fix(pointcloud): Add SSE calculation for orthographic projections

Desplandis · Desplandis · commit cae9463489f0 · 2023-12-20T11:48:30.000+01:00
diff --git a/src/Layer/PointCloudLayer.js b/src/Layer/PointCloudLayer.js
@@ -26,7 +26,7 @@ function initBoundingBox(elt, layer) {
     elt.obj.boxHelper.updateMatrixWorld();
 }
 
-function computeScreenSpaceError(context, pointSize, spacing, elt, distance) {
+function computeSSEPerspective(context, pointSize, spacing, elt, distance) {
     if (distance <= 0) {
         return Infinity;
     }
@@ -40,6 +40,30 @@ function computeScreenSpaceError(context, pointSize, spacing, elt, distance) {
     return Math.max(0.0, onScreenSpacing - pointSize);
 }
 
+function computeSSEOrthographic(context, pointSize, spacing, elt) {
+    const pointSpacing = spacing / 2 ** elt.depth;
+
+    // Given an identity view matrix, project pointSpacing from world space to
+    // clip space. v' = vVP = vP
+    const v = new THREE.Vector4(pointSpacing);
+    v.applyMatrix4(context.camera.camera3D.projectionMatrix);
+
+    // We map v' to the screen space and calculate the distance to the origin.
+    const dx = v.x * 0.5 * context.camera.width;
+    const dy = v.y * 0.5 * context.camera.height;
+    const distance = Math.sqrt(dx * dx + dy * dy);
+
+    return Math.max(0.0, distance - pointSize);
+}
+
+function computeScreenSpaceError(context, pointSize, spacing, elt, distance) {
+    if (context.camera.camera3D.isOrthographicCamera) {
+        return computeSSEOrthographic(context, pointSize, spacing, elt);
+    }
+
+    return computeSSEPerspective(context, pointSize, spacing, elt, distance);
+}
+
 function markForDeletion(elt) {
     if (elt.obj) {
         elt.obj.visible = false;
