Bresenham's Line Algorithm

♣ The Algorithm ::

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1. Compute the initial values:

   dx = x2 - x1 Inc2 = 2(dy - dx)
   dy = y2 - y1 d = Inc1 - dx
   Inc1 = 2dy
  

2. Set (x,y) equal to the lower left-hand endpoint and x_end equal to the largest value of x. If dx < 0, then x = x₂, y = y₂, x_end = x₁. If dx > 0, then x = x₁, y = y₁, x_end = x₂.
3. Plot a point at the current (x,y) coordinates.
4. Test to see whether the entire line has been drawn. If x = x_end, stop.
5. Compute the location of the next pixel. If d < 0, then d = d + Inc₁. If d >e; 0, then d = d + Inc₂, and then y = y + 1.
6. Increment x: x = x + 1.
7. Plot a point at the current (x,y) coordinates.
8. Go to step 4.

♣ C / C++ Code ::

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void BresenhamsLine(int x1, int y1, int x2, int y2) {
    int dx, dy, Inc1, Inc2, d, x, y, xend; 
 
    dx = x2-x1; 
    dy = y2 - y1; 
    Inc1 = 2*dy; 
    Inc2 = 2*(dy - dx); 
    d = Inc1 - dx; 
 
    if(dx < 0) { x=x2, y=y2, xend=x1; } else 
    if(dx > 0) { x=x1, y=y1, xend=x2; } 
 
    while(x <= xend) { 
        if(d < 0) { d += Inc1; } else 
        if(d >= 0) { d += Inc2, y++; } 
        x++; 
        putpixel(x, y, LIGHTCYAN); 
    } 
}

♣ JAVA Code ::

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public class BresenhamsLine extends JPanel { 
 
    private int x1, y1, x2, y2, dx, dy, Inc1, Inc2, d, x, y, xend;
 
    BufferedImage image = new BufferedImage(600, 600, BufferedImage.TYPE_INT_ARGB);  
    WritableRaster raster = image.getRaster(); 
 
    public BresenhamsLine(int x1, int y1, int x2, int y2) { 
        this.x1 = x1; 
        this.y1 = y1; 
        this.x2 = x2; 
        this.y2 = y2; 
    } 
 
    public void paintComponent(Graphics g) { 
        super.paintComponent(g); 
        int color[] = {250, 0, 0, 250}; 
        raster.setPixel(0, 0, color); 
 
        dx = x2 - x1; 
        dy = y2 - y1; 
        Inc1 = 2 * dy; 
        Inc2 = 2 * (dy - dx); 
        d = Inc1 - dx;
 
 
        if (dx < 0) { x = x2; y = y2; xend = x1; } else 
        if (dx > 0) { x = x1; y = y1; xend = x2; } 
 
        while (x <= xend) { 
            if (d < 0) { d += Inc1; } else 
            if (d >= 0) { d += Inc2; y++; } 
            x++;  
            g.drawImage(image, x, y, this); 
        }
    } 
} 

♣ Source Codes ::

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• Bresenham's Line Algorithm.cpp
• Bresenham's Line Algorithm.java

আবদুল্লাহ বিন ওমার (রাঃ) হতে বর্ণিত। 'রসূলুল্লাহ (সঃ) বলেছেনঃ তোমাদের কেউ নামায পড়লে সে যেন তার দু'কাপড়ে নামায পড়ে। সৌন্দর্য প্রকাশের অগ্রাধিকার আল্লাহর জন্যই।' (তাহাওয়ী, বায়হাকী, তাবরানী)