/// <summary>
/// For each mesh object in the viewport, this method calculates the vertex that when mapped to 2D is closest to the given 2D point on the screen
/// </summary>
/// <param name="pointToHitTest"> The point in screen coordinates to calculate the closest vertices for. </param>
/// <returns> A ClosestVertexResult containing the distance to the 2D point and the closest 3D vertex point for each geometry/model </returns>
public IEnumerable <ClosestVertexResult> FindClosestHits(Point pointToHitTest)
{
ProjectionCamera camera = mViewPort3D.Camera as ProjectionCamera;
if (camera == null)
{
throw new InvalidOperationException("No projection camera defined. Cannot find rectangle hits.");
}
List <ClosestVertexResult> results = new List <ClosestVertexResult>();
mViewPort3D.Children.Traverse <GeometryModel3D>(
(model, transform) =>
{
MeshGeometry3D geometry = model.Geometry as MeshGeometry3D;
if (geometry == null || geometry.Positions == null || geometry.TriangleIndices == null)
{
return;
}
Point3D[] point3Ds;
if (geometry.Positions.Count <= mMaximumVerticesPerMesh)
{
point3Ds = geometry.Positions.Select(transform.Transform).ToArray();
}
else
{
Rect3D bounds = geometry.Bounds;
point3Ds = GetBoundaryPointsBoundingBox(bounds).Select(transform.Transform).ToArray();
}
// transform the positions of the mesh to screen coordinates
Point[] point2Ds = mViewPort3D.Point3DtoPoint2D(point3Ds).ToArray();
double minSquaredDistanceToPoint = double.PositiveInfinity;
Point3D closestPoint = point3Ds[0];
Point closestPointIn2D = point2Ds[0];
for (int i = 0; i < point2Ds.Length; i++)
{
Point point = point2Ds[i];
double xDiff = point.X - pointToHitTest.X;
double yDiff = point.Y - pointToHitTest.Y;
double squaredDistance = xDiff * xDiff + yDiff * yDiff;
if (squaredDistance < minSquaredDistanceToPoint)
{
minSquaredDistanceToPoint = squaredDistance;
closestPoint = point3Ds[i];
closestPointIn2D = point;
}
}
ClosestVertexResult hitTestResult = new ClosestVertexResult(model, geometry, closestPoint,
closestPointIn2D, Math.Sqrt(minSquaredDistanceToPoint));
results.Add(hitTestResult);
});
return(results);
}
public ClosestVertexResult ResultOfClosestPointHit2D(Point position)
{
double minX = 0;
double minY = 0;
double maxX = mViewPort3D.ActualWidth;
double maxY = mViewPort3D.ActualHeight;
IEnumerable <ClosestVertexResult> hitsInView = FindClosestHits(position).Where(result =>
result.ClosestPointIn2D.X >= minX && result.ClosestPointIn2D.X <= maxX &&
result.ClosestPointIn2D.Y >= minY && result.ClosestPointIn2D.Y <= maxY);
IOrderedEnumerable <ClosestVertexResult> closestHits =
hitsInView.OrderBy(x => x.DistanceToPoint2D);
//Return the closest valid result, or null in case no valid result was found.
ClosestVertexResult closestHitInView = closestHits.FirstOrDefault();
return(closestHitInView);
}
/// <summary>
/// Returns the 3D point that the user most likely clicked on.
/// Returns the closest intersection with a mesh, if possible.
/// If useClosestMeshIfPossible is true it will otherwise returns the mesh vertex that is closest to the clicked 2D screen coordinate, if possible.
/// Returns the unprojected position otherwise.
/// Also returns the 2D point corresponding to the returned 3D point.
/// </summary>
/// <param name="position"> The point in screen coordinates to calculate the closest vertices for. </param>
/// <param name="useClosestMeshIfPossible"> When true the closest vertex point to the clicked position will be used when no mesh is hit at the exact mouse cursor area.</param>
public NearestPointInCamera CalculateMouseDownNearestPoint(Point position, bool useClosestMeshIfPossible)
{
if (mViewPort3D.FindNearest(position, out Point3D nearestPoint, out _, out _))
{
return(new NearestPointInCamera(position, nearestPoint));
}
if (useClosestMeshIfPossible)
{
ClosestVertexResult closestResult = ResultOfClosestPointHit2D(position);
if (closestResult != null)
{
return(new NearestPointInCamera(closestResult.ClosestPointIn2D, closestResult.ClosestPoint));
}
}
Point3D?unprojectedPosition = mViewPort3D.UnProject(position);
return(new NearestPointInCamera(position, unprojectedPosition));
}
