《基于MFC的OpenGL编程》Part 5 Transformations - Rotations, Translations and Scaling

Transformations - Translation, Rotation and Scaling

Translation is nothing but moving along an arbitrary axis. Rotation is spinning about an arbitrary axis. Scaling is increase or decrease in size along an arbitrary axis. One important point to remember is that OpenGL uses a right hand coordinate system where Z-ve goes into the Screen. An object said to be undergoing a transformation could be undergoing a translation, rotation and/or scaling. Understanding how different types of transformations work together is very important.

本文将对地球进行建模，让其围绕着太阳，此外它还会有月球伴随,而在下文中将会加入对鼠标和键盘的事件响应机制。

绘制代码

void  CCY457OpenGLView::RenderScene ()
{ // 绘制函数
         // Draw Sun
    glTranslatef( 0.0f , 0.0f , - 5.0f );
    glRotatef( 6 , 1.0f , 0.0f , 0.0f );
    glutWireSphere( 1.0f , 20 , 20 );
     // Draw Planet
    glPushMatrix();
        glTranslatef( - 1.2f , - 0.5f , - 2.0f );
        glRotatef( 6 , 1.0f , 0.0f , 0.0f );
        glutWireSphere( 0.5f , 20 , 20 );
         // Draw Moon
        glPushMatrix();
            glTranslatef( - 1.2f , - 0.5f , - 2.0f );
            glRotatef( 6 , 1.0f , 0.0f , 0.0f );
            glutWireSphere( 0.05f , 20 , 20 );
        glPopMatrix();
    glPopMatrix();
}