Aggravating OpenGL Texture Issue

Question

I'm having issues trying to get a texture loaded into VRAM. I'm using OpenGL on Mac OS X. I have geometry that I've successfully renderer by passing a color into my fragment shader. However, as soon as I try to load a texture, no geometry gets rendered and I can only see the background color. Here's my texture loading code:

char imageData[27] = {
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
    127, 127, 127,
};

glActiveTexture(GL_TEXTURE0);
GLuint textureID;
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 3, 3, 0, GL_RGB, GL_UNSIGNED_BYTE, imageData);

GLint uniform_location = glGetUniformLocation(bundle->GetShaderProgramID(), "texture");
std::cout << uniform_location <<std::endl;
glUniform1i(uniform_location, 0);

glEnable(GL_TEXTURE_2D);

And here's my fragment shader code:

uniform sampler2D texture;

void main()
{
    vec2 coord = vec2(0.5, 0.5);

    //gl_FragColor = vec4(coord, 0.0, 1.0);

    gl_FragColor = vec4(texture2D(texture, coord).rgb, 1.0);
}

I realize some of this code probably isn't necessary, but I've been trying everything I can think of.

Thanks.

BTW, always check errors with glGetError. If you have error, rendering may disappear. — alxx

Bahbar Bahbar · Accepted Answer · 2010-10-13T06:56:31

The most likely cause is that you don't have mipmapping off, and you did not specify mipmapping levels. So your texture is incomplete.

To turn it off on this texture object (to be done around the glTexImage2D call)

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

You do however realize that "everything breaks down" does not help at all figuring out what you see ? In general, a screenshot is worth a thousand words, but short of that, at least describing how it fails would help.

Aggravating OpenGL Texture Issue

1 Answers