如何使用GLFW轮询libdispatch块中的事件? [英] How to use GLFW to poll for events in a libdispatch block?
问题描述
按照如何在libdispatch中使用GLUT的答案?，我现在使用的是GLFW － —
Following up on the answer to How to use GLUT with libdispatch?, I'm now using GLFW instead —
以下代码设置了一个窗口，设置了一个计时器以轮询事件，并随着时间的流逝，使渲染更新入队:
The following code sets up a window, sets up a timer to poll for events, and, over time, enqueues render updates:
#include <dispatch/dispatch.h>
#include <GL/glfw.h>
float t=0;
int main(void)
{
dispatch_async(dispatch_get_main_queue(), ^{
glfwInit();
glfwDisable(GLFW_AUTO_POLL_EVENTS);
glfwOpenWindow(320,200,8,8,8,8,8,0,GLFW_WINDOW);
});
// Periodically process window events --- this isn't working.
dispatch_source_t windowEventTimer;
windowEventTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
uint64_t nanoseconds = 100 * NSEC_PER_MSEC;
dispatch_source_set_timer(windowEventTimer, dispatch_time(DISPATCH_TIME_NOW, nanoseconds), nanoseconds, 0);
dispatch_source_set_event_handler(windowEventTimer, ^{
glfwPollEvents();
});
dispatch_resume(windowEventTimer);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
for(int i=0;i<200;++i)
{
// Enqueue a rendering update.
dispatch_async(dispatch_get_main_queue(), ^{
glClearColor (0.2f, 0.2f, 0.4f, 1.0f);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f (1.0, 0.7, 0.7);
glBegin( GL_LINES );
glVertex3f(0,0,0);
glVertex3f(t+=0.02,.1,0);
glEnd();
glfwSwapBuffers();
});
// Wait a bit, to simulate complex calculations.
sleep(1);
}
});
dispatch_main();
}
动画将按预期更新，但是窗口框架没有绘制，并且窗口不响应事件.
The animation updates as expected, but the window frame does not draw, and the window does not respond to events.
推荐答案
浏览GLFW源，我认为我发现了问题:由GLFW创建的可可窗口的运行循环需要从线程0执行，但是GLFW不需要确保在线程0上发生_glfwPlatformPollEvents().(在
Digging through the GLFW source, I think I found the problem: the runloop of the Cocoa window created by GLFW needs to execute from Thread 0, but GLFW does not ensure that _glfwPlatformPollEvents() happens on Thread 0. (Identical symptoms were reported on this question about executing a Cocoa GUI on a thread other than 0.)
一种解决方法是使用CoreFoundation用来处理CFRunLoop内部主要libdispatch队列的相同私有接口.
A workaround is to use the same private interface CoreFoundation uses to process the main libdispatch queue from inside a CFRunLoop.
如果我将上面代码中的dispatch_main()调用替换为:
If I replace the dispatch_main() call in the above code with this:
while(1)
{
_dispatch_main_queue_callback_4CF(NULL);
usleep(10000);
}
...它按预期方式工作-绘制窗口框架，并且窗口处理事件.
...it works as expected — the window frame draws, and the window processes events.
我试图改善这种骇人听闻的情况，
Trying to improve this hacky situation, I:
- filed a feature request to make this a public libdispatch API
- requested that the GLFW documentation be updated to mention which thread is needed for Mac events.
这篇关于如何使用GLFW轮询libdispatch块中的事件?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
