2.First Polygon
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1 #include <windows.h> 2 #include <gl/glew.h> 3 #include <gl/glut.h> 4 5 /* 6 * Every OpenGL program is linked to a Rendering Context. 7 * A Rendering Context is what links OpenGL calls to the Device Context. 8 * In order for your program to draw to a Window you need to create a Device Context. 9 * The DC connects the Window to the GDI (Graphics Device Interface). 10 */ 11 12 HGLRC hRC = NULL; // Permanent rendering context 13 HDC hDC = NULL; // Private GDI device context 14 HWND hWnd = NULL; // Holds our window handle 15 HINSTANCE hInstance; // Holds the instance of the application 16 17 /* 18 * It‘s important to make this global so that each procedure knows if 19 * the program is running in fullscreen mode or not. 20 */ 21 22 bool keys[256]; // Array used for the keyboard routine 23 bool active = TRUE; // Window active flag set to TRUE by default 24 bool fullscreen = TRUE; // Fullscreen flag set to fullscreen mode by default 25 26 /* 27 * CreateGLWindow() has a reference to WndProc() but WndProc() comes after CreateGLWindow(). 28 */ 29 30 LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration for WndProc 31 32 /* 33 * The job of the next section of code is to resize the OpenGL scene 34 * whenever the window (assuming you are using a Window rather than fullscreen mode) has been resized. 35 */ 36 37 GLvoid ReSizeGLScene(GLsizei width, GLsizei height) // Resize and initialize the GL window 38 { 39 if (height == 0) { // Prevent a divide by zero by 40 height = 1; // Making height equal one 41 } 42 43 glViewport(0, 0, width, height); // Reset the current viewport 44 45 /* 46 * The following lines set the screen up for a perspective view. 47 * Meaning things in the distance get smaller. This creates a realistic looking scene. 48 * The perspective is calculated with a 45 degree viewing angle based on 49 * the windows width and height. The 0.1f, 100.0f is the starting point and 50 * ending point for how deep we can draw into the screen. 51 * 52 * The projection matrix is responsible for adding perspective to our scene. 53 * glLoadIdentity() restores the selected matrix to it‘s original state. 54 * The modelview matrix is where our object information is stored. 55 * Lastly we reset the modelview matrix. 56 */ 57 58 glMatrixMode(GL_PROJECTION); // Select the projection matrix 59 glLoadIdentity(); // Reset the projection matrix 60 61 // Calculate the aspect ratio of the window 62 gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f); 63 64 glMatrixMode(GL_MODELVIEW); // Seclet the modelview matrix 65 glLoadIdentity(); // Reset the modelview matrix 66 } 67 68 int InitGL(GLvoid) // All setup for OpenGL goes here 69 { 70 /* 71 * Smooth shading blends colors nicely across a polygon, and smoothes out lighting. 72 */ 73 74 glShadeModel(GL_SMOOTH); // Enables smooth shading 75 76 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Black background 77 78 /* 79 * Think of the depth buffer as layers into the screen. 80 * The depth buffer keeps track of how deep objects are into the screen. 81 */ 82 83 glClearDepth(1.0f); // Depth buffer setup 84 glEnable(GL_DEPTH_TEST); // Enable depth testing 85 glDepthFunc(GL_LEQUAL); // The typr of depth test to do 86 87 /* 88 * Next we tell OpenGL we want the best perspective correction to be done. 89 * This causes a very tiny performance hit, but makes the perspective view look a bit better. 90 */ 91 92 glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really nice perspective calculations 93 94 return TRUE; 95 } 96 97 /* 98 * For now all we will do is clear the screen to the color we previously decided on, 99 * clear the depth buffer and reset the scene. We wont draw anything yet. 100 */ 101 /******************************************************************************************************************************************/ 102 /******************************************************************************************************************************************/ 103 int DrawGLScene(GLvoid) // Here‘s where we do all the drawing 104 { 105 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear the screen and the depth buffer 106 glLoadIdentity(); // Reset the current modelview matrix 107 108 /* 109 * When you do a glLoadIdentity() what you are doing is moving back to 110 * the center of the screen with the X axis(轴) running left to right, 111 * the Y axis moving up and down, and the Z axis moving into, and out of the screen. 112 */ 113 /* 114 * glTranslatef(x, y, z) moves along the X, Y and Z axis, in that order. 115 * When you translate, you are not moving a set amount(数量) from the center of the screen, 116 * you are moving a set amount from wherever you currently were on the screen. 117 */ 118 glTranslatef(-1.5f, 0.0f, -6.0f); // Move left 1.5 units and into the screen 6.0 119 glBegin(GL_TRIANGLES); // Drawing using traingles 120 glVertex3f(0.0f, 1.0f, 0.0f); // Top 121 glVertex3f(-1.0f, -1.0f, 0.0f); // Bottom left 122 glVertex3f(1.0f, -1.0f, 0.0f); // Bottom right 123 glEnd(); // Finished drawing the traingles 124 125 glTranslatef(3.0f, 0.0f, 0.0f); // Move left 3 units 126 127 /* 128 * By drawing in a clockwise order, the square will be drawn as a back face. 129 * Meaning the side of the quad we see is actually the back. 130 * Objects drawn in a counter clockwise order will be facing us. 131 */ 132 133 glBegin(GL_QUADS); // Draw a quad 134 glVertex3f(-1.0f, 1.0f, 0.0f); // Top left 135 glVertex3f(1.0f, 1.0f, 0.0f); // Top right 136 glVertex3f(1.0f, -1.0f, 0.0f); // Bottom right 137 glVertex3f(-1.0f, -1.0f, 0.0f); // Bottom left 138 glEnd(); // Done drawing the quad 139 return TRUE; // everthing went OK 140 } 141 /******************************************************************************************************************************************/ 142 /******************************************************************************************************************************************/ 143 /* 144 * The job of KillGLWindow() is to release the Rendering Context, 145 * the Device Context and finally the Window Handle. 146 */ 147 148 GLvoid KillGLWindow(GLvoid) // Properly kill the window 149 { 150 if (fullscreen) { // Are we in fullscreen mode 151 152 /* 153 * We use ChangeDisplaySettings(NULL,0) to return us to our original desktop. 154 * After we‘ve switched back to the desktop we make the cursor visible again. 155 */ 156 157 ChangeDisplaySettings(NULL, 0); // if so switch back to the desktop 158 ShowCursor(TRUE); // Show mouse pointer 159 } 160 161 if (hRC) { // Do we have a rendering context 162 if (!wglMakeCurrent(NULL, NULL)) { // Are we able to release the DC and RC contexts 163 MessageBox(NULL, "Release of DC and RC failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION); 164 } 165 166 if (!wglDeleteContext(hRC)) { // Are we able to delete the RC 167 MessageBox(NULL, "Release rendering context failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION); 168 hRC = NULL; // Set RC to NULL 169 } 170 171 if (hDC && !ReleaseDC(hWnd, hDC)) { // Are we able to release the DC 172 MessageBox(NULL, "Release device context failed.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION); 173 hDC = NULL; // Set DC to NULL 174 } 175 if (hWnd && !DestroyWindow(hWnd)) { // Are we able to destroy the window 176 MessageBox(NULL, "Could not release hWnd.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION); 177 hWnd = NULL; // Set hWnd to NULL 178 } 179 180 if (!UnregisterClass("OpenGL", hInstance)) { // Are we able to unregister class 181 MessageBox(NULL, "Could not register class.", "SHUTDOWN ERROR", MB_OK | MB_ICONINFORMATION); 182 hInstance = NULL; // Set hInstance to NULL 183 } 184 } 185 } 186 187 /* 188 * The next section of code creates our OpenGL Window. 189 */ 190 191 BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag) 192 { 193 /* 194 * Find a pixel format that matches the one we want 195 */ 196 GLuint PixelFormat; // Holds the result after serching for a match 197 198 /* 199 * Before you create a window, you MUST register a Class for the window 200 */ 201 WNDCLASS wc; // Windows class structure 202 203 /* 204 * dwExStyle and dwStyle will store the Extended and normal Window Style Information. 205 */ 206 DWORD dwExStyle; // Window extend style 207 DWORD dwStyle; // Window style 208 209 RECT WindowRect; // Grabs rectangle upper left/lower right values 210 WindowRect.left = (long)0; // Set left value to 0 211 WindowRect.right = (long)width; // Set right value to requested width 212 WindowRect.top = (long)0; // Set top value to 0 213 WindowRect.bottom = (long)height; // Set bottom value to requested height 214 215 fullscreen = fullscreenflag; // Set the global fullscreen flag 216 217 /* 218 * The style CS_HREDRAW and CS_VREDRAW force the Window to redraw whenever it is resized. 219 * CS_OWNDC creates a private DC for the Window. Meaning the DC is not shared across applications. 220 * WndProc is the procedure that watches for messages in our program. 221 * No extra Window data is used so we zero the two fields. Then we set the instance. 222 * Next we set hIcon to NULL meaning we don‘t want an ICON in the Window, 223 * and for a mouse pointer we use the standard arrow. The background color doesn‘t matter 224 * (we set that in GL). We don‘t want a menu in this Window so we set it to NULL, 225 * and the class name can be any name you want. I‘ll use "OpenGL" for simplicity. 226 */ 227 hInstance = GetModuleHandle(NULL); // Grab an instance for our window 228 wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw on move, and own DC for window 229 wc.lpfnWndProc = (WNDPROC)WndProc; // WndProc handles message 230 wc.cbClsExtra = 0; // No extra window date 231 wc.cbWndExtra = 0; // No extra window date 232 wc.hInstance = hInstance; // set the instance 233 wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load the default icon 234 wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load the arrow pointer 235 wc.hbrBackground = NULL; // No background requried for GL 236 wc.lpszMenuName = NULL; // We don‘t want a menu 237 wc.lpszClassName = "OpenGL"; // set the class name 238 239 if (!RegisterClass(&wc)) { // Attempt to register the window class 240 MessageBox(NULL, "Failed to register the window class.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 241 return FALSE; // Exit and return false 242 } 243 244 if (fullscreen) { // attempt fullsreen model 245 246 /* 247 T* here are a few very important things you should keep in mind when switching to full screen mode. 248 * Make sure the width and height that you use in fullscreen mode is the same as 249 * the width and height you plan to use for your window, and most importantly, 250 * set fullscreen mode BEFORE you create your window. 251 */ 252 DEVMODE dmScreenSettings; // Device mode 253 memset(&dmScreenSettings, 0, sizeof(dmScreenSettings)); // Make sure memory‘s cleared 254 dmScreenSettings.dmSize = sizeof(dmScreenSettings); // Size of devmode structure 255 dmScreenSettings.dmPelsWidth = width; // Select window width 256 dmScreenSettings.dmPelsHeight = height; // Select window height 257 dmScreenSettings.dmBitsPerPel = bits; // Select bits per pixel 258 dmScreenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT; 259 260 /* 261 * In the line below ChangeDisplaySettings tries to switch to a mode that matches 262 * what we stored in dmScreenSettings. I use the parameter CDS_FULLSCREEN when switching modes, 263 * because it‘s supposed to remove the start bar at the bottom of the screen, 264 * plus it doesn‘t move or resize the windows on your desktop when you switch to 265 * fullscreen mode and back. 266 */ 267 //Try to set selected mode and get results. Note: CDS_FULLSCREEN gets rid of start bar 268 if (ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) { 269 //If the mode fails, offer two options. Quit or run in a window 270 if (MessageBox(NULL, "The requested fullscreen mode is not supported by\n your video card. Use" 271 "windowed mode instead?", "GL", MB_YESNO | MB_ICONEXCLAMATION) == IDYES) 272 { 273 fullscreen = FALSE; // Select windowed mode (fullscreen=FLASE) 274 } 275 else { 276 // Pop up a message box letting user know the programe is closing. 277 MessageBox(NULL, "Program will now close.", "ERROR", MB_OK | MB_ICONSTOP); 278 return FALSE; // Exit and return FALSE 279 } 280 } 281 } 282 283 if (fullscreen) { // Are we still in fullscreen mode 284 285 /* 286 * If we are still in fullscreen mode we‘ll set the extended style to WS_EX_APPWINDOW, 287 * which force a top level window down to the taskbar once our window is visible. 288 * For the window style we‘ll create a WS_POPUP window. 289 * This type of window has no border around it, making it perfect for fullscreen mode. 290 291 * Finally, we disable the mouse pointer. If your program is not interactive, 292 * it‘s usually nice to disable the mouse pointer when in fullscreen mode. It‘s up to you though. 293 */ 294 dwExStyle = WS_EX_APPWINDOW; // Window extended style 295 dwStyle = WS_POPUP; // Window style 296 ShowCursor(FALSE); // Hide mosue pointer 297 } 298 else { 299 300 /* 301 * If we‘re using a window instead of fullscreen mode, 302 * we‘ll add WS_EX_WINDOWEDGE to the extended style. This gives the window a more 3D look. 303 * For style we‘ll use WS_OVERLAPPEDWINDOW instead of WS_POPUP. 304 * WS_OVERLAPPEDWINDOW creates a window with a title bar, sizing border, 305 * window menu, and minimize / maximize buttons. 306 */ 307 dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window extended style 308 dwStyle = WS_OVERLAPPEDWINDOW; // Window style 309 } 310 311 /* 312 * By using the AdjustWindowRectEx command none of our OpenGL scene will be covered up by the borders, 313 * instead, the window will be made larger to account for the pixels needed to draw the window border. 314 * In fullscreen mode, this command has no effect. 315 */ 316 AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust window to true resqusted 317 318 /* 319 * WS_CLIPSIBLINGS and WS_CLIPCHILDREN are both REQUIRED for OpenGL to work properly. 320 * These styles prevent other windows from drawing over or into our OpenGL Window. 321 */ 322 if (!(hWnd = CreateWindowEx(dwExStyle, // Extended style for the window 323 "OpenGL", // Class name 324 title, // Window title 325 WS_CLIPSIBLINGS | // Requried window style 326 WS_CLIPCHILDREN | // Requried window style 327 dwStyle, // Select window style 328 0, 0, // Window position 329 WindowRect.right - WindowRect.left, // Calculate adjusted window width 330 WindowRect.bottom - WindowRect.top, // Calculate adjusted window height 331 NULL, // No parent window 332 NULL, // No menu 333 hInstance, // Instance 334 NULL))) // Don‘t pass anything to WM_CREATE 335 { 336 KillGLWindow(); //Reset the display 337 MessageBox(NULL, "Window creation error.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 338 return FALSE; // Retrurn FALSE; 339 } 340 341 /* 342 * aside from the stencil buffer and the (slow) accumulation buffer 343 */ 344 static PIXELFORMATDESCRIPTOR pfd = // pfd tells windows how we want things to be 345 { 346 sizeof(PIXELFORMATDESCRIPTOR), // Size of this pixel format descriptor 347 1, // Version number 348 PFD_DRAW_TO_WINDOW | // Format must support window 349 PFD_SUPPORT_OPENGL | // Format must support OpenGL 350 PFD_DOUBLEBUFFER, // Must support double buffer 351 PFD_TYPE_RGBA, // Request an RGBA format 352 bits, // Select our color depth 353 0, 0, 0, 0, 0, 0, // Color bits ignored 354 0, // No alpha buffer 355 0, // shift bit ignored 356 0, // No accumulation buffer 357 0, 0, 0, 0, // Accumulation bits ignored 358 16, // 16Bits Z_Buffer (depth buffer) 359 0, // No stencil buffer 360 0, // No auxiliary buffer 361 PFD_MAIN_PLANE, // Main drawing layer 362 0, // Reserved 363 0, 0, 0 // Layer makes ignored 364 }; 365 366 if (!(hDC = GetDC(hWnd))) { // Did we get a device context 367 KillGLWindow(); // Reset the display 368 MessageBox(NULL, "Can‘t create a GL device context.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 369 return FALSE; // Return FALSE 370 } 371 372 if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) { // Did window find a matching pixel format 373 KillGLWindow(); // Reset the display 374 MessageBox(NULL, "Can‘t find a suitable pixelformat.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 375 return FALSE; // Return FALSE; 376 } 377 378 if (!SetPixelFormat(hDC, PixelFormat, &pfd)) { // Are we able to set the pixel format 379 KillGLWindow(); // Reset the display 380 MessageBox(NULL, "Can‘t set the pixelformat.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 381 return FALSE; // Return FALSE; 382 } 383 384 if (!(hRC = wglCreateContext(hDC))) { // Are we able to rendering context 385 KillGLWindow(); // Reset the display 386 MessageBox(NULL, "Can‘t create a GL rendering context.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 387 return FALSE; // Return FASLE; 388 } 389 390 if (!wglMakeCurrent(hDC, hRC)) { // Try to activate the rendering context 391 KillGLWindow(); // Reset the display 392 MessageBox(NULL, "Can‘t activate the GL rendering context.", "ERROR", MB_OK | MB_ICONEXCLAMATION); 393 return FALSE; // Return FALSE 394 } 395 396 /* 397 * ReSizeGLScene passing the screen width and height to set up our perspective OpenGL screen. 398 */ 399 ShowWindow(hWnd, SW_SHOW); // Show the window 400 SetForegroundWindow(hWnd); // slightly higher priority 401 SetFocus(hWnd); // Sets keyboard focus to the window 402 ReSizeGLScene(width, height); // Set up our perspective GL screen 403 404 /* 405 * we can set up lighting, textures, and anything else that needs to be setup in InitGL(). 406 */ 407 if (!InitGL()) {以上是关于2.First Polygon的主要内容，如果未能解决你的问题，请参考以下文章