How OpenGL handles errors

This section focuses on glGetError, It's in almost every OpenGL In the version of , So in OpenGL It is commonly used in error handling . because OpenGL Implementation is related to version , But you can generally judge by prefix . Function function and version . If used correctly , But it can't render the expected effect , You can then use the document to determine whether it is a version problem .

The code framework ：

 For cleaning Error
static void GLClearError()
{
	while (glGetError() != GL_NO_ERROR);
}

// Used for inspection Error
static void GLCheckError()
{
	while (GLenum error = glGetError())
	{
		std::cout << "[OpenGL Error](" << error << ")" << std::endl;
	}
}

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  analysis ：  When using , We add these two functions to Error code to be detected Up and down . But the disadvantages of doing so are obvious , First of all, we don't know the specific type of error . secondly , We cannot pinpoint where the error occurred .             technological process ： The way to imitate a function is Find a reference object similar to the target function , Then analyze and imitate .

VS2019 Report errors

Target demand analysis ：（1） One error check takes many times   Call two functions , The process is tedious . Encapsulation makes calling easier .（2） Inaccurate positioning . Error code File path , Row number . Are important information for reporting errors .

    Code implementation ：                                                                                                                            

（1） terms of settlement ： Macro wrapping can simplify the form of our calls , Handle misuse ASSERT.

 __debugbreak() Is to compile built-in functions .

Be similar to DebugBreak, It's a portable Win32 Method （ Can't be in clang/gcc Next use ） To cause breakpoint exceptions . This allows the calling thread to signal the debugger to handle exceptions .

ps: Built in functions ： Code is usually inserted inline , Avoid the overhead of function calls , But faster than the equivalent inline function assembly .

Compiler intrinsics | Microsoft Docs

（2） terms of settlement ： Add more printing information .

// Show me the code 

#define ASSERT(x) if (!(x)) __debugbreak();
#define GLCall(x) GLClearError();x;ASSERT(GLLogCall(#x, __FILE__, __LINE__))

static  void GLClearError()
{
	while (glGetError() != GL_NO_ERROR);
}
static bool  GLLogCall(const char* function, const char* file, int line)
{
	while (GLenum error = glGetError())
	{
		std::cout << "[OpenGL Error] (" << error << ")" << function <<
			" " << file << ":" << line << std::endl;
		return false;
	}
	return true;
}

// call  ： By using GLCall To package every need to check for errors OpenGL function 

GLCall(glDrawElements(GL_TRIANGLES, 6, GL_INT,nullptr));

  Running results ：

Running results

Running results

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                          If there is a mistake , Your advice are most welcome ！！