OpenGL texture atlas bleeding

Question

I\'m trying to draw a basic 2d ground mesh made up of smaller tiles from a texture atlas (note the 1 pixel transparent border):

Answer 1

I had this exact same problem. I fixed it with this.

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

Answer 2

I had a similar issue with a texture atlas. I fixed it by insetting the image by 1.0/TEXTURE_ATLAS_PIXELS_PER_SIDE * 1/128.0. The 128 number you need to figure out by experimentation. The upside for me is no one is going to perceive 128th of a pixel being missing. I made this modification to the texture coordinates being sent to the graphics card and not in a shader. I have not tried doing this with texels in the shader, like you have. I've read different information on how to handle texture bleeding but for a texture atlas this was the easiest solution for me. Adding borders to my textures which are tightly packed and follow the power of two rule would cause me to have a lot of whitespace.

This is what worked for me on the iphone.

Answer 3

You could always switch your GL_TEXTURE_MIN/MAG_FILTER to GL_NEAREST :)

Answer 4

Your border shouldn't be transparent, but rather the pixels from the opposing side of each subtexture. For example the border on the right hand side of each sub-texture should be a copy of the left-most line of pixels, i.e. the pixels that it would wrap around to.

That is how you "cheat" wrapping for the texture sampler on the borders.

Answer 5

Try using GL_NEAREST for GL_TEXURE_MIN/MAX_FILTER and translate by 0.375f before drawing:

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.375f, 0.375f, 0.0f);