UIImage Effects

Hi Guys,
I want to display a short title screen animation as an intro.
Rather than use an array of images stored in my bundle,
and setting a timer to animate the frames, repeat x-number of times, etc.
I have loaded a single image, and used a timer where I can do something
to the image dynamically, and then set it back to the frame,
or I could still do it the usual way, and load different images for the animation
as my timer fires.

What I want to happen, is apply some effect to the image frame by frame,
until the image is destroyed, and then decrement it's transparency to zero.
One example would be to pixellate the image for each frame, until it was
such a mess that you can no longer make out the original image,
but if I were to animate this with any style at all it would require a lot of
images in my bundle if it weren't handled dynamically.

Is there some iOSsy way to slightly mess an image and reuse the result?
I can, and have done this before, by changing data in a bitmap for each frame,
but I have not written the effect I want this time
(making every pixel looking at the colour of it's neighbors or something).
It would be a waste of time, and I don't think I would learn anything putting
in that work, if there is an easy way to do it.

Thanks, Art.

 

I think I'm wanting to draw circles on it as well, this will be fun...
It's only an intro, I was trying to cheap out.

 

This is no good because it copies the image?

Code:

- (UIImage *)DrawCircleOnImage:(UIImage *)image
{
	UIGraphicsBeginImageContext(image.size);
	[image drawAtPoint:CGPointZero];
	CGContextRef ctx = UIGraphicsGetCurrentContext();
	[[UIColor yellowColor] setStroke];
    
	// 7 pixels from circle border
	CGRect circleRect = CGRectMake(422, 312,136,136);
	circleRect = CGRectInset(circleRect, 7, 7);
    
	CGContextStrokeEllipseInRect(ctx, circleRect);
	UIImage *retImage = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();
	return retImage;
}

 

I can't do that this time.
It's for the emulator I've mentioned in another thread,
it's not my app holding it up (the iOS boot screen isn't shown for long),
it's the emulator loading from floppy disk.
After seeing what I did last night I would make the choice to leave it there though.

The disk file is linear of course, but the emulator still uses a floppy disk interface
in every sense.
It still has to seek the file to the correct tracks and sectors when it reads or
writes that file.

So what I've done so far is drawn concentric circles over a 3.5inch floppy
disk graphic representing the current track being accessed,
It's a very nice effect, I want to go the whole way and divide those
tracks into sectors too, and only display the current arc of the circle.

Tell me I'm not creative

 

Rough idea since the app might not make it:



I am going to submit it before doing all of the work I'm prepared to do for that reason.

I will, & thanks, but more interested in improvements for my GPS app when I get back to it
than worrying about an intro screen for this one...

If this does get in, I'm sure I can contribute something to the emulator.
I'm in my element there.

 

Because it isn't an animation, it's the real position of the drive head,
and the read speed varies depending on the speed of the device.

 

I have learned a bit.
The disk file is always 880K, no matter how much information is on the disk,
the file always contains the full disk structure.
It has it's own boot block, and file allocation table that cannot be dodged
just because you have a fast computer.

I say "can't be dodged" for emulation.
For a single bundled game which is the only way that will work for App Store,
it would be possible to bypass the boot by loading a snapshot of all of the
emulated computer's RAM and register contents when the game has already loaded.
That would be a linear file.

I am working on a better visual reason not to bypass the boot.