計(jì)算機(jī)圖形學(xué)編程練習(xí)8MFC-明暗處理實(shí)現(xiàn)

1、計(jì)算機(jī)圖形學(xué)編程練習(xí)8：MFC+明暗處理實(shí)現(xiàn)MFC與OpenGL集成在Windows下編程，利用MFC是一個(gè)非常便捷的方法。本次練習(xí)的主要目的，是希望同學(xué)們?cè)贛FC應(yīng)用程序框架下進(jìn)行OpenGL編程。為此，需要對(duì)MFC生成的應(yīng)用程序進(jìn)行適當(dāng)?shù)某跏蓟?，關(guān)于這方面的內(nèi)容詳見：1 Crain, Dennis. Windows NT OpenGL: Getting Started. April 1994. (MSDN Library, Technical Articles)2 Rogerson, Dale. OpenGL I: Quick Start. December 1994. (MSDN Lib

2、rary, Technical Articles)3 D. Shreiner and The Khronos OpenGL ARB Working Group. OpenGL Programming Guide: The Official Guide to Learning OpenGL, Versions 3.0 and 3.1, 7th Ed., 2009. (附錄D)從設(shè)計(jì)目標(biāo)來說，OpenGL是流水線結(jié)構(gòu)(streamlined)、硬件無(wú)關(guān)(hardware-independent)、跨平臺(tái)的3D圖形編程API。但是，在實(shí)際應(yīng)用時(shí)，OpenGL的具體實(shí)現(xiàn)是與操作系統(tǒng)以及圖形硬件相關(guān)的。

3、為此，操作系統(tǒng)需要提供像素格式(pixel format)與繪制上下文管理函數(shù)(rendering context managnment functions)。Windows操作系統(tǒng)提供了通用圖形設(shè)備接口(generic graphics device interface, GDI)以及設(shè)備驅(qū)動(dòng)實(shí)現(xiàn)。為了使OpenGL命令得到正確的執(zhí)行，需要調(diào)用WGL函數(shù)，具體的步驟如下：Step 1: 添加成員變量在CView類(利用AppWizard生成)中添加如下成員變量：/ OpenGL Windows specificationHDC m_hDC;/ Device ContextHGLRC m_hG

4、LRC;/ Rendering ContextCPalette m_cGLLP;/ Logical PaletteStep 2: 設(shè)置像素格式創(chuàng)建CView類的WM_CREATE的消息響應(yīng)函數(shù)，進(jìn)行像素格式的設(shè)置，例如：int COpenGLRenderView:OnCreate(LPCREATESTRUCT lpCreateStruct) if (CView:OnCreate(lpCreateStruct) = -1)return -1;/ TODO: Add your specialized creation code hereint nPixelFormat;/ Pixel format

5、 indexHWND hWnd = GetSafeHwnd();/ Get the windows handlem_hDC = :GetDC(hWnd);/ Get the Device contextstatic PIXELFORMATDESCRIPTOR pfd = sizeof(PIXELFORMATDESCRIPTOR),/ Size of this structure1,/ Version of this structurePFD_DRAW_TO_WINDOW |/ Draw to Window (not to bitmap)PFD_SUPPORT_OPENGL |/ Support

6、 OpenGL calls in windowPFD_DOUBLEBUFFER,/ Double buffered modePFD_TYPE_RGBA,/ RGBA Color mode24,/ Want 24bit color 0,0,0,0,0,0,/ Not used to select mode0,0,/ Not used to select mode0,0,0,0,0,/ Not used to select mode32,/ Size of depth buffer0,/ Not used to select mode0,/ Not used to select modePFD_M

7、AIN_PLANE,/ Draw in main plane0,/ Not used to select mode0,0,0 ;/ Not used to select mode/ Choose a pixel format that best matches that described in pfdnPixelFormat = ChoosePixelFormat(m_hDC, &pfd);/ Set the pixel format for the device contextVERIFY(SetPixelFormat(m_hDC, nPixelFormat, &pfd);/ Create

8、 the rendering contextm_hGLRC = wglCreateContext(m_hDC);/ Create the palette if neededInitializePalette();/ Make the rendering context current, perform initialization, then deselect itVERIFY(wglMakeCurrent(m_hDC, m_hGLRC);GLSetupDef(m_hDC);wglMakeCurrent(NULL, NULL);return 0;上述步驟的具體含義參看參考文獻(xiàn)1-3.Step

9、3: 創(chuàng)建繪制上下文該步驟在Step 2中已完成，具體的就是：m_hGLRC = wglCreateContext(m_hDC);Step 4: 設(shè)置調(diào)色板創(chuàng)建CView類的一個(gè)成員函數(shù)，進(jìn)行調(diào)色板的設(shè)置，例如：void CTriangularPatchView:InitializePalette(void)PIXELFORMATDESCRIPTOR pfd;/ Pixel Format DescriptorLOGPALETTE *pPal;/ Pointer to memory for logical paletteint nPixelFormat;/ Pixel format indexi

10、nt nColors;/ Number of entries in paletteint i;/ Counting variableBYTE RedRange,GreenRange,BlueRange;/ Range for each color entry (7,7,and 3)/ Get the pixel format index and retrieve the pixel format descriptionnPixelFormat = GetPixelFormat(m_hDC);DescribePixelFormat(m_hDC, nPixelFormat, sizeof(PIXE

11、LFORMATDESCRIPTOR), &pfd);/ Does this pixel format require a palette? If not, do not create a/ palette and just return NULLif (!(pfd.dwFlags & PFD_NEED_PALETTE)return;/ Number of entries in palette. 8 bits yeilds 256 entriesnColors = 1 palVersion = 0 x300;/ Windows 3.0pPal-palNumEntries = nColors; /

12、 table size/ Build mask of all 1s. This creates a number represented by having/ the low order x bits set, where x = pfd.cRedBits, pfd.cGreenBits, and/ pfd.cBlueBits. RedRange = (1 pfd.cRedBits) -1;GreenRange = (1 pfd.cGreenBits) - 1;BlueRange = (1 pfd.cBlueBits) -1;/ Loop through all the palette ent

13、riesfor (i = 0; i palPalEntryi.peRed = (i pfd.cRedShift) & RedRange;pPal-palPalEntryi.peRed = (unsigned char)(double) pPal-palPalEntryi.peRed * 255.0 / RedRange);pPal-palPalEntryi.peGreen = (i pfd.cGreenShift) & GreenRange;pPal-palPalEntryi.peGreen = (unsigned char)(double)pPal-palPalEntryi.peGreen

14、* 255.0 / GreenRange);pPal-palPalEntryi.peBlue = (i pfd.cBlueShift) & BlueRange;pPal-palPalEntryi.peBlue = (unsigned char)(double)pPal-palPalEntryi.peBlue * 255.0 / BlueRange);pPal-palPalEntryi.peFlags = (unsigned char) NULL;/ Create the palettem_cGLLP.CreatePalette(pPal);/ Go ahead and select and r

15、ealize the palette for this device contextSelectPalette(m_hDC,(HPALETTE)m_cGLLP,FALSE);RealizePalette(m_hDC);/ Free the memory used for the logical palette structurefree(pPal);至此，已經(jīng)可以調(diào)用OpenGL函數(shù)了，一定要記?。篛penGL命令只在獲取了正確的繪制上下文后才能正確執(zhí)行，即wglMakeCurrent(m_hDC, m_hGLRC);/ issue OpenGL commands .wglMakeCurren

16、t(m_hDC, NULL);Step 5: 重載OnEraseBkgnd函數(shù)創(chuàng)建CView類的WM_ERASEBKGND的消息響應(yīng)函數(shù)，防止Windows進(jìn)行額外的背景清除操作，例如：BOOL COpenGLRenderView:OnEraseBkgnd(CDC* pDC) / TODO: Add your message handler code here and/or call defaultreturn FALSE;Step 6: 設(shè)置OpenGL的基本參數(shù)(可選)在CView類中添加頭文件：#include #include #include 以及成員函數(shù)：void GLSetupD

17、ef(void *pData);創(chuàng)建CView類的一個(gè)成員函數(shù)，進(jìn)行OpenGL的基本參數(shù)的設(shè)置，例如：void COpenGLRenderView:GLSetupDef(void *pData)/ set up clear colorglClearColor(1.0f, 1.0f, 1.0f, 1.0f);/ set up lightingGLfloat light_position04 = 52.0f, 16.0f, 50.0f, 0.0f;GLfloat light_position14 = 26.0f, 48.0f, 50.0f, 0.0f;GLfloat light_position

18、24 = -16.0f, 52.0f, 50.0f, 0.0f;GLfloat direction03 = -52.0f, -16.0f, -50.0f;GLfloat direction13 = -26.0f, -48.0f, -50.0f;GLfloat direction23 = 16.0f, -52.0f, -50.0f;GLfloat color04 = 1.0f, 0.0f, 0.0f, 1.0f;GLfloat color14 = 0.0f, 1.0f, 0.0f, 1.0f;GLfloat color24 = 0.0f, 0.0f, 1.0f, 1.0f;glLightfv(G

19、L_LIGHT0, GL_POSITION, light_position0);glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, direction0);glLightfv(GL_LIGHT0, GL_DIFFUSE, color0);glLightfv(GL_LIGHT0, GL_SPECULAR, color0);glLightfv(GL_LIGHT1, GL_POSITION, light_position1);glLightfv(GL_LIGHT1, GL_SPOT_DIRECTION, direction1);glLightfv(GL_LIGHT1, G

20、L_DIFFUSE, color1);glLightfv(GL_LIGHT1, GL_SPECULAR, color1);glLightfv(GL_LIGHT2, GL_POSITION, light_position2);glLightfv(GL_LIGHT2, GL_SPOT_DIRECTION, direction2);glLightfv(GL_LIGHT2, GL_DIFFUSE, color2);glLightfv(GL_LIGHT2, GL_SPECULAR, color2);glEnable(GL_LIGHTING);glEnable(GL_LIGHT0);glEnable(GL

21、_LIGHT1);glEnable(GL_LIGHT2);/ set up materialsGLfloat ambient4 = 0.3f, 0.3f, 0.3f, 0.5f;GLfloat material_ambient4 = 0.0f, 0.0f, 0.0f, 0.0f;GLfloat material_diffuse4 = 1.0f, 1.0f, 1.0f, 0.3f;GLfloat material_specular4 = 0.5f, 0.5f, 0.5f, 0.5f;GLfloat material_shininess = 51.2f;glLightModelfv(GL_LIGH

22、T_MODEL_AMBIENT, ambient);glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, material_diffuse);glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, material_ambient);glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, material_shininess);/ enable depth testglDepthFunc(GL_LESS);glEnable(GL_DEPTH_TEST);/ enable cull face/glCullFace(GL_BACK);/glEnable(GL_CULL_FACE);/ set up point size an