feat(core): optimization subdivision with horizon

iTowns · Jan 22, 2019 · 761660f · 761660f
1 parent 9a40a5e
commit 761660f
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diff --git a/src/Core/Prefab/Globe/GlobeLayer.js b/src/Core/Prefab/Globe/GlobeLayer.js
@@ -13,6 +13,7 @@ let magnitudeSquared = 0.0;
 
 // vectors for operation purpose
 const scaledHorizonCullingPoint = new THREE.Vector3();
+const scaledToSphere = new THREE.Vector3(1.0, 1.0, ellipsoidSizes.x / ellipsoidSizes.z);
 
 /**
  * @property {boolean} isGlobeLayer - Used to checkout whether this layer is a
@@ -89,6 +90,15 @@ class GlobeLayer extends TiledGeometryLayer {
         cameraPosition.copy(context.camera.camera3D.position).applyMatrix4(worldToScaledEllipsoid);
         magnitudeSquared = cameraPosition.lengthSq() - 1.0;
 
+        // pre-horizon subdivision
+        scaledHorizonCullingPoint.copy(context.camera.camera3D.position).multiply(scaledToSphere);
+
+        const distanceToCenter = scaledHorizonCullingPoint.length();
+        const distanceToHorizon = (distanceToCenter ** 2 - ellipsoidSizes.x ** 2) ** 0.5;
+        const distanceToGround = Math.max(distanceToCenter - ellipsoidSizes.x, 0);
+        const factor = Math.min(distanceToGround / ellipsoidSizes.x, 1.0) ** 0.25;
+        context.horizon = distanceToHorizon - (distanceToHorizon - distanceToGround) * 0.75 * (1 - factor);
+
         return super.preUpdate(context, changeSources);
     }
 

diff --git a/src/Core/Prefab/Planar/PlanarLayer.js b/src/Core/Prefab/Planar/PlanarLayer.js
@@ -45,6 +45,15 @@ class PlanarLayer extends TiledGeometryLayer {
         this.maxSubdivisionLevel = this.maxSubdivisionLevel || 5.0;
         this.maxDeltaElevation = this.maxDeltaElevation || 4.0;
     }
+
+    preUpdate(context, changeSources) {
+        const fov = THREE.Math.degToRad(context.camera.camera3D.fov * 0.5);
+        const ratioHorizon = 0.1;
+        const distanceToGround = context.camera.camera3D.position.z;
+        context.horizon = distanceToGround / Math.sin(Math.atan(ratioHorizon * Math.tan(fov)));
+
+        return super.preUpdate(context, changeSources);
+    }
 }
 
 export default PlanarLayer;
diff --git a/src/Layer/TiledGeometryLayer.js b/src/Layer/TiledGeometryLayer.js
@@ -396,6 +396,10 @@ class TiledGeometryLayer extends GeometryLayer {
             0.0,
             context.camera.camera3D.position.distanceTo(boundingSphereCenter) - node.boundingSphere.radius * subdivisionVector.x);
 
+        if (context.horizon && distance > context.horizon) {
+            return false;
+        }
+
         // Size projection on pixel of bounding
         node.screenSize = context.camera._preSSE * (2 * node.boundingSphere.radius * subdivisionVector.x) / distance;