我已经在一个 GL 程序上工作了一段时间,突然它开始出现错误。在尝试解决这些问题一段时间后,我编写了一个生成相同行为的简短测试程序:
#include <GL/glut.h>
#include <iostream>
#define CHECK_GL_ERR() printError(__LINE__)
void printError(int line)
{
GLenum err = glGetError();
if(err != GL_NO_ERROR)
{
std::cerr << "GL error on line " << line << ": " << gluErrorString(err) << std::endl;
}
}
void displayFunc()
{
CHECK_GL_ERR();
glBegin(GL_POINTS);
CHECK_GL_ERR();
glVertex3f(0, 0, 0);
CHECK_GL_ERR();
glEnd();
CHECK_GL_ERR(); //line 23
exit(0);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitWindowSize(300, 300);
glutCreateWindow("Test");
glutDisplayFunc(displayFunc);
glutMainLoop();
}
当我运行这个程序时,它会给出输出:
GL error on line 23: invalid operation
所以似乎glEnd();
导致错误。文档说:
GL_INVALID_OPERATION 如果执行 glEnd 而前面没有 glBegin 则生成。
在我的代码中不是这种情况。那么有没有人看到,为什么这段代码会给出错误消息?
PS:当然我知道 glBegin/End 已经被弃用/删除了很长时间,但是将一些少量代码组合在一起非常方便。在 GL 决定脾气暴躁之前,该程序也可以正常运行。
编辑
我刚刚用 glslDevil 做了一个跟踪,它给出了:
W! Program Start
| glXQueryExtension(0x1ab03f0, (nil), (nil))
| glXChooseFBConfig(0x1ab03f0, 0, 0x7fffb8fcf8b0, 0x7fffb8fcf8a4)
| glXGetVisualFromFBConfig(0x1ab03f0, 0x111)
| glXGetProcAddressARB(0x7f93c37526e5)
| glXCreateNewContext(0x1ab03f0, 0x111, 32788, (nil), 1)
| glXIsDirect(0x1ab03f0, 0x1ac8de8)
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glDrawBuffer(GL_FRONT)
| glReadBuffer(GL_FRONT)
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glViewport(0, 0, 300, 300)
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glGetError()
| glBegin(GL_POINTS)
| glGetError()
| glVertex3f(0,000000, 0,000000, 0,000000)
| glGetError()
| glEnd()
W! OpenGL error GL_INVALID_OPERATION detected
| glGetError()
| glXMakeContextCurrent(0x1ab03f0, 123731970, 123731970, 0x1ac8de8)
| glXDestroyContext(0x1ab03f0, 0x1ac8de8)
E! Child process exited
W! Program termination forced!