wu_circle+antialiasing.cpp

/***********************************************************************
This code is generated by the AlgoPascal translator

This code is distributed under the ALGLIB license
    (see http://www.alglib.net/copyrules.php for details)
***********************************************************************/

#include "ap.h"

/*-----------------------------------------------
This routines must be defined by the programmer:

void setpixel(int x, int y, double alpha);
-----------------------------------------------*/

void drawwucircle(int cx, int cy, int r);

/*************************************************************************
<<<<<<< HEAD
Рисование круга с использованием метода Ву для
антиалиасинга.
=======
Ðèñîâàíèå êðóãà ñ èñïîëüçîâàíèåì ìåòîäà Âó äëÿ
àíòèàëèàñèíãà.
>>>>>>> 58e3d87... Added Wu's antialiasing algorithms for circle, ellipsis, line
*************************************************************************/
void drawwucircle(int cx, int cy, int r)
{
    int x;
    int y;
    double t;
    double d;
    int j;
    int kx;
    int ky;
    int lastx;

    x = r;
    lastx = r;
    y = 0;
    t = 0;
    for(j = 0; j <= 3; j++)
    {
        kx = j%2*2-1;
        ky = j/2%2*2-1;
        setpixel(kx*x+cx, ky*y+cy, double(1));
        setpixel(kx*y+cx, ky*x+cy, double(1));
    }
    while(x>y)
    {
        y = y+1;
        d = ap::iceil(sqrt(double(r*r-y*y)))-sqrt(double(r*r-y*y));
        if( d<t )
        {
            x = x-1;
        }
        if( x<y )
        {
            break;
        }
        if( x==y&&lastx==x )
        {
            break;
        }
        for(j = 0; j <= 3; j++)
        {
            kx = j%2*2-1;
            ky = j/2%2*2-1;
            setpixel(kx*x+cx, ky*y+cy, 1-d);
            setpixel(kx*y+cx, ky*x+cy, 1-d);
            if( x-1>=y )
            {
                setpixel(kx*(x-1)+cx, ky*y+cy, d);
                setpixel(kx*y+cx, ky*(x-1)+cy, d);
            }
        }
        t = d;
        lastx = x;
    }
}