计算机图形学:窗口画线

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计算机图形学:窗口画线

#include<gl/glut.h>

#include<stdio.h>

class Point

{

private:

double x,y;

public:

void operator =(const Point a)

{

x=a.x;

y=a.y;

}

double getX()

{

return x;

}

double getY()

{

return y;

}

void setX(double a)

{

x=a;

}

void setY(double a)

{

y=a;

}

void setXY(double a,double b)

{

x=a;

y=b;

}

};

Point pt1,pt2;

int PointCount=0;

bool OnePoint=false,TwoPoint=false;

double Xl=50,Xr=350,Yt=50,Yb=250;

void mouseEvent(int button,int state,int x,int y);

void DisplayEvent();

void CodeClip(Point,Point);

void init(void)

{

glClearColor(1.0,1.0,1.0,0.0);

glClear(GL_COLOR_BUFFER_BIT);

glFlush();

glutSwapBuffers();

}

void resizeEvent(int w, int h)

{

glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

gluOrtho2D(0, w, h, 0);

glMatrixMode(GL_MODELVIEW);

glutPostRedisplay();

}

void DrawLine(Point a,Point b)

{

//printf("DrawLine????:/n");

//printf("x1=%f,y1=%f x2=%f,y2=%f ",a.getX(),a.getY(),b.getX(),b.getY());

glColor3f(0.0,0.0,0.0);

glBegin(GL_LINES);

glVertex2d(a.getX(),a.getY());

glVertex2d(b.getX(),b.getY());

glEnd(); printf("pt1.x=%f,pt1.y=%f ",pt1.getX(),pt1.getY());

CodeClip(pt1,pt2);

}

void DrawPolygon()

{ //printf("DrawPolygon?? ");

Point a1,a2,a3,a4;

a1.setXY(Xl,Yt);

a2.setXY(Xr,Yt);

a3.setXY(Xr,Yb);

a4.setXY(Xl,Yb);

glColor3f(0,0,1);

glBegin(GL_LINES);

glVertex2f(a1.getX(),a1.getY());

glVertex2f(a2.getX(),a2.getY());

glVertex2f(a3.getX(),a3.getY());

glVertex2f(a4.getX(),a4.getY());

glVertex2f(a1.getX(),a1.getY());

glEnd();

}

double PointCode(Point a)

{ //printf("PointCode?? ");

if(a.getX()==Xl||a.getX()==Xr)

if(a.getY()>=Yt&&a.getY()<=Yb)

return 0;//0x00;

else if(a.getY()<Yt)

return 8;

else if(a.getY()>Yb)

return 4;

if(a.getY()==Yt||a.getY()==Yb)

if(a.getX()<=Xr&&a.getY()>=Xl)

return 0;//0x00;

if(a.getX()<Xl)

if(a.getY()<=Yt)

return 9;//0x09;

else if(a.getY()>Yt&&a.getY()<Yb)

return 1;//0x01;

else if(a.getY()>=Yb)

return 5;//0x05;

else

;

else if(a.getX()>Xl&&a.getX()<Xr)

if(a.getY()<Yt)

return 8;//0x08;

else if(a.getY()>Yt&&a.getY()<Yb)

return 0;//0x00;

else if(a.getY()>Yb)

return 4;//0x04;

else

;

else if(a.getX()>Xr)

if(a.getY()<=Yt)

return 10;//0x0A;

else if(a.getY()>Yt&&a.getY()<Yb)

return 2;//0x02;

else if(a.getY()>=Yb)

return 6;//0x06;

else

;

}

void CodeClip(Point a1,Point a2)

{ printf("CodeClip?? ");

printf("a1.x=%f,a1.y=%f ",a1.getX(),a1.getY());

int done=0,accept=0,reject=0;

double c1,c2;

double x1,y1,x2,y2;

x1=a1.getX(); y1=a1.getY();

x2=a2.getX(); y2=a2.getY();

c1=PointCode(a1); printf("c1=%f ",c1);

c2=PointCode(a2); printf("c2=%f ",c2);

while(done==0)

{

if((int)c1&(int)c2)

{ printf("!!!!!!!!!!!!!!!!!!!!!!reject=1 ");

reject=1;

done=1;

}

if(((int)c1&(int)c2)==0)

{ //printf("???0 ");

if(c1==0&&c2==0)

{

done=1;

accept=1;

}

else if(c1==0)

{ printf("a1.x=%f,a1.y=%f ",a1.getX(),a1.getY());

Point pt=a1;

a1=a2;

a2=pt;

double t=c1;

c1=c2;

c2=t;

x1=a1.getX();y1=a1.getY(); printf("a1.x=%f,a1.y=%f ",a1.getX(),a1.getY());

x2=a2.getX();y2=a2.getY(); printf("c1=%f,c2=%f ",c1,c2);

}

else

{ printf("???? ");

if(a1.getX()<Xl) //a1??????

{

a1.setXY(Xl,(y2-y1)*(Xl-x1)/(x2-x1)+y1);//y1-(x1-Xl)*(y1-y2)/(x1-x2));

c1=PointCode(a1);

}

if(a1.getX()>Xr) //?

{

a1.setXY(Xr,(y2-y1)*(Xr-x1)/(x2-x1)+y1);

c1=PointCode(a1);

}

if(a1.getY()<Yt) //?

{

a1.setXY((Yt-y1)*(x2-x1)/(y2-y1)+x1,Yt);

c1=PointCode(a1);

}

if(a1.getY()>Yb) //?

{

a1.setXY((Yb-y1)*(x2-x1)/(y2-y1)+x1,Yb);

c1=PointCode(a1);

}

if(accept==1)

{ printf("accept==1 ");

glColor3f(0,1,0);

glBegin(GL_LINES);

glVertex2f(a1.getX(),a1.getY());

glVertex2f(a2.getX(),a2.getY());

glEnd();

}

void DrawPointPolygon(Point a)

{ //printf("DrawPointPolygon??: ");

Point b1,b2,b3,b4;

b1.setXY(a.getX()-5,a.getY()+5);

b2.setXY(a.getX()-5,a.getY()-5);

b3.setXY(a.getX()+5,a.getY()-5);

b4.setXY(a.getX()+5,a.getY()+5);

glColor3f(0.0,0.0,1.0);

glBegin(GL_LINES);

glVertex2f(b1.getX(),b1.getY());

glVertex2f(b2.getX(),b2.getY());

glVertex2f(b3.getX(),b3.getY());

glVertex2f(b4.getX(),b4.getY());

glVertex2f(b1.getX(),b1.getY());

glEnd();

}

void DrawPointCross(Point a)

{ //printf("DrawPointCross??: ");

Point b1,b2,b3,b4;

b1.setXY(a.getX()-6,a.getY());

b2.setXY(a.getX()+6,a.getY());

b3.setXY(a.getX(),a.getY()+6);

b4.setXY(a.getX(),a.getY()-6);

glColor3f(1.0,0.0,0.0);

glBegin(GL_LINES);

glVertex2f(b1.getX(),b1.getY());

glVertex2f(b2.getX(),b2.getY());

glVertex2f(b3.getX(),b3.getY());

glVertex2f(b4.getX(),b4.getY());

glEnd();

}

void mouseMoveEvent(int x,int y)

{

if(OnePoint==true)

{ //printf("mouseMoveEvent?? ");

pt2.setXY((double)x,(double)y);

TwoPoint=true;

glutPostRedisplay();

}

int main(int argc, char *argv[])

{

//??windows??

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

glutInitWindowSize(400, 300);

glutInitWindowPosition(200, 200);

glutCreateWindow("Line 2D");

glutReshapeFunc(resizeEvent);

glutDisplayFunc(DisplayEvent);

glutMouseFunc(mouseEvent);

glutMotionFunc(mouseMoveEvent);

glutMainLoop();

return 0;

}

void mouseEvent(int button,int state,int x,int y)

{

TwoPoint=false;

if(PointCount%2==0)

{ //printf("pointcount=0,PointCount=%d ",PointCount);

if(button==GLUT_LEFT_BUTTON)

{ //printf("button=GLUT_LEFT_BUTTON ");

if(state==GLUT_DOWN)

{

pt1.setX((double)x);

pt1.setY((double)y);

glClearColor(1.0,1.0,1.0,0.0);

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(1.0,0.0,0.0);

glBegin(GL_POINTS);

glVertex2f(pt1.getX(),pt1.getY());

glEnd();

PointCount++;

OnePoint=true;

}

else

{ //printf("pointcount=1,PointCount=%d ",PointCount);

if(button==GLUT_LEFT_BUTTON)

{ //printf("button=GLUT_LEFT_BUTTON ");

if(state==GLUT_UP)

{

pt2.setX((double)x);

pt2.setY((double)y);

PointCount++;

OnePoint=false;

TwoPoint=true; // printf("x2=%f,y2=%f ",pt2.getX(),pt2.getY());

}

if(TwoPoint==true)

DisplayEvent();

}

void DisplayEvent()

{ // printf("DisplayEvent??: ");

glClearColor(1.0,1.0,1.0,0.0);

glClear(GL_COLOR_BUFFER_BIT);

DrawPolygon();

if(TwoPoint==true)

{ //printf("TwoPoint==true ");

DrawPointCross(pt1);

DrawPointPolygon(pt2);

DrawLine(pt1,pt2);

}

glFlush();

glutSwapBuffers();

}