Are offscreen animations ignored by rendering and CPU? - cocos2d-iphone

Just wondering how Cocos manages the CPU cycle and graphics engine for CCSprites that are offscreen, including those in the middle of an animation. If you have many animated sprites going on and off the screen, I could check and stop each animation when it's off the screen then restart it when it is about to come back on, but I'm wondering if this is necessary?
Suppose you had a layer with a bunch of them and you make the layer invisible, but don't stop the sprite animations. Will they still use CPU time?

I just did a quick test (good question :) ), in a game where i can slide the screen over a large map that contains images of soldiers performing an 'idle' animation. They continue running when off-screen (I tacked a CCCallFunc in a sequence in a repeat forever, to a simple selector that logs).
I suspect they would also run when the object is not visible. It kind of makes sense, especially for animations. If you look at my use case, if the animation were stopped, it could cause a cognitive disconnect if the user slided the soldier in and out of view, especially when the soldier is doing a walk on the map - he could actually walk-in the view without the user having done any interaction with the screen.

Related

Rendering issue regarding imagery versus functionality

As I understand rendering textures in SDL2, everything is waiting behind the scenes and a texture appears after using the SDL_RenderPresent() function and vanishes with SDL_RenderClear(), which you use before advancing to the next frame.
I understand that as far as it goes for imagery, but what about functionality? I have two button textures linked to mouse events that I want to see and use at different times in different places. I've got them rendering during different enum states and each button does indeed appear and disappear on cue when the states change.
However, since both button textures are always "there" even while not being rendered, I can still mouse click on the invisible button that isn't being rendered at any given time. This doesn't seem to be an issue for mouse motion events, just mouse button events. How do I make a texture inactive as well as invisible when it's not being rendered?
I solved this one with some tinkering and a more experienced programmer named mbozzi's help to clue me in the right direction as to what was going on. The underlying issue was due to my completely decoupling the GUI logic and GUI rendering. Which is what we are always told to do: decouple everything, right? But I needed to couple the logic and rendering that I want to occur at the same time and place.
My event poll>>mouse input>>image rendering code was one giant loop. However, when I split that giant loop into separate mini event poll>>mouse input>>image rendering loops that each runs independently (but not concurrently, I just put them in their own different enum game states), that clears up the issue. So, if anyone has a similar problem with clicking invisible buttons, hopefully this will help.

Achieve Infinite Scrolling for a platformer game using cocos2d language objective c

I am trying to develop an 2D game using cocos2d library. I am still learning the framework.
Please understand that I am new to game development but not new to programming using objective c.
Here is the issue I am facing when it comes to my game development effort - I feel that I am missing the theoretical understanding of how to develop an infinite scrolling game. Is it possible for any of you to provide me some guidance on that ?
Here is my understanding of achieving infinite scrolling using cocos2d framework:
Cocos2d has a singleton director class which handles the current scene and scene transitions
In the current scene, I feel like I have to create an platform object consisting of several images and add them as a child to the current layer. And constantly run a move action to the platform sprite. So as and when I detect a particular image is off screen I have to replace it with another image. That way I will be able to create an infinite scrolling.
I am sorry if point 2 is not coherent. I just attempted to put my understanding of how to infinite scrolling.
Can you please help me with this ?
Thanks
I dissected how to implement scrolling with cocos2d-iphone in this article. What you probably want is the "fake scrolling" approach where two background images are moved and switch position after one completely left the screen.
You want to do this for the background layer only, not individual sprites. Your world isn't really moving, it's just the background panning that creates the illusion of movement. All sprites etc (player, enemies) movement is still relative to screen coordinates.
You'll find a working implementation in the code for my Learn Cocos2D 2 book in the Shoot'em Up project.
If you don't want to bother implementing this yourself, KoboldTouch supports endless/infinite scrolling for tilemaps. Here the game objects actually move along with the background infinitely (up to the maximum coordinates supported by float which is around +/- 16 million points).

Game Interface Design - VBO or Immediate Mode?

I've been developing a 2d RPG based on the LWJGL alongside with Java 1.6 for 3 months now. My next goal is to write all of the non-game-ish stuff. This includes menus, text input boxes, buttons and things like the inventory and character information screens. As I am a Computer Engineering student, I'm trying to write everything on my own (except, of course, for the OpenGL part of the LWJGL) so that I "test" myself on the writing of a simple 2d game engine.
I know that making such things from scratch requires basically mapping textures to quads (like the buttons), writing stuff on them and testing mouse/keyboard events which trigger other events inside the code.
The doubt I have is: should I use VBO's (as I'm using for the actual game rendering) or Immediate Mode when rendering such elements? I don't really know if Immediate Mode would be such a drop on performance. Another point is: do the interface elements have to be updated as fast as the game itself? I don't think so, because nothing is actually moving... Are actual games made like that?
Immediate Mode is more straightforward for the task, you would not need to take care about caching and controls composition/batching. Performance dropoff is not that big, unless you render a lot of text (thousands of letters) with each glyph in a separate glBegin..glEnd. If you don't use VBO anywhere else I would recommend trying it out for text output and doing everything else in easier Immediate Mode.
GUI elements might not change as often as game state does, but there's a catch - you could need to update them each time there's a cursor interaction (e.g. button gets OnMouseOver event and needs to be rendered with a highlight). These kind of events may happen very frequently, so thats why rendering may be needed at a full speed.

Cocos2D - Large Image

Is it possible to use a large image in Cocos2D, and allow, via swiping or pinching, for the user to zoom in and out?
I see from this post, that the max res for a Cocos2D image is 2048x2048. That is obviously larger than a device viewport, so I want the user to be able to move around the image.
I'm not creating a game, I'm making a sort of interactive biological cell, that will allow the user to tap arbitrary organelles, and see a popup of information about them.
Here is an idea of what the image will be, and obviously cramming the whole thing into a device viewport is not possible:
So really, before I delve too deep into this project, I'm just curious as to whether it is possible to use a large image, that allows the user the ability to arbitrarily move it around, and, if I can detect organelle touches, perhaps via CCSprites?
I recommend subclassing CCSprite and using your large image as the class's image. CCSprites certainly can detect touches by simply adding the basic CCTouchDispatcher delegate to the sprite's class:
[[CCTouchDispatcher sharedDispatcher] addTargetedDelegate:self priority:-1 swallowsTouches:YES];
Then also add this method to your CCSprite subclass:
-(BOOL) ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event
You can do anything you want with the touches at this point, scroll or whatever suits your needs.
You could break up your image into many multiple sprites and use a CCLayer to manage touches instead, it just depends on whether you really need your image to be that large, or if the limitations for a single image are enough for you to work with, considering they are pretty large too. My method here is a lot less complicated than that.
The max texture size is limited by OpenGL ES not just coscos2d and it changes by device. However, you can load the image into more than one texture and then position and move those textures around the screen. So really you could have the appearance of an image any size you would like but programmatically you will have to manage the different sprites (tiles) of the image.
CCSptites don't detect touches. CCLayers have will get the touch events you can then do a hit test to see if it hits a givcen CCSprite.

Draw shape shifting objects on (desktop)screen

I'm currently developing a program to show and control animated sprites on the desktopscreen. My problem is now to actually draw them onto the screen. The user should still be able to access other applications, as long as the sprite does not obstruct it.
My attempts are below and I hope, someone can point me in the right direction. I don't really care which library I need to use, as long as the performance is good enough for something around 20-30 animated sprites.
My attempts so far:
My first attempt was with Qt. I used a QWidget with a QLabel in it to show the pixmap of an object. The pixmap itself had an alpha channel and I used the "setMask(pixmap.mask()" method of QWidget to remove anything I don't want to show. But this method can't be used for rapidly shifting shapes, like moving creatures. If setMask is called all 50-100ms to change the mask to the next movementphase, then the cpu load gets to high with a lot of creatures moving at the same time.
My second attempt was to use one QWidget for all creatures. This way setMask ist called only one time and not once for every creature. It's possible to move more creatures this way, but the screen is flickering like hell when moving the mouse pointer over the creatures.
My third attempt were the XShape functions from Xlib to change the shape of each creature, but the performance is not much better then setMask.
I tried the transparency in Qt but if I use a QWidget over the whole screen the cpu load of X gets really high while moving the mouse. I don't know, if I can do something better here.
Create a QGLWidget and learn to use the OpenGL API to draw sprites within it, even if only using glDrawPixels rather than texture objects.
You certainly won't have any problems drawing a few tens of sprites, and the time spent learning OpenGL will be a good investment if you aspire to do more complex graphical things in future.
Not sure if this is your language but the ESheep is on GitHub, could get you started: https://github.com/Adrianotiger/desktopPet