ScriptableRenderPipeline/ScriptableRenderPipeline/Core/CoreRP/Editor/Volume/Drawers/Vector4ParameterDrawer.cs

using UnityEngine;
using UnityEngine.Experimental.Rendering;

namespace UnityEditor.Experimental.Rendering
{
    [VolumeParameterDrawer(typeof(Vector4Parameter))]
    sealed class Vector4ParametrDrawer : VolumeParameterDrawer
    {
        public override bool OnGUI(SerializedDataParameter parameter, GUIContent title)
        {
            var value = parameter.value;

            if (value.propertyType != SerializedPropertyType.Vector4)
                return false;

            value.vector4Value = EditorGUILayout.Vector4Field(title, value.vector4Value);
            return true;
        }
    }
}