Bug in Apple’s ‘GLPaint’ sample - dot always drawn before line!

[hypertext]

I was just messing around with Apple's GLPaint sample app to learn more about OpenGL, and I noticed that whenever you draw a line, it's always preceded by a dot. Basically, it looks like:

.________

Does anyone know why this happens? I'm guessing it's some weirdness with touchesBegan/Moved/Ended, but I can't verify. It's been driving me crazy all morning!

[rocotilos]

I havent look at the code, but just on top of my head,
I think that is because the detection of

touchesbegan (doing the dot)

and touchesmoved. (doing the line)

just remove the drawing code for touchesbegan. but u wont be able to create dots..

[hypertext]

Originally Posted by rocotilos

I havent look at the code, but just on top of my head,
I think that is because the detection of

touchesbegan (doing the dot)

and touchesmoved. (doing the line)

just remove the drawing code for touchesbegan. but u wont be able to create dots..

That's the weird part... touchesBegan just sets the start point, doesn't do any drawing. Wish I could post the code, but since it's an Apple sample I don't think they'd like that

[lukeca]

I was curious about this so I downloaded the sample code, I am not running into this dot issue, everything works just fine, I tried on both the device and simulator, no problem on either one?

[onemoreanimal]

I ran into the same problem, particularly when decreasing the size of the brush.

The solution is simple. Remove the conditional part of this code...

if (firstTouch) {
	firstTouch = NO;
	previousLocation = [touch previousLocationInView:self];
	previousLocation.y = bounds.size.height - previousLocation.y;
} else {
	location = [touch locationInView:self];
        location.y = bounds.size.height - location.y;
	previousLocation = [touch previousLocationInView:self];
	previousLocation.y = bounds.size.height - previousLocation.y;
}

to become this...

location = [touch locationInView:self];
location.y = bounds.size.height - location.y;
previousLocation = [touch previousLocationInView:self];
previousLocation.y = bounds.size.height - previousLocation.y;

The firstTouch part apparently doesn't do anything except draw the first dot, usually in a different place from the rest of the line.