实验五DD观察

1、设置裁剪窗口几何变换矩阵模50.0,-25.0,0.0,实验五 2D观察、3D观察、实验目的1 理解裁剪窗口和视口的区别2. 掌握 3D 编程概念：主要掌握视点和目标的改变对场景生成的影响二、实验环境硬件要求：PC机，主流配置，最好为独立显卡，显存 512M以上 软件环境：操作系统： Windows XP。语言开发工具： VC6.0。三、实验内容与要求1 在一个窗口中画出三个视口，每个视口画一个六边形，后面两个视 口中六边形是在第一个视口中六边形的基础上分别旋转了 120 度和240 度。/ 样本程序：两个视口中分别画两个三角形#include <glut.h>class wcPt

2、2D public: GLfloat x, y; ;void init (void) glClearColor (1.0, 1.0, 1.0, 0.0);/glMatrixMode (GL_PROJECTION); gluOrtho2D (-100.0, 100.0, -100.0, 100.0);/ 式glMatrixMode (GL_MODELVIEW);void triangle (wcPt2D *verts) GLint k;glBegin (GL_TRIANGLES);for (k = 0; k < 3; k+)glVertex2f (verts k.x, verts k.y)

3、; glEnd ( );void display (void)wcPt2D verts 3 = -50.0,-25.0,50.0 ;glClear (GL_COLOR_BUFFER_BIT); glLoadIdentity(); glColor3f (0.0, 0.0, 1.0); glViewport (0, 0, 300, 300);triangle (verts); /* 旋转三角形 并在右半窗口 */ glColor3f (1.0, 0.0, 0.0);glViewport (300, 0, 300, 300); glRotatef (180.0, 0.0, 0.0, 1.0); tr

4、iangle (verts); glFlush ( );int main (int argc, char * argv)glutInit (&argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); glutInitWindowPosition (50, 50); glutInitWindowSize (600, 300);glutCreateWindow ("Split-Screen Example"); init ( );glutDisplayFunc (display); glutMainLoop (

5、 );return 0;2. 附属程序为移动视点、 旋转物体的观察立方体的三维观察程序。 要求改 变立方体为规则八面体或十二面体，多面体经过多种几何变换(平移、 缩放)生成的三维观察场景。附属程序#include <stdlib.h>#include <glut.h>GLfloat vertices3 = -1.0,-1.0,-1.0,1.0,-1.0,-1.0,1.0,1.0,-1.0, -1.0,1.0,-1.0,-1.0,-1.0,1.0,1.0,-1.0,1.0, 1.0,1.0,1.0, -1.0,1.0,1.0;GLfloat colors3 = 0.0,0

6、.0,0.0,1.0,0.0,0.0,1.0,1.0,0.0, 0.0,1.0,0.0, 0.0,0.0,1.0,1.0,0.0,1.0, 1.0,1.0,1.0, 0.0,1.0,1.0;void polygon(int a, int b, int c , int d) glBegin(GL_POL YGON); glColor3fv(colorsd);glVertex3fv(verticesa); glVertex3fv(verticesb); glVertex3fv(verticesc); glVertex3fv(verticesd);glEnd();static GLfloat the

7、ta = 0.0,0.0,0.0;static GLint axis = 2;static GLdouble viewer= 0.0, 0.0, 5.0; void colorcube()polygon(0,3,2,1);polygon(2,3,7,6); polygon(0,4,7,3);polygon(1,2,6,5);polygon(4,5,6,7); polygon(0,1,5,4); void display() glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity();/更新视点位置 gluLookAt

8、(viewer0,viewer1,viewer2, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); glRotatef(theta0, 1.0, 0.0, 0.0);glRotatef(theta1, 0.0, 1.0, 0.0); /* 旋转立方体 */glRotatef(theta2, 0.0, 0.0, 1.0);colorcube();glutSwapBuffers();void mouse(int btn, int state, int x, int y) if(btn=GLUT_LEFT_BUTTON && state = GLUT_DOWN) axi

9、s = 0; if(btn=GLUT_MIDDLE_BUTTON && state = GLUT_DOWN) axis = 1; if(btn=GLUT_RIGHT_BUTTON && state = GLUT_DOWN) axis = 2; thetaaxis += 2.0;if( thetaaxis > 360.0 ) thetaaxis -= 360.0; glutPostRedisplay ();void keys(unsigned char key, int x, int y)/* 用 x, X, y, Y, z, and Z 键 移动视点 */

10、if(key = 'x') viewer0-= 1.0; if(key = 'X') viewer0+= 1.0;if(key = 'y') viewer1-= 1.0; if(key = 'Y') viewer1+= 1.0;if(key = 'z') viewer2-= 1.0; if(key = 'Z') viewer2+= 1.0; glutPostRedisplay ();void myReshape(int w, int h) glViewport(0, 0, w, h); glMatr

11、ixMode(GL_PROJECTION); glLoadIdentity();if(w<=h) glFrustum(-2.0, 2.0, -2.0 * (GLfloat) h/ (GLfloat) w,2.0* (GLfloat) h / (GLfloat) w, 2.0, 20.0);else glFrustum(-2.0, 2.0, -2.0 * (GLfloat) w/ (GLfloat) h,2.0* (GLfloat) w / (GLfloat) h, 2.0, 20.0);/* 或者用 gluPerspective(45.0, w/h, 1.0, 10.0); */ glM

12、atrixMode(GL_MODELVIEW);int main (i nt argc, char *argv) glut In it (&argc, argv);glutl ni tDisplayMode( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);glutl nitWin dowSize(500, 500); glutCreateWi ndow("colorcube");glutReshapeF un c(myReshape); glutDisplay Fun c(display);glutMouseF un c(mouse);

13、glutKeyboard Fun c(keys);glE nable(GL_DEPTH_TEST); glutMai nLoop(); return 0;3、编程实现自己的project.选作：4. 2D裁剪要求将实验三的画线程序按如下步骤修改：(1)按下键盘"1"，可用鼠标在窗口画若干任意条直线。如图 5-1所示。(2)按下键盘"2"，可用鼠标在窗口添加一个任意大小的裁剪窗口，窗口画完即完成直线的裁剪，使用编码裁剪算法，如图5-2所示。提示：画矩形结束时，同时把若干条直线的起点坐标和终点作为参数循环调 用裁剪算法，达到线段裁剪的目的。图5-1图5-2四

14、、附录: 编码裁剪法伪代码class wcPt2D public: float x,y; const GLint winLeftBitCode=0x1;const GLint winRightBitCode=0x2;const GLint winBottomBitCode=0x4;const GLint winTopBitCode=0x8;inline GLint inside (Glint code) return GLint (!code);inline GLint reject (GLint code1,GLint code2) return GLint (code1 & cod

15、e2)；inline GLint accept (GLint code1, GLint code2) return GLint (!(code1|code2);GLubyte encode(wcPt2D pt,wcPt2D winMin, wcPt2D winMax) GLubyte code=0x00;if (pt.x<winMin.x) code=code|winLeftBitCode;if (pt.x>winMax.x) code=code|winRightBitCode;if (pt.y<winMin.y) code=code|winBottomBitCode;if

16、(pt.y>winMax.y) code=code|winTopBitCode;return (code); void swapPts(wcPt2D *p1, wcPt2D *p2) wcPt2D tmp;tmp=*p1;*p1=*p2;*p2=tmp； void swapCodes(GLubyte *c1,GLubyte *c2) GLubyte tmp;tmp=*c1;*c1=*c2;*c2=tmp； void lineClipCohSuth(wcPt2D winMin, wcPt2D winMax,wcPt2D p1, wcPt2D p2) GLubyte code1,code2;

17、Glint done=false, plotLine=false;GLfloat m;while(!done) code1=encode(p1,winMin,winMax); code2=encode(p2,winMin,winMax);if (accept (code1,code2) done=true;plotLine=true; elseif (reject(code1,code2) done=true;else /* Label the point outside the window as p1*/if ( inside (code1) swapPts(&p1,&p2

18、); swapCodes(&code1,&code2);if (p2.x!=p1.x) m=(p2.y-p1.y)/(p2.x-p1.x);if (code1 & winLeftBitCode) p1.y+=(winMin.x-p1.x)*m; p1.x=winMin.x;elseif (code1 & winRightBitCode) p1.y+=(winMax.x-p1.x)*m; p1.x=winMax.x;elseif (code1 & winBottomBitCode) /*Need to update p1.x for nonvertical lin