Re: Group CGAffineTransform Animations?
Re: Group CGAffineTransform Animations?
- Subject: Re: Group CGAffineTransform Animations?
- From: Chunk 1978 <email@hidden>
- Date: Wed, 17 Jun 2009 14:37:44 -0400
still having issues. i've changed the order of transforms:
-=-=-=-
CGAffineTransform transform =
CGAffineTransformMakeTranslation(centerPoint.x, centerPoint.y);
transform = CGAffineTransformScale(transform, 2, 2);
transform = CGAffineTransformRotate(transform, kDegreesToRadian(90));
square.transform = transform;
-=-=-=-
although this code supposedly scales the Square before translating it
to it's new origin, it maintains the Squares original origin based on
it's original size. so eventhough the Square is now twice as big, it
is translated to the center of the screen minus it's new scale. i can
remedy it by adding this:
-=-=-=-
CGRect squareFrame = [square frame];
CGAffineTransform transform =
CGAffineTransformMakeTranslation(centerPoint.x +
squareFrame.size.width / 2, centerPoint.y + squareFrame.size.height /
2);
-=-=-=-
but that seems like a hack...
any ideas?
On Wed, Jun 17, 2009 at 12:31 PM, Kyle Sluder<email@hidden> wrote:
> On Wed, Jun 17, 2009 at 9:14 AM, Gordon Apple<email@hidden> wrote:
>> IMHO, matrix operations are one of the most confusing and cumbersome
>> aspects of Cocoa. Every time I use them, I end up trying most combinations
>> until I get the desired result. C++ doesn't have this problem. You can
>> simply write the matrix equations and be done with it. I love Objective C,
>> but operator overloading (and ctors/dtors) are the things I miss most.
>> Multiple inheritance -- not so much.
>
> This isn't a C++/ObjC issue. Whatever matrix library you were using
> under C++ happened to define matrix multiplication in such a way that
> it performed the operations in reverse order. XNA, on the other hand,
> follows the same pattern as Cocoa, even though it's written in C# and
> therefore has operator overloading.
>
> The AppKit team could very easily have implemented NSAffineTransform
> to transparently define a stack. But they didn't. Neither did the
> OpenGL people, or the XNA people. But it's not a language issue.
>
> --Kyle Sluder
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