图形学的几道基础练习（计算机图形学）

待我称王封你为后i 2022-05-09 04:40 311阅读 0赞

整理文件夹时发现曾经做的几个作业练习，发出来和大家一起学习吧。

PS：总工程下载：[https://download.csdn.net/download/weixin\_41918712/10698534][https_download.csdn.net_download_weixin_41918712_10698534]

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# **题目①** #

**在一个黑色的窗口中央画出矩形、三角形、点和线。**

> 踩坑记录：一开始画线部分，因为省略了glEnd()，导致生成图像时显示空白窗口。

**效果图**

![70][]

**题目①源码**

#pragma warning(disable:4996)
    #include<GL/glut.h>
    void myDisplay(void)
    {
    	glClearColor(0.0, 0.0, 0.0, 0.0);  //将清空颜色设为黑色
    	glClear(GL_COLOR_BUFFER_BIT);  //将窗口的背景设置为:清空颜色
    	glColor3f(1.0f, 1.0f, 1.0f);  //画一个矩形
    	glRectf(-0.8f, -0.8f, 0.8, 0.8f);
    	glBegin(GL_TRIANGLES);  //画两个三角形
    	glColor3f(1.0f, 1.0f, 0.0f);  glVertex2f(0.0f, -1.0f);//黄
    	glColor3f(1.0f, 0.0f, 1.0f);  glVertex2f(0.8f, 0.5f);//品红
    	glColor3f(0.0f, 1.0f, 1.0f);  glVertex2f(-0.8f, 0.5f);//青
    	glColor3f(1.0f, 0.0f, 0.0f);  glVertex2f(0.0f, 1.0f);//红
    	glColor3f(0.0f, 1.0f, 0.0f);  glVertex2f(0.8f, -0.5f);//绿
    	glColor3f(0.0f, 0.0f, 1.0f);  glVertex2f(-0.8f, -0.5f);//蓝
    	glEnd();
    	glPointSize(10);  //设置点的大小
    	glBegin(GL_POINTS);  //画7个点
    	glColor3f(1.0f, 1.0f, 0.0f);  glVertex2f(0.0f, 0.7f);//黄
    	glColor3f(1.0f, 1.0f, 1.0f);  glVertex2f(0.0f, 0.0f);//白
    	glColor3f(0.0f, 1.0f, 1.0f);  glVertex2f(0.53f, -0.33f);//青
    	glColor3f(1.0f, 0.0f, 1.0f);  glVertex2f(-0.53f, -0.33f);//品红
    	glColor3f(0.0f, 0.0f, 1.0f);  glVertex2f(0.53f, 0.33f);//蓝
    	glColor3f(0.0f, 1.0f, 0.0f);  glVertex2f(-0.53f, 0.33f);//绿
    	glColor3f(1.0f, 0.0f, 0.0f);  glVertex2f(0.0f, -0.7f);//红
    	glEnd();
    	glBegin(GL_LINES);//线
    	glColor3f(0.0, 0.0, 0.0);
    	glLineWidth(6);//线的宽度
    	glVertex2f(-0.8f, 0.5f);
    	glVertex2f(0.8f, -0.5f);
    	glVertex2f(0.0f, -1.0f);
    	glVertex2f(0.0f, 1.0f);
    	glVertex2f(0.8f, 0.5f);
    	glVertex2f(-0.8f, -0.5f);
    	glEnd();
    	glFinish();  //强制前面的OpenGL命令立即执行,不驻留缓存
    }
    int main(int argc, char *argv[])
    {
    	glutInit(&argc, argv);
    	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
    	glutInitWindowPosition(100, 100);  //设置窗口在屏幕中的位置
    	glutInitWindowSize(400, 400);  //设置窗口的大小
    	glutCreateWindow("Hello World!");
    	glutDisplayFunc(&myDisplay);
    	glutMainLoop();
    	return 0;
    }

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# **题目②** #

**利用OpenGL实现直线光栅化的DDA算法和Bresenham算法。**

**效果图**

![70 1][]

**题目②源码**

#pragma warning(disable:4996)
    #include<math.h>
    #include <GL/glut.h>
    #include<cstdio>
    void LineDDA(int x0, int y0, int x1, int y1)/*  LineDDA函数画线  */
    {
    	int x, y, dx, dy;
    	float m;
    	dx = x1 - x0;
    	dy = y1 - y0;
    	m = dy / dx;
    	y = y0;
    	glColor3f(1.0f, 1.0f, 0.0f);
    	glPointSize(1);
    	for (x = x0;x <= x1;x++) {
    		glBegin(GL_POINTS);
    		glVertex2i(x, (int)(y + 0.5));
    		glEnd();
    		y += m;
    	}
    }
    void Bresenhamline(int x0, int y0, int x1, int y1)/*  Bresenham函数画线  */
    {
    	int x, y, dx, dy;
    	float e;
    	dx = x1 - x0;
    	dy = y1 - y0;
    	e = -dx;
    	x = x0;
    	y = y0;
    	for (int i = 0;i<dx;i++) {
    		glBegin(GL_POINTS);
    		glVertex2i(x, y);
    		x++;
    		e = e + 2 * dy;
    		if (e >= 0) {
    			y++;
    			e = e - 2 * dx;
    		}
    	}
    }
    
    void myDisplayLine(void)
    {
    	glClear(GL_COLOR_BUFFER_BIT);
    	glColor3f(1.0f, 0.0f, 0.0f);
    	glRectf(25.0, 25.0, 75.0, 75.0);
    	glPointSize(5);
    	glBegin(GL_POINTS);
    	glColor3f(0.0f, 1.0f, 0.0f);
    	glVertex2f(0.0f, 0.0f);
    	glEnd();
    	LineDDA(0, 0, 200, 300);  //调用LineDDA函数画线
    	glBegin(GL_LINES);
    	glColor3f(1.0f, 0.0f, 0.0f);
    	glVertex2f(100.0f, 0.0f);
    	glColor3f(0.0f, 1.0f, 0.0f);
    	glVertex2f(180.0f, 240.0f);
    	glEnd();
    	glFlush();
    }
    void myDisplayBres(void)
    {
    	glClear(GL_COLOR_BUFFER_BIT);
    	glColor3f(1.0f, 0.0f, 0.0f);
    	glRectf(25.0, 25.0, 75.0, 75.0);
    	glPointSize(5);
    	glBegin(GL_POINTS);
    	glColor3f(0.0f, 1.0f, 0.0f);
    	glVertex2f(0.0f, 0.0f);
    	glEnd();
    	Bresenhamline(0, 0, 200, 300);  //调用Bresenhamline函数画线
    	glBegin(GL_LINES);
    	glColor3f(1.0f, 0.0f, 0.0f);
    	glVertex2f(100.0f, 0.0f);
    	glColor3f(0.0f, 1.0f, 0.0f);
    	glVertex2f(180.0f, 240.0f);
    	glEnd();
    	glFlush();
    }
    void Init() {
    	glClearColor(0.0, 0.0, 0.0, 0.0);
    	glShadeModel(GL_FLAT);
    }
    void Reshape(int w, int h) {
    	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
    	glMatrixMode(GL_PROJECTION);
    	glLoadIdentity();
    	gluOrtho2D(0.0, (GLdouble)w, 0.0, (GLdouble)h);
    }
    int main(int argc, char *argv[])
    {
    	int i;
    	printf("请选择实现直线光栅化的算法：\n1.DDA\t2.Bresenham\n");
    	while (scanf("%d", &i))
    	{
    		if (i == 1 || i == 2)  break;
    		else{}
    	}
    	glutInit(&argc, argv);
    	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
    	glutInitWindowPosition(100, 100);
    	glutInitWindowSize(400, 400);
    	glutCreateWindow("Hello World!");
    	Init();
    	if(i==1)  glutDisplayFunc(myDisplayLine);  //设置mydisplay函数，当需要进行画图时，这个函数就会被调用 
    	else if(i==2)  glutDisplayFunc(myDisplayBres);
    	else  return 0;
    	glutReshapeFunc(Reshape);  //调用此函数，重新建立用作新渲染画布的矩形区域
    	glutMainLoop();  //进行一个消息循环（现在只需要知道这个函数可以显示窗口，并且等待窗口关闭才会返回）
    	return 0;
    }

--------------------

# **题目③** #

**画顶点分别为A(1,1)，B(2,5), C(6,3) 的三角形ABC，同时画出绕B点逆时针旋转90度的三角形A’B’C’，最后在以上基础上再画出绕B点顺时针旋转90度的三角形A’’B’’C’’。**

**效果图**

![70 2][]

**题目③源码**

#pragma warning(disable:4996)
    #include <GL/glut.h>;
    void init(void)
    {
    	glClearColor(1.0, 1.0, 1.0, 0.0);
    	glMatrixMode(GL_PROJECTION);
    	gluOrtho2D(-15.0, 15.0, -15.0, 15.0);  //设置x、y显示的范围
    	glMatrixMode(GL_MODELVIEW);
    }
    void drawSquare(void)  //绘制三角形
    {
    	glBegin(GL_TRIANGLES);  //顶点指定需要按逆时针方向
    	glVertex2f(1.0f, 1.0f);
    	glVertex2f(2.0f, 5.0f);
    	glVertex2f(6.0f, 3.0f);
    	glEnd();
    }
    void myDraw(void)
    {
    	glClear(GL_COLOR_BUFFER_BIT);  //清空
    	glLoadIdentity();  //将当前矩阵设为单位矩阵
    	glPushMatrix();  //a：此处的push是为了表明堆栈当前状态
    	glColor3f(1.0f, 0.0f, 0.0f);  //红色三角形
    	drawSquare();  //调用drawSquare
    	glPopMatrix();  //这个pop使得堆栈状态回到a状态
    	glPushMatrix();  //作用同a,表明堆栈当前状态
    	glTranslatef(7.0, 3.0, 0.0);  //平移变换，x正方向平移7个单位，y正方向平移3个单位
    	glPushMatrix();  //c：这里的push保存了上面平移矩阵
    	glRotatef(90.0, 0.0, 0.0, 1.0);  //旋转变换，逆时针旋转90°	
    	glColor3f(0.0f, 1.0f, 0.0f);
    	drawSquare();  //绿色三角形，进行一个旋转和一个平移变换
    	glPopMatrix();  //这个pop使得堆栈状态回到c状态,栈里有(7.0, 3.0, 0.0)
    	glTranslatef(-10.0, 4.0, 0.0);
    	glPushMatrix();  //d：这里的push保存了上面平移矩阵，栈里由底到顶有(7.0, 3.0, 0.0)，(-10.0, 4.0, 0.0)
    	glRotatef(-90.0, 0.0, 0.0, 1.0);  //旋转变换，顺时针旋转90°
    	glColor3f(0.0f, 0.0f, 1.0f);
    	drawSquare();  //蓝色三角形，进行一个旋转和一个平移变换
    	glFlush();
    }
    void main(int argc, char** argv)
    {
    	glutInit(&argc, argv);
    	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    	glutInitWindowPosition(0, 0);
    	glutInitWindowSize(600, 600);
    	glutCreateWindow("Hello World !");
    	init();
    	glutDisplayFunc(myDraw);
    	glutMainLoop();
    }

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✎﹏﹏₯㎕《晴天》re so so si la si la so la si si si si la si la so ...﹍﹍﹍﹍﹍﹍

[https_download.csdn.net_download_weixin_41918712_10698534]: https://download.csdn.net/download/weixin_41918712/10698534
[70]: /images/20220509/97f300399e204fb39aabae944138661e.png
[70 1]: /images/20220509/9d0c80f8e6e740349fc4ff689e11ea0a.png
[70 2]: /images/20220509/b8d1c0186b334fe99d601105bb8bd4a0.png