Drawing a dotted line with the finger

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Drawing a dotted line with the finger

(9 posts) (6 voices)

Started 2 years ago by mint
Latest reply from ASuskin

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mint
Member

Hi cocos2d Community,

I'm new to iPhone Development and cocos2d, so probably I'll post more questions than answers in the next weeks. I hope to become a Cocos2d pro however, so I can help other people, too.

My first question is how to draw a line with your own finger. In FlightControl e.g. you draw a line from a plane to an airport. This should work using UIKit's touchesmoved event, but can anyone provide further details or maybe somebody knows an existing website with additional detail? I couldn't find anything.

Oh, I looked at apple's GLPaint sample app, but this is way too much OpenGL imo, and way too complicated. There's sooo much code in it, i can't believe it's all necessary. I know that Cocos2D is a 2d-OpenGL lib basically, but can I solve this problem with some High-Level Cocos2D code?

Thx in advance,
mint

Posted 2 years ago #
riq
Key Master

hi, search for RenderTexture in this forum.

Posted 2 years ago #
riq
Key Master

or look at the DrawingPrimitives.m file, or look at the drawPrimitivesTest target.

Posted 2 years ago #
mint
Member

Hi riq,
I apologize for not having responded to your helpful answer for 2 weeks, I was very busy (unfortunately not because of cocos, but because of school :) )

I think I'll display the line by placing small round sprites every 10th pixel in touchesMoved.

Thanx
mint

Posted 2 years ago #
ipodfreak0313
Member

mint,
Could you tell me how you coded that? Putting a round sprite every 10th pixel moved? I know it's been a long time since this post was created, but that's exactly what I'm looking for. Thanks!

Posted 8 months ago #

Affian
Member

Go look in the RenderTexture example, there's a block of code that draws the line that looks like this:

float distance = ccpDistance(start, end);
	if (distance > 1) {
		int d = (int)distance;
        float difx = end.x - start.x;
        float dify = end.y - start.y;
		for (int i = 0; i < d; i++) {
			float delta = i / distance;

			[[brush sprite] setPosition:ccp(start.x + (difx * delta), start.y + (dify * delta))];
			[[brush sprite] visit];
		}
	}

the loop incrementer (i++) will make it draw every pixel, if you set it to say i += 10 then it will draw every 10 pixels

Posted 7 months ago #

ASuskin
Member
I just want to make sure I understand this too.. wouldn't you want to make the for statement this:
```
for (int i = 0; i % 20 < 10 && i < d; i++)
```
This way, it will draw ten, skip ten, draw ten, skip ten...?
Wouldn't your way just draw one every ten?
Posted 6 months ago #
Gray Olson
Member

That was what his way was trying to do, draw one, skip ten...

Posted 6 months ago #
ASuskin
Member

Oh sorry, I misread (as always).. glad you figured it out

Posted 6 months ago #

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