Geometry & Recognition

Fixed-point version: 선분 길이가 4096 픽셀 정도까지는 1-pixel 이내의 오차로 그려진다.

void DDALine(CPoint A, CPoint B) {
    const int mulfac = 4096; // 2^12 = 4096;
    int dx = B.x - A.x;
    int dy = B.y - A.y;
    int adx = dx < 0 ? -dx : dx;
    int ady = dy < 0 ? -dy : dy;
    int steps = adx < ady ? ady : adx;
    if (steps == 0) SetPixel(A.x, A.y); //single point;
    else {
        int curX = A.x * mulfac;      
        int curY = A.y * mulfac;
        dx = (dx * mulfac) / steps;
        dy = (dy * mulfac) / steps;
        while (steps-- >= 0) {
            SetPixel(curX / mulfac, curY / mulfac);
            curX += dx;
            curY += dy;
        }
    }
}

void DDALine(int x0, int y0, int x1, int y1)  { 
    int dx = x1 - x0; 
    int dy = y1 - y0; 
    // calculate steps required for generating pixels 
    int steps = abs(dx) > abs(dy) ? abs(dx) : abs(dy); 
    float xinc = dx / (float)steps; 
    float yinc = dy / (float)steps; 
    float x = x0; 
    float y = x0; 
    for (int i = 0; i <= steps; i++) { 
        SetPixel(round(x), round(y));
        x += xinc;
        y += yinc;
    } 
}