实验三 OpenGL几何变换

一、实验目的和要求

1. 理解掌握一个OpenGL程序平移、旋转、缩放变换的方法。

二、实验内容及主要步骤代码

（1）阅读实验原理，运行示范实验代码，掌握OpenGL程序平移、旋转、缩放变换的方法；

（2）根据示范代码，尝试完成实验作业；

（3）形成以下图形，如下图所示。

主要步骤代码：

（1）示范实验源代码

voiddrawSquare(void){

    glBegin(GL_POLYGON);

    glVertex2f(-1.0f,-1.0f);

    glVertex2f(1.0f,-1.0f);

    glVertex2f(1.0f,1.0f);

    glVertex2f(-1.0f,1.0f);

    glEnd();

}

void myDraw(void){

    glClear(GL_COLOR_BUFFER_BIT);

    glLoadIdentity();

    glPushMatrix();

    glTranslatef(0.0f,2.0f,0.0f);

    glScalef(3.0,0.5,1.0);

    glColor3f(1.0,0.0,0.0);

drawSquare();

    glPopMatrix();

    glPushMatrix();

    glTranslatef(-3.0,0.0,0.0);

    glPushMatrix();

    glRotatef(45.0,0.0,0.0,1.0);

    glColor3f(0.0,1.0,0.0);

    drawSquare();

    glPopMatrix();

    glTranslatef(3.0,0.0,0.0);

    glPushMatrix();

    glRotatef(45.0,0.0,0.0,1.0);

    glColor3f(0.0,0.7,0.0);

    drawSquare();

    glPopMatrix();

    glTranslatef(3.0,0.0,0.0);

    glPushMatrix();

    glRotatef(45.0,0.0,0.0,1.0);

    glColor3f(0.0,0.4,0.0);

    drawSquare();

    glPopMatrix();

    glPopMatrix();  

    glTranslatef(0.0,-3.0,0.0);

    glScalef(4.0,1.5,1.0);

    glColor3f(0.0,0.0,1.0);

    drawSquare();

    glFlush();

}

 

三、实验作业

1.根据示范程序，能否在示范代码基础上修改形成以下图形？如下图所示，写出主要的步骤和代码。（不需要将整个程序都写下来）

答：

（1）源代码：

voiddrawDiamond(){

    glBegin(GL_POLYGON);

    glVertex2f(0.0f,0.0f);

    glVertex2f(1.0f,2.0f);

    glVertex2f(0.0f,4.0f);

    glVertex2f(-1.0f,2.0f);

    glEnd();

}

voidmyDisplay(){

    glClear(GL_COLOR_BUFFER_BIT);

    glLoadIdentity();

    glColor3f(1.0,0.0,0.0);

    drawDiamond();

    glRotatef(120.0,0.0,0.0,1.0);

    glColor3f(0.0,1.0,0.0);

    drawDiamond();

    glRotatef(120.0,0.0,0.0,1.0);

    glColor3f(0.0,0.0,1.0);

    drawDiamond();

    glFlush();

}

（2）运行结果：