2024-08-26 23:07:20 +03:00

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urp-use-built-in-shader-methods-transformations

Transform positions in a custom URP shader

To transform positions in a custom Universal Render Pipeline (URP) shader, follow these steps:

Add #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl" inside the HLSLPROGRAM in your shader file. The Core.hlsl file imports the ShaderVariablesFunction.hlsl file.
Use one of the following methods from the ShaderVariablesFunction.hlsl file.

Method	Syntax	Description
`GetNormalizedScreenSpaceUV`	`float2 GetNormalizedScreenSpaceUV(float2 positionInClipSpace)`	Converts a position in clip space to screen space.
`GetObjectSpaceNormalizeViewDir`	`half3 GetObjectSpaceNormalizeViewDir(float3 positionInObjectSpace)`	Converts a position in object space to the normalized direction towards the viewer.
`GetVertexNormalInputs`	`VertexNormalInputs GetVertexNormalInputs(float3 normalInObjectSpace)`	Converts the normal of a vertex in object space to a tangent, bitangent, and normal in world space. You can also input both the normal and a `float4` tangent in object space.
`GetVertexPositionInputs`	`VertexPositionInputs GetVertexPositionInputs(float3 positionInObjectSpace)`	Converts the position of a vertex in object space to positions in world space, view space, clip space, and normalized device coordinates.
`GetWorldSpaceNormalizeViewDir`	`half3 GetWorldSpaceNormalizeViewDir(float3 positionInWorldSpace)`	Returns the direction from a position in world space to the viewer, and normalizes the direction.
`GetWorldSpaceViewDir`	`float3 GetWorldSpaceViewDir(float3 positionInWorldSpace)`	Returns the direction from a position in world space to the viewer.

Structs

VertexPositionInputs

Use the GetVertexNormalInputs method to get this struct.

Field	Description
`float3 positionWS`	The position in world space.
`float3 positionVS`	The position in view space.
`float4 positionCS`	The position in clip space.
`float4 positionNDC`	The position as normalized device coordinates (NDC).

VertexNormalInputs

Use the GetVertexNormalInputs method to get this struct.

Field	Description
`real3 tangentWS`	The tangent in world space.
`real3 bitangentWS`	The bitangent in world space.
`float3 normalWS`	The normal in world space.

Example

The following URP shader draws object surfaces with colors that represent their position in screen space.

Shader "Custom/ScreenSpacePosition"
{
    SubShader
    {
        Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" }

        Pass
        {
            HLSLPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            struct Attributes
            {
                float4 positionOS : POSITION;
                float2 uv: TEXCOORD0;
            };

            struct Varyings
            {
                float4 positionCS  : SV_POSITION;
                float2 uv: TEXCOORD0;
                float3 positionWS : TEXCOORD2;
            };

            Varyings vert(Attributes IN)
            {
                Varyings OUT;
                OUT.positionCS = TransformObjectToHClip(IN.positionOS.xyz);

                // Get the position of the vertex in different spaces
                VertexPositionInputs positions = GetVertexPositionInputs(IN.positionOS);

                // Set positionWS to the screen space position of the vertex
                OUT.positionWS = positions.positionWS.xyz;

                return OUT;
            }

            half4 frag(Varyings IN) : SV_Target
            {
                // Set the fragment color to the screen space position vector
                return float4(IN.positionWS.xy, 0, 1);
            }
            ENDHLSL
        }
    }
}

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