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@pharan pharan/PaintBrush.cs
Created Nov 11, 2017

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Unity PaintBrush MonoBehaviour class based on https://pastebin.com/rMx1PVXi
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PaintBrush : MonoBehaviour
{
public int resolution = 512;
Texture2D whiteMap;
public float brushSize;
public Texture2D brushTexture;
Vector2 stored;
public static Dictionary<Collider, RenderTexture> paintTextures = new Dictionary<Collider, RenderTexture>();
void Start()
{
CreateClearTexture();// clear white texture to draw on
}
void Update()
{
Debug.DrawRay(transform.position, Vector3.down * 20f, Color.magenta);
RaycastHit hit;
if (Physics.Raycast(transform.position, Vector3.down, out hit))
//if (Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hit)) // delete previous and uncomment for mouse painting
{
Collider coll = hit.collider;
if (coll != null)
{
if (!paintTextures.ContainsKey(coll)) // if there is already paint on the material, add to that
{
Renderer rend = hit.transform.GetComponent<Renderer>();
paintTextures.Add(coll, getWhiteRT());
rend.material.SetTexture("_PaintMap", paintTextures[coll]);
}
if (stored != hit.lightmapCoord) // stop drawing on the same point
{
stored = hit.lightmapCoord;
Vector2 pixelUV = hit.lightmapCoord;
pixelUV.y *= resolution;
pixelUV.x *= resolution;
DrawTexture(paintTextures[coll], pixelUV.x, pixelUV.y);
}
}
}
}
void DrawTexture(RenderTexture rt, float posX, float posY)
{
RenderTexture.active = rt; // activate rendertexture for drawtexture;
GL.PushMatrix(); // save matrixes
GL.LoadPixelMatrix(0, resolution, resolution, 0); // setup matrix for correct size
// draw brushtexture
Graphics.DrawTexture(new Rect(posX - brushTexture.width / brushSize, (rt.height - posY) - brushTexture.height / brushSize, brushTexture.width / (brushSize * 0.5f), brushTexture.height / (brushSize * 0.5f)), brushTexture);
GL.PopMatrix();
RenderTexture.active = null;// turn off rendertexture
}
RenderTexture getWhiteRT()
{
RenderTexture rt = new RenderTexture(resolution, resolution, 32);
Graphics.Blit(whiteMap, rt);
return rt;
}
void CreateClearTexture()
{
whiteMap = new Texture2D(1, 1);
whiteMap.SetPixel(0, 0, Color.white);
whiteMap.Apply();
}
}
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