计算机图形学实验C++代码

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一、bresenham算法画直线

#include

void draw_pixel(int ix,int iy)

{

glBegin(GL_POINTS);

glVertex2i(ix,iy);

glEnd();

}

void Bresenham(int x1,int y1,int xEnd,int yEnd) {

int dx=abs(xEnd-x1),dy=abs(yEnd-y1);

int p=2*dy-dx;

int twoDy=2*dy,twoDyMinusDx=2*dy-2*dx;

int x,y;

if (x1>xEnd)

{

x=xEnd;y=yEnd;

xEnd=x1;

}

else

{

x=x1;

y=y1;

}

draw_pixel(x,y);

while(x

{

x++;

if(p<0)

p+=twoDy;

else

{

y++;

p+=twoDyMinusDx;

draw_pixel(x,y);

}

void display()

{

glClear(GL_COLOR_BUFFER_BIT);

Bresenham(0,0,400,400);

glFlush();

}

void myinit()

{

glClearColor(0.8,1.0,1.0,1.0);

glColor3f(0.0,0.0,1.0);

glPointSize(1.0);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

gluOrtho2D(0.0,500.0,0.0,500.0);

}

void main(int argc,char **argv )

{

glutInit(&argc,argv);

glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);

glutInitWindowSize(500,500);

glutInitWindowPosition(200.0,200.0);

glutCreateWindow("CG_test_Bresenham_Line example");

glutDisplayFunc(display);

myinit();

glutMainLoop();

}

二、中点法绘制椭圆

#include

inline int round(const float a){return int (a+0.5);}

void setPixel(GLint xCoord,GLint yCoord)

{

glBegin(GL_POINTS);

glVertex2i(xCoord,yCoord);

glEnd();

}

void ellipseMidpoint(int xCenter,int yCenter,int Rx,int Ry) {

int Rx2=Rx*Rx;

int Ry2=Ry*Ry;

int twoRx2=2*Rx2;

int twoRy2=2*Ry2;

int p;

int x=0;

int y=Ry;

int px=0;

int py=twoRx2*y;

void ellipsePlotPoints(int,int,int,int);

ellipsePlotPoints(xCenter,yCenter,x,y);

p=round(Ry2-(Rx2*Ry)+(0.25*Rx2));

while(px

x++;

px+=twoRy2;

if(p<0)

p+=Ry2+px;

else{

y--;

py-=twoRx2;

p+=Ry2+px-py;

}

ellipsePlotPoints(xCenter,yCenter,x,y);

}

p=round(Ry2*(x+0.5)*(x+0.5)+Rx2*(y-1)*(y-1)-Rx2*Ry2);

while(y>0){

y--;

py-=twoRx2;

if(p>0)

p+=Rx2-py;

else{

x++;

px+=twoRy2;

p+=Rx2-py+px;

}

ellipsePlotPoints(xCenter,yCenter,x,y);

}

void ellipsePlotPoints(int xCenter,int yCenter,int x,int y) {

setPixel(xCenter+x,yCenter+y);

setPixel(xCenter-x,yCenter+y);

setPixel(xCenter+x,yCenter-y);

setPixel(xCenter-x,yCenter-y);

}

void display()

{

glClear(GL_COLOR_BUFFER_BIT);

ellipseMidpoint(200,200,50,30);

glFlush();

}

void myinit()

{

glClearColor(0.8,1.0,1.0,1.0);

glColor3f(0.0,0.0,1.0);

glPointSize(1.0);