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;
}

Added it at the bottom for you. But as far as texturing is concerned, it just passes the uv data over to the fragment shader without any transformation. Just to ensure the UVs are being passed correctly/are not the problem - I've quickly rendered the UVs as colour (red,green). It seems to show the UV data gets into the frag shader without issues: imgur.com/N4Zp0ir — user955340

Nicol Bolas Nicol Bolas · Accepted Answer · 2013-04-20T10:24:06

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_ARBs 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.

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

2 Answers