Re: Group CGAffineTransform Animations?
Re: Group CGAffineTransform Animations?
- Subject: Re: Group CGAffineTransform Animations?
- From: Chunk 1978 <email@hidden>
- Date: Wed, 17 Jun 2009 15:10:10 -0400
... perhaps there's a way to set the transforming object's origin to
it's center some how? i could work with that...
On Wed, Jun 17, 2009 at 2:37 PM, Chunk 1978<email@hidden> wrote:
> 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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