Drawing a solid circle onto texture

Question

Has anyone modified Eric Haines' (Eric5h5) TextureDrawCircle script to draw a solid circle? It currently draws only the perimeter. Any suggestions on how a solid circle drawing algorithm would go?

Here's a link to Eric's lovely script: TextureDrawCircle - Unify Wiki

and here's a snippet:

 static function Circle (tex : Texture2D, cx : int, cy : int, r : int, col : Color) {
     var y = r;
     var d = 1/4 - r;
     var end = Mathf.Ceil(r/Mathf.Sqrt(2));
  
     for (x = 0; x <= end; x++) {
         tex.SetPixel(cx+x, cy+y, col);
         tex.SetPixel(cx+x, cy-y, col);
         tex.SetPixel(cx-x, cy+y, col);
         tex.SetPixel(cx-x, cy-y, col);
         tex.SetPixel(cx+y, cy+x, col);
         tex.SetPixel(cx-y, cy+x, col);
         tex.SetPixel(cx+y, cy-x, col);
         tex.SetPixel(cx-y, cy-x, col);
  
         d += 2*x+1;
         if (d > 0) {
             d += 2 - 2*y--;
         }
     }
 }

Thank you very much!

Answer 1

Best Answer

Answer by pajamajama · Dec 06, 2013 at 08:58 PM

Problem solved! Below is a modified function for creating a solid circle!

 public void Circle(Texture2D tex, int cx, int cy, int r, Color col)
     {
         int x, y, px, nx, py, ny, d;
         
         for (x = 0; x <= r; x++)
         {
             d = (int)Mathf.Ceil(Mathf.Sqrt(r * r - x * x));
             for (y = 0; y <= d; y++)
             {
                 px = cx + x;
                 nx = cx - x;
                 py = cy + y;
                 ny = cy - y;
 
                 tex.SetPixel(px, py, col);
                 tex.SetPixel(nx, py, col);
  
                 tex.SetPixel(px, ny, col);
                 tex.SetPixel(nx, ny, col);
 
             }
         }    
     }

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Bunny83 · Dec 06, 2013 at 09:07 PM 0

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and accepted :)

Keep in mind that SetPixel for filling a large area is quite slow. You might want to use GetPixels32, work on the array and assign it back to SetPixels32.

pajamajama · Dec 07, 2013 at 09:25 AM 1

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Thanks Bunny83!

Here's a modified Circle function that uses Get/SetPixels, in case it helps anyone.

     public void Circle(Texture2D tex, int cx, int cy, int r, Color col)
     {
         int x, y, px, nx, py, ny, d;
             Color[] tempArray = tex.GetPixels32;
 
         for (x = 0; x <= r; x++)
         {
             d = (int)Mathf.Ceil(Mathf.Sqrt(r * r - x * x));
             for (y = 0; y <= d; y++)
             {
                 px = cx + x;
                 nx = cx - x;
                 py = cy + y;
                 ny = cy - y;
 
                 tempArray[py*1024 + px] = col;
                 tempArray[py*1024 + nx] = col;
                 tempArray[ny*1024 + px] = col;
                 tempArray[ny*1024 + nx] = col;
             }
         }    
         tex.SetPixels32(tempArray);
         tex.Apply ();
     }

lvictorino pajamajama · May 17, 2016 at 02:21 PM 0

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Well... for those passing here... note that the 1024 value @pajamajama uses in the example above seems to be the size of his texture... to make it work with your texture replace 1024 by tex.width.

Drawing a solid circle onto texture

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