OpenGL的显示列表

我们用glNewList()命令来开始构造显示列表。第二个参数GL_COMPILE告诉OpenGL我们想预先在内存中构造这个列表，这样每次画的时候就不必重新计算怎么构造物体了。GL_COMPILE类似于编程。在你写程序的时候，把它装载到编译器里，你每次运行程序都需要重新编译。而如果他已经编译成了.exe文件，那么每次你只需要点击那个.exe文件就可以运行它了，不需要编译。当OpenGL编译过显示列表后，就不需要再每次显示的时候重新编译它了。这就是为什么用显示列表可以加快速度。

你可以在glNewList()和glEngList()中间加上任何你想加上的代码。可以设置颜色，贴图等等。唯一不能加进去的代码就是会改变显示列表的代码。显示列表一旦建立，你就不能改变它。

比如你想加上glColor3ub(rand()%255,rand()%255,rand()%255)，使得每一次画物体时都会有不同的颜色。但因为显示列表只会建立一次，所以每次画物体的时候颜色都不会改变。物体将会保持第一次建立显示列表时的颜色。 如果你想改变显示列表的颜色，你只有在调用显示列表之前改变颜色。

成员变量区：
    int m_GLPixelIndex;
    HGLRC m_hGLContext;//绘制环境

    GLfloat xrot;//绕x轴旋转量
    GLfloat yrot;//绕y轴旋转量

    GLfloat xspeed;                                    // X 旋转速度
    GLfloat yspeed;                                    // Y 旋转速度

    GLfloat    z;                                // 深入屏幕的距离

    GLuint filter;
    GLuint texture[1];
    GLfloat LightAmbient[4];                 // 环境光参数
    GLfloat LightDiffuse[4];                 // 漫射光参数
    GLfloat LightPosition[4];                 // 光源位置

    GLboolean bLighting;//是否启用光照 
    bool lPressed;
    bool fPressed;


    GLuint box;// 保存盒子的显示列表
    GLuint top;// 保存盒子顶部的显示列表
    GLuint xloop;// X轴循环变量
    GLuint yloop;// Y轴循环变量


static GLfloat boxcol[5][3];

static GLfloat topcol[5][3];

成员函数区：

BOOL COpenGLDemoView::PreTranslateMessage(MSG* pMsg) 
{
    // TODO: Add your specialized code here and/or call the base class
    if(pMsg->message == WM_KEYDOWN)
    {       
        SendMessage(pMsg->message, pMsg->wParam, pMsg->lParam);
        return true;
    }
    else
    {
        return CView::PreTranslateMessage(pMsg);
    }
}

void COpenGLDemoView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags) 
{
    // TODO: Add your message handler code here and/or call default
    switch(nChar)
    {
    case VK_LEFT:
        {//左键
            yspeed-=0.02f;
            break;
        }
    case VK_RIGHT:
        {//右键
            yspeed+=0.02f;
            break;
        }
    case VK_NEXT:
        {//Page_Down键按下
            z+=0.2f;
            break;
        }
    case VK_PRIOR:
        {//Page_Up键按下
            z-=0.2f;
            break;
        }
    case VK_UP:
        {//Page_Up键按下
            xspeed-=0.02f;
            break;
        }
    case VK_DOWN:
        {//Page_Up键按下
            xspeed+=0.02f;
            break;
        }
    case 'F':
        {
            fPressed = TRUE    ;
            break;
        }
    case 'L':
        {
            lPressed = TRUE;
            break;
        }
    
    default:
        break;
    }

    CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

void COpenGLDemoView::OnKeyUp(UINT nChar, UINT nRepCnt, UINT nFlags) 
{
    // TODO: Add your message handler code here and/or call default
    switch(nChar)
    {
    case 'F':
        {
            if(fPressed == TRUE)
            {
                filter=(filter+1)%3;
            }
            fPressed = FALSE;
            break;
        }
    case 'L':
        {
            if(lPressed==TRUE)
            {//防止长时间按着'L'键而导致光照持续变化
                bLighting = !bLighting;
                if(bLighting)
                {
                    glEnable(GL_LIGHTING);
                }
                else
                {
                    glDisable(GL_LIGHTING);
                }
            }
            lPressed = FALSE;
            break;
        }
    default:
        break;
    }

    CView::OnKeyUp(nChar, nRepCnt, nFlags);
}


GLvoid COpenGLDemoView::BuildLists()
{
    box=glGenLists(2);                                    // Generate 2 Different Lists
    glNewList(box,GL_COMPILE);                            // Start With The Box List
        glBegin(GL_QUADS);
            // Bottom Face
            glNormal3f( 0.0f,-1.0f, 0.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
            // Front Face
            glNormal3f( 0.0f, 0.0f, 1.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
            // Back Face
            glNormal3f( 0.0f, 0.0f,-1.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
            // Right face
            glNormal3f( 1.0f, 0.0f, 0.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
            // Left Face
            glNormal3f(-1.0f, 0.0f, 0.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
        glEnd();
    glEndList();
    top=box+1;                                            // Storage For "Top" Is "Box" Plus One
    glNewList(top,GL_COMPILE);                            // Now The "Top" Display List
        glBegin(GL_QUADS);
            // Top Face
            glNormal3f( 0.0f, 1.0f, 0.0f);
            glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
            glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
            glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
            glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
        glEnd();
    glEndList();
}

int COpenGLDemoView::DrawGLScene()                                   
{// Here's Where We Do All The Drawing
    
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    // Clear Screen And Depth Buffer

    glPushAttrib(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_CURRENT_BIT);
    glPushMatrix();

    glBindTexture(GL_TEXTURE_2D, texture[this->filter]);//绑定到选定的纹理上
    for (yloop=1;yloop<6;yloop++)
    {
        for (xloop=0;xloop<yloop;xloop++)
        {
            glLoadIdentity();                            // Reset The View
            glTranslatef(1.4f+(float(xloop)*2.8f)-(float(yloop)*1.4f),((6.0f-float(yloop))*2.4f)-7.0f,z);
            glRotatef(45.0f-(2.0f*yloop)+xrot,1.0f,0.0f,0.0f);
            glRotatef(45.0f+yrot,0.0f,1.0f,0.0f);
            glColor3fv(boxcol[yloop-1]);
            glCallList(box);
            glColor3fv(topcol[yloop-1]);
            glCallList(top);
        }
    }
    xrot+=this->xspeed;
    yrot+=this->yspeed;
    return TRUE;                                        // Everything Went OK
}

BOOL COpenGLDemoView::InitGL(GLvoid)                                        // All Setup For OpenGL Goes Here
{
    if (!LoadGLTextures())                                // Jump To Texture Loading Routine ( NEW )
    {
        return FALSE;                                    // If Texture Didn't Load Return FALSE
    }
    this->BuildLists();
    glEnable(GL_TEXTURE_2D);                            // Enable Texture Mapping ( NEW )

    glLightfv(GL_LIGHT1, GL_AMBIENT, LightAmbient);                // 设置环境光
    glLightfv(GL_LIGHT1, GL_DIFFUSE, LightDiffuse);                // 设置漫射光
    glLightfv(GL_LIGHT1, GL_POSITION,LightPosition);            // 设置光源位置
    glEnable(GL_LIGHT1);                            // 启用一号光源

    glShadeModel(GL_SMOOTH);                            // Enable Smooth Shading
    COLORREF color = ::GetSysColor(COLOR_3DFACE);
    glClearColor((float)GetRValue(color)/255.0f,
                 (float)GetGValue(color)/255.0f,
                 (float)GetBValue(color)/255.0f,
                 1.0);

    glClearDepth(1.0f);                                    // Depth Buffer Setup
    glEnable(GL_DEPTH_TEST);                            // Enables Depth Testing
    glDepthFunc(GL_LEQUAL);                                // The Type Of Depth Testing To Do
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);    // Really Nice Perspective Calculations

    return TRUE;                                        // Initialization Went OK
}

效果如图所示：