How to convert Custom Shaders to URP in Unity?

castana1962 · May 26, 2020, 10:11pm

Hi All
Sorry but I am new in the URP topics and I have a Unity project with Custom Shaders and I need to upgrade it to URP, for it, Could anybody advice about how to do it?
Thanks for your time
Alejandro

chrismarch_1 · May 26, 2020, 10:43pm

Your old unlit shaders shouldn’t need a ton of work, although you may need to remove LightMode Tags, like ForwardBase, if those snuck into your unlit shaders…

Your lit shaders will basically be incompatible, and you will need to either recreate them in Shader Graph, for maximum portability with future versions of URP, or base new versions of them off of stock URP shaders like Lit and SimpleLit, which are included in the packages:

Then, once your shaders are working, you will want to make them SRP Batching compatible, for better performance. This is done for you if you work through Shader Graph, otherwise, you will need to read the blog and then convert your CG to HLSL with the new functions, using the Unity GitHub as a reference for the new utility HLSL function names:

github.com

Unity-Technologies/Graphics/blob/f4d52d17e63826ecc1900fe070bff6090e250368/com.unity.render-pipelines.universal/ShaderLibrary/ShaderVariablesFunctions.hlsl

#ifndef UNITY_SHADER_VARIABLES_FUNCTIONS_INCLUDED
#define UNITY_SHADER_VARIABLES_FUNCTIONS_INCLUDED

VertexPositionInputs GetVertexPositionInputs(float3 positionOS)
{
    VertexPositionInputs input;
    input.positionWS = TransformObjectToWorld(positionOS);
    input.positionVS = TransformWorldToView(input.positionWS);
    input.positionCS = TransformWorldToHClip(input.positionWS);

    float4 ndc = input.positionCS * 0.5f;
    input.positionNDC.xy = float2(ndc.x, ndc.y * _ProjectionParams.x) + ndc.w;
    input.positionNDC.zw = input.positionCS.zw;

    return input;
}

VertexNormalInputs GetVertexNormalInputs(float3 normalOS)
{
    VertexNormalInputs tbn;

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github.com

Unity-Technologies/Graphics/blob/b448574baa796c1bd7186fc4b918eafddd76610d/com.unity.render-pipelines.core/ShaderLibrary/SpaceTransforms.hlsl

#ifndef UNITY_SPACE_TRANSFORMS_INCLUDED
#define UNITY_SPACE_TRANSFORMS_INCLUDED

// Return the PreTranslated ObjectToWorld Matrix (i.e matrix with _WorldSpaceCameraPos apply to it if we use camera relative rendering)
float4x4 GetObjectToWorldMatrix()
{
    return UNITY_MATRIX_M;
}

float4x4 GetWorldToObjectMatrix()
{
    return UNITY_MATRIX_I_M;
}

float4x4 GetWorldToViewMatrix()
{
    return UNITY_MATRIX_V;
}

// Transform to homogenous clip space

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How to convert Custom Shaders to URP in Unity?

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