《基于MFC的OpenGL编程》Part 14 Quadrics

      本文在第11篇文章的基础上，为其加入显示各种二次曲面的代码；

      Quadrics

Every quadric has a few settings associated with it. We have to create a quadric first and then customize its settings to render the shape we want. The gluNewQuadric function creates a state variable that describes the current drawing style, orientation, lighting mode, texturing mode and the callback functions. Once we use this function to create a new quadric, we can customize the drawing of shapes by changing its state using functions such as

gluQuadricDrawStyle - which selects the type of OpenGL drawing primitives that are used to drw the shape.

gluQuadricOrientation - which controls the direction of the lighting normals.

gluQuadricNormals - which controls the generation of lighting normals.

gluQuadricTexture - which generates texture coordinates automatically for the quadric.

1,在CCY457OpenGLView类中加入下列变量，用来表示二次曲面类型：

    //Quadric
    GLuint m_Quadric;

2，加入四个控制二次曲面类型的菜单项及其事件处理函数

void CCY457OpenGLView::OnQuadricSphere() 
{//球体
    m_Quadric = 0;
    InvalidateRect(NULL,FALSE);
}
void CCY457OpenGLView::OnUpdateQuadricSphere(CCmdUI* pCmdUI) 
{
    if(m_Quadric == 0)
        pCmdUI->SetRadio(TRUE);
    else
        pCmdUI->SetRadio(FALSE);    
}
void CCY457OpenGLView::OnQuadricCone() 
{//圆锥
    m_Quadric = 2;    
    InvalidateRect(NULL,FALSE);
}
void CCY457OpenGLView::OnUpdateQuadricCone(CCmdUI* pCmdUI) 
{
    if(m_Quadric == 2)
        pCmdUI->SetRadio(TRUE);
    else
        pCmdUI->SetRadio(FALSE);    
}
void CCY457OpenGLView::OnQuadricCylinder() 
{//柱体
    m_Quadric = 1;
    InvalidateRect(NULL,FALSE);
}
void CCY457OpenGLView::OnUpdateQuadricCylinder(CCmdUI* pCmdUI) 
{
    if(m_Quadric == 1)
        pCmdUI->SetRadio(TRUE);
    else
        pCmdUI->SetRadio(FALSE);    
}
void CCY457OpenGLView::OnQuadricDisk() 
{//圆盘
    m_Quadric = 3;
    InvalidateRect(NULL,FALSE);
}
void CCY457OpenGLView::OnUpdateQuadricDisk(CCmdUI* pCmdUI) 
{
    if(m_Quadric == 3)
        pCmdUI->SetRadio(TRUE);
    else
        pCmdUI->SetRadio(FALSE);
}
void CCY457OpenGLView::OnQuadricPartialdisk() 
{////半圆盘
    m_Quadric = 4;
    InvalidateRect(NULL,FALSE);
    
}
void CCY457OpenGLView::OnUpdateQuadricPartialdisk(CCmdUI* pCmdUI) 
{
    if(m_Quadric == 4)
        pCmdUI->SetRadio(TRUE);
    else
        pCmdUI->SetRadio(FALSE);    
}

3,绘制函数修改如下：

void CCY457OpenGLView::RenderScene ()
{//绘制函数
        glTranslatef(0.0f,0.0f,-5.0f);
        glRotatef(m_xRot,1.0f,0.0f,0.0f);
        glRotatef(m_yRot,0.0f,1.0f,0.0f);
        glEnable(GL_TEXTURE_2D);
        glBindTexture(GL_TEXTURE_2D,m_Texture[0]);
        GLUquadricObj* obj;
        obj = gluNewQuadric();
        gluQuadricNormals(obj, GLU_SMOOTH);
        gluQuadricTexture(obj, GL_TRUE);
        switch(m_Quadric)
        {
            case 0:    gluSphere(obj, 1, 20, 20);
                    break;
            case 1:    gluCylinder(obj, 1, 1, 3, 20, 20);
                    break;
            case 2: gluCylinder(obj, 0.1, 1, 3, 20, 20);
                    break;
            case 3: gluDisk(obj, 0.5, 1, 20, 20);
                    break;
            case 4: gluPartialDisk(obj, 0.5, 1, 20, 20, 10, 180);
                    break;
        }
        glDisable(GL_TEXTURE_2D);
}