glMatrixMode (GL_PROJECTION); gluOrtho2D(-200.0,200.0,-200.0,200.0); } void lineBres(GLfloat x0,GLfloat y0,GLfloat xEnd,GLfloat yEnd){ int dx = fabs(xEnd - x0),dy = fabs(yEnd - y0); int p = 2*dy - dx; int twoDy = 2*dy,twoDyMinusDx = 2*(dy - dx); int x,y; if(x0>xEnd){ x = xEnd; y = yEnd; xEnd = x0; } else{ x = x0; y = y0; } setPixel(x,y);
inline GLint round(const GLfloat a){return GLint(a+0.5);} void setPixel(int x,int y){ glBegin(GL_POINTS); glVertex2i(x,y); glEnd(); }
void init(){ glClearColor(1.0,1.0,1.0,0.0);
if(clipTest(-dy,p1.gety()-winMin.gety(),&u1,&u2)){ if(clipTest(dy,winMax.gety()-p1.gety(),&u1,&u2)){ if(u2<1.0){ p2.setCoords(p1.getx()+u2*dx,p1.gety()+u2*dy); } if(u1>0.0){ p1.setCoords(p1.getx()+u1*dx,p1.gety()+u1*dy); } glColor3f(0.0,0.0,0.0); lineBres(x1,y1,p1.getx(),p1.gety()); lineBres(p2.getx(),p2.gety(),x2,y2); glColor3f(1.0,0.0,0.0); lineBres(p1.getx(),p1.gety(),p2.getx(),p2.gety()); } } else{ glColor3f(0.0,0.0,0.0); lineBres(x1,y1,x2,y2); } } } void displayliangyoudongcaijian(){
class wcPt2D{ public: GLfloat x,yoord,GLfloat
yCoord){x=xCoord;y=yCoord;} GLfloat getx() const{return x;} GLfloat gety() const{return y;} };
glClear(GL_COLOR_BUFFER_BIT); glLineWidth(5.0); glColor3f(0.0,0.0,0.0); glBegin(GL_LINE_LOOP); glVertex2i(100,100); glVertex2i(100,-100); glVertex2i(-100,-100); glVertex2i(-100,100); glEnd(); glPointSize(4); wcPt2D test1[4] =
{{-100.0,-100.0},{100.0,100.0},{-170.0,-200.0},{200.0,-120.0}}; lineClipLiangBarsk(test1[0],test1[1],test1[2],test1[3]); lineClipLiangBarsk(test2[0],test2[1],test2[2],test2[3]);
lineClipLiangBarsk(test3[0],test3[1],test3[2],test3[3]); lineClipLiangBarsk(test4[0],test4[1],test4[2],test4[3]); lineClipLiangBarsk(test5[0],test5[1],test5[2],test5[3]); glFlush(); }
while(x<xEnd){ x++; if(p<0) p+=twoDy; else{ y++; p+=twoDyMinusDx; } setPixel(x,y); } } GLint clipTest(GLfloat p,GLfloat q,GLfloat *u1,GLfloat *u2){ GLfloat r; GLint returnValue = true;
init(); glutDisplayFunc(displayliangyoudongcaijian); glutMainLoop(); }
实
验
结
果
：
p1,wcPt2D p2){ GLfloat u1 = 0.0,u2 = 1.0,dx = p2.getx()-p1.getx(),dy; GLfloat x1 = p1.getx(),y1 = p1.gety(); GLfloat x2 = p2.getx(),y2 = p2.gety(); if(clipTest(-dx,p1.getx()-winMin.getx(),&u1,&u2)) if(clipTest(dx,winMax.getx()-p1.getx(),&u1,&u2)){ dy = p2.gety()-p1.gety();
void main(int argc, char* argv[]){ glutInit(&argc,argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowPosition(50,100); glutInitWindowSize(400,300); glutCreateWindow("梁友栋裁剪算法");
{{-100.0,-100.0},{100.0,100.0},{-50.0,50.0},{150.0,150.0}}; wcPt2D test4[4] =
{{-100.0,-100.0},{100.0,100.0},{-50.0,0.0},{60.0,50.0}}; wcPt2D test5[4] =
《计算机图形学实验》报告
任课教师：钱文华
2016 年春季学期
实验:梁友栋裁剪
实验时间：2016 年 11 月 17 日 实验地点：信息学院 2204 实验目的：掌握梁友栋裁剪
程序代码：#include <stdio.h> #include <glut.h> #include <stdlib.h> #include <math.h>
if(p<0.0){ r = q/p; if(r>*u2) returnValue = false; else if(r>*u1) *u1 = r;
} else if(p>0.0){ r = q/p; if(r<*u1) returnValue = false; else if(r<*u2) *u2 = r; } else if(q<0.0) returnValue = false; return(returnValue); } void lineClipLiangBarsk(wcPt2D winMin,wcPt2D winMax,wcPt2D
{{-100.0,-100.0},{100.0,100.0},{-150.0,-200.0},{200.0,120.0}}; wcPt2D test2[4] =
{{-100.0,-100.0},{100.0,100.0},{-150.0,-120.0},{0.0,0.0}}; wcPt2D test3[4] =