// Copyright (c) 2010 Bob Berkebile// Please direct any bugs/comments/suggestions to http://www.pixelplacement.com//// Permission is hereby granted, free of charge, to any person obtaining a copy// of this software and associated documentation files (the "Software"), to deal// in the Software without restriction, including without limitation the rights// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell// copies of the Software, and to permit persons to whom the Software is// furnished to do so, subject to the following conditions://// The above copyright notice and this permission notice shall be included in// all copies or substantial portions of the Software.//// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN// THE SOFTWARE.using UnityEngine;using System.Collections;public class Backdrop : MonoBehaviour{const string SHADER_CODE = "Shader \"UnlitAlpha\"{" +"Properties {" + "_Color (\"Color Tint (A = Opacity)\", Color) = (1,1,1,1) " + "_MainTex (\"Texture (A = Transparency)\", 2D) = \"\"" + "} " + "SubShader { " + "Tags {" + "Queue = Transparent" + "}" + "ZWrite Off Blend SrcAlpha OneMinusSrcAlpha Pass {" + "SetTexture[_MainTex] {" + "Combine texture * constant ConstantColor[_Color]" + "}" + "}" + "}" + "}";public Texture2D image;public float distance = 500;GameObject backdrop;Mesh mesh;float prevDistance;Vector3 prevRotation, prevPosition;Texture2D prevImage;void Start (){//check that we are on a camera!if(camera == null){Debug.LogError("Backdrop must be used on a camera!");Destroy(this);return;}//create backdrop GameObject and components:backdrop = new GameObject("Backdrop");backdrop.AddComponent<MeshFilter>();backdrop.AddComponent<MeshRenderer>();backdrop.transform.parent = transform;backdrop.renderer.material = new Material(SHADER_CODE);mesh = backdrop.GetComponent<MeshFilter>().mesh;mesh.vertices = CalcVerts();mesh.uv = new Vector2[] {new Vector2(0,0), new Vector2(1,0), new Vector2(0,1), new Vector2(1,1)};mesh.triangles = new int[] {1,0,3,3,0,2};}void Update(){//reset texture if it has changed:if( backdrop.renderer.material.mainTexture != image ){backdrop.renderer.material.mainTexture = image;}//nothing needs to be recalculated if distance hasn't changed or a move/rotate was attempted on billboard moved without our permission:if(distance == prevDistance && backdrop.transform.position == prevPosition && backdrop.transform.localEulerAngles == prevRotation ) return;//error for attempting a backdrop placement beyond camera's far clip plane:if(distance > camera.farClipPlane){Debug.LogError("Backdrop's distance is further than the camera's far clip plane. Extend the camera's far clip plane or reduce the billboard's distance.");return;}//error for attempting a backdrop placement before camera's near clip plane:if(distance < camera.nearClipPlane){Debug.LogError("Backdrop's distance is closer than the camera's near clip plane. Extend the distance or reduce the camera's near clip plane.");return;}//set backdrop's placement:backdrop.transform.position = transform.forward * distance;//calculate mesh:mesh.vertices = CalcVerts();mesh.RecalculateNormals();//readjust comparison values:prevDistance = distance;prevPosition = backdrop.transform.position;prevRotation = backdrop.transform.localEulerAngles;}Vector3[] CalcVerts(){return new Vector3[] {backdrop.transform.InverseTransformPoint(camera.ScreenToWorldPoint(new Vector3(0,0,distance))),backdrop.transform.InverseTransformPoint(camera.ScreenToWorldPoint(new Vector3(Screen.width,0,distance))),backdrop.transform.InverseTransformPoint(camera.ScreenToWorldPoint(new Vector3(0,Screen.height,distance))),backdrop.transform.InverseTransformPoint(camera.ScreenToWorldPoint(new Vector3(Screen.width,Screen.height,distance)))};}}
