实验10 Bezier曲线生成-实验提高-控制点生成B样条曲线

本代码根据已知控制点( 10, 5, 0 ),( 5, 10, 0 ),( -5, 15, 0 ),( -10, -5, 0 ),( 4, -4, 0 ),( 10, 5, 0 ), ( 5, 10, 0 ), ( -5, 15, 0 ), ( -10, -5, 0 )，( 10, 5, 0 )来生成三次B样条曲线。

#include<GL/glut.h>#include<stdio.h>#include<stdlib.h>#include<vector>usingnamespacestd;structPoint{floatc[2];float&x=c[0];float&y=c[1];Point(){x=0,y=0;}Point(floatx0,floaty0){x=x0,y=y0;}Point(constPoint&pt){x=pt.x,y=pt.y;}float&operator[](constinti){returnc[i];}};vector<Point>GctrlPt,GbsCurvePt;intGnumSegment=10;voidCalcBSPoints(){intnumCtrPt=GctrlPt.size();floatF0[2],F1[2],F2[2],F3[2];floatt=0;floatdt=1/(float)GnumSegment;//第一段NumSubSegment + 1个点，第二段之后每段为NumSubSegment个点,因为第二段之后的起点为前一段的终点intnumCurvePoint=(GnumSegment+1)+GnumSegment*(numCtrPt-4);GbsCurvePt.resize(numCurvePoint);//第一段起点编号为0，第二段之后的为1，原因见上for(inti=0;i<(numCtrPt-3);i++){for(intj=0;j<2;j++){F0[j]=(GctrlPt[i][j]+4*GctrlPt[1+i][j]+GctrlPt[2+i][j])/6.0f;F1[j]=(-3*GctrlPt[i][j]+3*GctrlPt[2+i][j])/6.0f;F2[j]=(3*GctrlPt[i][j]-6*GctrlPt[1+i][j]+3*GctrlPt[2+i][j])/6.0f;F3[j]=(-GctrlPt[i][j]+3*GctrlPt[1+i][j]-3*GctrlPt[2+i][j]+GctrlPt[3+i][j])/6.0f;}t=(i==0)?0:dt;//第一段起点参数为0，第二段之后的为dt，原因同上for(intj=(i==0)?0:1;j<GnumSegment+1;j++){for(intk=0;k<2;k++){GbsCurvePt[j+GnumSegment*i][k]=F0[k]+F1[k]*t+F2[k]*t*t+F3[k]*t*t*t;}t+=dt;}}}voidControlPoint(constvector<Point>&vpt){glPointSize(3);glBegin(GL_POINTS);for(unsignedinti=0;i<vpt.size();i++){glVertex2f(vpt[i].x,vpt[i].y);}glEnd();}voidPolylineGL(constvector<Point>&vpt){glBegin(GL_LINE_STRIP);for(unsignedinti=0;i<vpt.size();i++){glVertex2f(vpt[i].x,vpt[i].y);}glEnd();}voidmyDisplay(){glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0f,0.0f,0.0f);ControlPoint(GctrlPt);glColor3f(0.0f,1.0f,0.0f);PolylineGL(GctrlPt);if(GctrlPt.size()>=4){glColor3f(1.0f,1.0f,1.0f);CalcBSPoints();PolylineGL(GbsCurvePt);}glFlush();}voidInit(){glClearColor(0.0,0.0,0.0,0.0);glShadeModel(GL_SMOOTH);floatpoints[9][3]={{10,5,0},{5,10,0},{-5,15,0},{-10,-5,0},{4,-4,0},{10,5,0},{5,10,0},{-5,15,0},{-10,-5,0}};Point pt;for(inti=0;i<9;i++){Point pt=Point(points[i][0],points[i][1]);GctrlPt.push_back(pt);}}voidmyReshape(intw,inth){glViewport(0,0,(GLsizei)w,(GLsizei)h);glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(-30.0,30.0,-30.0*(GLfloat)h/(GLfloat)w,30.0*(GLfloat)h/(GLfloat)w,0.0,100.0);}intmain(intargc,char*argv[]){glutInit(&argc,argv);glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);glutInitWindowPosition(100,100);glutInitWindowSize(640,480);glutCreateWindow("B-Spline Curve");Init();glutDisplayFunc(myDisplay);glutReshapeFunc(myReshape);glutMainLoop();return0;}