Strange Lines on texture

OpenGL Development
#1

Hi, I am loading a 1024x512 png image and drawing it on the screen. when I translate it, sometimes a strange grey line shows along it.
Does anyone know what the problem is?
image: http://www.use.com/2dc0018cea8a9b9306d7
Thanks,
roland

#2

image(link) doesnt work

#3

hmm…

http://www.use.com/2dc0018cea8a9b9306d7

#4

If you are tiling the texture, did you try clamp to edge?
If you are using texture positions of <0 or >1 instead of tiling, are you sure there isn’t a semi transparent line in there?
Do you have one or multiple textures within one file?

Mike

#5

GL_CLAMP_TO_EDGE?

#6

Thanks for the replies.
I wasn’t using >1 or <0 texture coords, but the clamp fixed it :slight_smile:

Am I right that I have to put it just before the draw call each time? I tried to put it in my opengl init function and it didnt do anything?
eg.


        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_S, GL11.GL_CLAMP);
        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_WRAP_T, GL11.GL_CLAMP);
        GL11.glBegin(GL11.GL_QUADS);

Thanks again,
Roland

#7

Due to interpolation, it is entirely possible for OpenGL to sample outside of the bounds of your texture coordinates. GL12.GL_CLAMP_TO_EDGE fixes this. GL11.GL_CLAMP only clamps texture coordinates to 0.0-1.0, so it doesn’t do anything to prevent interpolation outisde of 0.0 - 1.0. Try it. =D

#8

No problems, I’m just happy that I can have some use of the knowledge I built up from trial and error :slight_smile:

Put it where you first create the texture and not at every draw.

Mike

#9

Does this mean I have to switch everything to 1.2?

Thanks :slight_smile:

#10

You don’t have to change the texture coordinates at all. Why on Earth would you want to change it to 1.2 in the first place?

#11

You effectively change your runtime requirements to GL1.2, but you don’t have to change anything in the code, just use GL12.GL_CLAMP_TO_EDGE and you are done.

#12

Make sure you add a check to make sure that the capability for 1.2 is there before calling that.

Mike

#13

How exactly ?
I would use GL11.glGetString(GL11.GL_VERSION); and then check

Yeah I have this line problem too, but only if I scale the whole screen, which is still experimental
I think its because the positions aren’t accurate enough anymore - but using Slick not sure this CLAMP will help me there.

#14

if (GLContext.getCapabilities().OpenGL12){
…
}

#15

Wow. Eternal embarrassment to me then. ._.

#16

Thanks :slight_smile: