OpengGL中图形绘制先后问题

OpengGL中图形绘制先后问题

　　在opengl中，场景绘制总有个先后的顺序，也有个程序先后的问题，图形程序在前在后，对最终的图形的影响如何？

（1）设置图中的点（蓝色）与线条（浅蓝）z分量都是0，如果绘制折线条程序在前，绘制点程序在后，则效果图形如下：

　　效果：点在线上

　　aaarticlea/png;base64,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" alt="" />

    glPointSize(4.0f);
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_POINTS);
    for(int i = ;i < ctrlVetP.size(); i++)
    {
        glVertex3f(ctrlVetP[i].x, ctrlVetP[i].y, );
    }
    glEnd(); 

    glLineWidth(1.5f);
    glColor3f(0.0,1.0,1.0);
    glBegin(GL_LINE_STRIP);
    for(int i = ;i < ctrlVetP.size(); i++)
    {
        glVertex3f(ctrlVetP[i].x, ctrlVetP[i].y, );
    }
    glEnd(); 

（2）设置图中的点（蓝色）与线条（浅蓝）z分量都是0，如果绘制点程序在前，绘制折线条程序在后，则效果图形如下：

　　效果：线在点之上

　　aaarticlea/png;base64,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" alt="" />

glLineWidth(1.5f);
    glColor3f(0.0,1.0,1.0);
    glBegin(GL_LINE_STRIP);
    for(int i = ;i < ctrlVetP.size(); i++)
    {
        glVertex3f(ctrlVetP[i].x, ctrlVetP[i].y, );
    }
    glEnd(); 

    glPointSize(4.0f);
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_POINTS);
    for(int i = ;i < ctrlVetP.size(); i++)
    {
        glVertex3f(ctrlVetP[i].x, ctrlVetP[i].y, );
    }
    glEnd(); 

　　总结：

　　（可能）Opengl在绘制程序上，统一深度的图形先绘制的显示在最前面，（即离屏幕最近的位置）后绘制的，被前面的遮挡，采用“层次”，即后面的深度总是最大的，（因为深度越大，离屏幕距离越近）