Seam visible when drawing textured quad

[Twinkletoes]

I'm drawing a textured quad full screen as triangles using ES2.0 (4 vertices, 6 indices).

I'm seeing a single pixel bright line along the seam between the two triangles. Every google result I get suggests this is due to Polygon Smoothing, but this feature is not available in ES2.0, so it can't be that!

Any thoughts?

[blu]

Sounds peculiar. Is that a trilist you're drawing (i.e. GL_TRIANGLES)? If so, is the artifact still there if you used a tri strip/fan instead (GL_TRIANGLE_STRIP/GL_TRIANGLE_FAN)?

[Twinkletoes]

I'm halfway through recoding to try exactly that. And yes, I'm using GL_TRIANGLES currently

[Twinkletoes]

Yup. Same problem with both TRIANGLES and TRIANGLELIST. Although not on every layer - just the background. Searching to see if I can see any rogue draw calls. (and yes, I've checked the texture image - it doesn't have the bright line on it!)

[blu]

So you get the same artifact in all three cases - GL_TRIANGLES, GL_TRIANGLE_STRIP and GL_TRIANGLE_FAN?

What types are your vertex attributes for that mesh, particularly the texture coordinates?

[Twinkletoes]

Everything is a float. Texture coords are in 0->1 space

[Twinkletoes]

Haven't tried a fan, but yes, exactly the same in the other two cases.

[jmacey]

how are you defining your texture?

glTexImage2D ( http://www.opengl.org/sdk/docs/man/xhtm ... mage2D.xml ) has a paramater called border make sure that is set to 0 else you will get a single pixel border. I've done this before

Jon

[Twinkletoes]

My line is diagonal across the middle, so it's not the texture border. OK - that's weird. It's at right angles to the triangle edge. Huh?!

[jmacey]

As you are using ES2.0 set the colour to the UV value in the shader and see what that does I use this to debug UVs from time to time. Can you post and image?