when to use CABasicAnimation and CAKeyFrameAnimation and CGAffineTransform?
CABasicAnimation
: provides basic, single-keyframe animation capabilities for a layer property.
CAKeyFrameAnimation:CAKeyframeAnimation provides generic keyframe animation capabilities for a layer property in the render tree.
CGAffineTransform:
The CGAffineTransform data structure represents a matrix used for affine transformations. A transformation specifies how points in one coordinate system map to points in another coordinate system. An affine transformation is a special type of mapping that preserves parallel lines in a path but does not necessarily preserve lengths or angles. Scaling, rotation, and translation are the most commonly used manipulations supported by affine transforms, but skewing is also possible.
For more read Core Animation Programming Guide
Related
Assuming I have a view (or image) like this:
And I'd like to transform it to look like this:
How do I create a CATransform3D matrix for that based on the 4 corners coordinates of the shape I'd like image to be transformed to?
You can't do that with a CGAffineTransform.
A CGAffineTransform is an euclidean transformation, meaning all parallel lines will remain parallel in all cases. You only can stretch, rotate, scale and translate the object.
It will be possible with a 3D affine transform. But there is no function to get the transform based on the projection (that's what you are asking for). You'll need to do the math yourself. I can't help you with that, but someone used to 3d gaming will do it it a breeze.
I would go down the path of using a 3rd party framework that makes the transformation for you. Take a look at this
I have a simple UIImageView in my view, but I can't seem to find any feature in Apple's documentation to change the UV Coordinates of this UIImageView, to convey my idea to you, this GIF file should preview how changing 4 vertices coordinates can change how the image gets viewed on the final UIImageView.
I tried to find a solution online too (other than documentation) and found none.
I use Swift.
You can achieve that very animation using UIView.transform or CALayer.transform. You'll need basic geometry to convert UV coordinates to a CGAffineTransform or CATransform3D.
I made an assumption that affine transform would suffice because in your animation the transform is affine (parallel lines stay parallel). In that case, 3 vertices are free -- the 4th one is constrained by the other 3.
If you have 3 vertices, you can compute the affine transform matrix using: Affine transformation algorithm
To achieve the infinite repeat, use UIImageResizingMode.Tile.
Is it possible to use a normalized coordinate system (from 0.0 to 1.0) instead of using pixel coordinates when drawing stuff with CoreGraphics? It would certainly make a lot of things easier...
Yes, use a CGAffineTransform. I do this in an app. keep all coordinates normalized to -1.0 to 1.0, create a transform based on the size of the view I am drawing into.
Example:
CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(offset.x, offset.y);
One can transform each point or create a path and transform the entire path:
CGMutablePathRef transformedPath = CGPathCreateMutable();
CGPathAddPath(transformedPath, &transform, path);
As #yurish points out one can also use CGContextScaleCTM, CGContextTranslateCTM, etc. instead of scaling the points/path if that works better for you.
Core graphics does not use pixel coordinates. It uses abstract points that are converted to pixels using current transformation matrix (CTM). You can use the normalized coordinate system if you adjust CTM appropriately (CGContextScaleCTM etc) .
I want to create the same transforming effect on XNA 4 as Photoshop does:
Transform tool is used to scale, rotate, skew, and just distort the perspective of any graphic you’re working with in general
This is what all the things i want to do in XNA with any textures http://www.tutorial9.net/tutorials/photoshop-tutorials/using-transform-in-photoshop/
Skew: Skew transformations slant objects either vertically or horizontally.
Distort: Distort transformations allow you to stretch an image in ANY direction freely.
Perspective: The Perspective transformation allows you to add perspective to an object.
Warping an Object(Im interesting the most).
Hope you can help me with some tutorial or somwthing already made :D, iam think vertex has the solution but maybe.
Thanks.
Probably the easiest way to do this in XNA is to pass a Matrix to SpriteBatch.Begin. This is the overload you want to use: MSDN (the transformMatrix argument).
You can also do this with raw vertices, with an effect like BasicEffect by setting its World matrix. Or by setting vertex positions manually, perhaps transforming them with Vector3.Transform().
Most of the transformation matrices you want are provided by the Matrix.Create*() methods (MSDN). For example, CreateScale and CreateRotationZ.
There is no provided method for creating a skew matrix. It should be something like this:
Matrix skew = Matrix.Identity;
skew.M12 = (float)Math.Tan(MathHelper.ToRadians(36.87f));
(That is to skew by 36.87f degrees, which I pulled off this old answer of mine. You should be able to find the full maths for a skew matrix via Google.)
Remember that transformations happen around the origin of world space (0,0). If you want to, for example, scale around the centre of your sprite, you need to translate that sprite's centre to the origin, apply a scale, and then translate it back again. You can combine matrix transforms by multiplying them. This example (untested) will scale a 200x200 image around its centre:
Matrix myMatrix = Matrix.CreateTranslation(-100, -100, 0)
* Matrix.CreateScale(2f, 0.5f, 1f)
* Matrix.CreateTranslation(100, 100, 0);
Note: avoid scaling the Z axis to 0, even in 2D.
For perspective there is CreatePerspective. This creates a projection matrix, which is a specific kind of matrix for projecting a 3D scene onto a 2D display, so it is better used with vertices when setting (for example) BasicEffect.Projection. In this case you're best off doing proper 3D rendering.
For distort, just use vertices and place them manually wherever you need them.
I'm trying to transform a rectangle to an quadrilateral and created a CATransform3D projection matrix as described by hfossli here.
The matrix works with a CALayer with out problem, but i would like/have to use it with GPUImage and the GPUImageTransformFilter, which takes a CATransform3D.
It doesn't really work.
The scaling doesn't fit, which means my transformed image gets cut of or points are not "stretched" to the position they should be. There are some threads which describe the translation from a OpenGL projection to a proper CATransform3D projection matrix like here.
It involves some scaling and y-flipping.
So I tried to scale and flip in reversed order in the hope to be able to use this CATransform3D matrix with the GPUImageTransformFilter, but couldn't really get it to work.
Did maybe someone solve this?