/* * overlay.c * * WGL/OpenGL program * * Copyright (C) 1997 by Nate Robins (ndr@pobox.com) * * This program is freely distributable without licensing fees and is * provided without guarantee or warrantee expressed or implied. This * program is not in the public domain. */ /* includes */ #include /* must include this before GL/gl.h */ #include /* OpenGL header file */ #include /* pragmas */ #pragma warning(disable : 4244) /* disable conversion warnings */ /* globals */ HDC hDC; /* device context */ HGLRC hRC; /* opengl context */ HGLRC hOverlayRC; /* opengl overlay context */ /* functions */ /* WindowProc() * Minimum Window Procedure */ LONG WINAPI WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) { LONG lRet = 1; PAINTSTRUCT ps; switch(uMsg) { case WM_CREATE: break; case WM_DESTROY: break; case WM_PAINT: BeginPaint(hWnd, &ps); EndPaint(hWnd, &ps); break; case WM_CHAR: if(wParam == 27) /* ESC */ PostQuitMessage(0); break; case WM_SIZE: wglMakeCurrent(hDC, hRC); glViewport(0, 0, LOWORD(lParam), HIWORD(lParam)); wglMakeCurrent(hDC, hOverlayRC); glViewport(0, 0, LOWORD(lParam), HIWORD(lParam)); break; case WM_CLOSE: PostQuitMessage(0); break; default: lRet = DefWindowProc(hWnd, uMsg, wParam, lParam); break; } return lRet; } /* oglCreateWindow * Create a window suitable for OpenGL rendering */ HWND oglCreateWindow(char* title, int x, int y, int width, int height) { WNDCLASS wc; HWND hWnd; HINSTANCE hInstance; /* get this modules instance */ hInstance = GetModuleHandle(NULL); /* fill in the window class structure */ wc.style = 0; /* no special styles */ wc.lpfnWndProc = (WNDPROC)WindowProc; /* event handler */ wc.cbClsExtra = 0; /* no extra class data */ wc.cbWndExtra = 0; /* no extra window data */ wc.hInstance = hInstance; /* instance */ wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); /* load a default icon */ wc.hCursor = LoadCursor(NULL, IDC_ARROW); /* load a default cursor */ wc.hbrBackground = NULL; /* redraw our own bg */ wc.lpszMenuName = NULL; /* no menu */ wc.lpszClassName = title; /* use a special class */ /* register the window class */ if (!RegisterClass(&wc)) { MessageBox(NULL, "RegisterClass() failed: Cannot register window class,", "Error", MB_OK); return NULL; } /* create a window */ hWnd = CreateWindow(title, /* class */ title, /* title (caption) */ WS_OVERLAPPEDWINDOW | /* resize handles, etc */ WS_CLIPSIBLINGS | WS_CLIPCHILDREN, /* style */ x, y, width, height, /* dimensions */ NULL, /* no parent */ NULL, /* no menu */ hInstance, /* instance */ NULL); /* don't pass anything to WM_CREATE */ /* make sure we got a window */ if (hWnd == NULL) { MessageBox(NULL, "CreateWindow() failed: Cannot create a window.", "Error", MB_OK); return NULL; } /* show the window (map it) */ ShowWindow(hWnd, SW_SHOW); /* send an initial WM_PAINT message (expose) */ UpdateWindow(hWnd); return hWnd; } /* oglPixelFormat() * Sets the pixel format for the context */ int oglSetPixelFormatOverlay(HDC hDC, BYTE type, DWORD flags) { int pf, maxpf; PIXELFORMATDESCRIPTOR pfd; LAYERPLANEDESCRIPTOR lpd; /* layer plane descriptor */ int nEntries = 2; /* number of entries in palette */ COLORREF crEntries[2] = { /* entries in custom palette */ 0x00000000, /* black (ref #0 = transparent) */ 0x00ff0000, /* blue */ }; /* get the maximum number of pixel formats */ maxpf = DescribePixelFormat(hDC, 0, 0, NULL); /* find an overlay layer descriptor */ for(pf = 0; pf < maxpf; pf++) { DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd); /* the bReserved field of the PIXELFORMATDESCRIPTOR contains the number of overlay/underlay planes */ if (pfd.bReserved > 0) { /* aha! This format has overlays/underlays */ wglDescribeLayerPlane(hDC, pf, 1, sizeof(LAYERPLANEDESCRIPTOR), &lpd); if (lpd.dwFlags & LPD_SUPPORT_OPENGL && lpd.dwFlags & flags) { goto found; } } } /* couldn't find any overlay/underlay planes */ MessageBox(NULL, "Fatal Error: Hardware does not support overlay planes.", "Error", MB_OK); return 0; found: /* now get the "normal" pixel format descriptor for the layer */ DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd); /* set the pixel format */ if(SetPixelFormat(hDC, pf, &pfd) == FALSE) { MessageBox(NULL, "SetPixelFormat() failed: Cannot set format specified.", "Error", MB_OK); return 0; } /* set up the layer palette */ wglSetLayerPaletteEntries(hDC, 1, 0, nEntries, crEntries); /* realize the palette */ wglRealizeLayerPalette(hDC, 1, TRUE); /* announce what we've got */ printf("Number of overlays = %d\n", pfd.bReserved); printf("Color bits in the overlay = %d\n", lpd.cColorBits); return pf; } /* main() * Entry point */ int main(int argc, char** argv) { HWND hWnd; /* window */ MSG msg; /* message */ /* create a window */ hWnd = oglCreateWindow("OpenGL", 0, 0, 200, 200); if (hWnd == NULL) exit(1); /* get the device context */ hDC = GetDC(hWnd); /* set the pixel format */ if (oglSetPixelFormatOverlay(hDC, PFD_TYPE_RGBA, LPD_DOUBLEBUFFER) == 0) exit(1); /* get the device context */ hDC = GetDC(hWnd); /* create an OpenGL overlay context */ hOverlayRC = wglCreateLayerContext(hDC, 1); /* create an OpenGL context */ hRC = wglCreateContext(hDC); wglMakeCurrent(hDC, hRC); /* now we can start changing state & rendering */ while(1) { /* first, check for (and process) messages in the queue */ while(PeekMessage(&msg, hWnd, 0, 0, PM_NOREMOVE)) { if(GetMessage(&msg, hWnd, 0, 0)) { TranslateMessage(&msg); /* translate virtual-key messages */ DispatchMessage(&msg); /* call the window proc */ } else { goto quit; } } /* make current and draw a triangle */ wglMakeCurrent(hDC, hRC); glClear(GL_COLOR_BUFFER_BIT); glRotatef(1.0, 0.0, 0.0, 1.0); glBegin(GL_TRIANGLES); glColor3f(1.0, 0.0, 0.0); glVertex2i( 0, 1); glColor3f(0.0, 1.0, 0.0); glVertex2i(-1, -1); glColor3f(0.0, 0.0, 1.0); glVertex2i( 1, -1); glEnd(); glFlush(); wglSwapLayerBuffers(hDC, WGL_SWAP_MAIN_PLANE); /* make current and draw a triangle */ wglMakeCurrent(hDC, hOverlayRC); glClear(GL_COLOR_BUFFER_BIT); glRotatef(-1.0, 0.0, 0.0, 1.0); glBegin(GL_TRIANGLES); glIndexi(1); glVertex2i( 0, 1); glVertex2i(-1, -1); glVertex2i( 1, -1); glEnd(); glFlush(); wglSwapLayerBuffers(hDC, WGL_SWAP_OVERLAY1); } quit: /* clean up */ wglMakeCurrent(NULL, NULL); /* make our context 'un-'current */ ReleaseDC(hDC, hWnd); /* release handle to DC */ wglDeleteContext(hRC); /* delete the rendering context */ wglDeleteContext(hOverlayRC); /* delete the overlay context */ DestroyWindow(hWnd); /* destroy the window */ return TRUE; }