Texture mapping on a cube appears wrong

Question

I've created a cube and then changed its coordinates to make it a beam like this (click me).

I am sure that the texture is being loaded fine as I have successfully loaded other textures in the project (using SOIL).

The code of the beam is this:

glBindTexture(GL_TEXTURE_2D, obstacle_texture);
glBegin(GL_QUAD_STRIP);
    // front
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, 0.0f);
    glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, 0.0f, 0.0f);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(side, height, 0.0f);
    glTexCoord2f(0.0f, 1.0f );  glVertex3f(0.0f, height, 0.0f);
    // back
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, -side);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(side, 0.0f, -side);
    glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, height, -side);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(0.0f, height, -side);
    // right
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(side, 0.0f, 0.0f);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(side, 0.0f, -side);
    glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, height, -side);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(side, height, 0.0f);
    // left
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, 0.0f);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(0.0f, 0.0f, -side);
    glTexCoord2f(1.0f, 0.0f);   glVertex3f(0.0f, height, -side);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(0.0f, height, 0.0f);
    // top
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, height, 0.0f);
    glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, height, 0.0f);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(side, height, -side);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(0.0f, height, -side);
    // bottom
    glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, 0.0f);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(side, 0.0f, 0.0f);
    glTexCoord2f(1.0f, 1.0f);   glVertex3f(side, 0.0f, -side);
    glTexCoord2f(0.0f, 1.0f);   glVertex3f(0.0f, 0.0f, -side);
glEnd(); 

The result is this:

There should be something wrong with texture mapping OR
I should have left the cube as it is and applied the texture to it, and then scale it (but I think this would make the texture look distorted).

What should I do?

Update #1: Before SOIL I had been using a loader for BMP files I've found at a site. I've used it now, and it looks like this:

Notice that it seems as if the cube has some triangular wholes where I've pointed it out. I am using SOIL like this:

GLuint tex_2d = SOIL_load_OGL_texture
        (
        imagepath,
        SOIL_LOAD_AUTO,
        SOIL_CREATE_NEW_ID,
        SOIL_FLAG_MIPMAPS | SOIL_FLAG_INVERT_Y | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT
        );
    glBindTexture(GL_TEXTURE_2D, tex_2d);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );

Answer 1

So, at least three problems here.

You're rendering a quad-strip, but giving coordinates as if you are rendering separate quads. So you'll get extra primitives being rendered. This is not the source of your problems, but you are spitting out bad geometry in there somewhere.

Some of the UV coordinates seem off - on some faces the coords proceed around the face, whereas in others the coords zig-zag.

Here are your first two faces:

glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);   glVertex3f(side, height, 0.0f);
glTexCoord2f(0.0f, 1.0f );  glVertex3f(0.0f, height, 0.0f);

glTexCoord2f(0.0f, 0.0f);   glVertex3f(0.0f, 0.0f, -side);
glTexCoord2f(0.0f, 1.0f);   glVertex3f(side, 0.0f, -side);
glTexCoord2f(1.0f, 0.0f);   glVertex3f(side, height, -side);
glTexCoord2f(1.0f, 1.0f);   glVertex3f(0.0f, height, -side);

In the second face, the middle two UV coordinates are diagonally opposed, but not so on the first. Only one of these can be correct, so on the face which is not correct, you will get bad texturing.

Your texture loading issue is likely to be a padding problem, with the texture being loaded having a different padding requirement to what GL is expecting (GL, by default, expects lines of texture data to be padded to 4 bytes). Either tell GL how your texture is padded, or change the texture such that it matches (this is why your BMP texture works better - the padding requirements for BMP coincidentally work with GL).

Possible fixes for this are:

• Tell GL how your texture is packed, using (for example) glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
• Change the dimensions of your texture, such that the padding matches without changing anything
• Change the loading of your texture, such that the padding is consistent with what GL expects

I suspect there might be something further wrong here, as you have a strange yellow stripe appearing on both the BMP and PNG textures, but I'd fix the obvious problems first.

Finally, standard advice - avoid the old style fixed-function pipeline with individual vertex submission, and use VBOs and draw calls.