I would like to add moving child nodes on a Sprite node, but want them to be clipped if they move outside the bounds, hence giving an impression of a 'window'. I know there is a UIView property called clipsToBounds that does the same. Is there a similar property for SKSpriteNode, and if not, how to achieve the same?
You could add the sprite supposed to be clipped to a SKCropNode. Then set the crop node's maskNode to a sprite node using an image that defines the crop region.
Related
Before AutoLayout I could do a view cut to a circle shape with setting .layer.cornerRadius to half of the view's height.
Now, using AutoLayout how can I achieve, to my view keep look like a circle?
I have already tried and failed:
using KVO to find out when frame changes. It gets called, but at that point setting cornerRadius on the view does not have any effect
calling -setNeedsLayout to have frame values before I set cornerRadius (does not work either)
You need to set the property masksToBounds on the layer.
xyz.layer.masksToBounds = YES;
Further, the reason why this actually won't affect Auto Layout is because the view's frame will remain the same regardless of its corner radius.
I have a lot of different sprite nodes with a physicsbody the same size as the object. For positioning I need to change the anchorpoint of the node, but this changes the position of the physicsbody as well. Is there a way to keep the anchorpoint for the physicsbody centered? Using a path for the physicsbody is no option because I have so many different objects.
The anchorPoint is a purely visual property, it defines how the texture is drawn relative to the node's position. The physics body remains unaffected by changing the anchorPoint, it remains centered on the node's position.
So in a sense, the physics body does remain centered on the sprite's position already. By changing the anchorPoint you merely changed where the sprite's texture is displayed, and I believe you assumed the physics body would center on the sprite's anchorPoint. It does not, for one every node can have a physics body but only few nodes (sprite, scene, video) have an anchorPoint property.
The best way to fix this is to create your sprite images so that the physics body is always assumed to be centered on the image. Leave transparent borders around the image to ensure the image size is always the same and the position of the body properly centered.
You can also use SKPhysicsBody bodyWithRectangleOfSize:center: initializer to define the center point of the body and to match it up with the sprite's anchorPoint. But this is tricky and counterproductive, as you'll have to constantly realign body and sprite anchorPoint if you make even the smallest change.
Other than that it's best to leave the anchorPoint alone, especially with physics.
An old thread but still pops up when I google searched... Here was how I solved the problem for myself.
I essentially just stacked my SKSpriteNodes. The highest level parent node would receive the SKPhysicsBody so that all the objects would stay together. If you add the SKPhysicsBody object as a child to another node, the physicsBody can essentially fall out of the other nodes (images would be left floating in my case) when gravity or other forces are applied and can return some wonky results if you aren't careful.
To further clarify:
Parent node with no image/texture associated with it, just a size and then the physicsBody. (This node had the modified anchor point)
I then added a child node that had my "body" texture. (position had to be adjusted to make up for the parent's anchor point)
Finally I added two more child nodes to the "body" node to make up the eyes.
This specifically allows you to use a texture based SKPhysicsBody or something more complicated that does not have a centering option.
The physicsBody worked just as I needed it to while still being able to manipulate SKActions in the way in which a modified anchor point allows.
Hope this helps someone.
Attached 1 is a screenshot from an app called GeniusScan where you can photograph any document and an adjustable rectangular grid shows on the imageview. You can easily adjust the borders of the grid with your fingers to select the portion of the image that you want to scan. It will be then transformed into the correct prospective.
1- How can I draw and interact with the grid on the imageview?
2- How can I return the corner points of the grid to my view controller.
Update: I found a wonderful class called BJImageCropper which allows to use fingers to ajust the borders, but only for a box like rectangle. Can anyone suggest how it can be updated to support shapes like in the GeniusScan app?
Dude:
I created a demo that solves both questions:
1- How can I draw and interact with the grid on the imageview?
By Adding 4 views that will act as interactive control points by adding UIPanGestureRecognizer and then drawing the grid using CAShapeLayer on top of your view.
2- How can I return the corner points of the grid to my view controller.
You must keep references to the four control points of your grid.
Here's the link to my code.
This isn't actually drawing on top of UIImageView. It's actually an overlay (view) on top of the UIImageView. You need to keep track of 4 points (have 4 views as subview of the layer), track their positions, once moved, use drawRect: to draw lines based on the 4 points.
The way I've implemented it in my app is, I overlay the UIImageView with a transparent 'SelectionView' (a custom view that I wrote). The selectionView contains 4 custom subview of class 'Vertex'. The vertex talk back to the selectionView via protocol method every time user touches/moves it (it's actually not important which vertex moved, just that it moved):
- (void)vertexMoved:(Vertex *)vertex;
Then the selectionView knows that it needs to re-draw, so it calls setNeedsDisplay which calls internally calls drawRect (you should never call drawRect) where I do the actual drawing of the bounding rect. Basically, iterate through each vertex and draw a line using Quartz APIs and fill it with semi transparent/hollow color.
This is how I am doing it atleast, I am sure there are other ways.
I can't find an answer for this one.
I would like to know how to have the image size in a calayer's to be lower than calayer's bound's size.
I've got several pawns in an iPad game, each is a CALayer and I have them resize simply with a contentsGravity=kCAGravityResizeAspect. Image is 128x128 inside of a CALayer of 30x30 so the image gets resized automatically to 30x30 and because of both being a box, aspect ratio maintains and works.
Here I set CALayer's bounds proportional relative to superview's size, so the Pawns always present the same relative size to the view. This one is inside my sprite class subclass of calayer:
-(void) setSpriteScaleToDice {
CGFloat newSize = [self superlayer].bounds.size.width * 0.066666667f;
self.bounds=CGRectMake(0.0f, 0.0f, newSize, newSize);
self.contentsGravity = kCAGravityResizeAspect;
}
Note that in my case the CALayer bounds gets a maximum of 30x30 which is small for a touch. That's the problem I'm facing, due to this small size it's difficult to "touch" them, sometimes touch fails...
One of the ideas that I'm thinking is to increase the "bounds" of the calayer, while keeping the image at its original size. The problem is that I've search a lot and tried several options with contentsGravity, contentsCenter, contentsScale, etc... without success.
In particular, as per apple docs looks like the way to go is with contentsCenter (and not using contentsGravity), however I get deformation in the bitmap...
Please, any idea is really welcome, and thanks in advance,
Luis
This is probably a silly question, but why are you using CALayers for this instead of UIViews? UIImageView has a contentMode property that lets you do this easily (not to mention being easier to use for touch event handling).
That said, CALayer has a contentsRect property that appears to let you define a sub-rectangle for contents to be drawn within, so that may let you do what you want.
Another option would be to place your image layer inside a larger layer and use that for the hit test.
CAlayer CGFloat contentsScale
/* Defines the scale factor applied to the contents of the layer. If
* the physical size of the contents is '(w, h)' then the logical size
* (i.e. for contentsGravity calculations) is defined as '(w /
* contentsScale, h / contentsScale)'. Applies to both images provided
* explicitly and content provided via -drawInContext: (i.e. if
* contentsScale is two -drawInContext: will draw into a buffer twice
* as large as the layer bounds). Defaults to one. Animatable. */
If you want your image drawn in the CALayer at a size other than the CALayer you need to create your own drawInContext: method and draw the image rather than setting the CALayer's contents property. Do not set the contents property, create your own to track the image you want to draw.
I am attempting to reveal (through animation) a UIView. Specifically I want to show the center portion of the view and then slowly reveal the outer edges of it (sort of like pulling back a curtain).
My first attempt was to simply set the bounds rect to be smaller and animate it to be the full size of the view's frame, but this did not have the desired effect since by changing the bounds I was also changing the frame.
If what I am trying to do does not sound possible (at least not in a simple manner), at least I would like to be able to have is some way to make the subviews of the main view stationary relative to the screen, NOT their parent view, as the parent resizes (this would give a similar effect).
Any ideas?
Thank you,
-Matt
It definitely is possible. What you need to do is
For the view you're animating, setAutoresizesSubviews:NO and setClipsToBounds:YES.
Set the view's bounds (NOT the frame) to a rect with zero size and origin at the center point of the rect you want the view to occupy when it is fully revealed (in the view's own coordinate system). In other words, startBounds.origin.x should equal half of endBounds.size.width and similarly for y.
Position the view by setting its center (in the parent view's coordinate system).
In an animation block, change the view's bounds to zero origin and full size.
In the animation's completion block, you probably want to setAutoresizesSubviews:YES again.
You may also need to set the view's autoresizing mask to be fully flexible (springs but no struts), depending on what other layout gets triggered as you resize.
Sounds like you want to change its clipping. A cheap (code-wise) way to do that would be to insert the view into a parent view (with autoresizing set to center it), set the parent to clip its children and then animate the parent's frame.