OpenGL: INVALID_OPERATION following glEnableVertexAttribArray

Question

I\'m porting a functioning OpenGL app from Windows to OSX, and keep getting an \"invalid operation\" (code 1282) error after calling glEnableVertexAttribArray()

Answer 1

You're seeing this error on OS X because it only supports the OpenGL Core Profile if you're using OpenGL 3.x or higher. Your code is not Core Profile compliant. You were most likely using the Compatibility Profile on Windows.

Specifically, the Core Profile requires a Vertex Array Object (VAO) to be bound for all vertex related calls. So before calling glEnableVertexAttribArray(), or other similar functions, you will need to create and bind a VAO:

GLuint vaoId = 0;
glGenVertexArrays(1, &vaoId);
glBindVertexArray(vaoId);

On how to find out the error conditions: In this case, it's not nearly as easy as it should be. Let's say you work with a GL3 level feature set. In an ideal world, you would go to www.opengl.org, pull down the "Documentation" menu close to the top-left corner, choose "OpenGL 3.3 Reference Pages", click on glEnableVertexAttribArray in the left pane, and look at the "Errors" section on the page. Then you see that... GL_INVALID_OPERATION is not listed as a possible error.

Next, you might want to check if there's anything better in the latest version. You do the same, but choose "OpenGL 4 Reference Pages" instead. The error condition is still not listed.

By now you realize, like many before you, that these man pages are often faulty. So you go to the ultimate source: the specs. This time you choose "OpenGL Registry" in the Documentation menu. This gives you links to all the spec documents in PDF format. Again, let's try 3.3 first. Search for "EnableVertexAttribArray" in the document and there is... still no GL_INVALID_OPERATION documented as a possible error.

Last resort, checking the very latest spec document, which is 4.4. Again looking for "EnableVertexAttribArray", it's time for a heureka:

An INVALID_OPERATION error is generated if no vertex array object is bound.

I'm quite certain that the error also applies to GL3. While it's reasonably common for the man pages to be incomplete, it's much rarer for the spec documents to be missing things. The very closely related glVertexAttribPointer() call has this error condition documented in GL3 already.