fix(CylinderSource): generate correct normals for directed cylinders

This fixes incorrect normals for capped or directed cylinders

Author: daker

Sources/Filters/Sources/CylinderSource/index.js

@@ -65,6 +65,8 @@ function vtkCylinderSource(publicAPI, model) {
       // y coordinate
       xbot[1] = 0.5 * model.height + model.center[1];
       xtop[1] = -0.5 * model.height + model.center[1];
+      nbot[1] = 0.0;
+      ntop[1] = 0.0;
       tcbot[1] = 0.0;
       tctop[1] = 1.0;
 
@@ -100,6 +102,13 @@ function vtkCylinderSource(publicAPI, model) {
     if (model.capping) {
       // Generate points for top/bottom polygons
       for (let i = 0; i < model.resolution; i++) {
+        nbot[0] = 0.0;
+        nbot[1] = 1.0;
+        nbot[2] = 0.0;
+        ntop[0] = 0.0;
+        ntop[1] = -1.0;
+        ntop[2] = 0.0;
+
         // x coordinate
         xbot[0] = model.radius * Math.cos(i * angle + model.initAngle);
         xtop[0] = xbot[0];
@@ -109,8 +118,6 @@ function vtkCylinderSource(publicAPI, model) {
         xtop[0] += model.center[0];
 
         // y coordinate
-        nbot[1] = 1.0;
-        ntop[1] = -1.0;
         xbot[1] = 0.5 * model.height + model.center[1];
         xtop[1] = -0.5 * model.height + model.center[1];
 
@@ -154,6 +161,11 @@ function vtkCylinderSource(publicAPI, model) {
       .translate(...model.center.map((c) => c * -1))
       .apply(points);
 
+    vtkMatrixBuilder
+      .buildFromRadian()
+      .rotateFromDirections([0, 1, 0], model.direction)
+      .apply(normalsData);
+
     const dataset = outData[0]?.initialize() || vtkPolyData.newInstance();
     dataset.getPoints().setData(points, 3);
     dataset.getPolys().setData(polys, 1);