glew first init in GLX

最新推荐文章于 2021-11-17 16:26:25 发布

原创最新推荐文章于 2021-11-17 16:26:25 发布 · 231 阅读

1 ·

CC 4.0 BY-SA版权

C++ 同时被 2 个专栏收录

9 篇文章

订阅专栏

Linux

6 篇文章

订阅专栏

本文详细介绍了如何使用X11和OpenGL库在Linux环境下创建窗口并进行基本的渲染操作。通过设置X11显示配置、获取帧缓冲配置、创建GL上下文，实现了窗口的创建、OpenGL初始化及事件循环，展示了基础的渲染流程。

#include <cstdlib>
#include <X11/Xlib.h>
#include <X11/XKBlib.h>

#define GLEW_STATIC

#include <GL/glew.h>
#include <GL/glx.h>
// #include <GL/gl.h>
#include <GL/glu.h>

#include <cassert>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>
#include <memory.h>
#include <iostream>

Display *display;
int defaultScreen;
GLXFBConfig *fbConfig;
XVisualInfo *visual;
Window root;
Colormap colorMap;

Window createWindow() {
	XSetWindowAttributes swa;
	swa.colormap = colorMap;
	swa.event_mask = ExposureMask | KeyPressMask;
	unsigned long valueMask = CWColormap | CWEventMask;
	auto window = XCreateWindow(display, root, 100, 100, 320, 240, 0, visual->depth, InputOutput, visual->visual,
								valueMask, &swa);
	XMapWindow(display, window);
	XStoreName(display, window, "show me");
	XFlush(display);
	// XSync(display, 0);
	return window;
}

void render() {
	glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

int main() {
	// connect to X Server
	auto displayName = getenv("DISPLAY");
	display = XOpenDisplay(displayName);
	assert(display);

	// get default screen
	defaultScreen = DefaultScreen(display);

	// get frame buffer configurations
	int att[] = {GLX_RENDER_TYPE, GLX_RGBA_BIT, GLX_DOUBLEBUFFER, True, GLX_DEPTH_SIZE, 16, None};
	int nelements;
	fbConfig = glXChooseFBConfig(display, defaultScreen, att, &nelements);
	assert(fbConfig);

	// get visual
	visual = glXGetVisualFromFBConfig(display, *fbConfig);
	assert(visual);

	// get root window
	root = RootWindow(display, defaultScreen);
	colorMap = XCreateColormap(display, root, visual->visual, AllocNone);

	// create gl context
	auto glContext = glXCreateNewContext(display, *fbConfig, GLX_RGBA_TYPE, 0, GL_TRUE);

	// =================================================================
	// create window

	auto window1 = createWindow();
	glXMakeCurrent(display, window1, glContext);
	GLenum err = glewInit();
	assert(GLEW_OK == err);
	glXMakeCurrent(display, None, 0);
	XDestroyWindow(display, window1);


	auto window = createWindow();

	// init opengl status, or create resources

	// message loop
	for (;;) {


		XEvent event;
		// XNextEvent(app.display, &event);
		if (XCheckMaskEvent(display, ExposureMask | KeyPressMask, &event)) {
			switch (event.type) {
				case Expose:
					break;
				case KeyPress:
					auto keySys = XkbKeycodeToKeysym(display, event.xkey.keycode, 0,
													 event.xkey.state & ShiftMask ? 1 : 0);
					if (keySys == XK_Escape) { goto L_EXIT; }

					// Root::GetInstance()->SetInvalidate();

					break;
			}
		} else {

			if (event.xexpose.window == window) {

				glXMakeCurrent(display, event.xexpose.window, glContext);

				// render
				render();

				// swap buffer
				glXSwapBuffers(display, event.xexpose.window);

			}
			pthread_yield();

		}


	}

	L_EXIT:

	// clear
	XFreeColormap(display, colorMap);
	if (glXGetCurrentDrawable() == window) {
		glXMakeCurrent(display, None, 0);
	}
	XDestroyWindow(display, window);
	XFree(visual);
	XFree(fbConfig);

	if (glXGetCurrentContext() == glContext) {
		glXMakeCurrent(display, None, 0);
	}
	glXDestroyContext(display, glContext);

	// disconnect to X Server
	XCloseDisplay(display);

	return 0;
}