How do you create filled flat circles (say white) that build out from each other in random overlap to fill the iPhone screen but ease-dissolve so that the screen never gets filled - on touch? On touch release they stop being created as they continue to ease transparency to 0 and are cleared from memory.
An example in code would be killer.
What you're doing shouldn't be too hard to do, but it would take some time to actually code. I'd be surprised but impressed if anyone were to make an example for you.
You could probably figure this out for yourself and learn some pretty good coding lessons on the way.
In order to do what you want, you need a pretty good handle on some concepts such as these:
(Cocos2d)
Touch Detection
Drawing Shapes
Random Numbers
Opacity
Timed Fade Animation (Your "Ease-Dissolve")
and utmost important:
**memory management!**
Related
I am developing a game for iPhone and I came across a question whether this can be done using UIAnimation or I have to switch to OpenGL.
If you see the picture above, you can realize there is a rectangle (it will have background image) having many holes in it. User is supposed to touch on holes and initiate the animation. The holes are actually on the image and are not some view. Do you know any article or tutorial I need to read in order to understand this can be done using UIAnimation?
It's more like chess. When you tap a hole, there is a view placed and moved at z-axis and then when you press the other hole, the view is moved to that hole and so on.
I believe it can be done with UIViews too. The holes can be made by using an image with "transparent" holes in it. You can place this UIView on top of a background image(if required). When touches are detected, you can animate another view on top of this view using addSubview:. You can keep this other view outside the screen bounds initially so that the animation seems like a sliding animation.
yes UIView is also an option in your case. if you feel that you will use high quality lots of graphic and will do lots of animation stuff at once on the screen, openGL will be the best or perhaps the gane you are making is a 2d game so you must consider COCOS2D "http://www.cocos2d-iphone.org/" for kick starting your game you'll surely get many effects and other glittering stuff with it. and bes of all it is openGL based..!! Performance will be too high for you..!!
Best of luck..!!
I am trying to implement the style of 3D rotational animation you see in the Elements and the Wired iPad applications. The animation has the UIScrollView style acceleration so it looks like they have connected a UIScrollView to a sequence of images.
I have tried implementing it in UIKit, using an "empty" UIScrollView to increment through an array of images and set the contents of a UIImageView, based on the content offset. This works but even with scaled down images on the simulator, it is very sluggish. I am not sure how I could optimise it to make it run faster.
Source Code on GitHub
I have also tried doing something similar in Cocos2D. Cocos could animate the sequence very smoothly but I couldn't control the animation. I tried using a scroll view and setDisplayFrame to step through an animation but it didn't work.
Any help or suggestions on either option would be greatly appreciated.
I'm not 100% sure I understand the effect you're trying to achieve, but if you're referring to the images in "The Elements" app which you can spin around, then yeah, you probably don't want to be doing that with an UIScrollView.
You can control the animation of content in Cocos2d. While you can set an animation to "just run", you can also manually set frames directly out of an animation, so if you can get smooth animation out of Cocos, you should be able to do it interactively. Look at the atlas sprite object - you can set the rect of an animation frame directly.
However, again, I'm not sure this is the best approach, either, since that's a lot of frames for a texture. If you're going to be doing a lot of 3D photographic objects, you might consider looking into the video codecs and scrubbing along a video instead of trying to pack all the frames of a rotation animation into a series of textures.
Just so you know, the guy who made "The Elements" wrote an article about the development of the app, and here's what he had to say about the 3D rotatable objects:
"Creating fluidly spinning objects with the level of crystal clear photographic quality I demanded is actually harder than it might seem. A number of the obvious things the more technical of you might think of turn out not to work for reasons too complicated to get into here. Suffice to say that John designed a brilliant solution that uses the iPad's excellent graphics subsystem to lend a hand in ways it's not normally intended to."
I don't know how exactly they achieved the 3D objects, but perhaps that "uses the iPad's excellent graphics subsystem" mention gives you a clue where to head from here...
Is there a way to capture the amount of screen that is making contact with the users? I assume there is since this finger painting app shows the ipad responding to only the pixels that the user makes contact with.
Thanks so much in advance for your help!
The size of the touch is abstracted away by the framework, and UITouches only contain calculated (“best estimated”) points instead of the raw, actual areas that were touched. I would guess that the “pressure” was calculated from the duration and the direction of the touch.
In a nutshell, there is no public API to get the contact area.
I don't think Apple provides APIs for the size of the touch, or as #nickthedude said (I think) any kind of way to measure pressure. Basically, you need to implement your own algorithm/policy for determining line thickness/opacity/other effects. I believe a common way to do this is to measure the amount of time spent for the stroke, and work from there. For instance, if the user moved more quickly, you might want a thinner line segment. Apple really should just provide a canvas view of some kind. Best of luck!
to get the exact area you may have to roll your own but you can get uievents pretty easily and then do some magic from there. Basically impliment/override touchesBegan, touchesEnded, touchesMoved on the UIView in question and put in your custom code there.
Looking at the video maybe the amount of touches in the UIEvent set might correspond to the "pressure" of the touch, then again maybe not.
What if you laid down a series of successively smaller square uiviews wherever the user touched then if the touches "spilled" into the larger uiviews behind the smaller front ones than you could conjecture that the touch pressure was harder. Something to try I guess. Good luck.
Why not just describe what you want to do and foxus on asking about that instead - it may not have anything at all to do with the example that has you so otherwise enthralled - I can use a camera to monitor your hand from across the table and paint pixels on the screen via BT, completely ignoring any contact between your fingers and the screen.
I've been programming the iphone for a couple of months now and have 3 apps in the store already.
However, I have not done any kind of graphics programming in the platform.
Given that I'm planning on starting my 5th app (the 4th is under Apple's review) I wanted to ask for some pointers as to where to get information for this (been googling for a while but nothing matches what I'm looking for)
I need to create an App where I can 'drop' some shapes from a menu (a rectangle, circle, squares, and then some complex shapes) onto a main window.
the idea is that the user can drag them around. BUT, I want them to 'snap' to each other (kind of like in a CAD package where a circle has quadrants on the edges that snap to any other geometry entity in the drawing).
So if I had a circle on the left of the screen and a rectangle on the right and then I move the circle around, it would stop moving to the right If I hit the rectangles edges. Not completely stop but giving some sort of 'resistance' to the continuity of the movement.
Also, if I have several overlapping drawings, is there a way to 'divide' them (any overlapping becomes a shape on itself but is removed from any other shape composing the overlap)?
The reason for this is that I need to calculate the area of the drawing (along with other properties)
I'm thinking of CALayer 1, 2, 3,..., n on of top of the other, each one with a drawing (with CGPath?), that may or may not overlap the others.
Then I need to somehow obtain information of the 'projection' of all those on a single CALayer.
I'm clueless here.
Should I look into Quartz2D? is CALayer and CGPath enough for this?
this is not for a game. Just an engineering application I have in mind.
Any help is appreciated.
regards
dh
iPhone Application Programming Guide has a chapter on drawing.
You might get some ideas where to start by looking at the appropriate lectures from iPhone Application Programming lectures at Stanford. They include hight quality video lectures (filmed by Apple) over at iTunesU, slides and example source code.
I'm developing a 2D game for the iPhone using OpenGL ES and I'd like to use a 320x480 bitmapped image as a persistent background.
My first thought was to create a 320x480 quad and then map a texture onto it that represents the background. So... I created a 512x512 texture with a 320x480 image on it. Then I mapped that to the 320x480 quad.
I draw this background every frame and then draw animated sprites on top of it. This works fine except that the drawing of all of these objects (background + sprites) is too slow.
I did some testing and discovered that my slowdown is in the pixel pipeline. Not surprisingly, the large background image is the main culprit. To prove this, I removed the background draw and everything else rendered very fast.
I am looking for advice on how to keep my background and also improve performance.
Here's some more info:
1) I am currently testing on the Simulator (still waiting on Apple for the license)
2) The background is a PVR texture squeezed down to 128k
3) I had hoped that there might be a way to cache this background into a color buffer but haven't had any luck with that. that may be due to my inexperience with OpenGL ES or it just might be a stupid idea that won't work :)
4) I realize that the entire background does not always have to refresh, just the parts that have been drawn over by the moving sprites. I started to look into techniques for refreshing (as necessary) parts of the the background either as separate textures or with a scissor box, however this seems less than elegant.
Any tips/advice would be greatly appreciated...
Thank you.
Do not do performance testing on the simulator. Ever!
The differences to the real hardware are huge. In both directions.
If you draw the background every frame:
Do not clear the framebuffer. The background will overdraw the whole thing anyway.
Do you really need a background texture ?
What about using a color gradient via vertex colors ?
Try using the 2bit mode for the texture.
Turn of all render steps that you do not need for the background.
E.g.: Lighting, Blending, Depth-Test, ...
If you could post some of your drawing code it would be a lot easier to help you.
If you're making a 2D game, is there any reason you aren't using an existing library? Specifically, the cocos2d for iPhone may be worth your time. I can't answer your question about how to fix the issue doing it all yourself, but I can say that I've done exactly what you're talking about (having one full screen background with sprites on top) with cocos2d and it works great. (Assuming 60 fps is fast enough for you.) You may have your reasons for doing it yourself, but if you can, I would highly suggest at least doing a quick prototype with cocos2d and seeing if that doesn't help you along. (Details and source for the iPhone version are here: http://code.google.com/p/cocos2d-iphone/)
Thanks to everyone who provided info on this. All of the advice helped out in one way or another.
However, I wanted to make it clear that the main issue here turned out to be the behavior of simulator itself (as implied by Andreas in his response). Once I was able to get the application on the device, it performed much, much better. I mention this because, prior to developing my game, I had seen a lot of posts that indicated that the device was much slower than the simulator. This might be true in some instances (e.g. general application logic) but in my experience, animation (particularly 3d transformations) are much faster on the device.
I dont have much experience with OpenGL ES, but this problem occurs generally.
Your idea about the 'color buffer' is good intuition, essentially you want to be storing your background as a frame buffer and loading it directly onto your rendering buffer before drawing the foreground.
In OpenGL this is fairly straight forward with Frame Buffer Objects (FBO's). Unfortunatly I dont think OpenGL ES supports them, but it might give you somewhere to start looking.
you may want to try using VBOs (Vertex Buffer Objects) and see if that speeds up things. Tutorial is here
In addition, I just saw, that since OpenGL ES v1.1, there is a function called glDrawTex (Draw Texture) that is designed for
fast rendering of background paintings, bitmapped font glyphs, and 2D framing elements in games
You could use frame buffer objects similar to the GLPaint example from Apple.
Use a texture atlas to minimize the number of draw calls you make. You can use glTexCoordPointer for setting your texture coordinates that maps each image to its correct position. Remember to set your vertex buffer too. Ideally one draw call will render your entire 2D scene.
Avoid enabling/disabling states where possible.