I've known that there are 4 types of transition effect: horizon, vertical, flip, curve.
But, what I want is the transition effect used in Podcast application.
It's similar with the flip effect, but it's slightly different. As you can see the picture below, it looks like it has volume; so it's more spectacular.
How can I make a transition effect like this?
The animation is probably done with three separate views - the outgoing, the side, and the incoming. The anchor point of each view's layer can be set such that they all rotate around the same central vertical axis, which is half of the side's width inset into the screen. The side view is initially rotated to M_PI_2, the back view to M_PI.
All three layers can then be rotated by M_PI. This will give the appearance of a rotating solid object. The main view's sublayer transform should be adjusted to give some perspective to the rotation. This involves setting the .m34 value to a small number, there are plenty of examples of this around on the web.
*all angles in radians, some may need to be negative, this is just an explanation of the principles
Related
I have been looking for the solution on the web for a long time. Most tutorials are fairly simple about adding shadow to a UIView. I also noticed that if we add a shadow to an UIImageView. The shadow shape could perfectly fit the shape of the content image if the image itself has alpha channel in it. Say for example, if the image is an animal with transparent background, the shadow shape is also the same as that animal (not a rectangle shadow as same as UIImageView frame).
But these are not enough. What I need to do is to add some changes to the shadow so it may have some rotation angle and compressed (squeezed or shift) effect so that looks like the sunlight comes from a certain spot.
To demonstrate what I need, I upload 2 images below, which I captured from the Google Map App created by Apple. You can imagine the Annotation Pin is an image which has the Pin shape, so the shadow is also "pin shaped", but it is not simply "offset" with a CGSize, you can see the top of the shadow is shifted right about 35 degrees and slightly squeezed the height.
When we tap and hold and pin, the shadow is also animated away from the pin, so I believe that such shadow can be made programmably.
The best shadow tutorial I can found so far is http://nachbaur.com/blog/fun-shadow-effects-using-custom-calayer-shadowpaths But unfortunately, that cannot make this effect.
If anyone know the answer or know any better words to search for, please let me know. Thank you.
(Please note that the shape of the image is dynamic in the App, so using any tool like Photoshop to pre-render the shadow is not an option.)
In order to create dynamic effects like this, you have to use Core Graphics. It's incredibly powerful once you know how to use it. Basically you need to set a skew transform on the context, set up a shadow and draw the image. You will probably have to use transparency layers as well.
It doesn't sound like you can use CALayer shadows, since that is meant to solve a specific use-case. The approach Apple takes with the pin marks on the map is to have two separate images that are created ahead of time (e.g. in Photoshop) and they position them within the map relative to a reference point.
If you really do need to do this at run-time, it should still be possible by using either Core Graphics or ImageKit. To get a blurred shadow appearance, you can use the kCICategoryBlur CIFilter. You can then convert the image to grayscale. And to get that compressed look you just need to resize and skew the image.
Once you have two separate images, you can either take the CGImageRef for the shadow image and can set that as the content of another sublayer, or you can add it as a separate view.
If you know what all the shapes are, you could just render a shadow image in Photoshop or something.
I'm trying to write a fairly simple animation using Core Animation to simulate a book cover being opened. The book cover is an image, and I'm applying the animations to its layer object.
As well as animating a rotation around the y axis (The the anchorPoint property set of the left of the screen), I need to scale the right hand edge of the image up so it appears to "get closer" to the user and create the illusion of depth. Flipboard, for example, does this scaling really well.
I can't find any way of scaling an image like this, so only one edge is scaled and the image ends up nonrectangular.
All help appreciated with this one!
CoreAnimation, by default, "flattens" its 3D hierarchy into a 2D world at z=0. This causes perspective and the like to not work properly. You need to host your layer in a CATransformLayer, which will render its sublayers as a true 3D layer hierarchy.
I got a tiled map and I want to make lava lakes. I wish to have some kind of lava texture image on the background looping diagonally slowly. I could make it with four 960x640 images and move all of them diagonally etc. But when I do, a black/white line appears between each...
... and someone suggested me "CCParallax". I have never used it and am not sure if it really can achieve the effect I am seeking.
Also note that as the player moves on the map, the parallax will need to simulate that as well etc.
So my question is, what would you do for this effect? Four looping images or "CCParallax"?
CCParallaxNode is pretty limited because you can't specify endless parallax scrolling without modifying the class. It also doesn't quite fit your use case.
Using four 960x640 images is wasteful. Just to make some lakes underneath the background this is overkill and will negatively affect performance.
The solution depends a bit on how big the lakes are. For example, if these are just 1 or 3x3 tiles in size you could add a textured sprite underneath each lake. If on the other hand your tilemap consists mostly of a few narrow pathways while the rest is lava lakes, then you need a different approach.
You might want to try GL_REPEAT to repeat a single sprite's texture over a defined area. That allows you to use a relatively small texture, for example 64x64, that will be repeated over the rectangle you specified.
You can then modify the sprite's position each frame to scroll the texture. Every time the sprite has moved 64 pixels in horizontal or vertical direction, you subtract 64 pixels (sprite.contentSize.width) from the sprite's position to reset it back to its original state. That means the sprite will never move further than 64 pixels from its initial position in any direction but you still get smooth scrolling.
I am facing this problem while trying to rotate the map in my iPhone app
The view gets clipped and rotation also happens. I want to avoid the clipping. Any tips ?
heres the code:
viewToRotate.layer.transform = CATransform3DMakeRotation(0.8, 0., 0., 1.);
You need your map rotated in 3D ? If not (which is what I think you need), then just use CGAffineTransformMakeRotation (be careful, as it requires the angle in radians).
Also, if you don't want your map to be clipped, you need to make your map bigger, like in the image below (open in new tab to see it bigger)
http://img593.imageshack.us/img593/4498/calculatemapboundswhenr.png
First, you need to calculate the diagonal of the rectangle (your visible map) as instructed in the image above (which I call "radius" because that would be the radius of the smallest circle bigger than your rectangle).
Second, using the radius, you need to calculate the (smallest) square that will allow your map to be seen without clipping. This square will be used to set the bounds of your map (caution: NOT the frame - Apple specifies that, when using rotation, you should not use frame - just bounds and / or center).
Make sure this square is centered on the center of your visible map rectangle (i.e. the square should have X pixels above AND below the small rectangle ... and Y pixels left AND right of the small rectangle).
Hope it helps !
Did you ever figure out the solution?
The only way I could do it was to make the MapView in Interface Builder much bigger than the actual size of the screen area its supposed to cover, then I centered the MapView such that its center was in the center of the narrower viewable area.
Rotation seemed to work similarly to how it works in the built-in Maps app.
My guess is that you have to do this so that the image tiles streaming in from Google cover a wide enough area to "fill in the blanks" so to speak, even if they're not always visable.
If you apply a little math, you could probably programmatically size and position the MapView such that you void clipping, but don't require more tiles than is absolutely necessary.
I do not really understand the way I'm suppose to render a side-scroller? How do I know what to render when my character move? What kind of positionning should I use for the characters?
I hope my question is clear
The easiest way i've found to do it is have a characterX and characterY variable [integer or float, whatever you want] Then have a cameraX and cameraY variable. Every object in the scene is drawn at theObjectX-cameraX, theObjectY-cameraY...
CameraX/CameraY are tweened by a similar-to-midpoint formula so eventually they'll reach playerx/playery[Cx = (Cx*99+Px)/100] ... yeah
By doing this, every object moves in the stage's space, and is transformed only on render [saving you from headaches]
Use a matrix to define a camera reference frame.
Use space partitioning to split up your level into screens/windows.
Think of your player sprite as any other entity, like enemies and interactive objects.
Now what you want is the abstraction of a camera. You can define a camera as a 3x3 matrix with this layout:
[rotX_X, rotY_X, 0]
[rotX_Y, rotY_Y, 0]
[transX, transY, 1]
The 2x2 sub-matrix in the top-left corner is a rotation matrix. transX and transY defines the translation part, i.e the origin. You also get scaling for free. Just simply scale the rotation part with a scalar, and you have yourself a zoom.
For this to work properly with rotation, your sprites need to be polygons/primitives, say like triangles or quads; you can't just apply the matrix to the positions of the sprites when drawing. If you don't need rotation, just transforming the center point will work fine.
If you want the camera to follow the player, use the player's position as the camera origin. That is the translation vector [transX, transY]
So how do you apply the matrix to entity positions and model vertices? You do a vector-matrix multiplication.
v' = vM^-1, where v' is the new vector, v is the old vector, and M^-1 is the matrix inverse. A camera needs to be an inverse transform because it defines a local coordinate system. An analogy could be: If you are in front of me and I turn left from my reference frame, I am turning your right. This applies to all affine and linear transformations, like scaling, rotation and translation.
Split up your level into sub-parts so you can cull objects and scenery which does not need to be rendered. Your viewport is of a certain size/resolution. Only render scenery and entities which intersect with your viewport. Instead of checking each and every entity against the viewport bounds, assign each entity to a certain sub-screen and test the bounds of the sub-screen against the viewport and camera bounds. If your divide your levels into parts which are the same size as your viewport, then the maximum number of screens visible
at any particular time is:
2 if your camera only scrolls left and right.
4 if your camera scrolls left, right, up and down.
4 if your camera scrolls in any direction, and additionally can be rotated.
A screen-change is an event you can use to activate entities belonging to that screen. That could be enemies, background animations, doors or whatever you like.
If this is your first foray into writing a side-scroller, I'd suggest considering using an already existing game engine (like Construct or Gamemaker or XNA or whatever fits your experience level) so you don't have to worry about what order to render things and how to make it all work. Mess with that a bit--probably exploring a few of them--to get a feel for how they do things then venture out to your own once you've gotten used to it.
Not that there's anything wrong with baptism by fire but it can get pretty overwhelming in my opinion.