This is not to say that graphics theory , Is not to say that URP The difference between this branch （ in addition 2 Branches ：built-in,HDRP）, Finally, I want to talk about custom programming pipeline （ Custom becomes equivalent to , Implement a whole rendering engine ）, Then I'll say , But now is not the time to say custom programming

In fact, the following is still HLSL Programming ,Shader Code （ Just put on a URP Skin of formwork ）

Catalog

Unity Of ShadowMask principle

Various names , The concept is confused

actual combat Shader shadow ” Magic reform “....？？

1. No shadow

2. There is a shadow

3. The shadow is gone again

4. EH , Have a

Reference resources

---

Unity Of ShadowMask principle

Many new to graphics rendering Renderer, In particular, the entry tool is Unity Classmate ,

It's easy to confuse all kinds of Shadow Concept ;

The first time I saw such code ：Pass{ “ShadowCaster", It's preconceived that this is rendering Shadow Code for

The basic principle of projection is

1. The light source

2. Occluder （ Projection source ）

3. Shadow painting （Object Render)

 

Actually ShadowCaster Pass, Is the projection source （ Mainly to tell the engine , How to locate , The granularity of shadows , Whether to offset , Then the engine will bake the corresponding shadow map at some time ）; The shadow drawing and color drawing are the same , It's all in ForwardPass( perhaps DefferPass, This next article will talk about ）

void InitializeInputData(Varyings input, half3 normalTS, out InputData inputData)
{
//...........

    inputData.shadowMask = SAMPLE_SHADOWMASK(input.lightmapUV);

Because the code above , We know ,.shadowMask Store in inputData

therefore ,

half4 UniversalFragmentPBR(InputData inputData, SurfaceData surfaceData)
{
//.......
   
// To ensure backward compatibility we have to avoid using shadowMask input, as it is not present in older shaders
#if defined(SHADOWS_SHADOWMASK) && defined(LIGHTMAP_ON)
    half4 shadowMask = inputData.shadowMask;
#elif !defined (LIGHTMAP_ON)
    half4 shadowMask = unity_ProbesOcclusion;
#else
    half4 shadowMask = half4(1, 1, 1, 1);
#endif

    Light mainLight = GetMainLight(inputData.shadowCoord, inputData.positionWS, shadowMask);

From this code , We know shadowMask It's actually mixed with the main light （ Parallel light ） Calculated together , In fact, light ==1, shadow ==0, light ++, shadow --; It's not that hard to understand

however , Doesn't a point light need shadows ？

#ifdef _ADDITIONAL_LIGHTS
    uint pixelLightCount = GetAdditionalLightsCount();
    for (uint lightIndex = 0u; lightIndex < pixelLightCount; ++lightIndex)
    {
        Light light = GetAdditionalLight(lightIndex, inputData.positionWS, shadowMask);

Because of this code , We also know , The shadow of a point light source is the same as that of a moving light

// Parallel light （ Other tools have similar names ：Main Lit, The main light source , Direct light sources )
light.shadowAttenuation = MainLightShadow(shadowCoord, positionWS, shadowMask, _MainLightOcclusionProbes);

// Point source , Spotlights    ( Other tools have similar names ：Other Lit, Auxiliary light , Indirect light sources ) 
light.shadowAttenuation = AdditionalLightShadow(perObjectLightIndex, positionWS, shadowMask, occlusionProbeChannels);

Let's look at another piece of code ：

#ifdef CALCULATE_BAKED_SHADOWS
    half bakedShadow = BakedShadow(shadowMask, occlusionProbeChannels);
#else
    half bakedShadow = 1.0h;
#endif

  So we know shadowMask Only again Baked It works in mode , By the way, I also know the keywords to be given ：occlusionProbeChannels

Various names , The concept is confused

< make a concrete analysis , Then add >

The conclusion is the conclusion of the previous article ：

Better believe than have no book

In fact, there are not so many profound reasons

Master the theory of the world （ In fact, it is impossible to master all ）, It's not as good as a sentence of code

actual combat Shader shadow ” Magic reform “....？？

1. No shadow

According to the code of the previous article （ Realize point light source and spotlight ）, A shadow ？？

At first I thought , It's this question

  It turned out , Or code （ official ） setting

#if !defined(ADDITIONAL_LIGHT_CALCULATE_SHADOWS)
    return 1.0h;
#endif

 < Because I've been cheated by the authorities many times , So it's not a waste of time , Just look at the code , Can find a solution from the code >

2. There is a shadow

//  The official recommended way to open macros ,_ADDITIONAL_LIGHT_SHADOWS_CASCADE I don't know what the effect is 
//#pragma multi_compile _ _MAIN_LIGHT_SHADOWS
//#pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE

//#define _ADDITIONAL_LIGHT_SHADOWS_CASCADE
//#define _ADDITIONAL_LIGHT_SHADOWS;

// Visual measurement ,_ADDITIONAL_LIGHT_SHADOWS opened , It will ADDITIONAL_LIGHT_CALCULATE_SHADOWS open 
// So just  ADDITIONAL_LIGHT_CALCULATE_SHADOWS  That's it ,_ADDITIONAL_LIGHT_SHADOWS_CASCADE The temporary effect is unknown 
#define ADDITIONAL_LIGHT_CALCULATE_SHADOWS 0;
// Test whether the macro is open , Need someone to pay IDE Support 
#if !defined(ADDITIONAL_LIGHT_CALCULATE_SHADOWS)
    abc = 1 //ADDITIONAL_LIGHT_CALCULATE_SHADOWS Defined , So even if this line of error is incomplete code , No errors reported 
#endif

            //Light light = GetAdditionalLight(lightIndex, positionWS);
            float4 shadowMask = SAMPLE_SHADOWMASK(i.uv.zw);//lightmapUV
            Light light = GetAdditionalLight(lightIndex,positionWS,shadowMask);
// Now this light The structure will carry shadow information 

3. The shadow is gone again

Let's change it , period （ What we want ？）

 

4. EH , Have a

 

 < Last , You still find that the character's video doesn't >

here , The difference between shadow and no shadow is ： Whether static objects are checked , whether MeshRenderer

However SkinnedMeshRenderer There is no such option ,《Unity2020》 

 

Reference resources

Unity Real time shadow implementation ——Shadow Mapping - You know

Shadowmask vs DistanceShadowmask - Unity Forum

How to be in unity Of URP Under the shadow _ Huang Lang's blog -CSDN Blog _unity urp shadow

Unity SRP To make things （ Four ） shadow - You know