这里总结了几种在unity实现描边效果的方法，首先准备一个模型导入在unity中，使用默认shader，上传一张原始图，以便后面实现功能效果的对比
一、边缘光，这里参照官方的一个SurfaceShader Example，Rim Lighting
1.在unity创建一个SurfaceShader，命名RimLighting
Shader "Custom/RimLighting" {
Properties {
_Color ("Color", Color) = (1,1,1,1)
_MainTex ("Albedo (RGB)", 2D) = "white" {}
//边缘光颜色
_RimColor("Rim Color",Color) =(1,1,1,1)
//边缘光强度
_RimPower("Rim Power", Range(0.5,8.0)) = 3.0
}
SubShader {
Tags { "RenderType"="Opaque" }
LOD 200
CGPROGRAM
// Physically based Standard lighting model, and enable shadows on all light types
#pragma surface surf Standard fullforwardshadows
// Use shader model 3.0 target, to get nicer looking lighting
#pragma target 3.0
sampler2D _MainTex;
struct Input {
float2 uv_MainTex;
//法线
float3 worldNormal;
//视角方向
float3 viewDir;
};
fixed4 _Color;
fixed4 _RimColor;
half _RimPower;
void surf (Input IN, inout SurfaceOutputStandard o) {
// Albedo comes from a texture tinted by color
fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
o.Albedo = c.rgb;
o.Alpha = c.a;
half rim = 1.0 - saturate(dot(normalize(IN.viewDir), IN.worldNormal));
o.Emission = _RimColor.rgb * pow(rim, _RimPower);
}
ENDCG
}
FallBack "Diffuse"
}2.将模型材质的shader改为刚才所写的shader，Custom/RimLighting
3.更改后，具体效果如下
二、法线外拓,用一个Pass渲染边框，一个Pass渲染实物
- 创建一个UnlitShader，命名为NormalUnlitShader
Shader "Custom/NormalUnlitShader"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
_Outline("Out Line",Range(0.001,0.005))=0.002
_Color("Color",Color)=(1,1,1,1)
}
CGINCLUDE
#include "UnityCG.cginc"
struct v2f
{
float4 pos:POSITION;
float4 color:COLOR;
};
sampler2D _MainTex;
float _Outline;
fixed4 _Color;
v2f vert(appdata_base v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
float3 norm = mul((float3x3)UNITY_MATRIX_IT_MV, v.normal);
float2 offset = TransformViewToProjection(norm.xy);
o.pos.xy += offset * o.pos.z * _Outline;
o.color = _Color;
return o;
}
ENDCG
SubShader
{
Cull Front
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
fixed4 frag (v2f i) : COLOR
{
return i.color;
}
ENDCG
}
CGPROGRAM
#pragma surface surf Lambert
struct Input {
float2 uv_MainTex;
};
void surf(Input IN, inout SurfaceOutput o) {
fixed4 c = tex2D(_MainTex, IN.uv_MainTex);
o.Albedo = c.rgb;
o.Alpha = c.a;
}
ENDCG
}
}
2.这里再换成新建的NormalUnlitShader，就会发现一些问题，他会在一些我们并不像描边的地方也改变了颜色，这就是因为这根据模型法线并不是全部都均匀的向外扩展，才导致这样的情况
3.再换一个Sphere模型应用与怪物同一个材质球，就会发现Sphere模型，是能达到我们的需求的，也能很明显的看出两者的差别，因为球的法线都是均匀的往外扩展的，这个方法的使用就需要以后根据实际的要求来使用
三、屏幕特效，描边效果
- 新建一个辅助摄像机，设置参数如下，并将模型的Layer设置为Monster，这样辅助摄像机就能单独看见这个怪物模型
2.写一个纯色shader，辅助摄像机用RenderWithShader，纯色渲染一张纹理处理
Shader "Custom/UnlitSolidColor"
{
SubShader
{
Pass
{
//返回蓝色
Color(0,0,1,1)
}
}
}
3.将纯色纹理，可以模糊放大几次，次数越多，边框就越宽，这里需要使用到一个像素偏移函数，Graphics.BlitMultiTap和一个Blur效果shader
Shader "Custom/OutterLineBlur" {
Properties {
_MainTex ("", 2D) = "white" {}
}
Category {
ZTest Always Cull Off ZWrite Off Fog { Mode Off }
Subshader {
Pass {
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"
struct v2f {
float4 pos : POSITION;
half4 uv[2] : TEXCOORD0;
};
float4 _MainTex_TexelSize;
float4 _BlurOffsets;
v2f vert (appdata_img v)
{
v2f o;
float offX = _MainTex_TexelSize.x * _BlurOffsets.x;
float offY = _MainTex_TexelSize.y * _BlurOffsets.y;
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
float2 uv = MultiplyUV (UNITY_MATRIX_TEXTURE0, v.texcoord.xy-float2(offX, offY));
o.uv[0].xy = uv + float2( offX, offY);
o.uv[0].zw = uv + float2(-offX, offY);
o.uv[1].xy = uv + float2( offX,-offY);
o.uv[1].zw = uv + float2(-offX,-offY);
return o;
}
sampler2D _MainTex;
fixed4 _Color;
fixed4 frag( v2f i ) : COLOR
{
fixed4 c;
c = tex2D( _MainTex, i.uv[0].xy );
c += tex2D( _MainTex, i.uv[0].zw );
c += tex2D( _MainTex, i.uv[1].xy );
c += tex2D( _MainTex, i.uv[1].zw );
return c /2 ;
}
ENDCG
}
}
}
Fallback off
}4.将扩大后的纹理与原来的纹理，做一个对比，并依据原来纹理剔除掉中间部分，就只剩下一个边框纹理，这里需要使用一个剔除shader
Shader "Custom/OutterLineCutoff" {
Properties {
_MainTex ("", 2D) = "white" {}
}
Category {
BlendOp RevSub
Blend One One
ZTest Always Cull Off ZWrite Off Fog { Mode Off }
Subshader {
Pass {
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
sampler2D _MainTex;
sampler2D _MainTex1;
struct appdata
{
float4 vertex : POSITION;
float4 texcoord : TEXCOORD0;
};
struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD0;
};
v2f vert (appdata v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = v.texcoord.xy;
return o;
}
half4 frag(v2f i) : COLOR
{
fixed4 c = tex2D(_MainTex, i.uv);
return c;
}
ENDCG
}
}
}
FallBack "Diffuse"
}5.在主摄像机上，使用OnRenderImage函数，将得到的轮廓纯色纹理与摄像机的图像使用混合shader进行混合
Shader "Custom/OutterLineComposer" {
Properties {
_MainTex ("", 2D) = "white" {}
}
Category {
ZTest Always Cull Off ZWrite Off Fog { Mode Off }
Blend SrcAlpha OneMinusSrcAlpha
Subshader {
Pass {
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"
struct v2f {
float4 pos : POSITION;
half2 uv : TEXCOORD0;
};
v2f vert (appdata_img v)
{
v2f o;
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
o.uv = v.texcoord.xy;
return o;
}
sampler2D _MainTex;
fixed4 frag( v2f i ) : COLOR
{
return tex2D( _MainTex, i.uv );
}
ENDCG
}
}
}
Fallback off
}6.绑定在主摄像机的脚本
using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
public class outline : MonoBehaviour {
/// <summary>
/// 辅助摄像机
/// </summary>
public Camera outlineCamera;
#region 纯红色材质 solidColorMaterail
public Shader solidColorShader;
private Material m_solid=null;
private Material solidMaterail
{
get
{
if (m_solid == null)
{
m_solid = new Material(solidColorShader);
}
return m_solid;
}
}
#endregion
#region 合并材质 compositeMaterial
public Shader compositeShader;
private Material m_composite=null;
private Material compositeMaterial
{
get
{
if (m_composite == null)
m_composite = new Material(compositeShader);
return m_composite;
}
}
#endregion
#region 模糊材质 blurMaterial
public Shader blurShader;
private Material m_blur=null;
private Material blurMaterial
{
get
{
if (m_blur == null)
m_blur = new Material(blurShader);
return m_blur;
}
}
#endregion
#region 剔除材质 cutoffShader
public Shader cutoffShader;
private Material m_cutoff=null;
private Material cutoffMaterial
{
get
{
if (m_cutoff == null)
m_cutoff = new Material(cutoffShader);
return m_cutoff;
}
}
#endregion
/// <summary>
/// 辅助摄像机渲染的RenderTexture
/// </summary>
private RenderTexture outlineRenderTex;
/// <summary>
/// 模糊扩大次数
/// </summary>
public int Iterations = 2;
// Use this for initialization
void Start () {
outlineRenderTex = new RenderTexture((int)outlineCamera.pixelWidth, (int)outlineCamera.pixelHeight, 16);
}
// Update is called once per frame
void Update () {
}
void OnPreRender()
{
outlineCamera.targetTexture = outlineRenderTex;
outlineCamera.RenderWithShader(solidMaterail.shader, "");
}
void OnRenderImage(RenderTexture source, RenderTexture desture)
{
RenderTexture _renderTexture = RenderTexture.GetTemporary(outlineRenderTex.width, outlineRenderTex.height, 0);
MixRender(outlineRenderTex,ref _renderTexture);
Graphics.Blit(_renderTexture, desture, compositeMaterial);
RenderTexture.ReleaseTemporary(_renderTexture);
}
void MixRender(RenderTexture in_outerTexture, ref RenderTexture _renderTexture)
{
RenderTexture buffer = RenderTexture.GetTemporary(in_outerTexture.width, in_outerTexture.height, 0);
RenderTexture buffer2 = RenderTexture.GetTemporary(in_outerTexture.width, in_outerTexture.height, 0);
Graphics.Blit(in_outerTexture, buffer);
//多次模糊放大
for (int i = 0; i < Iterations; i++)
{
FourTapCone(buffer, buffer2, i);
Graphics.Blit(buffer2, buffer);
}
Graphics.Blit(in_outerTexture, buffer, cutoffMaterial);
Graphics.Blit(buffer, _renderTexture);
RenderTexture.ReleaseTemporary(buffer);
RenderTexture.ReleaseTemporary(buffer2);
}
float Spread = 0.8f;
public void FourTapCone(RenderTexture source, RenderTexture dest, int iteration)
{
float off = 0.5f + iteration * Spread;
Graphics.BlitMultiTap(source, dest, blurMaterial,
new Vector2(off, off),
new Vector2(-off, off),
new Vector2(off, -off),
new Vector2(-off, -off)
);
}
}
7.具体效果如下，因为这里是在主摄像机设置的屏幕特效，他可以忽略掉所有的遮挡，这是优点也是弊端
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