private void Camera1OnCameraChanged(object sender, CameraChangedRoutedEventArgs cameraChangedRoutedEventArgs)
{
if (!(AlignWithCameraCheckBox.IsChecked ?? false))
{
return;
}
// On each change of camera we will update the orientation of billboard objects.
// When using PlaneVisual3D, TextBlockVisual3D or TextVisual3D we can simply call the AlignWithCamera method.
// If we did some changes to the Camera1 in the code,
// it is recommended to call Refresh before calling AlignWithCamera method:
// Camera1.Refresh();
bool fixYAxis = FixYAxisCheckBox.IsChecked ?? false;
PlaneVisual1.AlignWithCamera(Camera1);
TextBlockVisual3D1.AlignWithCamera(Camera1);
if (fixYAxis)
{
// To show a billboard with fixed Y axis, we first call AlignWithCamera and then set the UpDirection back to Y axis.
PlaneVisual1.HeightDirection = Ab3d.Common.Constants.UpVector; // = new Vector3D(0, 1, 0);
TextBlockVisual3D1.UpDirection = Ab3d.Common.Constants.UpVector;
}
if (FixScreenSizeCheckBox.IsChecked ?? false)
{
// When FixScreenSizeCheckBox is checked, we update the size of the billboards in 3D works
// so that they are rendered to the same size on the screen.
//
// This is done with the GetWorldSize method that calculates a size in 3D world coordinates from a size provided in 2D screen coordinates.
// You can also use CameraUtils.GetOrthographicWorldSize and CameraUtils.GetPerspectiveWorldSize methods to get the same results but with more low level parameters.
//
// It is also possible to get the opposite value - size on screen - with the following methods:
// Camera1.GetScreenSize(Size worldSize, Point3D targetPosition3D)
// CameraUtils.GetPerspectiveScreenSize(Size worldSize, double lookDirectionDistance, double fieldOfView, Size viewport3DSize)
// CameraUtils.GetOrthographicScreenSize(Size worldSize, double cameraWidth, Size viewport3DSize)
// Set the size so that it will be shown in 200 x 40 box on the screen.
Size worldSize = Camera1.GetWorldSize(new Size(200, 40), TextBlockVisual3D1.Position);
// With TextBlockVisual3D we can use multiple methods to adjust the size of the text:
// 1) Change FontSize property - this is the most performance expensive method because this will require to update the text (and render the bitmap if it is used to show the content of TextBlockVisual3D - for example when in DXEngine).
// 2) Change Size property - this is better but would require to update the plane's MeshGeometry3D. This creates a lot of objects on each camera change and require frequent garbage collections.
// TextBlockVisual3D1.Size = worldSize;
// 3) Scale the TextBlockVisual3D1 to the required size. This is by far the fastest and most efficient method because only the transformation is changed:
var scaleTransform3D = TextBlockVisual3D1.Transform as ScaleTransform3D;
if (scaleTransform3D == null)
{
scaleTransform3D = new ScaleTransform3D();
// To prevent scaling the position (multiplying it with the scale factor), we need to set the center of scale
scaleTransform3D.CenterX = TextBlockVisual3D1.Position.X;
scaleTransform3D.CenterY = TextBlockVisual3D1.Position.Y;
scaleTransform3D.CenterZ = TextBlockVisual3D1.Position.Z;
TextBlockVisual3D1.Transform = scaleTransform3D;
}
// Calculate required scale to get the size of the TextBlockVisual3D to the required worldSize
double scaleFactor = worldSize.Width / TextBlockVisual3D1.Size.Width;
scaleTransform3D.ScaleX = scaleFactor;
scaleTransform3D.ScaleY = scaleFactor;
scaleTransform3D.ScaleZ = scaleFactor;
// Do the same for PlaneVisual3D
worldSize = Camera1.GetWorldSize(new Size(200, 40), PlaneVisual1.CenterPosition);
// The easiest way to update the size of a PlaneVisual3D is to change its Size.
// But because this creates a new MeshGeometry3D, this can produce a lot of garbage because this is called on each frame (on each camera change).
// Therefore it is better to use ScaleTransform3D to update the size.
//PlaneVisual1.Size = worldSize;
scaleTransform3D = PlaneVisual1.Transform as ScaleTransform3D;
if (scaleTransform3D == null)
{
scaleTransform3D = new ScaleTransform3D();
// To prevent scaling the position (multiplying it with the scale factor), we need to set the center of scale
scaleTransform3D.CenterX = PlaneVisual1.CenterPosition.X;
scaleTransform3D.CenterY = PlaneVisual1.CenterPosition.Y;
scaleTransform3D.CenterZ = PlaneVisual1.CenterPosition.Z;
PlaneVisual1.Transform = scaleTransform3D;
}
scaleFactor = worldSize.Width / PlaneVisual1.Size.Width;
scaleTransform3D.ScaleX = scaleFactor;
scaleTransform3D.ScaleY = scaleFactor;
scaleTransform3D.ScaleZ = scaleFactor;
}
else
{
// When FixScreenSizeCheckBox is unchecked, reset the size back to initial size
TextBlockVisual3D1.Transform = null;
PlaneVisual1.Transform = null;
// The following code is used if we do not use ScaleTransform3D but instead change the Size
//if (TextBlockVisual3D1.Size.Width != 80)
// TextBlockVisual3D1.Size = new Size(80, 20);
//if (PlaneVisual1.Size.Width != 80)
// PlaneVisual1.Size = new Size(80, 20);
}
// Update all tree objects
foreach (var treePlaneVisual in TreesPlaceholerVisual3D.Children.OfType <PlaneVisual3D>())
{
treePlaneVisual.AlignWithCamera(Camera1);
if (fixYAxis)
{
treePlaneVisual.HeightDirection = Ab3d.Common.Constants.UpVector;
}
}
// After objects were rotated, we can reorder them so that those farther away from the camera are rendered first.
// This way the objects will be correctly visible through transparent objects.
_transparencySorter.Sort(TransparencySorter.SortingModeTypes.ByCameraDistance);
UpdateOverlayCanvasElements();
}
