Re: Problem with Grouping the rotated object.

FROM : Gregory Weston
DATE : Wed Apr 02 20:47:06 2008

Quincey Morris wrote:

> On Apr 2, 2008, at 04:00, Ghufran Ahamad wrote:
>

>> [xform translateXBy:center.x yBy:center.y];
>> [xform rotateByDegrees:[curGraphic GetAngle]];
>> [xform translateXBy:-center.x yBy:-center.y];

> This looks kind of wrong. Mathematically, wouldn't you want:
>
>     [xform translateXBy:-center.x yBy:-center.y];
>     [xform rotateByDegrees:[curGraphic GetAngle]];
>     [xform translateXBy:center.x yBy:center.y];
>
> ?


Nope. The way the matrix multiplication works, the effect is that the 
transformations take place in the opposite order of the way they 
appeared in code.