private void OnTilePointerPressed(object sender, PointerRoutedEventArgs e)
{
var tileGrid = (Grid)sender;
var colorElement = (Rectangle)tileGrid.FindName("ColorElement");
// Set the CenterPoint of the backing Visual, so the rotation axis will defined from the middle.
colorElement.Visual().CenterPoint = new Vector3(tileGrid.RenderSize.ToVector2() / 2, 0.0f);
// Calculate distance from corner of quadrant to Center
_center = colorElement.Visual().CenterPoint;
var xSquared = Math.Pow(tileGrid.ActualWidth / 2, 2);
var ySquared = Math.Pow(tileGrid.ActualHeight / 2, 2);
_distanceToCenter = (float)Math.Sqrt(xSquared + ySquared);
// || DEFINE THE EXPRESSION FOR THE ROTATION ANGLE ||
// We calculate the Rotation Angle such that it increases from 0 to 3 as the cursor position moves away from the center.
// Combined with animating the Rotation Axis, the image is "push down" on the point at which the cursor is located.
var pointerPositionProperties = ElementCompositionPreview.GetPointerPositionPropertySet(tileGrid);
var pointerPosition = pointerPositionProperties.GetSpecializedReference <PointerPositionPropertySetReferenceNode>().Position;
var angleExpressionNode = 3 * (EF.Clamp(EF.Distance(_center, pointerPosition), 0, _distanceToCenter) % _distanceToCenter / _distanceToCenter);
var rotationAngleAnimation = _compositor.CreateScalarKeyFrameAnimation();
rotationAngleAnimation.Duration = TimeSpan.FromMilliseconds(600);
rotationAngleAnimation.InsertExpressionKeyFrame(0.4f, angleExpressionNode);
rotationAngleAnimation.InsertKeyFrame(1.0f, 0.0f);
colorElement.Visual().StartAnimation("RotationAngleInDegrees", rotationAngleAnimation);
// || DEFINE THE EXPRESSION FOR THE ROTATION AXIS ||
// The RotationAxis will be defined as the axis perpendicular to vector position of the hover pointer (vector from center to hover position).
// The axis is a vector calculated by first converting the pointer position into the coordinate space where the center point (0, 0) is in the middle.
// The perpendicular axis is then calculated by transposing the cartesian x, y components and negating one (e.g. Vector3(-y,x,0) )
var axisAngleExpressionNode = EF.Floor((pointerPosition.X - _center.X) * EF.Conditional(pointerPosition.X == _center.X, 0, 1));
var rotationAxisAnimation = _compositor.CreateScalarKeyFrameAnimation();
rotationAxisAnimation.Duration = TimeSpan.FromMilliseconds(600);
rotationAxisAnimation.InsertExpressionKeyFrame(0.4f, axisAngleExpressionNode);
rotationAxisAnimation.InsertKeyFrame(1.0f, 0.0f);
colorElement.Visual().StartAnimation("RotationAxis.Y", rotationAxisAnimation);
}
private void TiltUIElement()
{
// Grab the backing Visual for the UIElement image
_tiltVisual = ElementCompositionPreview.GetElementVisual(tiltImage);
// Set the CenterPoint of the backing Visual, so the rotation axis will defined from the middle
_tiltVisual.CenterPoint = new Vector3((float)tiltImage.Width / 2, (float)tiltImage.Height / 2, 0f);
// Grab the PropertySet containing the hover pointer data that will be used to drive the rotations
// Note: We have a second UIElement we will grab the pointer data against and the other we will animate
_hoverPositionPropertySet = ElementCompositionPreview.GetPointerPositionPropertySet(HitTestRect);
// Calculate distance from corner of quadrant to Center
var center = new Vector3((float)tiltImage.Width / 2, (float)tiltImage.Height / 2, 0);
var xSquared = Math.Pow(tiltImage.Width / 2, 2);
var ySquared = Math.Pow(tiltImage.Height / 2, 2);
var distanceToCenter = (float)Math.Sqrt(xSquared + ySquared);
// || DEFINE THE EXPRESSION FOR THE ROTATION ANGLE ||
// We calculate the Rotation Angle such that it increases from 0 to 35 as the cursor position moves away from the center.
// Combined with animating the Rotation Axis, the image is "push down" on the point at which the cursor is located.
// Note: We special case when the hover position is (0,0,0) as this is the starting hover position and and we want the image to be flat (rotationAngle = 0) at startup.
var hoverPosition = _hoverPositionPropertySet.GetSpecializedReference <PointerPositionPropertySetReferenceNode>().Position;
var angleExpressionNode =
EF.Conditional(
hoverPosition == new Vector3(0, 0, 0),
ExpressionValues.CurrentValue.CreateScalarCurrentValue(),
35 * ((EF.Clamp(EF.Distance(center, hoverPosition), 0, distanceToCenter) % distanceToCenter) / distanceToCenter));
_tiltVisual.StartAnimation("RotationAngleInDegrees", angleExpressionNode);
// || DEFINE THE EXPRESSION FOR THE ROTATION AXIS ||
// The RotationAxis will be defined as the axis perpendicular to vector position of the hover pointer (vector from center to hover position).
// The axis is a vector calculated by first converting the pointer position into the coordinate space where the center point (0, 0) is in the middle.
// The perpendicular axis is then calculated by transposing the cartesian x, y components and negating one (e.g. Vector3(-y,x,0) )
var axisAngleExpressionNode = EF.Vector3(
-(hoverPosition.Y - center.Y) * EF.Conditional(hoverPosition.Y == center.Y, 0, 1),
(hoverPosition.X - center.X) * EF.Conditional(hoverPosition.X == center.X, 0, 1),
0);
_tiltVisual.StartAnimation("RotationAxis", axisAngleExpressionNode);
}
