Laurens-Packages/Packages/com.unity.visualeffectgraph/Editor/Models/Contexts/Implementations/VFXPlanarPrimitiveHelper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.VFX;

namespace UnityEditor.VFX
{
    enum VFXPrimitiveType
    {
        Triangle,
        Quad,
        Octagon,
    }

    static class VFXPlanarPrimitiveHelper
    {
        public class OctagonInputProperties
        {
            [Range(0, 1), Tooltip("Sets the amount by which the octagonal particle shape is cropped, allowing for a tighter fit and reducing potential overdraw by eliminating transparent pixels.")]
            public float cropFactor = (int)(0.5f * (1.0f - Mathf.Tan(Mathf.PI / 8.0f)) * 1000.0f + 0.5f) / 1000.0f; // regular octagon with 3 decimals
        }

        public static VFXTaskType GetTaskType(VFXPrimitiveType prim)
        {
            switch (prim)
            {
                case VFXPrimitiveType.Triangle: return VFXTaskType.ParticleTriangleOutput;
                case VFXPrimitiveType.Quad: return VFXTaskType.ParticleQuadOutput;
                case VFXPrimitiveType.Octagon: return VFXTaskType.ParticleOctagonOutput;
                default: throw new NotImplementedException();
            }
        }

        public static string GetShaderDefine(VFXPrimitiveType prim)
        {
            switch (prim)
            {
                case VFXPrimitiveType.Triangle: return "VFX_PRIMITIVE_TRIANGLE";
                case VFXPrimitiveType.Quad: return "VFX_PRIMITIVE_QUAD";
                case VFXPrimitiveType.Octagon: return "VFX_PRIMITIVE_OCTAGON";
                default: throw new NotImplementedException();
            }
        }
    }
}