Problem with MSDN 2D animate sprite example?

XNA Framework

TehOne

I was following the example/tutorial on this page http://msdn2.microsoft.com/en-us/library/bb203866.aspx and I think it may have a problem. It seems to skip the last frame of the image.

Here is my example image, it is 256x64 with 4 64x64 frames as specified in the example.

http://tehone.com/images/xna/ball-4frames.png

If you plug in the code on that page with this image, it skips the last frame of my image. Is there a mistake with the example Or am I missing something

Thanks.
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Re: XNA Framework Problem with MSDN 2D animate sprite example?

TehOne 

Btw... If i change the code and get rid of the -1 in the new Frame calculation, then the animation works fine.

Can anyone tell me why they would be -1 from the framecount in the first place 

Thanks again.

From this:

// class AnimatedTexture
public void UpdateFrame( float elapsed )
{
  if (Paused)
    return;
  TotalElapsed += elapsed;
  if (TotalElapsed > TimePerFrame)
  {
    Frame++;
    // Keep the Frame between 0 and the total frames, minus one
    Frame = Frame % (framecount - 1);
    TotalElapsed -= TimePerFrame;
  }
}


To this:
// class AnimatedTexture
public void UpdateFrame( float elapsed )
{
  if (Paused)
    return;
  TotalElapsed += elapsed;
  if (TotalElapsed > TimePerFrame)
  {
    Frame++;
    // Keep the Frame between 0 and the total frames, minus one
    Frame = Frame % framecount;
    TotalElapsed -= TimePerFrame;
  }
}


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Re: XNA Framework Problem with MSDN 2D animate sprite example?

dczraptor

it just depends on whether you set framecount = 0 or framecount = 1 at the beginning of your program. If you set it to framecount = 1, then you will need Frame = Frame % (framecount -1) to get a correct number, while if you do framecount = 0, then you will not need to subtract one.



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Re: XNA Framework Problem with MSDN 2D animate sprite example?

TehOne

If you look at the example on MSDN, you will see that framecount is actually a parameter to the Load method of the AnimatedTexture class. And, you (according to what I can tell from the example) are supposed to set this to the total amount of frames in your image. My image (and the example given in the code) has 4 frames. But that example, out of the box, skips the 4th frame of the image. That was where my confusion comes from (or my thinking that the example is wrong).

Thanks.


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Re: XNA Framework Problem with MSDN 2D animate sprite example?

NinjaCoder

Ooh, my first post. :-)

I believe TehOne is right - in the example MSDN gives you line 50 has something like:

Frame = Frame % (framecount) - 1;

Where it should be:

Frame = Frame % (framecount);

This is cause FrameCount % FrameCount equals zero, so you'll loop back to the first frame of your animation (index zero).

Yay zero-based arrays!


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