如何使这个简单的OpenGL代码（在“宽松的” 3.3和4.2配置文件中工作）在严格的3.2和4.2核心配置文件中工作？

metaleap：

我注意到一些3D代码不会在严格的核心配置文件中呈现，但可以在“正常”（非明确要求仅作为核心提供）配置文件上下文中呈现。为了解决这个问题，我编写了最小的，最简单的OpenGL程序，仅绘制了一个三角形和一个矩形：

在此处输入图片说明

我在这里将OpenGL程序发布为要点。

With the useStrictCoreProfile variable set to false, the program outputs no error messages to the console and draws a quad and a triangle as per the above screenshot, both on an Intel HD OpenGL 3.3 and on a GeForce with OpenGL 4.2.

However, with useStrictCoreProfile set to true, it clears the background color but does not draw the tri & quad, console output is this:

GLCONN: OpenGL 3.2.0 @ NVIDIA Corporation GeForce GT 640M LE/PCIe/SSE2 (GLSL: 1.50 NVIDIA via Cg compiler)
LASTERR: OpenGL error at step 'render.VertexAttribPointer()': GL_INVALID_OPERATION
LASTERR: OpenGL error at step 'render.DrawArrays()': GL_INVALID_OPERATION
LASTERR: OpenGL error at step 'render.VertexAttribPointer()': GL_INVALID_OPERATION
LASTERR: OpenGL error at step 'render.DrawArrays()': GL_INVALID_OPERATION
LASTERR: OpenGL error at step '(post loop)': GL_INVALID_OPERATION
EXIT

... if a 4.2 strict core profile is requested instead of 3.2, same issue. Applies to 3 different nvidia GPUs so I assume I'm not conforming to the strict core profile properly. What was I doing wrong, and how can I fix this?

Note, you won't find a glEnableVertexAttribArray call in the above Gist, as it's inside the glutil package I'm importing -- but this does get called as the last step in the gist's compileShaders() func.

postgoodism :

You're not creating/binding a Vertex Array Object with glGenVertexArrays() and glBindVertexArray(). VAOs encapsulate a bunch of vertex attribute state, including which attributes are enabled, detailed per-attribute information, etc. They were optional when the feature was originally introduced, but they're now required in strict/core contexts according to section 10.4 of the OpenGL core specification:

当没有绑定顶点数组时，任何修改，绘制或查询顶点数组状态的命令都会生成INVALID_OPERATION错误。这在初始GL状态下发生，并且可能是由于BindVertexArray或DeleteVertexArrays的副作用而发生的。

这是一个有关如何使用VAO的非常粗糙的示例：

// At initialization time:
GLuint vao = 0;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
// Set up your vertex attribute state:
//  - glBindBuffer(GL_ARRAY_BUFFER,...);
//  - glEnableVertexAttribArray(...);
//  - glVertexAttribPointer(...);
//  - etc. -- Refer to OpenGL docs to see what is/isn't included in the VAO!
glBindVertexArray(0); // unbinds vao

// At draw time:
glBindVertexArray(vao); // automatically sets up previously-bound vertex attribute state
glDrawArrays(...);
glBindVertexArray(0); // unbinds vao

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编辑于 2020-09-15

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