unity里standard pbr(一）

关注forwardbase下的

standard.shader

#pragma vertex vertBase

#pragma fragment fragBase

#include "UnityStandardCoreForward.cginc"

跟踪到UnityStandardCoreForward.cginc

#if UNITY_STANDARD_SIMPLE

#include "UnityStandardCoreForwardSimple.cginc"

VertexOutputBaseSimple vertBase (VertexInput v) { return vertForwardBaseSimple(v); }

VertexOutputForwardAddSimple vertAdd (VertexInput v) { return vertForwardAddSimple(v); }

half4 fragBase (VertexOutputBaseSimple i) : SV_Target { return fragForwardBaseSimpleInternal(i); }

half4 fragAdd (VertexOutputForwardAddSimple i) : SV_Target { return fragForwardAddSimpleInternal(i); }

#else

#include "UnityStandardCore.cginc"

VertexOutputForwardBase vertBase (VertexInput v) { return vertForwardBase(v); }

VertexOutputForwardAdd vertAdd (VertexInput v) { return vertForwardAdd(v); }

half4 fragBase (VertexOutputForwardBase i) : SV_Target { return fragForwardBaseInternal(i); }

half4 fragAdd (VertexOutputForwardAdd i) : SV_Target { return fragForwardAddInternal(i); }

#endif

UNITY_STANDARD_SIMPLE开关是简化版意思，进下边的分支

顶点着色器 vertForwardBase

先看输出

struct VertexOutputForwardBase

{

    float4 pos                          : SV_POSITION;

    float4 tex                          : TEXCOORD0;

    half3 eyeVec                        : TEXCOORD1;

    half4 tangentToWorldAndParallax[]  : TEXCOORD2;    // [3x3:tangentToWorld | 1x3:viewDirForParallax]

    half4 ambientOrLightmapUV           : TEXCOORD5;    // SH or Lightmap UV

    SHADOW_COORDS()

    UNITY_FOG_COORDS()

    // next ones would not fit into SM2.0 limits, but they are always for SM3.0+

    #if UNITY_REQUIRE_FRAG_WORLDPOS

        float3 posWorld                 : TEXCOORD8;

    #endif

    #if UNITY_OPTIMIZE_TEXCUBELOD

        #if UNITY_REQUIRE_FRAG_WORLDPOS

            half3 reflUVW               : TEXCOORD9;

        #else

            half3 reflUVW               : TEXCOORD8;

        #endif

    #endif

    UNITY_VERTEX_OUTPUT_STEREO

};

UNITY_REQUIRE_FRAG_WORLDPOS要不要worldpos，要

reflUVW是用来做反射的，要
UNITY_VERTEX_OUTPUT_STEREO 是用来做实例化的，不要
简化成

struct VertexOutputForwardBase

{

    float4 pos                          : SV_POSITION;

    float4 tex                          : TEXCOORD0;

    half3 eyeVec                        : TEXCOORD1;

    half4 tangentToWorldAndParallax[]  : TEXCOORD2;    // [3x3:tangentToWorld | 1x3:viewDirForParallax]

    half4 ambientOrLightmapUV           : TEXCOORD5;    // SH or Lightmap UV

    SHADOW_COORDS()

    UNITY_FOG_COORDS()

    float3 posWorld                     : TEXCOORD8;

    half3 reflUVW                       : TEXCOORD9;

};

再来看顶点着色器

VertexOutputForwardBase vertForwardBase (VertexInput v)

{

    VertexOutputForwardBase o;

    UNITY_SETUP_INSTANCE_ID(v);

    UNITY_INITIALIZE_OUTPUT(VertexOutputForwardBase, o);

    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);

    float4 posWorld = mul(unity_ObjectToWorld, v.vertex);

    #if UNITY_REQUIRE_FRAG_WORLDPOS

        o.posWorld = posWorld.xyz;

    #endif

    o.pos = UnityObjectToClipPos(v.vertex);

    o.tex = TexCoords(v);

    o.eyeVec = NormalizePerVertexNormal(posWorld.xyz - _WorldSpaceCameraPos);

    float3 normalWorld = UnityObjectToWorldNormal(v.normal);

    #ifdef _TANGENT_TO_WORLD

        float4 tangentWorld = float4(UnityObjectToWorldDir(v.tangent.xyz), v.tangent.w);

        float3x3 tangentToWorld = CreateTangentToWorldPerVertex(normalWorld, tangentWorld.xyz, tangentWorld.w);

        o.tangentToWorldAndParallax[].xyz = tangentToWorld[];

        o.tangentToWorldAndParallax[].xyz = tangentToWorld[];

        o.tangentToWorldAndParallax[].xyz = tangentToWorld[];

    #else

        o.tangentToWorldAndParallax[].xyz = ;

        o.tangentToWorldAndParallax[].xyz = ;

        o.tangentToWorldAndParallax[].xyz = normalWorld;

    #endif

    //We need this for shadow receving

    TRANSFER_SHADOW(o);

    o.ambientOrLightmapUV = VertexGIForward(v, posWorld, normalWorld);

    #ifdef _PARALLAXMAP

        TANGENT_SPACE_ROTATION;

        half3 viewDirForParallax = mul (rotation, ObjSpaceViewDir(v.vertex));

        o.tangentToWorldAndParallax[].w = viewDirForParallax.x;

        o.tangentToWorldAndParallax[].w = viewDirForParallax.y;

        o.tangentToWorldAndParallax[].w = viewDirForParallax.z;

    #endif

    #if UNITY_OPTIMIZE_TEXCUBELOD

        o.reflUVW       = reflect(o.eyeVec, normalWorld);

    #endif

    UNITY_TRANSFER_FOG(o,o.pos);

    return o;

}

UNITY_SETUP_INSTANCE_ID是instance用的，不要

UNITY_INITIALIZE_OUTPUT啥也没干，不要

UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO不要

NormalizePerVertexNormal相等于什么都没做

_TANGENT_TO_WORLD是切线空间和世界空间转换矩阵 保留

o.ambientOrLightmapUV = VertexGIForward(v, posWorld, normalWorld);
因为打算用pbr来做角色，没有lightmap，所以这儿等于

o.ambientOrLightmapUV = 0 ；

_PARALLAXMAP视差贴图，不用

去掉分支后代码如下

VertexOutputForwardBase vertForwardBase (VertexInput v)

{

    VertexOutputForwardBase o;

    float4 posWorld = mul(unity_ObjectToWorld, v.vertex);

    o.posWorld = posWorld.xyz;

    o.pos = UnityObjectToClipPos(v.vertex);

    o.tex = TexCoords(v);

    o.eyeVec = NormalizePerVertexNormal(posWorld.xyz - _WorldSpaceCameraPos);

    float3 normalWorld = UnityObjectToWorldNormal(v.normal);

	float4 tangentWorld = float4(UnityObjectToWorldDir(v.tangent.xyz), v.tangent.w);

	float3x3 tangentToWorld = CreateTangentToWorldPerVertex(normalWorld, tangentWorld.xyz, tangentWorld.w);

	o.tangentToWorldAndParallax[0].xyz = tangentToWorld[0];

	o.tangentToWorldAndParallax[1].xyz = tangentToWorld[1];

	o.tangentToWorldAndParallax[2].xyz = tangentToWorld[2];

    //We need this for shadow receving

    TRANSFER_SHADOW(o);

    o.ambientOrLightmapUV = 0;

	o.reflUVW       = reflect(o.eyeVec, normalWorld);

    UNITY_TRANSFER_FOG(o,o.pos);

    return o;

}

　至此顶点着色器完事，下篇开始像素着色器