Straight CorridorGeometry.

CHANGES.md

@@ -9,6 +9,7 @@ Change Log
   * Removed `Camera.heading` and `Camera.tilt`. They were deprecated in Cesium 1.6. Use `Camera.setView`.
   * Removed `Camera.setPositionCartographic`, which was was deprecated in Cesium 1.6. Use `Camera.setView`.
 * Fixed incorrect ellipse texture coordinates. [#2363](https://github.com/AnalyticalGraphicsInc/cesium/issues/2363) and [#2465](https://github.com/AnalyticalGraphicsInc/cesium/issues/2465)
+* Fixed a bug that would cause incorrect geometry for long Corridors and Polyline Volumes. [#2513](https://github.com/AnalyticalGraphicsInc/cesium/issues/2513)
 * Fixed a bug in imagery loading that could cause some or all of the globe to be missing when using an imagery layer that does not cover the entire globe.
 * Added support for rendering a water effect on Quantized-Mesh terrain tiles.
 * Added `pack` and `unpack` functions to `Matrix2` and `Matrix3`.

Source/Core/CorridorGeometryLibrary.js

@@ -160,6 +160,9 @@ define([
         return positions;
     }
 
+    var scratchForwardProjection = new Cartesian3();
+    var scratchBackwardProjection = new Cartesian3();
+
     /**
      * @private
      */
@@ -207,7 +210,17 @@ define([
             nextPosition = positions[i + 1];
             forward = Cartesian3.normalize(Cartesian3.subtract(nextPosition, position, forward), forward);
             cornerDirection = Cartesian3.normalize(Cartesian3.add(forward, backward, cornerDirection), cornerDirection);
-            var doCorner = !Cartesian3.equalsEpsilon(Cartesian3.negate(cornerDirection, scratch1), normal, CesiumMath.EPSILON2);
+
+            var forwardProjection = Cartesian3.multiplyByScalar(normal, Cartesian3.dot(forward, normal), scratchForwardProjection);
+            Cartesian3.subtract(forward, forwardProjection, forwardProjection);
+            Cartesian3.normalize(forwardProjection, forwardProjection);
+
+            var backwardProjection = Cartesian3.multiplyByScalar(normal, Cartesian3.dot(backward, normal), scratchBackwardProjection);
+            Cartesian3.subtract(backward, backwardProjection, backwardProjection);
+            Cartesian3.normalize(backwardProjection, backwardProjection);
+
+            var doCorner = !CesiumMath.equalsEpsilon(Math.abs(Cartesian3.dot(forwardProjection, backwardProjection)), 1.0, CesiumMath.EPSILON1);
+
             if (doCorner) {
                 cornerDirection = Cartesian3.cross(cornerDirection, normal, cornerDirection);
                 cornerDirection = Cartesian3.cross(normal, cornerDirection, cornerDirection);

Source/Core/PolylineVolumeGeometryLibrary.js

@@ -290,6 +290,9 @@ define([
         return cleanedPositions;
     };
 
+    var scratchForwardProjection = new Cartesian3();
+    var scratchBackwardProjection = new Cartesian3();
+
     PolylineVolumeGeometryLibrary.computePositions = function(positions, shape2D, boundingRectangle, geometry, duplicatePoints) {
         var ellipsoid = geometry._ellipsoid;
         var heights = scaleToSurface(positions, ellipsoid);
@@ -338,7 +341,17 @@ define([
             cornerDirection = Cartesian3.add(forward, backward, cornerDirection);
             cornerDirection = Cartesian3.normalize(cornerDirection, cornerDirection);
             surfaceNormal = ellipsoid.geodeticSurfaceNormal(position, surfaceNormal);
-            var doCorner = !Cartesian3.equalsEpsilon(Cartesian3.negate(cornerDirection, scratch1), surfaceNormal, CesiumMath.EPSILON2);
+
+            var forwardProjection = Cartesian3.multiplyByScalar(surfaceNormal, Cartesian3.dot(forward, surfaceNormal), scratchForwardProjection);
+            Cartesian3.subtract(forward, forwardProjection, forwardProjection);
+            Cartesian3.normalize(forwardProjection, forwardProjection);
+
+            var backwardProjection = Cartesian3.multiplyByScalar(surfaceNormal, Cartesian3.dot(backward, surfaceNormal), scratchBackwardProjection);
+            Cartesian3.subtract(backward, backwardProjection, backwardProjection);
+            Cartesian3.normalize(backwardProjection, backwardProjection);
+
+            var doCorner = !CesiumMath.equalsEpsilon(Math.abs(Cartesian3.dot(forwardProjection, backwardProjection)), 1.0, CesiumMath.EPSILON1);
+
             if (doCorner) {
                 cornerDirection = Cartesian3.cross(cornerDirection, surfaceNormal, cornerDirection);
                 cornerDirection = Cartesian3.cross(surfaceNormal, cornerDirection, cornerDirection);

Specs/Core/CorridorGeometrySpec.js

@@ -180,6 +180,23 @@ defineSuite([
         expect(m.indices.length).toEqual(3 * 8);
     });
 
+    it('computes straight corridors', function() {
+        var m = CorridorGeometry.createGeometry(new CorridorGeometry({
+            vertexFormat : VertexFormat.POSITION_ONLY,
+            positions : Cartesian3.fromDegreesArray([
+                -67.655, 0.0,
+                -67.655, 15.0,
+                -67.655, 20.0
+            ]),
+            cornerType: CornerType.BEVELED,
+            width : 400000,
+            granularity : Math.PI / 6.0
+        }));
+
+        expect(m.attributes.position.values.length).toEqual(3 * 4);
+        expect(m.indices.length).toEqual(3 * 2);
+    });
+
     var positions = Cartesian3.fromDegreesArray([
          90.0, -30.0,
          90.0, -31.0

Specs/Core/PolylineVolumeGeometrySpec.js

@@ -169,6 +169,23 @@ defineSuite([
         expect(m.indices.length).toEqual(3 * (8 * 2 + 4 * 7 * 2 + 4));
     });
 
+    it('computes straight volume', function() {
+        var m = PolylineVolumeGeometry.createGeometry(new PolylineVolumeGeometry({
+            vertexFormat : VertexFormat.POSITION_ONLY,
+            polylinePositions : Cartesian3.fromDegreesArray([
+                -67.655, 0.0,
+                -67.655, 15.0,
+                -67.655, 20.0
+            ]),
+            cornerType: CornerType.BEVELED,
+            shapePositions: shape,
+            granularity : Math.PI / 6.0
+        }));
+
+        expect(m.attributes.position.values.length).toEqual(3 * 32);
+        expect(m.indices.length).toEqual(3 * 20);
+    });
+
     var positions = [new Cartesian3(1.0, 0.0, 0.0), new Cartesian3(0.0, 1.0, 0.0), new Cartesian3(0.0, 0.0, 1.0)];
     var volumeShape = [new Cartesian2(0.0, 0.0), new Cartesian2(1.0, 0.0), new Cartesian2(0.0, 1.0)];
     var volume = new PolylineVolumeGeometry({