #ifdef HAS_NORMALS
-    v_normalEC = normal * attributes.normalMC;
+    v_normalEC = normalize(normal * attributes.normalMC);
     #endif
 
     #ifdef HAS_TANGENTS

diff --git a/Source/Shaders/Model/MaterialStageFS.glsl b/Source/Shaders/Model/MaterialStageFS.glsl
@@ -64,7 +64,6 @@ vec3 computeNormal(ProcessedAttributes attributes)
 
 void materialStage(inout czm_modelMaterial material, ProcessedAttributes attributes, SelectedFeature feature)
 {
-
     #ifdef HAS_NORMALS
     material.normalEC = computeNormal(attributes);
     #endif

diff --git a/Source/Shaders/Model/ModelVS.glsl b/Source/Shaders/Model/ModelVS.glsl
@@ -111,6 +111,10 @@ void main()
     float show = 1.0;
     #endif
 
+    #ifdef HAS_POINT_CLOUD_BACK_FACE_CULLING
+    show *= pointCloudBackFaceCullingStage();
+    #endif
+
     #ifdef HAS_POINT_CLOUD_COLOR_STYLE
     v_pointCloudColor = pointCloudColorStylingStage(attributes, metadata);
     #endif

diff --git a/Source/Shaders/Model/PointCloudStylingStageVS.glsl b/Source/Shaders/Model/PointCloudStylingStageVS.glsl
@@ -31,4 +31,15 @@ float pointCloudPointSizeStylingStage(in ProcessedAttributes attributes, in Meta
 float pointCloudPointSizeStylingStage(in ProcessedAttributes attributes, in Metadata metadata) {
   return getPointSizeFromAttenuation(v_positionEC);
 }
+#endif
+
+#ifdef HAS_POINT_CLOUD_BACK_FACE_CULLING
+float pointCloudBackFaceCullingStage() {
+  #if defined(HAS_NORMALS) && !defined(HAS_DOUBLE_SIDED_MATERIAL)
+  // This needs to be computed in eye coordinates so we can't use attributes.normalMC
+  return step(-v_normalEC.z, 0.0);
+  #else
+  return 1.0;
+  #endif
+}
 #endif