TextureFloodFill

Description

Two extension methods for Texture2D which allows you to perform a floodfill operation on the texture.

FloodFillArea will fill the area around the reference point as long as the color stays the same. The reference coler is taken from the start-point-pixel.

FloodFillBorder will fill the area around the reference point until it reaches the given border color.

Both functions only perform a 4-direction method (north,east,south,west). This equals the behaviour of usual filling methods like in MS Paint.

Usage

Place this script somewhere in your project or in "Assets/Standard Assets/" if you want to use the functions from a foreign language (not C#).

To use it you can simply call the desired function like this from any language:

    texture.FloodFillArea(10,10,Color.red);
    // When you're done call Apply to commit your changes.
    texture.Apply();

where "texture" is a Texture2D variable with a texture that is "writable".

TextureExtension.cs

public static class TextureExtension
{
    public struct Point
    {
        public short x;
        public short y;
        public Point(short aX, short aY) { x = aX; y = aY; }
        public Point(int aX, int aY) : this((short)aX, (short)aY) { }
    }
 
    public static void FloodFillArea(this Texture2D aTex, int aX, int aY, Color aFillColor)
    {
        int w = aTex.width;
        int h = aTex.height;
        Color[] colors = aTex.GetPixels();
        Color refCol = colors[aX + aY * w];
        Queue<Point> nodes = new Queue<Point>();
        nodes.Enqueue(new Point(aX, aY));
        while (nodes.Count > 0)
        {
            Point current = nodes.Dequeue();
            for (int i = current.x; i < w; i++)
            {
                Color C = colors[i + current.y * w];
                if (C != refCol || C == aFillColor)
                    break;
                colors[i + current.y * w] = aFillColor;
                if (current.y + 1 < h)
                {
                    C = colors[i + current.y * w + w];
                    if (C == refCol && C != aFillColor)
                        nodes.Enqueue(new Point(i, current.y + 1));
                }
                if (current.y - 1 >= 0)
                {
                    C = colors[i + current.y * w - w];
                    if (C == refCol && C != aFillColor)
                        nodes.Enqueue(new Point(i, current.y - 1));
                }
            }
            for (int i = current.x - 1; i >= 0; i--)
            {
                Color C = colors[i + current.y * w];
                if (C != refCol || C == aFillColor)
                    break;
                colors[i + current.y * w] = aFillColor;
                if (current.y + 1 < h)
                {
                    C = colors[i + current.y * w + w];
                    if (C == refCol && C != aFillColor)
                        nodes.Enqueue(new Point(i, current.y + 1));
                }
                if (current.y - 1 >= 0)
                {
                    C = colors[i + current.y * w - w];
                    if (C == refCol && C != aFillColor)
                        nodes.Enqueue(new Point(i, current.y - 1));
                }
            }
        }
        aTex.SetPixels(colors);
    }
 
    public static void FloodFillBorder(this Texture2D aTex, int aX, int aY, Color aFillColor, Color aBorderColor)
    {
        int w = aTex.width;
        int h = aTex.height;
        Color[] colors = aTex.GetPixels();
        byte[] checkedPixels = new byte[colors.Length];
        Color refCol = aBorderColor;
        Queue<Point> nodes = new Queue<Point>();
        nodes.Enqueue(new Point(aX, aY));
        while (nodes.Count > 0)
        {
            Point current = nodes.Dequeue();
 
            for (int i = current.x; i < w; i++)
            {
                if (checkedPixels[i + current.y * w] > 0 || colors[i + current.y * w] == refCol)
                    break;
                colors[i + current.y * w] = aFillColor;
                checkedPixels[i + current.y * w] = 1;
                if (current.y + 1 < h)
                {
                    if (checkedPixels[i + current.y * w + w] == 0 && colors[i + current.y * w + w] != refCol)
                        nodes.Enqueue(new Point(i, current.y + 1));
                }
                if (current.y - 1 >= 0)
                {
                    if (checkedPixels[i + current.y * w - w] == 0 && colors[i + current.y * w - w] != refCol)
                        nodes.Enqueue(new Point(i, current.y - 1));
                }
            }
            for (int i = current.x - 1; i >= 0; i--)
            {
                if (checkedPixels[i + current.y * w] > 0 || colors[i + current.y * w] == refCol)
                    break;
                colors[i + current.y * w] = aFillColor;
                checkedPixels[i + current.y * w] = 1;
                if (current.y + 1 < h)
                {
                    if (checkedPixels[i + current.y * w + w] == 0 && colors[i + current.y * w + w] != refCol)
                        nodes.Enqueue(new Point(i, current.y + 1));
                }
                if (current.y - 1 >= 0)
                {
                    if (checkedPixels[i + current.y * w - w] == 0 && colors[i + current.y * w - w] != refCol)
                        nodes.Enqueue(new Point(i, current.y - 1));
                }
            }
        }
        aTex.SetPixels(colors);
    }
}

Author: Bunny83