1、如果上述两种条件都不成立,则按第三种情况处理。求出线段与窗口某边的交点,在交点处把线段一分为二,其中必有一段完全在窗口外,可弃之,对另一段则重复上述处理。4实验代码:#include stdio.hstdlib.hvoid LineGL(int x0,int y0,int x1,int y1)glBegin (GL_LINES);glColor3f (1.0f, 0.0f, 0.0f); glVertex2f (x0,y0);glColor3f (0.0f, 1.0f, 0.0f); glVertex2f (x1,y1);glEnd ();struct outcodeunsigned all;
2、unsigned left,right,top,bottom;struct Rectanglefloat xmin,xmax,ymin,ymax;Rectangle rect;int x0,y0,x1,y1;GLboolean bClip = false;void compoutcode(float x,float y,Rectangle rect,outcode *outcode)outcode-all=0;top=outcode-bottom=0;if(y(float)rect.ymax)top=1; all+=1;else if(yleft=0;if(x(float)rect.xmax)
3、 right=1;else if(xleft)y=y0+(y1-y0)*(rect.xmin-x0)/(x1-x0);x=(float)rect.xmin;else if(outcodeout-top)x=x0+(x1-x0)*(rect.ymax-y0)/(y1-y0);y=(float)rect.ymax;right)y=y0+(y1-y0)*(rect.xmax-x0)/(x1-x0);x=(float)rect.xmax;bottom)x=x0+(x1-x0)*(rect.ymin-y0)/(y1-y0);y=(float)rect.ymin;all=outcode0.all)x0=x
4、;y0=y;x1=x;y1=y;while(!done);if(accept)LineGL(x0,y0,x1,y1);return accept;void myDisplay()glClear(GL_COLOR_BUFFER_BIT);glRectf(rect.xmin,rect.ymin,rect.xmax,rect.ymax);if (!bClip)cohensutherlandlineclip(rect, x0,y0,x1,y1);glFlush();void Init()glClearColor(0.0, 0.0, 0.0, 0.0);glShadeModel(GL_FLAT);rec
5、t.xmin=100; /窗口的大小rect.xmax=300;rect.ymin=100;rect.ymax=300;x0 = 450,y0 = 0, x1 = 0, y1 = 450;/裁剪前的直线端点printf(Press key c to Clip!nPress key r to Restore!n);void Reshape(int w, int h)glViewport(0, 0, (GLsizei) w, (GLsizei) h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, (GLdouble) w,
6、 0.0, (GLdouble) h);void keyboard(unsigned char key, int x, int y)switch (key)case :bClip = true;glutPostRedisplay();/重画break;bClip = false;Init();/xexit(0);default:int main(int argc, char *argv)glutInit(&argc, argv);glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);glutInitWindowPosition(100, 100);glutIn
7、itWindowSize(640, 480);glutCreateWindow(Hello World!glutDisplayFunc(myDisplay);glutReshapeFunc(Reshape);glutKeyboardFunc(keyboard);glutMainLoop();return 0;5实验思考题请分别给出直线的三种不同位置情况,测试实验代码是否存在问题,有的话请调试改正。可能的话,可以尝试实现梁友栋裁剪算法。glut.hvoid LineGL(int x0,int y0,int x1,int y1) glBegin (GL_LINES); glColor3f (1.0
8、f, 0.0f, 0.0f); glColor3f (0.0f, 1.0f, 0.0f); glEnd (); unsigned all; unsigned left,right,top,bottom; float xmin,xmax,ymin,ymax;struct Rectangle rect;int bClip = 0;void compoutcode(float x,float y,struct Rectangle rect,struct outcode *outcode) outcode- if(y else if(y else if(x y=y0+(y1-y0)*(rect.xmi
9、n-x0)/(x1-x0); x=(float)rect.xmin; else if(outcodeout- x=x0+(x1-x0)*(rect.ymax-y0)/(y1-y0); y=(float)rect.ymax; y=y0+(y1-y0)*(rect.xmax-x0)/(x1-x0); x=(float)rect.xmax; x=x0+(x1-x0)*(rect.ymin-y0)/(y1-y0); y=(float)rect.ymin; x0=x; x1=x; while(! if(accept) LineGL(x0,y0,x1,y1); return accept; glClear
10、(GL_COLOR_BUFFER_BIT); glRectf(rect.xmin,rect.ymin,rect.xmax,rect.ymax); if (! cohensutherlandlineclip(rect, x0,y0,x1,y1); glFlush(); glClearColor(0.0, 0.0, 0.0, 0.0); glShadeModel(GL_FLAT); rect.xmin=100; rect.xmax=300; rect.ymin=100; rect.ymax=300; x0 = 450,y0 = 0, x1 = 0, y1 = 450; printf( glView
11、port(0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h); switch (key) case bClip = 1; glutPostRedisplay(); break; bClip = 0; Init(); exit(0); default: glutInit(& glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE); glutInitWindowPosition(100, 100); glutInitWindowSize(640, 480); glutCreateWindow( glutDisplayFunc(myDisplay); glutReshapeFunc(Reshape); glutKeyboardFunc(keyboard); glutMainLoop(); return 0;
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