super sampling

vtk/src/advection/AdvectionKernel.h

@@ -19,7 +19,7 @@ public:
      * @param longitude Longitude of particle
      * @return A pair of latitude and longitude of particle.
      */
-    virtual std::pair<double, double> advect(int time, double latitude, double longitude) const = 0;
+    virtual std::pair<double, double> advect(int time, double latitude, double longitude, int dt) const = 0;
 
     // Taken from Parcels https://github.com/OceanParcels/parcels/blob/daa4b062ed8ae0b2be3d87367d6b45599d6f95db/parcels/tools/converters.py#L155
     const static double metreToDegrees(double metre) {

vtk/src/advection/EulerAdvectionKernel.cpp

@@ -4,9 +4,9 @@
 
 using namespace std;
 
-EulerAdvectionKernel::EulerAdvectionKernel(std::shared_ptr<UVGrid> grid, int dt) : grid(grid), dt(dt) {}
+EulerAdvectionKernel::EulerAdvectionKernel(std::shared_ptr<UVGrid> grid) : grid(grid) {}
 
-std::pair<double, double> EulerAdvectionKernel::advect(int time, double latitude, double longitude) const {
+std::pair<double, double> EulerAdvectionKernel::advect(int time, double latitude, double longitude, int dt) const {
   auto [u, v] = bilinearinterpolate(*grid, time, latitude, longitude);
 
   return {latitude + metreToDegrees(v * dt), longitude + metreToDegrees(u * dt)};

vtk/src/advection/EulerAdvectionKernel.h

@@ -15,10 +15,9 @@
 class EulerAdvectionKernel: public AdvectionKernel {
 private:
     std::shared_ptr<UVGrid> grid;
-    int dt;
 public:
-    explicit EulerAdvectionKernel(std::shared_ptr<UVGrid> grid, int dt);
+    explicit EulerAdvectionKernel(std::shared_ptr<UVGrid> grid);
-    std::pair<double, double> advect(int time, double latitude, double longitude) const override;
+    std::pair<double, double> advect(int time, double latitude, double longitude, int dt) const override;
 
 };
 

vtk/src/advection/RK4AdvectionKernel.cpp

@@ -3,9 +3,9 @@
 
 using namespace std;
 
-RK4AdvectionKernel::RK4AdvectionKernel(std::shared_ptr<UVGrid> grid, int dt): grid(grid), dt(dt) { }
+RK4AdvectionKernel::RK4AdvectionKernel(std::shared_ptr<UVGrid> grid): grid(grid) { }
 
-std::pair<double, double> RK4AdvectionKernel::advect(int time, double latitude, double longitude) const {
+std::pair<double, double> RK4AdvectionKernel::advect(int time, double latitude, double longitude, int dt) const {
     auto [u1, v1] = bilinearinterpolate(*grid, time, latitude, longitude);
 //    lon1, lat1 = (particle.lon + u1*.5*particle.dt, particle.lat + v1*.5*particle.dt);
     double lon1 = longitude + metreToDegrees(u1 * 0.5*dt);

vtk/src/advection/RK4AdvectionKernel.h

@@ -12,10 +12,9 @@
 class RK4AdvectionKernel: public AdvectionKernel {
 private:
     std::shared_ptr<UVGrid> grid;
-    int dt;
 public:
-    explicit RK4AdvectionKernel(std::shared_ptr<UVGrid> grid, int dt);
+    explicit RK4AdvectionKernel(std::shared_ptr<UVGrid> grid);
-    std::pair<double, double> advect(int time, double latitude, double longitude) const override;
+    std::pair<double, double> advect(int time, double latitude, double longitude, int dt) const override;
 
 };
 

vtk/src/layers/LGlyphLayer.cpp

@@ -17,7 +17,6 @@
 
 #include "../CartographicTransformation.h"
 
-
 vtkSmartPointer<SpawnPointCallback> LGlyphLayer::createSpawnPointCallback() {
   auto newPointCallBack = vtkSmartPointer<SpawnPointCallback>::New();
   newPointCallBack->setData(data);
@@ -72,27 +71,27 @@ LGlyphLayer::LGlyphLayer(std::shared_ptr<UVGrid> uvGrid, std::unique_ptr<Advecti
 
 // creates a few points so we can test the updateData function
 void LGlyphLayer::spoofPoints() {
-    this->points->InsertNextPoint(-4.125, 61.375 , 0);
+  this->points->InsertNextPoint(-4.125, 61.375, 0);
   this->points->InsertNextPoint(6.532949683882039, 53.24308582564463, 0); // Coordinates of Zernike
   this->points->InsertNextPoint(5.315307819255385, 60.40001057122271, 0); // Coordinates of Bergen
-    this->points->InsertNextPoint( 6.646210231365825, 46.52346296009023, 0); // Coordinates of Lausanne
+  this->points->InsertNextPoint(6.646210231365825, 46.52346296009023, 0); // Coordinates of Lausanne
-    this->points->InsertNextPoint(-6.553894313570932, 62.39522131195857, 0); // Coordinates of the top of the Faroe islands
+  this->points->InsertNextPoint(-6.553894313570932, 62.39522131195857,
+                                0); // Coordinates of the top of the Faroe islands
 
   this->points->Modified();
 }
 
-// returns new coords for a point; used to test the updateData function
-std::pair<double, double> advect(int time, double lat, double lon) {
-    return {lat + 0.01, lon + 0.01};
-}
-
 void LGlyphLayer::updateData(int t) {
+  const int SUPERSAMPLINGRATE = 4;
   double point[3];
   for (vtkIdType n = 0; n < this->points->GetNumberOfPoints(); n++) {
     this->points->GetPoint(n, point);
-        auto [yNew, xNew] = advector->advect(t, point[1], point[0]);
+    for (int i = 0; i < SUPERSAMPLINGRATE; i++) {
-        this->points->SetPoint(n, xNew, yNew, 0);
+      std::tie(point[1], point[0]) = advector->advect(t, point[1], point[0], (t-lastT)/SUPERSAMPLINGRATE);
     }
+    this->points->SetPoint(n, point[0], point[1], 0);
+  }
+  lastT = t;
   this->points->Modified();
 }
 

vtk/src/layers/LGlyphLayer.h

@@ -16,6 +16,7 @@ private:
   vtkSmartPointer<vtkPolyData> data;
   std::unique_ptr<AdvectionKernel> advector;
   std::shared_ptr<UVGrid> uvGrid;
+  int lastT = 1000;
 
 public:
   /** Constructor.

vtk/src/main.cpp

@@ -22,10 +22,9 @@ using namespace std;
 
 int main() {
   shared_ptr<UVGrid> uvGrid = std::make_shared<UVGrid>();
-  auto kernelRK4 = make_unique<RK4AdvectionKernel>(uvGrid, DT);
+  auto kernelRK4 = make_unique<RK4AdvectionKernel>(uvGrid);
 
   auto l = new LGlyphLayer(uvGrid, move(kernelRK4));
-//  l->spoofPoints();
 
   Program *program = new Program(DT);
   program->addLayer(new BackgroundImage("../../../../data/map_661-661.png"));