這篇文章(MFC單文檔視圖中嵌入GLFW窗口)提到了glfw嵌入mfc的辦法,採用的查找進程PID再嵌入的方法,進程間通信採用UDP,略微繁瑣。
其實不必如此麻煩,SetParent直接就可以辦到。
先上最終效果,其中的三角形是實時旋轉的:
第1步 創建標準Win32 SDK窗口
#include <windows.h>
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("HelloWin") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;//WNDCLASSEX比WNDCLASS多兩個結構成員--cbSize(指定WNDCLASSEX結構的大小--字節) --hIconSm(標識類的小圖標)
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground= (HBRUSH) (COLOR_WINDOW+1) ;//白色//(HBRUSH)(COLOR_MENU +1)界面灰
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName= szAppName ;
if (!RegisterClass (&wndclass))
{
MessageBox ( NULL, TEXT ("This program requires Windows NT!"),szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow( szAppName, // window class name
TEXT ("The Hello Program"), // window caption
WS_OVERLAPPED|WS_CAPTION|WS_SYSMENU,
CW_USEDEFAULT,// initial x position
CW_USEDEFAULT,// initial y position
CW_USEDEFAULT,// initial x size
CW_USEDEFAULT,// initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL) ; // creation parameters
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
return 0;
case WM_PAINT:
HDC hdc;
PAINTSTRUCT ps ;
hdc = BeginPaint(hwnd, &ps);
//DrawText (hdc, s, -1, &rect,DT_SINGLELINE | DT_CENTER | DT_VCENTER) ;
EndPaint(hwnd, &ps);
return 0 ;
case WM_DESTROY:
PostQuitMessage(0);
return 0 ;
case WM_QUIT:
return 0;
}
return DefWindowProc (hwnd, message, wParam, lParam);
}
這一長段麻煩又難記,我每次都是複製粘貼了再改。要麼就是直接用封裝好的窗口類(涉及靜態函數做消息轉發,有人看再寫吧,再說這部分內容網上也多)。
第2步 在WinMain中創建glfw窗口
在CreateWindow後加入glfw的窗口創建過程:
//初始化glfw
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//創建glfw窗口
window = glfwCreateWindow(400, 400, "openGL", NULL, NULL);
if (window == NULL)
{
OutputDebugString("Failed to create GLFW window");
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
//註冊glad函數地址
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
OutputDebugString("Failed to initialize GLAD");
return -1;
}
glViewport(0, 0, 400, 400);
//背景顏色
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
添加include,鏈接好lib,然後上面這段直接插入到主消息循環之前(就是WinMain裏那個while的前面)。
注意:有人說glfw的init只能做一次,做多次會發生其他窗口不渲染的bug,我自己沒有試過。
此時會打開2個窗口,並且glClearColor設置的顏色並沒有生效,單獨關閉opengl窗口也沒反應。第1個問題是因爲opengl的渲染循環沒有建立;第2個問題是因爲GLFW截獲了WM_CLOSE消息的響應,要設置glfwSetWindowShouldClose才能讓他捕獲關閉事件。
第3步 使用SetParent將GLFW窗口嵌入主窗口
繼續加入代碼:
//取得glfw窗口句柄並將其嵌入父窗口
HWND hwndGLFW = glfwGetWin32Window(window);
SetWindowLong(hwndGLFW, GWL_STYLE, WS_VISIBLE);
MoveWindow(hwndGLFW, 0, 0, 400, 400, TRUE);
SetParent(hwndGLFW, hwnd);
注意glfwGetWin32Window函數是不在glfw3.h裏的,要在include處加入以下代碼才能使用:
#define GLFW_EXPOSE_NATIVE_WIN32
#include <GLFW/glfw3native.h>
SetWindowLong這句是重設窗口外觀,不加的話GLFW的窗口會嵌入主窗口,但是標題欄什麼的一應俱全,只是不能拖出主窗口外而已。不加的話效果就像這樣:
MoveWindow這句如果不加的話,因爲GLFW窗口彈出的位置不固定,所有你會發現每次打開主程序時GLFW窗口都在隨機的位置。
第4步 在主消息循環中加入opengl渲染
在主消息循環中加入:
if (!glfwWindowShouldClose(window))
{
//刷新顏色緩衝和深度
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
現在的主消息循環長這樣:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!glfwWindowShouldClose(window))
{
//刷新顏色緩衝和深度
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
TranslateMessage(&msg);
DispatchMessage(&msg);
}
此時opengl已經開始渲染了,可以看到底色了。
然後可以畫個三角形,再讓它隨時間旋轉。如果這樣做了,你就會發現,只有鼠標在窗口上不停移動,三角形纔會轉,一停下就不轉了。這是因爲主消息循環只有在接收到消息時才刷新,只有你不停地造,動鼠標啊,按鍵盤啊,拖滾輪什麼的它才更新。
這顯然不符合要求。所以我們還需要開一個新線程。
第5步 使用多線程爲GLFW窗口進行渲染
加入一個函數:
void RenderProc()
{
glfwMakeContextCurrent(window);
while (!glfwWindowShouldClose(window))
{
float time = glfwGetTime();
//刷新顏色緩衝和深度
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
shader->UseProgram();
shader->Uniform("angle", time);
triangle->Bind();
triangle->DrawTriangles();
//
glfwSwapBuffers(window);
glfwPollEvents();
}
delete shader;
delete triangle;
glfwTerminate();
}
其中的shader和triangle分別是對着色器和VAO的封裝。其初始化函數爲:
void Init()
{
float triangle_vertex[] =
{
0.0f,0.5f,0.0f,1.0f,0.0f,0.0f,
-0.5f,-0.5f,0.0f,0.0f,1.0f,0.0f,
0.5f,-0.5f,0.0f,0.0f,0.0f,1.0f
};
triangle=new TVertexArray(sizeof(triangle_vertex), triangle_vertex, { 3,3 });
shader=new TShader("tri_vertex.glsl", "tri_fragment.glsl");
}
在glClearColor後加入:
Init();
//將渲染移交線程前需要將當前上下文設爲null
glfwMakeContextCurrent(NULL);
std::thread RenderThread(RenderProc);
這裏首先初始化了shader和triangle指針,然後將opengl的context設爲Null,這是因爲glfwMakeContextCurrent的說明裏說了,將渲染函數移交到新線程的時候,要先在舊線程裏把上下文設爲空,再在新的線程裏設置上下文。否則的話,在渲染中GetLocation和VAO的綁定操作等都會出錯。
因爲渲染已經移交新線程,主消息循環可以刪掉和glfw, opengl相關的內容了。
然後消息循環後需要把thread阻塞一下,確認關閉:
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
RenderThread.join();
最後在WndProc中WM_DESTROY消息處加入glfwSetWindowShouldClose,讓主窗口帶着glfw窗口關閉:
case WM_DESTROY:
glfwSetWindowShouldClose(window, true);
PostQuitMessage(0);
return 0;
現在的關閉流程是這樣:
主窗口點擊關閉->WM_DESTROY消息發出->glfwSetWindowShouldClose函數設置glfw窗口可以關閉->PostQuitMessage函數調用->主消息循環退出->RenderThread線程阻塞,等待glfw窗口、渲染循環以及RenderThread線程退出(glfw窗口可能在主消息循環結束前就已經退出,此處阻塞主要起檢查並等待的作用)->主程序返回
現在流程就很完善了。寫個旋轉三角形,三角形可以不停旋轉,主窗口也可以正常響應。
最終效果:
最後是整個main.cpp文件:
#include <windows.h>
#include <thread>
#include <memory>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#define GLFW_EXPOSE_NATIVE_WIN32
#include <GLFW/glfw3native.h>
#include "TShader.h"
#include "TVertexArray.h"
GLFWwindow* window;
TVertexArray *triangle;
TShader *shader;
void Init();
void RenderProc();
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("HelloWin");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;//WNDCLASSEX比WNDCLASS多兩個結構成員--cbSize(指定WNDCLASSEX結構的大小--字節) --hIconSm(標識類的小圖標)
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);//白色//(HBRUSH)(COLOR_MENU +1)界面灰
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);
return 0;
}
hwnd = CreateWindow(szAppName, // window class name
TEXT("The Hello Program"), // window caption
WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_SIZEBOX,
CW_USEDEFAULT,// initial x position
CW_USEDEFAULT,// initial y position
CW_USEDEFAULT,// initial x size
CW_USEDEFAULT,// initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL); // creation parameters
//初始化glfw
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//創建glfw窗口
window = glfwCreateWindow(400, 400, "openGL", NULL, NULL);
if (window == NULL)
{
OutputDebugString("Failed to create GLFW window");
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
//註冊glad函數地址
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
OutputDebugString("Failed to initialize GLAD");
return -1;
}
glViewport(0, 0, 400, 400);
//取得glfw窗口句柄並將其嵌入父窗口
HWND hwndGLFW = glfwGetWin32Window(window);
SetWindowLong(hwndGLFW, GWL_STYLE, WS_VISIBLE);
MoveWindow(hwndGLFW, 0, 0, 400, 400, TRUE);
SetParent(hwndGLFW, hwnd);
//背景顏色
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
Init();
//將渲染移交線程前需要將當前上下文設爲null
glfwMakeContextCurrent(NULL);
std::thread RenderThread(RenderProc);
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
RenderThread.join();
return msg.wParam;
}
void Init()
{
float triangle_vertex[] =
{
0.0f,0.5f,0.0f,1.0f,0.0f,0.0f,
-0.5f,-0.5f,0.0f,0.0f,1.0f,0.0f,
0.5f,-0.5f,0.0f,0.0f,0.0f,1.0f
};
triangle=new TVertexArray(sizeof(triangle_vertex), triangle_vertex, { 3,3 });
shader=new TShader("tri_vertex.glsl", "tri_fragment.glsl");
}
void RenderProc()
{
glfwMakeContextCurrent(window);
while (!glfwWindowShouldClose(window))
{
float time = glfwGetTime();
//刷新顏色緩衝和深度
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
shader->UseProgram();
shader->Uniform("angle", time);
triangle->Bind();
triangle->DrawTriangles();
//
glfwSwapBuffers(window);
glfwPollEvents();
}
delete shader;
delete triangle;
glfwTerminate();
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
return 0;
case WM_PAINT:
HDC hdc;
PAINTSTRUCT ps;
RECT rect;
GetClientRect(hwnd, &rect);
hdc = BeginPaint(hwnd, &ps);
DrawText (hdc, "This is text", -1, &rect,DT_SINGLELINE | DT_CENTER | DT_VCENTER) ;
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
glfwSetWindowShouldClose(window, true);
PostQuitMessage(0);
return 0;
case WM_QUIT:
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
至於opengl窗口和主窗口的通信,就按多線程的通信方式來就行,最簡單就直接用全局變量,其他地方寫,RenderProc裏讀,就可以修改渲染內容了。或者用mutex啊condition_variable這些設施進行雙向通信都行。
限於篇幅TShader類和TVertexArray類就不粘貼了,你看過LearnOpenGL網站的話相信能寫出來,或者替換成你自己的渲染過程也行。
參考文獻
[1] MFC單文檔視圖中嵌入GLFW窗口
[2] cv::namedWindow, GLFWwindow以及其他程序嵌入到MFC中的教程