c画圆算法

‘壹’ c语言画圆

把整个表格当作一个矩阵...
或者圆的直径为边长的正方形覆盖的表格为矩阵...
或者用穷举...满足到圆心直线距离与半径长的差在一定范围内的点才保留...

‘贰’ 利用C语言编写 能够画出任意圆算法程序(利用画点函数)

上次刚写过，在VC下运行的，
int
dx,dy,incrE,incrNE,d,x,y;
if
((point[1].x-point[0].x)==0){
//垂直的直线
x=point[0].x;
for(y=point[0].y;y<point[1].y;y++)
pDC->SetPixel(x,y,50);
}
else
if(abs((point[1].y-point[0].y)/(point[1].x-point[0].x))<=1){
//斜率
-1到
1
之间
dx=point[1].x-point[0].x;
dy=point[0].y-point[1].y;
d=dx-2*dy;
incrE=-2*dy;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
if(point[0].y>point[1].y){
while(x<point[1].x)
{
if(d>=0){
d+=incrE;
x++;
}
else
{d+=incrNE;
x++;
y--;
}
pDC->SetPixel(x,y,50);
}
}
else
if(point[0].y<=point[1].y){
dy=point[1].y-point[0].y;
incrE=-2*dy;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(x<point[1].x)
{
if(d>=0){
d+=incrE;
x++;
}
else
{d+=incrNE;
x++;
y++;
}
pDC->SetPixel(x,y,50);
}
}
}
else
{
//斜率
<-1
和
>1的直线
if(point[1].x>=point[0].x){
dx=point[1].x-point[0].x;
dy=point[1].y-point[0].y;
d=2*dx-dy;
incrE=2*dx;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(x<point[1].x)
{
if(d<0){
d+=incrE;
y++;
}
else
{d+=incrNE;
pDC->SetPixel(x,y,50);
x++;
y++;
}
pDC->SetPixel(x,y,50);
}
}
else
if((point[1].y-point[0].y)/(point[1].x-point[0].x)<-1){
dx=point[1].x-point[0].x;
dy=point[0].y-point[1].y;
d=2*dx-dy;
incrE=2*dx;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(y<point[1].y)
{
if(d>0){
d+=incrE;
y++;
}
else
{d+=incrNE;
x--;
y++;
}
pDC->SetPixel(x,y,50);
}
}
}

‘叁’ 如何用C语言画一个园

#include <stdio.h>
#include <math.h>
void main()
{
double y;
int x,m;
for(y=10;y>=-10;y--)
{
m=2.5*sqrt(100-y*y); /*计算行y对应的列坐标m，2.5是屏幕纵横比调节系数因为屏幕的
行距大于列距，不进行调节显示出来的将是椭圆*/
for(x=1;x<30-m;x++) printf(" "); /*图形左侧空白控制*/
printf("*"); /*圆的左侧*/
for(;x<30+m;x++) printf(" "); /*图形的空心部分控制*/
printf("*\n"); /*圆的右侧*/
}
}

‘肆’ 画圆的常见算法

画圆的基本算法有逐点比较和DDA积分法，
代码示例 WinC下运行

#include "Conio.h"
#include "graphics.h"
#include "process.h"
#define Ni_circle 0
#define Shun_circle 1
#define closegr closegraph

void initgr();
void draw_Base_circle();
void draw_cabu_circle();
void close_graph();
void acrroods();
static float x0,y0;

void initgr(void) /* BGI初始化 */
{
int gd = DETECT, gm = 0; /* 和gd = VGA,gm = VGAHI是同样效果 */
registerbgidriver(EGAVGA_driver);/* 注册BGI驱动后可以不需要.BGI文件的支持运行 */
initgraph(&gd, &gm, "");
}

void acrroods() /*屏幕中心坐标 */
{
x0=getmaxx()/2;
y0=getmaxy()/2;
}

void draw_Base_circle() /*画圆及写参数*/
{
line(x0-200,y0,x0+200,y0); outtextxy(x0+220,y0,"Z");
line(x0,y0-180,x0,y0+180); outtextxy(x0+10,y0+180,"X");
outtextxy(x0-10,y0+10,"O");
circle(x0,y0,150);
textcolor(YELLOW);
directvideo=0;
gotoxy(46,2);cprintf("Circle start:X0 Y0 Z150");
gotoxy(46,3);cprintf("Circle end :X0 Y0 Z150");
gotoxy(46,4);cprintf("Units :Pixel");
gotoxy(46,5);cprintf("Circle now:");
}

void close_graph() /*关图形系统*/
{
closegraph();
}

void draw_cabu_circle(int sstep,int Directory)/*关键的圆插补函数*/
{
int flag=0;
float Fm,Xm,Ym;
Xm=x0+150; Ym=y0;
moveto(Xm,Ym);
setcolor(RED);
while(1) /*分象限，顺圆和逆圆讨论*/
{
Fm=(Xm-x0)/(Xm-x0)+(Ym-y0)/(Ym-y0)-150/150;/*圆判断公式*/
if(Fm>=0){
if(!Directory){ /*逆圆判断*/
if(Xm>=x0&&Ym<=y0)
{
if(flag) break; /*if语句判断象限，以下一样*/
else Xm=Xm-sstep;
}
if(Xm<=x0&&Ym<=y0)
{
flag=1; Ym=Ym+sstep;
}
if(Xm<=x0&&Ym>=y0)
Xm=Xm+sstep;
if(Xm>=x0&&Ym>=y0)
Ym=Ym-sstep;
}
else { /*it is Directory's else*/
if(Xm>x0&&Ym<y0)
Ym=Ym+sstep;
if(Xm<=x0&&Ym<=y0)
Xm=Xm+sstep;
if(Xm<x0&&Ym>y0) {
flag=1; Ym=Ym-sstep;}
if(Xm>=x0&&Ym>=y0) {
if(flag) break;
Xm=Xm-sstep;}
}
}
else{ /*it is Fm's else*/
if(!Directory) {
if(Xm>x0&&Ym<y0)
{
if(flag) break;
else Ym=Ym-sstep;
}
if(Xm<=x0&&Ym<=y0)
{
flag=1; Xm=Xm-sstep;
}
if(Xm<=x0&&Ym>=y0)
Ym=Ym+sstep;
if(Xm>=x0&&Ym>=y0)
Xm=Xm+sstep;
}
else{
if(Xm>x0&&Ym<y0)
Xm=Xm+sstep;
if(Xm<=x0&&Ym<=y0)
Ym=Ym-sstep;
if(Xm<=x0&&Ym>=y0){
flag=1; Xm=Xm-sstep;}
if(Xm>=x0&&Ym>=y0) {
if(flag) break;
else Ym=Ym+sstep;}
}
}
lineto(Xm,Ym);
gotoxy(58,5); printf("X%3.0f Y0 Z%3.0f ",Ym-y0,Xm-x0);
delay(800);
}
}

void circle_demo(int Directory) /*控制圆插补两次*/
{
int i=0,sstep;
initgr(); /* BGI初始化 */
sleep(2);
acrroods(&x0,&y0);
for(i=0;i<2;i++)
{
draw_Base_circle(150);
if(i==0){
sstep=6;
draw_cabu_circle(sstep,Directory);}
else{
sstep=1;
draw_cabu_circle(sstep,Directory);}
getch();
cleardevice();
setcolor(WHITE);
}
}

/* 圆插补部分的函数区结束*/

int main(void)
{
int choice=0;
initgr(); /* BGI初始化 */

while(choice!=4)
{
setfillstyle(1,RED);
bar(200,30,400,80);
setcolor(GREEN);
settextstyle(3,0,10);
outtextxy(220,50,"DEMO PROGRAM BY P.Y.F");
setcolor(WHITE);
settextstyle(0,0,1);
outtextxy(200,140,"2. Shun_Circle demo.");
outtextxy(200,160,"3. Ni_Circle demo.");
outtextxy(200,180,"4. Quit the program.");
outtextxy(160,200,"Please enter your choice:"); gotoxy(46,13);
scanf("%d",&choice);

switch(choice)
{
case 2: circle_demo(Ni_circle);break;
case 3: circle_demo(Shun_circle);break;
case 4: break;
default: printf("\nChoice wrong,try again!");
}
}

getch(); /* 暂停一下，看看前面绘图代码的运行结果 */
closegr(); /* 恢复TEXT屏幕模式 */
return 0;
}

具体看看《计算机图形学》。

‘伍’ c语言中如何用line画一个圆

#include <math.h>
#include <graphics.h> /*预定义库函数*/
void circlePoint(int x,int y) /*八分法画圆程序*/
{
circle(320+x*20,240+y*20,3);
circle(320+y*20,240+x*20,3);
circle(320-y*20,240+x*20,3);
circle(320-x*20,240+y*20,3);
circle(320-x*20,240+y*20,3);
circle(320-x*20,240-y*20,3);
circle(320-y*20,240-x*20,3);
circle(320+y*20,240-x*20,3);
circle(320+x*20,240-y*20,3);
}
void MidBresenhamcircle(int r) /* 中点Bresenham算法画圆的程序 */
{
int x,y,d;
x=0;y=r;d=1-r; /* 计算初始值 */
while(x<y)
{ circlePoint(x,y); /* 绘制点(x,y)及其在八分圆中的另外7个对称点 */
if(d<0) d+=2*x+3; /* 根据误差项d的判断,决定非最大位移方向上是走还是不走 */
else
{ d+=2*(x-y)+5;
y--;
}
x++;
delay(900000);
} /* while */
}
main()
{
int i,j,r,graphmode,graphdriver;
detectgraph(&graphdriver,&graphmode); initgraph(&graphdriver,&graphmode," ");
printf("中点Bresenhamcircle算法画圆的程序\n"); /*提示信息*/
printf("注意 |r|<=11");
printf("\n输入半径值 r:");
scanf("%d",&r);
printf("按任意键显示图形...");
getch(); cleardevice(); setbkcolor(BLACK);
for(i=20;i<=620;i+=20) /*使用双循环画点函数画出表格中的纵坐标*/
for(j=20;j<=460;j++)
putpixel(i,j,2);
for(j=20;j<=460;j+=20) &n欢迎光临学网,收藏本篇文章 [1] [2]

$False$

bsp; /*使用双循环画点函数画出表格中的横坐标*/
for(i=20;i<=620;i++)
putpixel(i,j,2); outtextxy(320,245,"0"); /*原点坐标*/
outtextxy(320-5*20,245,"-5");circle(320-5*20,240,2); /*横坐标值*/
outtextxy(320+5*20,245,"5");circle(320+5*20,240,2);
outtextxy(320-10*20,245,"-10");circle(320-10*20,240,2);
outtextxy(320+10*20,245,"10");circle(320+10*20,240,2);
outtextxy(320-15*20,245,"-15");circle(320-15*20,240,2);
outtextxy(320+15*20,245,"15");circle(320+15*20,240,2);
outtextxy(320,240-5*20,"-5");circle(320,240-5*20,2); /*纵坐标值*/
outtextxy(320,240+5*20,"5");circle(320,240+5*20,2);
outtextxy(320,240-10*20,"-10");circle(320,240-10*20,2);
outtextxy(320,240+10*20,"10");circle(320,240+10*20,2);
outtextxy(20,10,"The center of the circle is (0,0) "); /*坐标轴左上角显示提示信息*/
setcolor(RED); /*标记坐标轴*/
line(20,240,620,240); outtextxy(320+15*20,230,"X");
line(320,20,320,460); outtextxy(330,20,"Y");
setcolor(YELLOW);
MidBresenhamcircle(r);
setcolor(BLUE); /*绘制圆*/
circle(320,240,r*20);
setcolor(2);
getch(); closegraph();
}

‘陆’ C++中，中点画圆算法，编译时出现错误 ，哪儿错了

变量y0不是yo

‘柒’ C语言绘制圆弧算法

http://wenku..com/view/a3aa271e227916888486d77e.html

‘捌’ C语言用Bresenham算法画圆，哪位高手教教，主要是算法里的内容，谢谢！

的确哈，关键在于对delta的理解
可以看到，都是delta=2*(1-radius)这样的，起作用应该是判断要画的点x、y坐标的变化趋势，先把我注释了的代码贴下，加了getch();可以看到画的过程
-----------------------------------------------------------------
#include<graphics.h>
#include<stdio.h>

void BresenhemCircle(int centerx, int centery, int radius, int color, int type);

void main()
{
int drive=DETECT,mode;
int i,j;
initgraph(&drive,&mode,"");
BresenhemCircle(300,200,100,15,0);
getch();
}

void BresenhemCircle(int centerx, int centery, int radius, int color, int type)
{
int x =type = 0;/*初始横坐标为原点*/
int y = radius; /*初始纵坐标远离原点*/
int delta = 2*(1-radius);
int direction;
while (y >= 0)
{
getch();
if (!type)/*执行*/
{
/*在上半圆画两点*/
putpixel(centerx+x, centery+y, color);
putpixel(centerx-x, centery+y, color);
/*在下半圆画两点*/
putpixel(centerx-x, centery-y, color);
putpixel(centerx+x, centery-y, color);
getch();
}
else/*不执行*/
{
line(centerx+x, centery+y, centerx+x, centery-y);
line(centerx-x, centery+y, centerx-x, centery-y);
getch();
}
/*以下代码设置下次四点的位置，圆是对称的，且此方法相当于同时画四个圆弧
观察右上方圆弧可知，前一半是x增的要快些，后一半是y减的快些*/
if (delta < 0)
{
if ((2*(delta+y)-1) < 0)
direction = 1; /*选择横向加*/
else
direction = 2;
}
else if(delta > 0)
{
if ((2*(delta-x)-1) > 0)
direction = 3; /*选择纵向减*/
else
direction = 2;
}
else
direction=2;

switch(direction)
{
case 1:
x++;/*只横坐标远离原点*/
delta += (2*x+1); /*小执行到这，所以加*/
break;
case 2:
x++;
y--;/*横向远离，同时纵向靠近*/
delta += 2*(x-y+1); /*即(2*x+1)+(-2*y+1)*/
break;
case 3:
y--;/*只纵坐标靠近原点*/
delta += (-2*y+1); /*大执行到这，所以减*/
break;
}
}
}

‘玖’ 怎样用C语言画圆

#include <windows.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[])
{
char arg[50]={0};
arg[0]= '\ " ';
strcpy(arg+1,argv[0]);
int len=int(strlen(arg));
arg[len]= '\ " ';

HWND hWnd=FindWindow(NULL,arg); //找到程序运行窗口的句柄
HDC hDC=GetDC(hWnd);//通过窗口句柄得到该窗口的设备场境句柄
HPEN hPen,hOldPen; //画笔
int i=0;

for(;i <500;++i)
SetPixel(hDC,10+i,10+i,0x0000ff);//用画点的办法画一根线,最后一个参数是颜色（32位）

hPen=CreatePen(PS_SOLID,2,0x00ff00);//生成绿色画笔
hOldPen=(HPEN)SelectObject(hDC,hPen);//把画笔引入设备场境

MoveToEx(hDC,20,50,NULL); //设置画线起点
LineTo(hDC,520,550); //画到终点

Arc(hDC,100,100,300,300,350,500,350,500);//画圆

SelectObject(hDC,hOldPen);
ReleaseDC(hWnd,hDC);

//下面是对比，表明它确实是控制台程序

printf( "hello console ");
system( "pause ");
return 0;

}

‘拾’ bresenham法画圆的C程序

int Bres(int x0,int y0,double r,int color)

{
int x,y,d;
x=0;
y=(int)r;
d=(int)(3-2*r);
while(x<y)
{
cirpot(x0,y0,x,y,color);
if(d<0)
d+=4*x+6;
else
{
d+=4*(x-y)+10;
y--;
}
x++;
}
if(x==y)
cirpot(x0,y0,x,y,color);
return(0);
}
int cirpot(int x0,int y0,int x,int y,int color)
{
setcolor(color);
putxicl((x0+x),(y0+y));
putxicl((x0+y),(y0+x));
putxicl((x0+y),(y0-x));
putxicl((x0+x),(y0-y));
putxicl((x0-x),(y0-y));
putxicl((x0-y),(y0-x));
putxicl((x0-y),(y0+x));
putxicl((x0-x),(y0+y));
setcolor(color);
return(0);
}

这是圆的算法，你若要整个程序，把你的电邮给我，我给你发过去、
运行环境是Turboc 2.0
int Bresline(int x1,inty1,int x2,int y2,int color)
{
int color,itag;
int dx,dy,tx,ty,inc1,inc2,d,curx,cury;
setcolor(color);
putxicl(x1,y1);
if(x1==x2&&y1==y2)
{
setcolor(color);
return(1);
}
itag=0;
dx=abs(x2-x1);
dy=abs(y2-y1);
if(dx<dy)
{
itag=1;]
iswap(&x1,&y1);
iswap(&x2,&y2);
iswap(&dx,&dy);
}
tx=(x2-x1)>0? 1:-1;
ty=(y2-y1)>0? 1:-1;
curx=x1;
cury=y1;
inc1=2*dy;
inc2=2*(dy-dx);
d=inc1-dx;
while(curx!x2)
{
if(d<0)
{
d+=inc1;
}
else
{
cury+=ty;
d+=inc2;
}
if(itag)
setpixel(cury,curx);