Cleanup:

packages/engine/Source/Scene/ClippingPolygonCollection.js

@@ -361,8 +361,6 @@ ClippingPolygonCollection.prototype.remove = function (polygon) {
   polygons.splice(index, 1);
 
   this.polygonRemoved.raiseEvent(polygon, index);
-  this._dirty = true;
-
   return true;
 };
 
@@ -394,7 +392,6 @@ ClippingPolygonCollection.prototype.removeAll = function () {
     const polygon = polygons[i];
     this.polygonRemoved.raiseEvent(polygon, i);
   }
-  this._dirty = true;
   this._polygons = [];
 };
 

packages/engine/Source/Shaders/Builtin/Functions/clipPolygons.glsl

@@ -3,7 +3,7 @@ float getSignedDistance(vec2 uv, highp sampler2D clippingDistance) {
     return (signedDistance - 0.5) * 2.0;
 }
 
-void czm_clipPolygons(highp sampler2D clippingDistance, int polygonsLength, vec2 clippingPosition, int regionIndex) {
+void czm_clipPolygons(highp sampler2D clippingDistance, int extentsLength, vec2 clippingPosition, int regionIndex) {
     // Position is completely outside of polygons bounds
     vec2 rectUv = clippingPosition;
     if (regionIndex < 0 || rectUv.x <= 0.0 || rectUv.y <= 0.0 || rectUv.x >= 1.0 || rectUv.y >= 1.0) {
@@ -15,8 +15,10 @@ void czm_clipPolygons(highp sampler2D clippingDistance, int polygonsLength, vec2
 
     vec2 clippingDistanceTextureDimensions = vec2(textureSize(clippingDistance, 0));
     vec2 sampleOffset = max(1.0 / clippingDistanceTextureDimensions, vec2(0.005));
-    float dimension = max(ceil(log2(float(polygonsLength))), float(polygonsLength));
-    vec2 polygonTextureSize = clippingDistanceTextureDimensions / dimension;
+    float dimension = float(extentsLength);
+    if (extentsLength > 2) {
+       dimension = ceil(log2(float(extentsLength)));
+    }
 
     vec2 textureOffset = vec2(mod(float(regionIndex), dimension), floor(float(regionIndex) / dimension)) / dimension;
     vec2 uv = textureOffset + rectUv / dimension;

packages/engine/Source/Shaders/GlobeVS.glsl

@@ -223,7 +223,7 @@ void main()
         vec4 extents = unpackClippingExtents(u_clippingExtents, regionIndex);
 
         vec2 rectUv = (sphericalLatLong.yx - extents.yx) * extents.wz;
-        float padding = 5000.0 * czm_geometricToleranceOverMeter;
+        float padding = 0.1;
         if (rectUv.x > -padding && rectUv.y > -padding && rectUv.x < 1.0 + padding && rectUv.y < 1.0 + padding) {
             v_clippingPosition = rectUv;
             v_regionIndex = regionIndex;

packages/engine/Source/Shaders/Model/ModelClippingPolygonsStageFS.glsl

@@ -2,5 +2,6 @@ void modelClippingPolygonsStage()
 {
   vec2 clippingPosition = v_clippingPosition;
   int regionIndex = v_regionIndex;
+
   czm_clipPolygons(model_clippingDistance, CLIPPING_POLYGON_REGIONS_LENGTH, clippingPosition, regionIndex);
 }

packages/engine/Source/Shaders/Model/ModelClippingPolygonsStageVS.glsl

@@ -3,11 +3,14 @@ void modelClippingPolygonsStage(ProcessedAttributes attributes)
     vec2 sphericalLatLong = czm_approximateSphericalCoordinates(v_positionWC);
     sphericalLatLong.y = czm_branchFreeTernary(sphericalLatLong.y < czm_pi, sphericalLatLong.y, sphericalLatLong.y - czm_twoPi);
 
+    vec3 radii = czm_ellipsoidRadii;
+    float maxRadii = max(radii.x, max(radii.y, radii.z));
+
     for (int regionIndex = 0; regionIndex < CLIPPING_POLYGON_REGIONS_LENGTH; regionIndex++) {
         vec4 extents = czm_unpackClippingExtents(model_clippingExtents, regionIndex);
-        
+
         vec2 rectUv = (sphericalLatLong.yx - extents.yx) * extents.wz;
-        float padding = 2500.0 * czm_geometricToleranceOverMeter;
+        float padding = 0.1;
         if (rectUv.x > -padding && rectUv.y > -padding && rectUv.x < 1.0 + padding && rectUv.y < 1.0 + padding) {
             v_clippingPosition = rectUv;
             v_regionIndex = regionIndex;

packages/engine/Source/Shaders/PolygonSignedDistanceFS.glsl

@@ -46,7 +46,10 @@ void main() {
     out_FragColor = vec4(1.0);
 
     // Get the relevant region of the texture
-    float dimension = max(ceil(log2(float(u_extentsLength))), float(u_extentsLength));
+    float dimension = float(u_extentsLength);
+    if (u_extentsLength > 2) {
+        dimension = ceil(log2(float(u_extentsLength)));
+    }
     int regionIndex = getPolygonIndex(dimension, v_textureCoordinates);
 
     for (int polygonIndex = 0; polygonIndex < u_polygonsLength; polygonIndex++) {
@@ -59,8 +62,8 @@ void main() {
          if (polygonExtentsIndex == regionIndex) {
             float clipAmount = czm_infinity;
             vec4 extents = getExtents(polygonExtentsIndex);
-            vec2 textureOffset = vec2(mod(float(polygonExtentsIndex), dimension), floor(float(polygonExtentsIndex) / dimension));
-            vec2 p = getCoordinates(v_textureCoordinates * dimension - textureOffset, extents);
+            vec2 textureOffset = vec2(mod(float(polygonExtentsIndex), dimension), floor(float(polygonExtentsIndex) / dimension)) / dimension;
+            vec2 p = getCoordinates((v_textureCoordinates - textureOffset) * dimension, extents);
             float s = 1.0;
 
             // Check each edge for absolute distance

packages/engine/Specs/Scene/ClippingPolygonCollectionSpec.js

@@ -309,11 +309,11 @@ describe("Scene/ClippingPolygonCollection", function () {
     expect(arrayBufferView[2]).toEqualEpsilon(
       10111.67578125,
       CesiumMath.EPSILON10
-    ); // north - south
+    ); // 1 / (north - south)
     expect(arrayBufferView[3]).toEqualEpsilon(
       15428.873046875,
       CesiumMath.EPSILON10
-    ); // east - west
+    ); // 1 / (east - west)
     expect(arrayBufferView[4]).toBe(0); // padding
     expect(arrayBufferView[5]).toBe(0); // padding
     expect(arrayBufferView[6]).toBe(0); // padding