【OpenGL】Shader实例分析-钻石效果
发表于2018-10-18
最近研究了一个玻璃折射的效果（用在钻石上），虽然没有达到最满意的效果，还是先分享出来，待以后有更好的想法再补充。
先看效果吧：
这里面有两个效果，左边是unity的免费插件Gem Shader，右边的是我自己实现的，我将分别介绍这两个效果的实现方法。
一、知识补充：
钻石的图片：
两个shader都使用了CubeMap……
Shader "FX/Diamond"
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Properties ｛
_Color ("Color", Color) = (1,1,1,1)
_ReflectTex ("Reflection Texture", Cube) = "dummy.jpg" ｛
TexGen CubeReflect
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_RefractTex ("Refraction Texture", Cube) = "dummy.jpg" ｛
TexGen CubeReflect
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SubShader ｛
Tags ｛
"Queue" = "Transparent"
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// First pass - here we render the backfaces of the diamonds. Since those diamonds are more-or-less
// convex objects, this is effectively rendering the inside of them
Pass ｛
Color (0,0,0,0)
Offset -1, -1
Cull Front
ZWrite Off
SetTexture [_RefractTex] ｛
constantColor [_Color]
combine texture * constant, primary
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SetTexture [_ReflectTex] ｛
combine previous, previous +- texture
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// Second pass - here we render the front faces of the diamonds.
Pass ｛
Fog ｛ Color (0,0,0,0)｝
ZWrite on
Blend One One
SetTexture [_RefractTex] ｛
constantColor [_Color]
combine texture * constant
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SetTexture [_ReflectTex] ｛
combine texture + previous, previous +- texture
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// Older cards. Here we remove the bright specular highlight
SubShader ｛
// First pass - here we render the backfaces of the diamonds. Since those diamonds are more-or-less
// convex objects, this is effectively rendering the inside of them
Pass ｛
Color (0,0,0,0)
Cull Front
SetTexture [_RefractTex] ｛
constantColor [_Color]
combine texture * constant, primary
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// Second pass - here we render the front faces of the diamonds.
Pass ｛
Fog ｛ Color (0,0,0,0)｝
ZWrite off
Blend One One
SetTexture [_RefractTex] ｛
constantColor [_Color]
combine texture * constant
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// Ancient cards without cubemapping support
// We could use a 2D refletction texture, but the chances of getting one of these cards are slim, so we won't bother.
SubShader ｛
Pass ｛
Color [_Color]
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Shader "stalendp/myDiamondShader" ｛
Properties ｛
_Color ("Color", Color) = (1,1,1,1)
_ReflectTex ("Reflection Texture", Cube) = "" ｛ ｝
_RefractTex ("Refraction Texture", Cube) = "" ｛ ｝
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CGINCLUDE
#include "UnityCG.cginc"
fixed4 _Color;
samplerCUBE _RefractTex;
samplerCUBE _ReflectTex;
struct v2f ｛
half4 pos:SV_POSITION;
half3 Reflect : TEXCOORD0;
half3 RefractR : TEXCOORD1;
half3 RefractG : TEXCOORD2;
half3 RefractB : TEXCOORD3;
half Ratio : TEXCOORD4;
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v2f vert(appdata_full v) ｛
float EtaR = 0.65;
float EtaG = 0.67;
float EtaB = 0.69;
float FresnelPower = 5.0;
float F = ((1.0-EtaG) * (1.0-EtaG)) / ((1.0+EtaG) * (1.0+EtaG));
float3 i = -normalize(ObjSpaceViewDir(v.vertex));
float3 n = normalize(v.normal); // ??????
v2f o;
o.Ratio = F + (1.0 - F) * pow((1.0 - dot(-i, n)), FresnelPower) ;
o.RefractR = refract(i, n, EtaR);
o.RefractG = refract(i, n, EtaG);
o.RefractB = refract(i, n, EtaB);
o.Reflect = reflect(i, n);
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
return o;
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fixed4 frag(v2f i) : COLOR0 ｛
float3 refractColor, reflectColor;
refractColor.r = float3(texCUBE(_RefractTex, i.RefractR)).r;
refractColor.g = float3(texCUBE(_RefractTex, i.RefractG)).g;
refractColor.b = float3(texCUBE(_RefractTex, i.RefractB)).b;
reflectColor = float3(texCUBE(_ReflectTex, i.Reflect));
return 2*_Color * pow(fixed4(lerp( _Color * refractColor * 5, reflectColor * 2, i.Ratio), 1), 1.8);
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ENDCG
SubShader ｛
Pass ｛
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
ENDCG
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FallBack Off
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来自：https://blog.csdn.net/stalendp/article/details/46360409