Unity Shader 转 3D Max

LiteralliJeff · 发表于 2022-12-25 14:32

项目在进行角色Shader优化的时候，或多或少会涉及到模型法线的调整。法线通常在光照和视角计算，还有描边计算有着重要的影响。目前的做法是美术同学在max制作好角色模型，导入Unity后调试Shader，有些细微效果来回倒腾浪费时间。所以就有了将Unity Shader在Max中实现的需求。
Max 自定义Shader

Max中自定义Shader 是DirectX Shader。新建一个fx文件，一些结构跟Unity的ShaderLab有些区别，但是都是用的HLSL语法，所以只需了解变换结构即可。

变换矩阵变化如下

//UNITY_MATRIX_MVP
float4x4 WvpXf : WorldViewProjection < string UIWidget = &#34;None&#34;; > ;

//unity_ObjectToWorld
float4x4 WorldXf : World < string UIWidget = &#34;None&#34;; > ;
//世界空间向量转换
float4x4 WorldITXf : WorldInverseTranspose < string UIWidget = &#34;None&#34;; > ;

//UNITY_MATRIX_MV
float4x4 WvXf : WorldView < string UIWidget = &#34;None&#34;; > ;
//View空间向量转换
float4x4 WvITXf : WorldViewInverseTranspose < string UIWidget = &#34;None&#34;; > ;

//UNITY_MATRIX_T_MV
float4x4 ViewIXf : ViewInverse < string UIWidget = &#34;None&#34;; > ;
//UNITY_MATRIX_IT_MV
float4x4 ViewITXf : ViewInverseTranspose < string UIWidget = &#34;None&#34;; > ;

//UNITY_MATRIX_V
float4x4 ViewXf : View < string UIWidget = &#34;None&#34;; > ;
//UNITY_MATRIX_P
float4x4 ProjectionXf : Projection < string UIWidget = &#34;None&#34;; > ;

float4x4 ProjInverse : ProjectionInverse < string UIWidget = &#34;None&#34;; > ;

视角变量和灯光参数

//视角变量
WorldView = normalize(ViewIXf[3].xyz - Pw);
//灯光参数定义
float3 lightDir : Direction <
string UIName = &#34;Light Direction&#34;;
string Object = &#34;TargetLight&#34;;
> = {-0.577, -0.577, 0.577};

变量定义，注意这里的纹理声明一定要指定Texcoord和MapChannel，同时纹理需要声明采样器：

/// Point Lamp 0 ////////////
float3 lightDir : Direction <
string UIName = &#34;Light Direction&#34;;
string Object = &#34;TargetLight&#34;;
> = {-0.577, -0.577, 0.577};

/// Base
Texture2D <float4> _BaseMap <
string UIName = &#34;Base Map&#34;;
string ResourceType = &#34;2D&#34;;
int Texcoord = 0;
int MapChannel = 1;
>;
float4 _BaseColor <
string UIName = &#34;_BaseColor&#34;;
string UIWidget = &#34;Color&#34;;
> = float4( 1.0f, 1.0f, 1.0f, 1.0f );

float _HighLightScale <
string UIName = &#34;High Light Scale&#34;;
string UIWidget = &#34;slider&#34;;
float UIMin = 0.0f;
float UIMax = 2.0f;
float UIStep = 0.01f;
> = 1.0f;`
纹理采样器：
`SamplerState _BaseMapSampler
{
MinFilter = Linear;
MagFilter = Linear;
MipFilter = Linear;
AddressU = Wrap;
AddressV = Wrap;
};

声明顶点shader和片元shader，这点和Unity ShaderLab几乎一致

/* data from application vertex buffer */
struct appdata {
float4 vertex    : POSITION;
float4 normal    : NORMAL;
float4 uv    : TEXCOORD0;
float3 color       : COLOR;
};

/* data passed from vertex shader to pixel shader */
struct v2f {
float4 positionCS : SV_Position;
float4 uv    : TEXCOORD0;
float3 color : TEXCOORD1;
};

v2f std_VS(appdata v) {
v2f o = (v2f)0;
o.uv = v.uv;
o.color = v.color;
o.positionCS = mul(Po,WvpXf);
return o;
}

///////// PIXEL SHADING //////////////////////

float4 std_PS(v2f i) : SV_Target {
float4 baseColor = _BaseMap.Sample(_BaseMapSampler, i.uv.xy);
float4 col = float4(baseColor.rgb, 1) * _BaseColor;
return col;
}

设置调用函数，这里指定裁剪，深度测试等效果

RasterizerState RS_CullBack
{
FillMode = SOLID;
CullMode = Back;
FrontCounterClockwise = false;
};

DepthStencilState Depth
{
DepthEnable = TRUE;
DepthFunc = 4;//LESSEQUAL
DepthWriteMask = ALL;
};

fxgroup dx11
{
technique11 Main_11 <
string Script = &#34;Pass=p0;&#34;;
> {
pass p0 < string Script = &#34;Draw=geometry;&#34;; >
{
      SetRasterizerState(RS_CullBack);
      SetDepthStencilState( Depth, 0 );
      SetVertexShader(CompileShader(vs_5_0,std_VS()));
      SetGeometryShader( NULL );
      SetPixelShader(CompileShader(ps_5_0,std_PS()));
}

}
}
fxgroup dx10
{
technique10 Main_10 <
string Script = &#34;Pass=p0;&#34;;
> {
pass p0 <
string Script = &#34;Draw=geometry;&#34;;
>
{
      SetRasterizerState(RS_CullBack);
      SetDepthStencilState( Depth, 0 );
      SetVertexShader(CompileShader(vs_4_0,std_VS()));
      SetGeometryShader( NULL );
      SetPixelShader(CompileShader(ps_4_0,std_PS()));
}

}

Max 中点击材质球编辑器，点击如下采样笔选择视图模型，获取当前模型的材质球。 ![7ae92f6a8cce97c5efe7d79653618375](Unity Shader 转 3D Max.resources/A79AB964-E7C4-452F-9973-C44D809D1C9F.png)
编辑器中选择材质类型 DirectX Shader， ![3c047f3f3009b17167256367d5b10ad0](Unity Shader 转 3D Max.resources/0000BE4A-9230-4DB8-8032-4E841D69F68F.png)
指定我们刚刚写的shader，同时调试参数即可： ![9c6784392fc531e37ae0e7e22c634e24](Unity Shader 转 3D Max.resources/EE63702A-030B-4EC9-B5B6-EC2F85F02E41.png)

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