Gradient Texture Material Property Drawer

GradientTextureDrawer.cs

using UnityEngine;
using UnityEditor;
using System;
using System.Runtime.InteropServices;

/// <summary>
/// Use with "[GradientTexture]" before a texture shader property.
/// Gives a gradient editor instead of a texture selector when viewing
/// in the editor.  Meaning you don't have to open any paint programs
/// to make gradient textures.
/// 
/// This is probably the hackiest code I've ever written...  Good luck!
///     -Aaron "Pyredrid" B-D
/// </summary>
public class GradientTextureDrawer : MaterialPropertyDrawer {
	//This is fairly arbitrary, just remember that textures generated are currently
	//nearest/point filtered due to the whole serializing gradients thing (read below)
	private const int WIDTH = 256;

	private Gradient textureGradient;
	
	public override void OnGUI(Rect position, MaterialProperty prop, string label, MaterialEditor editor) {
		Texture value = (prop.textureValue);
		EditorGUI.BeginChangeCheck();
		EditorGUI.showMixedValue = prop.hasMixedValue;

		if (textureGradient == null) {
			textureGradient = TextureToGradient((Texture2D)prop.textureValue);
		}

		EditorGUILayout.LabelField(label);
		textureGradient = EditorGUILayout.GradientField(textureGradient);

		EditorGUI.showMixedValue = false;
		if (EditorGUI.EndChangeCheck()) {
			value = GradientToTexture(textureGradient);
			prop.textureValue = value;
		}
	}

	private Texture2D GradientToTexture(Gradient gradient) {
		Texture2D texture = new Texture2D(WIDTH, 2);
		texture.filterMode = FilterMode.Point;
		texture.wrapMode = TextureWrapMode.Clamp;

		//After setting up the texture, store the gradients colors in regular intervals...
		//Also serialize the gradient iteself into the texture
		//This no doubt has issue, security problems, bugs, overflows...
		//codeHackery++;
		byte[] gradientBytes = gradient.RawSerializeEx();
		Color32[] gradientColorArray = new Color32[WIDTH];
		Color32[] colorArray = new Color32[WIDTH];

		for (int i = 0; i < WIDTH; i += 4) {
			if (i < gradientBytes.Length) {
				Color32 color = new Color32(gradientBytes[i + 0], gradientBytes[i + 1], gradientBytes[i + 2], gradientBytes[i + 3]);
				gradientColorArray[i / 4] = color;
			} else {
				break;
			}
		}
		for (int i = 0; i < WIDTH; i++) {
			colorArray[i] = gradient.Evaluate((float)i / WIDTH);
		}
		texture.SetPixels32(0, 0, WIDTH, 1, colorArray);
		texture.SetPixels32(0, 1, WIDTH, 1, gradientColorArray);

		texture.Apply();
		return texture;
	}

	private Gradient TextureToGradient(Texture2D texture) {
		if (texture == null) {
			return new Gradient();
		}
		try {
			//Unity, why the fuck can't GetPixels32() be used to get a block of pixels...
			//Seriously, the documentation even says "to get a block of pixels"
			//Why doesn't this do the same stuff as GetPixels()
			//What the fuck unity
			//codeHackery++;
			Color[] gradientColorArrayNon32 = new Color[WIDTH];
			byte[] gradientBytes = new byte[WIDTH * 4];
			gradientColorArrayNon32 = texture.GetPixels(0, 1, WIDTH, 1);
			for (int i = 0; i < WIDTH; i += 4) {
				gradientBytes[i + 0] = (byte)(gradientColorArrayNon32[i].r / 256);
				gradientBytes[i + 1] = (byte)(gradientColorArrayNon32[i].g / 256);
				gradientBytes[i + 2] = (byte)(gradientColorArrayNon32[i].b / 256);
				gradientBytes[i + 3] = (byte)(gradientColorArrayNon32[i].a / 256);
			}
			//After all that, we now have a serialized byte array of the gradient
			//stored in the texture itself.
			//codeHackery++;
			Gradient gradient = RawDeserializeEx<Gradient>(gradientBytes);
			return gradient;
		} catch (Exception e) {
			Debug.LogException(e);
			return new Gradient();
		}
	}

	//Both of these are taken from somewhere on stackoverflow
	//They're pretty terribly hacky and also only being used because Unity is bad
	//By which I mean, all of Unity's structs and classes aren't
	//Marked with System.Serializable, they do their own weird thing...
	//Whatever that is...  <.<'
	//codeHackery++;

	public static byte[] RawSerializeEx(object obj) {
		int rawsize = Marshal.SizeOf(obj);
		byte[] data = new byte[rawsize];
		GCHandle handle = GCHandle.Alloc(data, GCHandleType.Pinned);
		IntPtr buffer = handle.AddrOfPinnedObject();
		Marshal.StructureToPtr(obj, buffer, false);
		handle.Free();
		return data;
	}

	public static T RawDeserializeEx<T>(byte[] data) where T : class {
		int rawsize = Marshal.SizeOf(typeof(T));
		if (rawsize > data.Length) {
			return null;
		}
		GCHandle handle = GCHandle.Alloc(data, GCHandleType.Pinned);
		IntPtr buffer = handle.AddrOfPinnedObject();
		T retobj = Marshal.PtrToStructure<T>(buffer);
		handle.Free();
		return retobj;
	}
}