Initial commit.

Author: mattatz

.gitignore

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+[Ll]ibrary/
+[Tt]emp/
+[Oo]bj/
+[Bb]uild/
+[Pp]rojectSettings/
+
+# Autogenerated VS/MD solution and project files
+*.csproj
+*.unityproj
+*.sln
+*.suo
+*.user
+*.userprefs
+*.pidb
+*.booproj
+
+# Unity3D Generated File On Crash Reports
+sysinfo.txt

Captures/suibokuga.gif

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+unity-cellular-automaton-based-ink-simulation
+=====================
+
+Cellular automaton based ink simulation for Unity.
+
+![suibokuga](https://raw.githubusercontent.com/mattatz/unity-cellular-automaton-based-ink-simulation/master/Captures/suibokuga.gif)
+
+## Sources
+
+- Simple cellular automation-based simulation of ink behaviour and its application to Suibokuga-like 3D rendering of trees - http://kucg.korea.ac.kr/seminar/2004/src/PA-04-09.pdf
+

README.md

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+using UnityEngine;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Utils {
+	public class FboPingPong {
+
+		private int _readTex  = 0;
+		private int _writeTex = 1;
+		private RenderTexture[] _buffer;
+
+		/// <summary>
+		/// Init the specified width_ and height_.
+		/// </summary>
+		/// <param name="width_">Width_.</param>
+		/// <param name="height_">Height_.</param>
+		public FboPingPong (int width_, int height_, FilterMode filterMode = FilterMode.Point, TextureWrapMode wrapMode = TextureWrapMode.Repeat){
+
+			_readTex  = 0;
+			_writeTex = 1;
+
+			_buffer = new RenderTexture [2];
+
+			for (int i = 0; i < 2; i++){
+				_buffer [i] = new RenderTexture (width_, height_, 0, RenderTextureFormat.ARGBFloat);
+				_buffer [i].hideFlags  = HideFlags.DontSave;
+				_buffer [i].filterMode = filterMode;
+				_buffer [i].wrapMode   = wrapMode;
+				_buffer [i].Create ();
+			}
+
+			Clear ();
+		}
+
+		/// <summary>
+		/// Swap buffers.
+		/// </summary>
+		public void Swap (){
+			//RenderTexture temp = _buffer[0];
+			//_buffer [0] = _buffer [1];
+			//_buffer [1] = temp;
+			int t     = _readTex;
+			_readTex  = _writeTex;
+			_writeTex = t;
+		}
+
+		/// <summary>
+		/// Clear buffers.
+		/// </summary>
+		public void Clear (){
+			for (int i = 0; i < _buffer.Length; i++){
+				RenderTexture.active = _buffer [i];
+				GL.Clear (false, true, Color.black);
+				RenderTexture.active = null;
+			}
+		}
+
+		/// <summary>
+		/// Delete buffers.
+		/// </summary>
+		public void Delete (){
+			if (_buffer != null) {
+				for (int i = 0; i < _buffer.Length; i++){
+					_buffer[i].Release ();
+					_buffer[i].DiscardContents ();
+					_buffer[i] = null;
+				}
+			}
+		}
+
+		/// <summary>
+		/// Gets the read tex.
+		/// </summary>
+		/// <returns>The read tex.</returns>
+		public RenderTexture GetReadTex (){
+			return _buffer [_readTex];	
+		}
+
+		/// <summary>
+		/// Gets the write tex.
+		/// </summary>
+		/// <returns>The write tex.</returns>
+		public RenderTexture GetWriteTex (){
+			return _buffer [_writeTex];
+		}
+
+	}
+
+}
+
+

Suibokuga/Assets/Scenes.meta

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+using UnityEngine;
+using System.Collections;
+ 
+using Utils;
+
+[RequireComponent (typeof (Camera) ) ]
+public class Suibokuga : MonoBehaviour {
+
+	[SerializeField] Shader shader;
+	Material mat;
+
+	[SerializeField] Texture2D paper;
+	[SerializeField, Range(0f, 1f)] float alpha = 1.0f;
+	[SerializeField, Range(0f, 0.005f)] float evaporation = 0.0001f;
+
+	[SerializeField, Range(0, 10)] int iterations = 4;
+	[SerializeField] int size = 1024;
+
+	FboPingPong fpp;
+
+	bool dragging = false;
+	Vector2 previous;
+
+	void Start () {
+		fpp = new FboPingPong(size, size);
+		mat = new Material(shader);
+
+		mat.SetTexture("_PaperTex", paper);
+
+		Init();
+	}
+	
+	void Update () {
+
+		Vector3 mousePos = Input.mousePosition;
+		Vector2 current = new Vector2(mousePos.x / Screen.width, mousePos.y / Screen.height);
+		mat.SetVector("_Prev", previous);
+
+		if(dragging) {
+			mat.SetVector("_Brush", new Vector3(current.x, current.y, 0.015f));
+		} else {
+			mat.SetVector("_Brush", new Vector3(0, 0, 0));
+		}
+
+		if(Input.GetMouseButtonDown(0)) {
+			dragging = true;
+		} else if(Input.GetMouseButtonUp(0)) {
+			dragging = false;
+		}
+
+		previous = current;
+
+		mat.SetFloat("_Alpha", alpha);
+		mat.SetFloat("_Evaporation", evaporation);
+
+		for(int i = 0; i < iterations; i++) {
+			Graphics.Blit(fpp.GetReadTex(), fpp.GetWriteTex(), mat, 1); // update
+			fpp.Swap();
+		}
+	}
+
+	void Init () {
+		Graphics.Blit(fpp.GetReadTex(), fpp.GetWriteTex(), mat, 0); // init
+		fpp.Swap();
+	}
+
+	void OnRenderImage (RenderTexture src, RenderTexture dst) {
+		Graphics.Blit(fpp.GetReadTex(), dst, mat, 2);
+	}
+
+	void OnGUI () {
+		const float offset = 10;
+		if(GUI.Button(new Rect(offset, offset, 100, 30), "Reset")) {
+			Init();
+		}
+	}
+
+}