Echo/Assets/_Project/Scripts/Interaction/InteractOutlineTarget.cs

using UnityEngine;

namespace Interaction
{
    public class InteractOutlineTarget : MonoBehaviour
    {
        [SerializeField] private Renderer[] renderers;
        [SerializeField] private bool autoFindRenderers = true;
        [SerializeField] private float outlineWidth = 0.02f;
        [SerializeField] private float emission = 1f;

        [Header("Debug")]
        [SerializeField] private bool debugLog;

        private bool highlighted;
        private Material outlineMaterial;
        private MaterialPropertyBlock mpb;
        private Material[][] originalSharedMaterials;

        private static readonly int OutlineColorId = Shader.PropertyToID("_OutlineColor");
        private static readonly int OutlineWidthId = Shader.PropertyToID("_OutlineWidth");
        private static readonly int EmissionId = Shader.PropertyToID("_Emission");

        public void SetOutlineMaterial(Material material)
        {
            outlineMaterial = material;
        }

        public void SetHighlighted(bool value, Color color)
        {
            if (outlineMaterial == null)
            {
                if (debugLog) Debug.Log($"[InteractOutlineTarget] Missing outlineMaterial on '{name}'", this);
                return;
            }

            if (renderers == null || renderers.Length == 0)
            {
                if (autoFindRenderers)
                {
                    renderers = GetComponentsInChildren<Renderer>(true);
                }
            }

            if (renderers == null || renderers.Length == 0) return;

            if (mpb == null) mpb = new MaterialPropertyBlock();

            if (value)
            {
                mpb.SetColor(OutlineColorId, color);
                mpb.SetFloat(OutlineWidthId, outlineWidth);
                mpb.SetFloat(EmissionId, emission);
            }

            if (value && !highlighted)
            {
                CacheOriginalMaterialsIfNeeded();
                AppendOutlineMaterial();
                highlighted = true;
            }
            else if (!value && highlighted)
            {
                RestoreOriginalMaterials();
                highlighted = false;
            }

            for (int i = 0; i < renderers.Length; i++)
            {
                var r = renderers[i];
                if (r == null) continue;
                r.SetPropertyBlock(value ? mpb : null);
            }
        }

        private void CacheOriginalMaterialsIfNeeded()
        {
            if (originalSharedMaterials != null && originalSharedMaterials.Length == (renderers == null ? 0 : renderers.Length))
            {
                return;
            }

            if (renderers == null)
            {
                originalSharedMaterials = null;
                return;
            }

            originalSharedMaterials = new Material[renderers.Length][];
            for (int i = 0; i < renderers.Length; i++)
            {
                var r = renderers[i];
                originalSharedMaterials[i] = r != null ? r.sharedMaterials : null;
            }
        }

        private void AppendOutlineMaterial()
        {
            if (renderers == null) return;

            for (int i = 0; i < renderers.Length; i++)
            {
                var r = renderers[i];
                if (r == null) continue;

                var mats = r.sharedMaterials;
                if (mats == null)
                {
                    r.sharedMaterials = new[] { outlineMaterial };
                    continue;
                }

                for (int j = 0; j < mats.Length; j++)
                {
                    if (mats[j] == outlineMaterial) goto NextRenderer;
                }

                var newMats = new Material[mats.Length + 1];
                for (int j = 0; j < mats.Length; j++) newMats[j] = mats[j];
                newMats[mats.Length] = outlineMaterial;
                r.sharedMaterials = newMats;
            NextRenderer: ;
            }
        }

        private void RestoreOriginalMaterials()
        {
            if (renderers == null || originalSharedMaterials == null) return;

            int count = Mathf.Min(renderers.Length, originalSharedMaterials.Length);
            for (int i = 0; i < count; i++)
            {
                var r = renderers[i];
                if (r == null) continue;
                r.sharedMaterials = originalSharedMaterials[i];
            }
        }
    }
}