Hi,
When trying to animate objects time/frame based in Silverlight (in contrast to using something like DoubleAnimation or Storyboard, which is not suitable e.g. for fast paced games), for example moving a spaceship in a particular direction every frame, the movement is jumpy and not really smooth. The screen even seems to tear.
There seems to be no difference between CompositionTarget and DistpatcherTimer.
I use the following approach (in pseudocode):
Register Handler to Tick-Event of a DispatcherTimer
In each Tick:
Compute the elapsed time from the last frame in milliseconds
Object.X += movementSpeed * ellapsedMilliseconds
This should result in a smooth movement, right? But it doesn't.
Here is an example (Controls: WASD and Mouse): Silverlight Game.
Although the effect I described is not too prevalent in this sample, I can assure you that even moving a single rectangle over a canvas produces a jumpy animation.
Does someone have an idea how to minimize this. Are there other approaches to to frame based animation exept using Storyboards/DoubleAnimations which could solve this?
Edit: Here a quick and dirty approach, animating a rectangle with minimum code (Controls: A and D) Animation Sample
Xaml:
<Grid x:Name="LayoutRoot" Background="Black">
<Canvas Width="1000" Height="400" Background="Blue">
<Rectangle x:Name="rect" Width="48" Height="48"
Fill="White"
Canvas.Top="200"
Canvas.Left="0"/>
</Canvas>
</Grid>
C#:
private bool isLeft = false;
private bool isRight = false;
private DispatcherTimer timer = new DispatcherTimer();
private double lastUpdate;
public Page()
{
InitializeComponent();
timer.Interval = TimeSpan.FromMilliseconds(1);
timer.Tick += OnTick;
lastUpdate = Environment.TickCount;
timer.Start();
}
private void OnTick(object sender, EventArgs e)
{
double diff = Environment.TickCount - lastUpdate;
double x = Canvas.GetLeft(rect);
if (isRight)
x += 1 * diff;
else if (isLeft)
x -= 1 * diff;
Canvas.SetLeft(rect, x);
lastUpdate = Environment.TickCount;
}
private void UserControl_KeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Key.D)
isRight = true;
if (e.Key == Key.A)
isLeft = true;
}
private void UserControl_KeyUp(object sender, KeyEventArgs e)
{
if (e.Key == Key.D)
isRight = false;
if (e.Key == Key.A)
isLeft = false;
}
Thanks!
Andrej
