Extruded polygon

CHANGES.md

@@ -9,6 +9,7 @@ Beta Releases
 * Breaking changes:
   *
 * `loadArrayBuffer`, `loadBlob`, `loadJson`, `loadText`, and `loadXML` now support loading data from data URIs.
+* Fixed extruded polygons rendered in the southern hemisphere. [#1490](https://github.com/AnalyticalGraphicsInc/cesium/issues/1490)
 * Fixed Primitive picking that have a closed appearance drawn on the surface. [#1333](https://github.com/AnalyticalGraphicsInc/cesium/issues/1333)
 
 ### b26 - 2014-03-03

Source/Core/PolygonGeometry.js

@@ -393,6 +393,8 @@ define([
         });
     }
 
+    var createGeometryFromPositionsExtrudedPositions = [];
+
     function createGeometryFromPositionsExtruded(ellipsoid, positions, granularity, hierarchy, perPositionHeight) {
         var topGeo = createGeometryFromPositions(ellipsoid, positions, granularity, perPositionHeight).geometry;
         var edgePoints = topGeo.attributes.position.values;
@@ -433,10 +435,14 @@ define([
 
         geos.walls = [];
         var outerRing = hierarchy.outerRing;
-        var windingOrder = PolygonPipeline.computeWindingOrder2D(outerRing);
+        var tangentPlane = EllipsoidTangentPlane.fromPoints(outerRing, ellipsoid);
+        var positions2D = tangentPlane.projectPointsOntoPlane(outerRing, createGeometryFromPositionsExtrudedPositions);
+
+        var windingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
         if (windingOrder === WindingOrder.CLOCKWISE) {
-            outerRing = outerRing.reverse();
+            outerRing.reverse();
         }
+
         var wallGeo = computeWallIndices(outerRing, granularity, perPositionHeight);
         geos.walls.push(new GeometryInstance({
             geometry : wallGeo
@@ -445,10 +451,15 @@ define([
         var holes = hierarchy.holes;
         for (i = 0; i < holes.length; i++) {
             var hole = holes[i];
-            windingOrder = PolygonPipeline.computeWindingOrder2D(hole);
-            if (windingOrder !== WindingOrder.CLOCKWISE) {
-                hole = hole.reverse();
+
+            tangentPlane = EllipsoidTangentPlane.fromPoints(hole, ellipsoid);
+            positions2D = tangentPlane.projectPointsOntoPlane(hole, createGeometryFromPositionsExtrudedPositions);
+
+            windingOrder = PolygonPipeline.computeWindingOrder2D(positions2D);
+            if (windingOrder === WindingOrder.CLOCKWISE) {
+                hole.reverse();
             }
+
             wallGeo = computeWallIndices(hole, granularity);
             geos.walls.push(new GeometryInstance({
                 geometry : wallGeo

Specs/Scene/GeometryRenderingSpec.js

@@ -1038,6 +1038,52 @@ defineSuite([
             };
             render3D(instance, afterView);
         });
+
+        it('renders with correct winding order in southern hemisphere', function() {
+            var primitive = new Primitive({
+                geometryInstances : new GeometryInstance({
+                    geometry : PolygonGeometry.fromPositions({
+                        vertexFormat : PerInstanceColorAppearance.VERTEX_FORMAT,
+                        ellipsoid : ellipsoid,
+                        positions : ellipsoid.cartographicArrayToCartesianArray([
+                            Cartographic.fromDegrees(-108.0, -25.0, 500000),
+                            Cartographic.fromDegrees(-100.0, -25.0, 500000),
+                            Cartographic.fromDegrees(-100.0, -30.0, 500000),
+                            Cartographic.fromDegrees(-108.0, -30.0, 500000)
+                        ]),
+                        perPositionHeight : true,
+                        extrudedHeight: 0
+                    }),
+                    id : 'extrudedPolygon',
+                    attributes : {
+                        color : new ColorGeometryInstanceAttribute(1.0, 1.0, 0.0, 1.0)
+                    }
+                }),
+                appearance : new PerInstanceColorAppearance({
+                    closed : true,
+                    translucent : false
+                }),
+                asynchronous : false
+            });
+
+            var frameState = createFrameState();
+            primitive.update(context, frameState, []);
+            viewSphere3D(frameState.camera, primitive._boundingSphere, primitive.modelMatrix);
+
+            var transform = Transforms.eastNorthUpToFixedFrame(primitive._boundingSphere.center);
+            frameState.camera.controller.rotateDown(-CesiumMath.PI_OVER_TWO, transform);
+            frameState.camera.controller.moveForward(primitive._boundingSphere.radius * 0.75);
+
+            context.getUniformState().update(context, frameState);
+
+            ClearCommand.ALL.execute(context);
+            expect(context.readPixels()).toEqual([0, 0, 0, 0]);
+
+            render(context, frameState, primitive);
+            expect(context.readPixels()).toEqual([0, 0, 0, 0]);
+
+            primitive = primitive && primitive.destroy();
+        });
     }, 'WebGL');