Handy Unity3D C# functions (2. colors)

Posted on May 09, 2014, by Richard Knol

Unity has the Color structure to define colors. But it does not offer a lot of features by default.

The functions below were written for the Unity3D AssetStore package Texture2D+. It adds functions to the Unty API for converting colors to and from Hex, convert colors between RGB and HSB. And allows you to perform basic image manipulation like scale, rotate, crop, contrast, etc on Textures. Here's the link to the Texture2D+ package in the AssetStore and here's the link to the documentation.

Convert Color to Hex String

On the web the color notation #RRGGBB is often used. So lets convert a Unity Color to a hexadecimal color string :

public static string HexString(Color aColor) {
	return HexString((Color32)aColor, false);
}
public static string HexString(Color aColor, 
		bool includeAlpha) {
	return HexString((Color32)aColor, includeAlpha);
}
public static string HexString(Color32 aColor, 
		bool includeAlpha) {
	String rs = Convert.ToString(aColor.r,16).ToUpper();
	String gs = Convert.ToString(aColor.g,16).ToUpper();
	String bs = Convert.ToString(aColor.b,16).ToUpper();
	String a_s = Convert.ToString(aColor.a,16).ToUpper();
	while(rs.Length < 2) rs= "0" + rs;
	while(gs.Length < 2) gs= "0" + gs;
	while(bs.Length < 2) bs= "0" + bs;
	while(a_s.Length < 2) a_s= "0" + a_s;
	if(includeAlpha) return "#"+ rs + gs + bs + a_s;
	return "#"+ rs + gs + bs;
}

Convert Hex String to Color

And of course we need to be able to do the opposit as well: Create a Color structure from a hex string:

public static Color MakeColor(string aStr) {
	Color clr = new Color(0,0,0);
	if(aStr!=null && aStr.Length>0) {
		try {
			string str = aStr.Substring(1, aStr.Length - 1);
			clr.r = (float)System.Int32.Parse(str.Substring(0,2), 
				NumberStyles.AllowHexSpecifier) / 255.0f;
			clr.g = (float)System.Int32.Parse(str.Substring(2,2), 
				NumberStyles.AllowHexSpecifier) / 255.0f;
			clr.b = (float)System.Int32.Parse(str.Substring(4,2), 
				NumberStyles.AllowHexSpecifier) / 255.0f;
			if(str.Length==8) clr.a = System.Int32.Parse(str.Substring(6,2), 
				NumberStyles.AllowHexSpecifier) / 255.0f;
			else clr.a = 1.0f;
		} catch(Exception e) {
			Debug.Log("Could not convert "+aStr+" to Color. "+e);
			return new Color(0,0,0,0);
		}
	}
	return clr;
}

Convert RBG float values to Color

But what if the input string is not in the #RRGGBB format, but written like "0.3, 0.5, 1.0". This next functions looks whether the "#" character or the "," separator is present"

public static Color MakeColor(string aStr) {
	Color clr = new Color(0,0,0);
	if(aStr!=null && aStr.Length>0) {
		try {
			if(aStr.Substring(0,1)=="#") {  // #FFFFFF format
				string str = aStr.Substring(1, aStr.Length - 1);
				clr.r = (float)System.Int32.Parse(str.Substring(0,2), 
					NumberStyles.AllowHexSpecifier) / 255.0f;
				clr.g = (float)System.Int32.Parse(str.Substring(2,2), 
					NumberStyles.AllowHexSpecifier) / 255.0f;
				clr.b = (float)System.Int32.Parse(str.Substring(4,2), 
					NumberStyles.AllowHexSpecifier) / 255.0f;
				if(str.Length==8) clr.a = System.Int32.Parse(str.Substring(6,2), 
					NumberStyles.AllowHexSpecifier) / 255.0f;
				else clr.a = 1.0f;
			} else if(aStr.IndexOf(",",0)>=0) {  // 0.3, 1.0, 0.2 format
				int p0 = 0;
				int p1 = 0;
				int c = 0;
				p1 = aStr.IndexOf(",",p0);
				while(p1>p0 && c<4) {
					clr[c++] = float.Parse(aStr.Substring(p0,p1-p0));
					p0=p1+1;
					if(p0 < aStr.Length) p1 = aStr.IndexOf(",",p0);
					if(p1 < 0) p1 = aStr.Length;
				}
				if(c<4) clr.a = 1.0f;
			}
		} catch(Exception e) {
			Debug.Log("Could not convert "+aStr+" to Color. "+e);
			return new Color(0,0,0,0);
		}
	}
	return clr;
}

Convert Color to HSB Vector

This is all for RGB colors, which is nice, but often in games you need to alter colors in a different way. For instance fade something to grey, intensify a color to highlight an object, etc. In this case using HSB to describe colors is much more convenient. To fade something to grey, simply reduce the Saturation, To makesomething darket, reduce the Brightness. I use a Vector3 or Vector4 to represent HSB colors. So first lets convert a normal RGB color to a HSB Vector:

public static Vector3 MakeHSB(Color c) {
    float minValue = Mathf.Min(c.r, Mathf.Min(c.g, c.b));
    float maxValue = Mathf.Max(c.r, Mathf.Max(c.g, c.b));
    float delta = maxValue - minValue;
    float h = 0.0f;
    float s = 0.0f;
    float b = maxValue;

    // # Calculate the hue (in degrees of a circle, between 0 and 360)
    if(maxValue == c.r) {
        if(c.g >= c.b) {
            if(delta == 0.0f) h = 0.0f;
            else h = 60.0f * (c.g - c.b) / delta;
        } else if(c.g < c.b) {
            h = 60.0f * (c.g - c.b) / delta + 360f;
        }
    } else if(maxValue == c.g) {
        h = 60.0f * (c.b - c.r ) / delta + 120f;
    } else if(maxValue == c.b) {
        h = 60.0f * (c.r - c.g) / delta + 240f;
    }

    // Calculate the saturation (between 0 and 1)
    if(maxValue == 0.0) s = 0.0f;
    else s = 1.0f - (minValue / maxValue);
    return new Vector3(h / 360.0f, s, b);
}

The Vector's x, y, and z now represent hue, saturation and brightness.

If you also need alpha, a Vector4 is needed:

public static Vector4 MakeHSBA(Color c) {
    float minValue = Mathf.Min(c.r, Mathf.Min(c.g, c.b));
    float maxValue = Mathf.Max(c.r, Mathf.Max(c.g, c.b));
    float delta = maxValue - minValue;
    float h = 0.0f;
    float s = 0.0f;
    float b = maxValue;

    // # Calculate the hue (in degrees of a circle, between 0 and 360)
    if(maxValue == c.r) {
        if(c.g >= c.b) {
            if(delta == 0.0f) h = 0.0f;
            else h = 60.0f * (c.g - c.b) / delta;
        } else if(c.g < c.b) {
            h = 60.0f * (c.g - c.b) / delta + 360f;
        }
    } else if(maxValue == c.g) {
        h = 60.0f * (c.b - c.r ) / delta + 120f;
    } else if(maxValue == c.b) {
        h = 60.0f * (c.r - c.g) / delta + 240f;
    }

    // Calculate the saturation (between 0 and 1)
    if(maxValue == 0.0) s = 0.0f;
    else s = 1.0f - (minValue / maxValue);
    return new Vector4(h / 360.0f, s, b, c.a);
}

Convert HSB float values to Color

And now the opposit, converting a HSBA Vector4 or HSB Vector3 into a Color:

public static Color MakeColor(Vector3 hsb) {
	return MakeColor(new Vector4(hsb.x, hsb.y, hsb.z, 1.0f));
}
public static Color MakeColor(Vector4 hsba) {
    // When saturation = 0, then r, g, b represent grey value (= brightness (z)).
    float r = hsba.z;
    float g = hsba.z;
    float b = hsba.z;
	if(hsba.y > 0.0f) {  // saturation > 0
        // Calc sector
    	float secPos = (hsba.x * 360.0f) / 60.0f;
    	int secNr = Mathf.FloorToInt(secPos);
    	float secPortion = secPos - secNr;

    	// Calc axes p, q and t
    	float p = hsba.z * (1.0f - hsba.y);
    	float q = hsba.z * (1.0f - (hsba.y * secPortion));
    	float t = hsba.z * (1.0f - (hsba.y * (1.0f - secPortion)));

    	// Calc rgb
       	if(secNr == 1) {
            r = q;
            g = hsba.z;
            b = p;
        } else if(secNr == 2) {
            r = p;
            g = hsba.z;
            b = t;
        } else if(secNr == 3) {
            r = p;
            g = q;
            b = hsba.z;
        } else if(secNr == 4) {
            r = t;
            g = p;
            b = hsba.z;
        } else if(secNr == 5) {
            r = hsba.z;
            g = p;
            b = q;
        } else {
            r = hsba.z;
            g = t;
            b = p;
        }
    }
    return new Color(r, g, b, hsba.w);
}