Merging two images to create scrolling background

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Merging two images to create scrolling background

(9 posts) (4 voices)

Started 1 year ago by adpro
Latest reply from adpro

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adpro
Member
Hello,

I currently have a scrolling background working by using something similar to the example in Texture2dText.m

The code is as follows...
```
CCSprite *sprite = [CCSprite spriteWithFile:@"pattern1.png" rect:CGRectMake(0, 0, 4096, 4096)];
		[self addChild:sprite z:-1 tag:kTagSprite1];
		[sprite setPosition:ccp(size.width/2,size.height/2)];
		ccTexParams params = {GL_LINEAR,GL_LINEAR,GL_REPEAT,GL_REPEAT};
		[sprite.texture setTexParameters:&params];
```
I'm wondering if there's any way to make a texture that is two images merged together, then use this example to make the repeating texture.

I'm using an image that is 1024 in width, and some given height. Lets say it's 512. Either way, the widths are squares.

So, I'm using 1024 for the width, as it's the max size for the 3G if I'm not mistaken, and I want my game to be available for 3G.

Now, the only problem is, my scrolling background will be moving fast, so I want to have a background that is at least 2048 in width. I'm ok with using 2048.

So, the question is, can I merge two images that are 1024 width together, to make a texture that is 2048, then use the above to repeat the 2048 image for the total background for scrolling?

I searched the forums but couldn't find much. I found a few similar posts, but couldn't find an answer.

If anyone could help be, I would really appreciate it!

EDIT:

I feel I didn't explain this well.

I'm trying to do this....

I have two images that are 1024 in width. They fit together in order to make a continuous background that is 2048 wide.

I want to merge both images to create one texture that is 2048.

Can I do this?

After that I want to use the above method to create a repeating texture so I can move it to make a seemingly endless scrolling background.

Can I do this as well?

Thanks!
Posted 1 year ago #
robodude666
Member

I imagine you can create a CCNode/CCSprite that has two sprites as children (via addChild) and put the two images side by side. There might be a better way, though I'm not aware as I haven't used large sprites yet.

I haven't used setTexParameters before, so I can't exactly comment on how it would be used... but you can simply monitor if the left most sprite is off screen. If it is, move it to the very right of the sprite that's currently on screen. Assuming you're scrolling from right to left, etc.

-robodude666

Posted 1 year ago #
adpro
Member

Hmm... I've never added two images side by side to make one sprite. If that's possible, I think it would work. Do you have any sample code at all? I looked around and can't find a way of merging two sprites side by side. I mean, I could add them to the scene side by side, but then I would have two different sprites, and I need just one for what I'm doing.

Posted 1 year ago #
adpro
Member

Anyone have any suggestions for me by chance? I've been looking everywhere and can't find anything.

Or, if anyone has another way of looping two images as a scrolling background, I'm all ears!

Posted 1 year ago #
Blue Ether
Member

Why would you want to merge them into one texture? Then you couldn't really effectively loop the background. In order to loop the background, you need to reposition one texture while it is off-screen, keeping the on-screen texture where it is. Why do you think the speed of the scrolling matters? It doesn't change the amount of texture that is on-screen at any one time.

Looping background techniques have been addressed MANY times on this forum. There are as many different methods to accomplish this as there are games or coders. Do a search first, please.

Posted 1 year ago #
adpro
Member

Hello Blue

I did a search, as I stated above.

I'm using GL_REPEAT, as stated above. That means it actually loops the texture for you, so all you have to do is move the ONE texture in ONE direction without having to write a function to figure out when to replace the current texture. Have you used it before? It doesn't sound like it. So, I'm asking if you can merge two textures because GL_REPEAT seems to perform best for doing looping backgrounds. From what I understand GL_REPEAT uses more of the graphics card than alternatives. So, again, I like GL_REPEAT, and this post is directly related to using GL_REPEAT for scrolling backgrounds. If it's possible to join textures like I want, it could really help some other programmers as well, so I thought I would ask. You know, to progress technology and make lives easier for the independent developers.

Also, there are no posts for looping backgrounds that involve two textures AND using GL_REPEAT. If you find one, please let me know about it and I will take a look at it. As I stated above, which you obviously failed to read, I can't find anything.

So, I'm trying to see if there is a way to merge both textures, because I'm under the impression that using GL_REPEAT is much better on CPU performance, and it honestly flows a lot better than writing a loop that checks to see when to replace my image with the next one, then move it back to where it is, and all that.

So, before you go assuming I didn't do a search, please read my posts thoroughly so you know exactly what you are replying to.

Posted 1 year ago #
cocos0d
Member

Hi adpro,

Not sure it will help, but I've been using code based on this post:

http://www.cocos2d-iphone.org/forum/topic/713#post-4408

but GL_REPEAT sounds like a much better approach - I'll give it a shot!

Posted 1 year ago #
Blue Ether
Member

adpro:

Or, if anyone has another way of looping two images as a scrolling background, I'm all ears!

You never explained why GL_REPEAT is a necessity. There are a plethora of other techniques for looping background images that do not use GL_REPEAT. You asked for other ways of looping two images, and I told you to do a search, as there are many ways that have been discussed on these forums.

Posted 1 year ago #
adpro
Member

@ cocos0d

I saw that post a while ago actually. I believe it is the post that lead me to use GL_REPEAT.

I'm going to check the differences using GL_REPEAT and how they affect performance. I do have a scrolling background setup in a schedule loop, but I feel it is slightly affecting performance. It might not be enough after optimizing everything else to matter, but I always strive for maximum performance. I should also go back and check my logic for that, as I set that up a while ago. I'm cleaning up my code by creating a whole new project, cause I sucked at planning this thing this time around. So, my logic may not have been the greatest for my last scrolling schedule. I'll test it all out and compare and post results, but I assume letting the graphics card handle more is probably better, and I believe that would be the end result here, wouldn't it?

If anyone does know a way of using openGL or using cocos2d textures or anything to combine two textures together like I want it, it would really help me. I think it would really help anyone, actually. It would be nice to create a sprite that is 3000 pixels wide, but is made up of multiple images.

I found a couple of things I can try, but I have no experience with openGL, so I probably won't get around to testing anything out for a few days. I'll post my results if I find anything so others can use this as well. The more I look, the less optimistic I am, though.

In the meantime, if anyone has some input, I'm all ears.

@Blue Ether

Also, Blue. Sure, I said I'm all ears to other suggestions. I should have said I'm all ears to 'good' suggestions that are known to work well. Sorry about that. I guess I didn't make myself clear enough. However, you saying "Why would you want to merge them into one texture?" shows me that you did not fully read my post or my main questions about what my original goal was. The whole reason for the first post was to use GL_REPEAT, and you obviously didn't understand my goals, so you should have kept your comments to yourself.

End of side discussion.

Back to talking about merging textures so I can accomplish my goal, if it's possible. Are there any openGL gurus here?

Posted 1 year ago #

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