ShaderCurve

An utility for Unity to bake AnimationCurve into texture and evaluate them in shaders.

Requirements

• Unity 2019.4+

Installation

Add UPM git dependencies to your project.

Package	Git URL	Description
Core	https://github.com/ruccho/ShaderCurve.git?path=/Packages/io.github.ruccho.shadercurve	Core package of ShaderCurve.
ShaderGraph	https://github.com/ruccho/ShaderCurve.git?path=/Packages/io.github.ruccho.shadercurve.shadergraph	Optional package to use ShaderCurve with ShaderGraph.

Bake AnimationCurve into texture

1. Create ShaderCurve Asset

• Right click on Project view, select ShaderCurveAsset.

2. Configure

• Curves
  • Each ShaderCurve asset can contain multiple AnimationCurve.
• Texture Format
  • Default texture format ARGB32 only supports curves whose range fits in [0 .. 1]. Select RGBAFloat to use out-of-range values.
• Resolution
  • The resolution in the time direction. Higher values make evaluations smooth. Default is 1024.

3. Bake

• Click Bake to bake curves into a texture with specified settings.
• Baked textures will appear as children of each ShaderCurve asset.

Use baked textures in shaders

Cg/HLSL (Builtin Render Pipeline)

• Include "Packages/io.github.ruccho.shadercurve/Runtime/ShaderCurve.cginc"
• Declare baked texture and its xxx_TexelSize property (they are required to evaluation).
• Use ShaderCurve_Evaluate(curve, curve_ts, resolution, index, t) to evaluate.
  • curve (sampler2D): Baked texture.
  • curve_ts (float4): TexelSize of curve texture.
  • resolution (uint): Use the value you specified in bake settings.
  • index (uint): Index of AnimationCurve in ShaderCurve asset.
  • time (float): Time to evaluate. [0 .. 1]

Shader "Custom/ShaderCurveSample"
{
    Properties
    {
        _CurveTex("ShaderCurve Texture", 2D) = "white" {}
        _CurveResolution("ShaderCurve Resolution", Float) = 1024
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"
            #include "Packages/io.github.ruccho.shadercurve/Runtime/ShaderCurve.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _CurveTex;
            float4 _CurveTex_TexelSize;
            float _CurveResolution;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {

                float t = frac(_Time.y);

                float r = ShaderCurve_Evaluate(_CurveTex, _CurveTex_TexelSize, _CurveResolution, 0, t);

                fixed4 col = fixed4(r, r, r, 1.0);
                
                return col;
            }
            ENDCG
        }
    }
}

ShaderGraph (UniversalRP / HighDefinitionRP)

• io.github.ruccho.shadercurve.shadergraph package is required to use evaluation node.

• Use Evaluate ShaderCurve node.