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List:       swiff-info
Subject:    [swiff-info] Re: Matrix values
From:       Nick Main <d_nick_main>
Date:       1999-09-08 0:59:39
[Download RAW message or body]

The swf matrix is a standard 2d coord transform
matrix, thus for all points:

new x = (x * scaleX) + (y * rotskew1 ) + translateX
new y = (x * rotskew0) + (y * scaleY ) + translateY

(I think that's correct)

So, to rotate through angle A and scale in both
directions by S:
    scaleX   = S * cos(A)
    scaleY   = S * cos(A)
    rotSkew0 = S * -sin(A)
    rotSkew1 = S *  sin(A)

If A = 0 then sin(A) = 0 and cos(A) = 1 - so only the
scale parameters play a role.

There are no separate operations - the whole transform
is a single action.

Hope that helps a little !

--Nick

--- jcartier wrote:
> Hi all,
> 
> I'm looking for some clarification of the SWF matrix
> definition, in particular the rotate/skew values.
> 
> What exactly do the RotateSkew0 and RotateSkew1
> values represent? 
> 
> Also, am I correct in assuming the matrix operations
> are applied in scale, rotate, then translate order?
> 
> Thanks for your help.
> 
> --Jeremy
> 
> 
> 
> 
>
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