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Rendering directly to a composited window in vista+ with opengl.

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opengl-transparency-demo.cpp
C++
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#define _WIN32_WINNT 0x0500
 
#include <windows.h>
#include <windowsx.h>
#include <GL/gl.h>
#include <GL/glu.h>
 
#include <dwmapi.h>
 
#pragma comment (lib, "opengl32.lib")
#pragma comment (lib, "glu32.lib")
 
#pragma comment (lib, "dwmapi.lib")
 
#include <assert.h>
#include <tchar.h>
 
#ifdef assert
#define verify(expr) if(!expr) assert(0)
#else verify(expr) expr
#endif
 
const TCHAR szAppName[]=_T("TransparentGL");
const TCHAR wcWndName[]=_T("TransparentGL");
 
HDC hDC;
HGLRC m_hrc;
int w = 240;
int h = 240;
 
BOOL initSC() {
glEnable(GL_ALPHA_TEST);
glEnable(GL_DEPTH_TEST);
glEnable(GL_COLOR_MATERIAL);
 
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
 
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0, 0, 0, 0);
 
return 0;
}
 
void resizeSC(int width,int height) {
glViewport(0,0,width,height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
 
glMatrixMode(GL_MODELVIEW );
glLoadIdentity();
}
 
BOOL renderSC() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
 
glPushMatrix();
 
glColor3f(0, 1, 1);
glBegin(GL_TRIANGLES); // Drawing Using Triangles
glColor3f(1.0f,0.0f,0.0f); // Set The Color To Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top
glColor3f(0.0f,1.0f,0.0f); // Set The Color To Green
glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
glColor3f(0.0f,0.0f,1.0f); // Set The Color To Blue
glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
glEnd();
 
glPopMatrix();
glFlush();
 
return 0;
}
 
BOOL CreateHGLRC(HWND hWnd) {
PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR),
1, // Version Number
PFD_DRAW_TO_WINDOW | // Format Must Support Window
PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
PFD_SUPPORT_COMPOSITION | // Format Must Support Composition
PFD_DOUBLEBUFFER, // Must Support Double Buffering
PFD_TYPE_RGBA, // Request An RGBA Format
32, // Select Our Color Depth
0, 0, 0, 0, 0, 0, // Color Bits Ignored
8, // An Alpha Buffer
0, // Shift Bit Ignored
0, // No Accumulation Buffer
0, 0, 0, 0, // Accumulation Bits Ignored
24, // 16Bit Z-Buffer (Depth Buffer)
8, // Some Stencil Buffer
0, // No Auxiliary Buffer
PFD_MAIN_PLANE, // Main Drawing Layer
0, // Reserved
0, 0, 0 // Layer Masks Ignored
};
 
HDC hdc = GetDC(hWnd);
int PixelFormat = ChoosePixelFormat(hdc, &pfd);
if (PixelFormat == 0) {
assert(0);
return FALSE ;
}
 
BOOL bResult = SetPixelFormat(hdc, PixelFormat, &pfd);
if (bResult==FALSE) {
assert(0);
return FALSE ;
}
 
m_hrc = wglCreateContext(hdc);
if (!m_hrc){
assert(0);
return FALSE;
}
 
ReleaseDC(hWnd, hdc);
 
return TRUE;
}
 
LRESULT CALLBACK WindowFunc(HWND hWnd,UINT msg, WPARAM wParam, LPARAM lParam) {
PAINTSTRUCT ps;
 
switch(msg) {
case WM_CREATE:
break;
 
case WM_DESTROY:
if(m_hrc) {
wglMakeCurrent(NULL, NULL);
wglDeleteContext(m_hrc) ;
}
PostQuitMessage(0) ;
break;
 
default:
return DefWindowProc(hWnd,msg,wParam,lParam);
}
 
return 0;
}
 
int WINAPI _tWinMain(HINSTANCE hThisInst, HINSTANCE hPrevInst, LPSTR str,int nWinMode) {
WNDCLASSEX wc;
memset(&wc, 0, sizeof(wc));
wc.cbSize = sizeof(WNDCLASSEX);
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = (WNDPROC)WindowFunc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hThisInst;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)CreateSolidBrush(0x00000000);
wc.lpszClassName = szAppName;
 
if(!RegisterClassEx(&wc)) {
MessageBox(NULL, _T("RegisterClassEx - failed"), _T("Error"), MB_OK | MB_ICONERROR);
return FALSE;
}
 
HWND hWnd = CreateWindowEx(WS_EX_APPWINDOW, szAppName, wcWndName,
WS_VISIBLE | WS_POPUP, 200, 150, w, h,
NULL, NULL, hThisInst, NULL);
 
if(!hWnd) {
MessageBox(NULL, _T("CreateWindowEx - failed"), _T("Error"), MB_OK | MB_ICONERROR);
return FALSE;
}
 
DWM_BLURBEHIND bb = {0};
HRGN hRgn = CreateRectRgn(0, 0, -1, -1);
bb.dwFlags = DWM_BB_ENABLE | DWM_BB_BLURREGION;
bb.hRgnBlur = hRgn;
bb.fEnable = TRUE;
DwmEnableBlurBehindWindow(hWnd, &bb);
CreateHGLRC(hWnd);
 
HDC hdc = GetDC(hWnd);
wglMakeCurrent(hdc, m_hrc);
initSC();
resizeSC(w, h);
ReleaseDC(hWnd, hdc);
 
MSG msg;
while(1) {
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else {
HDC hdc = GetDC(hWnd);
wglMakeCurrent(hdc, m_hrc);
 
renderSC();
 
SwapBuffers(hdc);
ReleaseDC(hWnd, hdc);
}
}
 
return (FALSE);
}

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