I'm currently using box2d with cocos2d on iPhone. I have quite a complex scene set up, and I want the end user to be able to record it as video as part of the app. I have implemented a recorder using the AVAssetWriter etc. and have managed to get it recording frames grabbed from OpenGL pixel data.
However, this video recording seems to a) slow down the app a bit, but more importantly b) only record a few frames per second at best.
This led me to the idea of rendering a Box2D scene, manually firing ticks and grabbing an image every tick. However, dt could be an issue here.
Just wondering if anyone has already done this, or if anyone has any better ideas?
A good solution I guess would be to use a screen recorder solution like ScreenFlow or similar...
I think your box2d is a good idea... however, you would want to used a fixed-time step. if you use dt the steps in the physics simulation will be to big, and box2d will be unstable and jittery.
http://gafferongames.com/game-physics/fix-your-timestep/
The frame rate will take a hit, but you'll get every frame. I don't think you'll be able to record every frame and still maintain a steady frame rate - that seems to be asking a lot of the hardware.
Related
I'm currently just trying to learn to use the animator within Unity, I'm very in-exp at animation and don't understand it even in the editor as I focus on programming/scripting.
I have an animation and the states for the animations as-well as the conditions all working perfectly however the animation check for the next state is way to slow. I've tried changing the speed of the actual state but it speeds the animation up and makes it look like my character is walking insanely fast.
I've tried messing around with the frames, making them over a longer time period and making the speed of the state faster however it seems to counter act each other, when I make it longer frames the pace of the animation is slow and then when I make the speed of the state go quicker it just makes the frames tick faster making the animation faster.
What I believe is happening is that the check for the next state of animation is happening once the full animation has been played. However what I need is the check to be happening constantly (as if frame by frame of the unity game not the animation).
Any advice would be great, I've tried using youtube to solve this before coming here however most people are creating a platformer game where as I'm trying to aim for a top down 2d, all directional character movement instead of the linear x axis character movement., and outside libraries.
I deeply apologise for my inability to find a suitable source. I have literally just came across an article online that came across a simple solution.
here:https://answers.unity.com/questions/221601/slow-animation-response.html
basically if you can't be bothered to click the link and you are having the same problem,
find exit-time by clicking the transition and then in the inspector and untick it.
Sorry.
I've got an iPhone game that is basically finished, but I have been spending some time profiling as I want to get the power usage down as low as possible, but I'm an OpenGL ES noob so I'm looking for some pointers.
The game is a fairly simple puzzle game, so 90% of the time the board is redrawing for no reason. At the moment I have a 'dirty' flag and only render anything if it is set, but then I draw everything, when most of the time only a tiny part of board needs updating (ie the timer, or one of the pieces).
Is there a common strategy to use with OpenGL for only updating parts of the screen, or does it assume that you want to redraw everything, all of the time?
Your application should wait until something in the scene changes before rendering a new frame. Core Animation caches the last image presented to the user and continues to display it until a new frame is presented.So you don't need to draw every time , just check for the update, and draw only when there is any update.
EDIT: For more details check opengl es programming guide-
here's [a link]http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/Performance/Performance.html
I'm wanting to figure out if a user is not moving at all, walking, or running using the iPhone. I'm not trying to implement a pedometer. I just want to know around about if someone is moving briskly, slowly, or not at all. I don't need mph or anything like that.
I think the accelerometer may be able to do this for me, but I was wondering if someone knows of any tutorials or example code that might be able to point me in the right direction?
Thanks to all that reply
The accelerometer won't do you any good here - it will only capture changes in velocity.
Just track the current location periodically and calculate the speed.
There are no hard thresholds for walking vs. running motion, so you will have to experiment a bit. The AccelerometerGraph sample code should get you started on how to get and interpret accelerometer data.
The Accelerometer is good, but if the user has an iPhone 4 or iPad 2 you should use the gyroscope.
CMMotionManager and Event Handeling Guide - Motion Events
Apple Documentation is the best example you can get!
People have a different bounce in their step between walking and running which can be measured with the accelerometer, but this differs between individuals (what shoes they are wearing, what surface they are upon, what part of the body is attached to the iPhone etc.), and this motion can probably be imitated by shaking the iPhone just right while standing still.
Experiment by recording the two types of acceleration profiles, and then use some sort of pattern matching to pick the most likely profile candidate from the current recorded acceleration data.
I am working on a Labyrinth style app for iPhone using Chipmunk and openAL. I got everything working except the ball rolling sound. What I have tried is playing a small sound for each update in the ball's position so that the overall effect sounds like the ball is rolling. Based on advice on this forum I tired using velocity of the ball to adjust pitch of the sound. I have the following problems:
I cant hear the sound at all when I am playing this sound in a chipmunk call back. I can hear it elsewhere.
Even if I got this working somehow, the sound I should play has to be very very short as the ball doenst take too long to roll. THere has to be a alternate way.
Can anybody please help? I can even pay for a simple application that did this if the sound is also included.
I recommend cheating... record (or find somewhere) some longish looping sounds of the ball rolling at different speeds. Have one of them playing, based on the speed of the ball. As the ball's speed changes, you can cross-fade from one sample to another. My guess is that that will sound more realistic than just varying the pitch of a single sample.
Of course, it may be enough just to have one longish looping sample, and only vary the volume proportional to the ball's speed. I'll have to go track down my labyrinth game and check. :)
I'm working on a relatively simple 2D side-scrolling iPhone game. The controls are tilt-based. I use OpenGL ES 1.1 for the graphics. The game state is updated at a rate of 30 Hz... And the drawing is updated at a rate of 30 fps (via NSTimer). The smoothness of the drawing is ok... But not quite as smooth as a game like iFighter. What can I do to improve the smoothness of the game?
Here are the potential issues I've briefly considered:
I'm varying the opacity of up to 15 "small" (20x20 pixels) textures at a time... Apparently varying the opacity in this manner can degrade drawing performance
I'm rendering at only 30 fps (via NSTimer)... Perhaps 2D games like iFighter are rendered at a higher frame rate?
Perhaps the game state could be updated at a faster rate? Note the acceleration vales are updated at 100 Hz... So I could potentially update part of the game state at 100 hz
All of my textures are PNG24... Perhaps PNG8 would help (due to smaller size etc)
It's really hard to debug graphics problems with this. Try using the openGL ES instruments to find where are the bottlenecks. It's quite handy. Also, look at the WWDC videos on openGL. They're really good.
One thing I noticed is that you said "I'm rendering at only 30 fps". Does it mean you're manually setting up a timer or something? This is not a good way, instead you should use CADisplayLink to get notified when the screen wants to update. It could improve your smoothness.
To complete Mo's answer on the 30fps...
The fact that you request the update at 30fps does not mean you're going to get it. I'm not an iphone programmer, but I can tell you that if your frame rendering takes 100ms, you're guaranteed to never update faster than 10fps. And if you're actually rendering at 10fps, then smoothness is gone.
So, measure the time you take to render to get an idea of what actual frame rate you get. As to how to optimize the rendering specifically for iphone, I'll leave that to people more expert than me on the subject.