Issue with loading a texture on the GPU with OpenGL 4.1 Core profile

Question

I’ve been trying to render a texture on the whole screen in OpenGL 4.1 using the Core profile and followed a few tutorials on the matter, but all I have so far is a blank screen.

I tried using my texture coordinates as color components and got the result I expected so the vertice data must be in order, but using the dimensions of the texture as color components I determined the size of the texture in my shader is 1x1 when it should be 2x2, so I guess I am doing something wrong when uploading it to the GPU.

This is my pixel data:

const GLubyte pixels[] = {
    255, 255, 255, 255,     0, 0, 0, 255,
    0, 0, 0, 255,           255, 255, 255, 255,
};

This is how I load my texture:

glGenTextures(1, &texture);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)pixels);

I also tried using a buffer:

glGenTextures(1, &texture);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glGenBuffers(1, &texture_buffer);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, texture_buffer);
glBufferData(GL_PIXEL_UNPACK_BUFFER, sizeof(pixels), pixels, GL_STATIC_DRAW);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)0);

And this is how I render:

glUseProgram(shader_program);
// Binding my vba and vbo, uploading vertices.
glUniform1i(texture_location, 0);
// Enabling vertex attrib arrays.
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
// Drawing arrays, disabling vertex attrib arrays.

I have also put the whole source file on pastebin, it uses GLFW for windowing and does some basic error checking.

I’d be really grateful if someone could point out what I am missing here.

Answer 1

You seem to not change GL_TEXTURE_MIN_FILTER and not fill all the mipmap layers. This will usually result in the texture not being applied, since by default the filter uses mipmapping.