【读书笔记】translate和rotate_transfer和rotate-优快云博客

本文介绍了OpenGL中深度测试的概念及实现方法，并通过一个具体的示例详细解释了如何使用OpenGL进行三维物体的绘制，包括坐标变换操作如平移和旋转等。

开启深度测试

void RenderScene()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(0, 300, 0, 0, 1, 0, 0, 0, -1);

	glTranslatef(100, 0, 0.0);
	glRotated(Rot, 0, 1.0, 0);
	glBegin(GL_QUADS);  //以下面都是参考世界坐标
	glColor3f(0.0f,1.0f,0.0f);			// 顶：绿色
	glVertex3f( 40.0f, 40.0f,-40.0f);glVertex3f(-40.0f, 40.0f,-40.0f);glVertex3f(-40.0f, 40.0f, 40.0f);glVertex3f( 40.0f, 40.0f, 40.0f);	
	glColor3f(1.0f,0.0f,0.0f);			//底：红
	glVertex3f( 40.0f,-40.0f, 40.0f);glVertex3f(-40.0f,-40.0f, 40.0f);glVertex3f(-40.0f,-40.0f,-40.0f);glVertex3f( 40.0f,-40.0f,-40.0f);
	glColor3f(0.0f,0.0f,1.0f);			//前：蓝
	glVertex3f( 40.0f, 40.0f, 40.0f);glVertex3f(-40.0f, 40.0f, 40.0f);glVertex3f(-40.0f,-40.0f, 40.0f);glVertex3f( 40.0f,-40.0f, 40.0f);			
	glColor3f(1.0f,1.0f,1.0f);			//后：白
	glVertex3f( 40.0f,-40.0f,-40.0f);glVertex3f(-40.0f,-40.0f,-40.0f);glVertex3f(-40.0f, 40.0f,-40.0f);glVertex3f( 40.0f, 40.0f,-40.0f);		
	glColor3f(1.0f,1.0f,0.0f);			//左：黄
	glVertex3f(-40.0f, 40.0f, 40.0f);glVertex3f(-40.0f, 40.0f,-40.0f);glVertex3f(-40.0f,-40.0f,-40.0f);glVertex3f(-40.0f,-40.0f, 40.0f);			
	glColor3f(1.0f,0.0f,1.0f);			//右：罗兰
	glVertex3f( 40.0f, 40.0f,-40.0f);glVertex3f( 40.0f, 40.0f, 40.0f);glVertex3f( 40.0f,-40.0f, 40.0f);glVertex3f( 40.0f,-40.0f,-40.0f);
	glEnd();

	Rot += 10.0f;
	if (Rot >360.0f)
		Rot = 0.0f;

	glutSwapBuffers();
}

LoadIdentity后，世界与局部坐标系重合。glTranslate先将物体的局部坐标系原点移至局部坐标系的（100,0,0 ）处（该处也是世界坐标系的(100,0,0)处），然后局部坐标系绕局部坐标系的y轴旋转Rot度数。（这里物体和局部坐标系的关系始终都是）最后得到的结果应该是：