函数CGLGetCurrentContext什么时候应该返回NULL，什么时候不应该返回NULL? [英] When should the function CGLGetCurrentContext return NULL and when it shouldn't?
问题描述
我正在使用需要获取OpenGL低级上下文的API编写程序，但是我无法理解函数CGLGetCurrentContext何时应返回值(代表上下文的整数)，以及何时返回不应该.
I am writing a program using an API that needs to get an OpenGL low-level context, but I am unable to understand when does the function CGLGetCurrentContext should return a value (an integer representing the context), and when it shouldn't.
现在，函数CGLGetCurrentContext()返回NULL，这破坏了我的程序.我该如何解决?
Right now, the function CGLGetCurrentContext() is returning NULL, and this is breaking my program. How can I fix this?
此功能的目的是什么? OpenGL上下文如何建模?
What is the purpose of this function? How are OpenGL contexts modeled?
推荐答案
OpenGL具有绑定到工作线程的活动渲染上下文的概念.这样您就可以认为CGLGetCurrentContext()返回了一些线程局部变量.如果满足以下条件，则预计会返回一些值:
OpenGL has a conception of an active rendering context bound to the working thread. So that you may consider CGLGetCurrentContext() as returning some thread-local variable. It is expected to return some value if:
- 某些代码创建了OpenGL上下文.
- 某些代码在当前工作线程中激活了OpenGL上下文.
- 您在同一工作线程中调用
CGLGetCurrentContext()，并且之前的代码没有将其停用.
- Some code created an OpenGL context.
- Some code activated OpenGL context within current working thread.
- You call
CGLGetCurrentContext()within the same working thread, and the code before didn't deactivated it.
由于您尚未指定代码的详细信息，因此我可能认为OpenGL是由非您编写的代码管理的，这使得很难说明为什么CGLGetCurrentContext()可能为NULL.
As you have not specified details of your code, I may consider that OpenGL is managed by code not written by you, which makes it difficult to suggest why CGLGetCurrentContext() might be NULL.
我只能说我的macOS应用程序使用CGLGetCurrentContext()并且可以按预期工作.
I may only say that my macOS application uses CGLGetCurrentContext() and it works as expected.
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