Unity 画图效果

1.PS做一个带透明通道圆作为笔刷2.通过设置颜色把这个笔刷纹理渲染到RenderTexture上

using UnityEngine;using System.Collections;using System;using System.Collections.Generic;using System.Linq;using System.IO;public class Painting : MonoBehaviour {private RenderTexture texRender;public Material mat;public Texture  brushTypeTexture;private enum BrushColor{red,green,blue,pink,yellow,gray,black,white,count,}private float brushScale = 0.5f;private BrushColor brushColorType = BrushColor.black;private Color [] brushColor = new Color[(int)BrushColor.count] {Color.red,Color.green,Color.blue,new Color(255,0,255),Color.yellow,Color.gray,Color.black,Color.white};void Start () {texRender = new RenderTexture (Screen.width, Screen.height,24,RenderTextureFormat.ARGB32);Clear (texRender);}Vector3 startPosition = Vector3.zero;Vector3 endPosition = Vector3.zero;void Update () {if(Input.GetMouseButton(0)){OnMouseMove(new Vector3(Input.mousePosition.x,Input.mousePosition.y,0));}if(Input.GetMouseButtonUp(0)){OnMouseUp();}}void OnMouseUp(){startPosition = Vector3.zero;}void OnMouseMove(Vector3 pos){endPosition = pos;DrawBrush(texRender,(int)endPosition.x,(int)endPosition.y,brushTypeTexture,brushColor[(int)brushColorType],brushScale);if(startPosition.Equals(Vector3.zero)){startPosition = endPosition;return;}float distance = Vector3.Distance(startPosition,endPosition);if (distance > 1){int d = (int)distance;for (int i = 0; i < d; i++){float difx = endPosition.x - startPosition.x;float dify = endPosition.y - startPosition.y;float delta = (float)i / distance;DrawBrush(texRender,new Vector2(startPosition.x + (difx * delta), startPosition.y + (dify * delta)),brushTypeTexture,brushColor[(int)brushColorType],brushScale);}}startPosition = endPosition;}void Clear(RenderTexture destTexture){Graphics.SetRenderTarget (destTexture);GL.PushMatrix();GL.Clear(true,true,Color.white);GL.PopMatrix();}void DrawBrush(RenderTexture destTexture,Vector2 pos,Texture sourceTexture,Color color,float scale){DrawBrush (destTexture,(int)pos.x, (int)pos.y, sourceTexture,color,scale);}void DrawBrush(RenderTexture destTexture,int x,int y,Texture sourceTexture,Color color,float scale){DrawBrush (destTexture, new Rect (x, y, sourceTexture.width, sourceTexture.height), sourceTexture,color,scale);}void DrawBrush(RenderTexture destTexture,Rect destRect,Texture sourceTexture,Color color,float scale){float left = destRect.left - destRect.width*scale / 2.0f;float right = destRect.left + destRect.width*scale / 2.0f;float top = destRect.top - destRect.height*scale / 2.0f;float bottom = destRect.top + destRect.height*scale / 2.0f;Graphics.SetRenderTarget (destTexture);GL.PushMatrix();GL.LoadOrtho();mat.SetTexture("_MainTex",brushTypeTexture);mat.SetColor ("_Color",color);mat.SetPass(0);GL.Begin(GL.QUADS);GL.TexCoord2(0.0f, 0.0f); GL.Vertex3(left/Screen.width, top/Screen.height, 0);GL.TexCoord2(1.0f, 0.0f); GL.Vertex3(right/Screen.width, top/Screen.height, 0);    GL.TexCoord2(1.0f, 1.0f); GL.Vertex3(right/Screen.width, bottom/Screen.height, 0);GL.TexCoord2(0.0f, 1.0f); GL.Vertex3(left/Screen.width, bottom/Screen.height, 0);GL.End();GL.PopMatrix();}bool bshow = true;void OnGUI() {if(bshow){GUI.DrawTexture(new Rect(0,0,Screen.width,Screen.height),texRender,ScaleMode.StretchToFill);}if(GUI.Button(new Rect(0,150,100,30),"clear")){Clear (texRender);}if(GUI.Button(new Rect(100,150,100,30),"hide")){bshow = !bshow;}int width = Screen.width / (int)BrushColor.count;for(int i=0; i<(int)BrushColor.count; i++){if(GUI.Button(new Rect(i*width,0,width,30),Enum.GetName(typeof(BrushColor),i))){brushColorType = (BrushColor)i;}}GUI.Label (new Rect (0, 200, 300, 30), "brushScale : " + brushScale.ToString("F2"));brushScale = (int)GUI.HorizontalSlider (new Rect (120, 205, 200, 30), brushScale*10.0f, 1, 50) / 10.0f;if(brushScale < 0.1f)brushScale = 0.1f;}}

Shader "Painting"{Properties{_MainTex ("MainTex (RGB) Trans (A)", 2D) = "white" {}_Color ("Color", Color) = (1,1,1,1)}SubShader{Tags{ "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane""CanUseSpriteAtlas"="True"}Cull OffLighting OffZWrite OffFog { Mode Off }Blend One OneMinusSrcAlphaPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct v2f{float4 vertex : SV_POSITION;half2 texcoord : TEXCOORD0;};fixed4 _Color;v2f vert(appdata_base IN){v2f OUT;OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);OUT.texcoord = IN.texcoord;return OUT;}sampler2D _MainTex;fixed4 frag(v2f IN) : SV_Target{float4 col = _Color * tex2D(_MainTex, IN.texcoord);col.rgb *= col.a;return col;}ENDCG}}}