Collision detection: A comparison

Dar Scott dsc at
Fri Oct 4 13:53:01 EDT 2002

On Friday, October 4, 2002, at 11:31 AM, Dar Scott wrote:

> I have used the alpha bytes from imagedata.  That might depend on the type 
> of image, too; maybe I was lucky in it working for me.
> I would start with making a function that given an imagedata string, X & Y 
> pixel coordinate within that image and the width of the image returns the 
> character containing the alpha.  I say char instead of number incase you 
> can get by without the number and compare the char directly.  I think 
> there are some clues to working with imagedata at Ken Ray's site.

Brain warp!

I just looked at my code.  I used alphadata, not imagedata:

   put the alphaData of image "Test Image" into dat

It may be that imagedata has the same info, but the dictionary says the 
fourth byte is 0, so I would guess not.  Also, alphadata will be easier to 

I should know better than to go by memory.


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