• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>

            Shuffy

            不斷的學習,不斷的思考,才能不斷的進步.Let's do better together!
            posts - 102, comments - 43, trackbacks - 0, articles - 19
            視見體

            Viewing Volume is nothing but the region of 3D Cartesian space in that will occupy the window. It is nothing but the minimum and maximum x, y and z values that are inside the window. So if a vertex is outside this range of x, y and z values then they are clipped by OpenGL before rendering can occur.

            Z Buffer

            The new term we have to deal with in addition to width and height of an object in 3D graphics is depth. The depth of an object is its distance from the viewpoint. The viewpoint is the location from which we are looking at that point. This depth value goes into the depth or Z-buffer. If we are drawing 2 objects that have some pixels that overlap, the first object will after it is rendered have its depth value in the depth buffer. When the next object is rendered, OpenGL will check to see whether the pixel it’s about to draw is in front of (with respect to the viewpoint) any pixel from the first object that’s already drawn. It does this by checking the Z value of the current pixel with the value that is already in the buffer. If the new pixel is closer to the viewpoint, OpenGL places its depth value in the depth buffer. This is how the Z-buffer works.

            正交投影和透視投影

            One term we need to understand very well to learn 3D Graphics well is projection. Well, computer graphics at its simplest is all about setting a color to a pixel on screen. And a pixel on a screen can have only two dimensions. So 3D graphics is merely an illusion. The 3D coordinates that we specify will have to be projected onto a 2D surface to create this illusion for us. And we have to specify how this projection works. By specifying a projection we specify the clipping or viewing volume.

            基本3D圖形繪制

            1,CCY457OpenGLView.h中加入下列變量

            BOOL m_bPoint;        //Status of Point
            BOOL m_bLine;        //Status of Line
            BOOL m_bPolygon;    //Status of Polygon
            BOOL m_bTriangle;    //Status of Triangle

            并且在構造函數中初始化

            CCY457OpenGLView::CCY457OpenGLView()
            {
                m_bPoint    
            = FALSE;
                m_bLine        
            = FALSE;
                m_bPolygon    
            = FALSE;
                m_bTriangle 
            = FALSE;
                m_bCube           
            = FALSE;        
                m_bTorus       
            = FALSE;        
                m_bTeapot       
            = FALSE;        
                m_bIcosahedron 
            = FALSE;
                m_bSimpleCube  
            = FALSE;    
            }

            2,加入五個菜單項及其對應的事件處理程序。

             

            void CCY457OpenGLView::OnObjectsTeapot() 
            {
            //畫茶壺
                m_bCube           = FALSE;        
                m_bTorus       
            = FALSE;        
                m_bTeapot       
            = TRUE;        
                m_bIcosahedron 
            = FALSE;
                m_bSimpleCube  
            = FALSE;        
                InvalidateRect(NULL,FALSE);    
            }
            void CCY457OpenGLView::OnObjectsCube() 
            {
            //畫立方體
                m_bCube           = TRUE;    
                m_bTorus       
            = FALSE;        
                m_bTeapot       
            = FALSE;        
                m_bIcosahedron 
            = FALSE;
                m_bSimpleCube  
            = FALSE;        
                InvalidateRect(NULL,FALSE);    
            }
            void CCY457OpenGLView::OnObjectsIcosahedron() 
            {
            //畫二十面體
                m_bCube           = FALSE;        
                m_bTorus       
            = FALSE;        
                m_bTeapot       
            = FALSE;        
                m_bIcosahedron 
            = TRUE;
                m_bSimpleCube  
            = FALSE;    
                InvalidateRect(NULL,FALSE);    
            }
            void CCY457OpenGLView::OnObjectsTorus() 
            {
            //畫環面
                m_bCube           = FALSE;        
                m_bTorus       
            = TRUE;        
                m_bTeapot       
            = FALSE;        
                m_bIcosahedron 
            = FALSE;
                m_bSimpleCube  
            = FALSE;            
                InvalidateRect(NULL,FALSE);    
            }

            void CCY457OpenGLView::OnObjectsSimplecube() 
            {
            //畫簡單立方體
                m_bCube           = FALSE;        
                m_bTorus       
            = FALSE;        
                m_bTeapot       
            = FALSE;        
                m_bIcosahedron 
            = FALSE;
                m_bSimpleCube  
            = TRUE;        
                InvalidateRect(NULL,FALSE);
            }

            3,由于開始繪制3維圖形,因此使用第一篇文章的OnSize()函數。

            4,RenderScene中加入具體的繪制代碼:

            void CCY457OpenGLView::RenderScene ()
            {
            //繪制函數
                if(m_bPoint==TRUE)
                {
                    glPointSize(
            3.0f);
                    glBegin(GL_POINTS);
                        glVertex2f(
            0.0f,0.0f);
                        glVertex2f(
            1.0f,0.0f);
                        glVertex2f(
            0.0f,1.0f);
                    glEnd();
                }
                
            if(m_bLine==TRUE)
                {
                    glBegin(GL_LINES);
                        glVertex2f(
            0.0f,0.0f);
                        glVertex2f(
            1.0f,0.0f);
                    glEnd();
                }
                
            if(m_bTriangle==TRUE)
                {
                    glBegin(GL_TRIANGLES);
                        glVertex2f(
            0.0f,0.0f);
                        glVertex2f(
            2.0f,0.0f);
                        glVertex2f(
            0.0f,2.0f);
                    glEnd();
                }
                
            if(m_bPolygon==TRUE)
                {
                    glBegin(GL_POLYGON);
                        glVertex2f(
            0.0f,0.0f);
                        glVertex2f(
            3.0f,0.0f);
                        glVertex2f(
            4.0f,3.0f);
                        glVertex2f(
            1.5f,6.0f);
                        glVertex2f(
            -1.0f,3.0f);
                    glEnd();
                }
                
            //Replace the current matrix with Identity Matrix
                glLoadIdentity();
                glTranslatef(
            0.0f,0.0f,-5.0f);
                glRotatef(
            -30.0f,1.0f,1.0f,0.0f);
                
            //Draw a Cube
                if(m_bCube)
                {
                    glutWireCube(
            1.0f);
                }
                
            //Draw a Torus
                if(m_bTorus)
                {
                    glutWireTorus(
            0.5f1.0f5050);
                }
                
            //Draw a Teapot
                if(m_bTeapot)
                {
                    glutWireTeapot(
            1.0f);
                }
                
            //Draw a Icosahedron
                if(m_bIcosahedron)
                {
                    glutWireIcosahedron();
                }
                
            //Draw a cube by specifying the vertices individually
                if(m_bSimpleCube)
                {
                    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
                    
                    
            //Front Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            -1.0f,-1.0f,0.0f);
                        glVertex3f( 
            1.0f,-1.0f,0.0f);
                        glVertex3f( 
            1.0f1.0f,0.0f);
                        glVertex3f(
            -1.0f1.0f,0.0f);
                    glEnd();
                    
            //Back Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            -1.0f,-1.0f,-1.0f);
                        glVertex3f(
            -1.0f1.0f,-1.0f);
                        glVertex3f( 
            1.0f1.0f,-1.0f);
                        glVertex3f( 
            1.0f,-1.0f,-1.0f);
                    glEnd();
                    
            //Left Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            -1.0f,-1.0f0.0f);
                        glVertex3f(
            -1.0f1.0f0.0f);
                        glVertex3f(
            -1.0f1.0f,-1.0f);
                        glVertex3f(
            -1.0f,-1.0f,-1.0f);
                    glEnd();
                    
            //Right Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            1.0f,-1.0f0.0f);
                        glVertex3f(
            1.0f,-1.0f,-1.0f);
                        glVertex3f(
            1.0f1.0f,-1.0f);
                        glVertex3f(
            1.0f1.0f0.0f);
                    glEnd();
                    
            //Top Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            -1.0f1.0f,  0.0f);
                        glVertex3f( 
            1.0f1.0f,  0.0f);
                        glVertex3f( 
            1.0f1.0f-1.0f);
                        glVertex3f(
            -1.0f1.0f-1.0f);
                    glEnd();
                    
            //Botton Face
                    glBegin(GL_POLYGON);
                        glVertex3f(
            -1.0f-1.0f,  0.0f);
                        glVertex3f(
            -1.0f-1.0f-1.0f);
                        glVertex3f( 
            1.0f-1.0f-1.0f);
                        glVertex3f( 
            1.0f-1.0f,  0.0f);
                    glEnd();
                }
            }

            作者:洞庭散人

            出處:http://phinecos.cnblogs.com/    

            本文版權歸作者和博客園共有,歡迎轉載,但未經作者同意必須保留此段聲明,且在文章頁面明顯位置給出原文連接,否則保留追究法律責任的權利。
            原文鏈接:http://www.cnblogs.com/phinecos/archive/2008/11/05/1327385.html
            久久国产午夜精品一区二区三区| 伊人热热久久原色播放www| 一本一本久久A久久综合精品| 久久久国产打桩机| 久久国产免费观看精品| 久久天天躁狠狠躁夜夜2020老熟妇| 亚洲精品无码久久毛片| 精品久久久久久无码专区不卡| 国产三级精品久久| 久久精品国产亚洲AV无码麻豆 | 久久久久久久国产免费看| 久久久国产打桩机| 久久免费大片| 青青国产成人久久91网| 热99RE久久精品这里都是精品免费| 2021精品国产综合久久| 色狠狠久久综合网| 国产精品99久久久久久宅男| 日韩精品久久久肉伦网站 | 三级片免费观看久久| 精品久久久久久中文字幕| 久久久久亚洲av综合波多野结衣 | 欧美日韩成人精品久久久免费看 | 久久精品欧美日韩精品| 久久妇女高潮几次MBA| 久久婷婷人人澡人人| 久久99精品久久久久久齐齐| 久久福利青草精品资源站| 亚洲精品白浆高清久久久久久| 老司机午夜网站国内精品久久久久久久久 | 亚洲va久久久噜噜噜久久天堂| 久久精品无码一区二区日韩AV| 麻豆精品久久精品色综合| 久久精品aⅴ无码中文字字幕重口 久久精品a亚洲国产v高清不卡 | 久久亚洲高清观看| 91精品国产91久久综合| 久久久久久久人妻无码中文字幕爆| 亚洲AV日韩精品久久久久| 日韩精品久久久久久免费| 久久99久久99精品免视看动漫| 久久久久亚洲AV无码观看|