OpenGL Textures are all black in 3.3 - but work in 3.1

Question

I'm currently working on a simple 3D scene in OpenGL3.3, but when trying to texture the objects - all of them are textured entirely black. However, if I change the context version to 3.1; it has no problem rendering the textures correctly over the models.

I'm not sure if this suggests I'm using deprecated functionality/methods, but I'm struggling to see where the problem could be.

Setting up the texture

(load texture from file)
...
glGenTextures(1, &TexID);               // Create The Texture ( CHANGE )
glBindTexture(GL_TEXTURE_2D, TexID);

glTexImage2D(GL_TEXTURE_2D, 0, texture_bpp / 8, texture_width, texture_height, 0, texture_type, GL_UNSIGNED_BYTE, texture_imageData);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
...

Binding the Texture to Render

// mLocation is the layout location in the shader, from glGetUniformLocation
// mTextureUnit is the specified texture unit to load into. Currently using 0.
// mTextureID is the ID of the loaded texture, as generated above.
glActiveTexture( GL_TEXTURE0 + mData.mTextureUnit );
glBindTexture( GL_TEXTURE_2D, mData.mTextureID );
glUniform1i( mLocation, mData.mTextureUnit );

Fragment Shader

uniform sampler2D diffusemap;
in vec2 passUV;
out vec3 outColour;
...
outColour = texture( diffusemap, passUV ).rgb;

All textures being used are power of 2, square sizes.

---

Images showing the problem.

GL3.1: http://i.imgur.com/NUgj6vA.png

GL3.3: http://i.imgur.com/oOc0jcd.png

---

Vertex Shader

#version 330 core

uniform mat4 p;
uniform mat4 v;
uniform mat4 m;

in vec3 vertex;
in vec3 normal;
in vec2 uv;

out vec3 passVertex;
out vec3 passNormal;
out vec2 passUV;

void main( void )
{
    gl_Position = p * v * m * vec4( vertex, 1.0 );

    passVertex = vec3( m * vec4( vertex, 1.0 ) );
    passNormal = vec3( m * vec4( normal, 1.0 ) );
    passUV = uv;
}

Answer 1

In the line:

glTexImage2D(GL_TEXTURE_2D, 0, texture_bpp / 8, texture_width, texture_height, 0, texture_type, GL_UNSIGNED_BYTE, texture_imageData);

The assumption that (texture_bpp / 8) will return the correct format type is incorrect. It should be one of the GLenum values that specifies the internal-format such as GL_RGBA.

Correcting it to (or whichever format matches the internal-format of the texture file) fixes the issue entirely and works on both GL3.3 and GL3.1:

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texture_width, texture_height, 0, texture_type, GL_UNSIGNED_BYTE, texture_imageData);

Answer 2

For the sake of completeness, the internal format of a texture should be an enumerator. And one of the sized enumerators, not one of the unsized ones. Please stop using GL_RGB when you can use GL_RGB8 .

Answer correctly identifies the issue, but it would be helpful to have it explained why the previous assumption would work on 3.1 and not on 3.3.

The ability to use a number on the range [1, 4] was deprecated in OpenGL 3.0 and removed in OpenGL 3.1. However , at that time, there wasn't a way to say, "give me the actual core profile of OpenGL version 3.1"; the WGL/GLX_CONTEXT_CORE_PROFILE_BIT_ARB s didn't exist. Therefore, when you got a 3.1 context, it was perfectly legal for an implementation to export the ARB_compatibility extension , which still allowed all of the removed functionality.

In 3.2, the ability to explicitly select a profile was added to OpenGL. At which point, you would not get someone exposing ARB_compatibility in a core profile. That's why your code works when you ask for 3.1 (since it's free to give you 3.1 compatibility), but not when you ask for 3.3 core profile.