private List <AABB> BuildVertOverlapAABBs(GameObject gameObject, Sprite sprite, RTMesh rtMesh)
        {
            if (sprite == null && rtMesh == null)
            {
                return(new List <AABB>());
            }

            const float overlapAmount     = 0.2f;
            float       halfOverlapAmount = overlapAmount * 0.5f;
            AABB        modelAABB         = sprite != null?ObjectBounds.CalcSpriteModelAABB(gameObject) : rtMesh.AABB;

            Vector3        modelAABBSize  = modelAABB.Size;
            List <BoxFace> modelAABBFaces = BoxMath.AllBoxFaces;

            const float sizeEps = 0.001f;

            Vector3[] overlapAABBSizes = new Vector3[modelAABBFaces.Count];
            overlapAABBSizes[(int)BoxFace.Left]   = new Vector3(overlapAmount, modelAABBSize.y + sizeEps, modelAABBSize.z + sizeEps);
            overlapAABBSizes[(int)BoxFace.Right]  = new Vector3(overlapAmount, modelAABBSize.y + sizeEps, modelAABBSize.z + sizeEps);
            overlapAABBSizes[(int)BoxFace.Bottom] = new Vector3(modelAABBSize.x + sizeEps, overlapAmount, modelAABBSize.z + sizeEps);
            overlapAABBSizes[(int)BoxFace.Top]    = new Vector3(modelAABBSize.x + sizeEps, overlapAmount, modelAABBSize.z + sizeEps);
            overlapAABBSizes[(int)BoxFace.Back]   = new Vector3(modelAABBSize.x + sizeEps, modelAABBSize.y + sizeEps, overlapAmount);
            overlapAABBSizes[(int)BoxFace.Front]  = new Vector3(modelAABBSize.x + sizeEps, modelAABBSize.y + sizeEps, overlapAmount);

            var overlapAABBs = new List <AABB>();

            for (int boxFaceIndex = 0; boxFaceIndex < modelAABBFaces.Count; ++boxFaceIndex)
            {
                BoxFace modelAABBFace = modelAABBFaces[boxFaceIndex];
                Vector3 faceCenter    = BoxMath.CalcBoxFaceCenter(modelAABB.Center, modelAABB.Size, Quaternion.identity, modelAABBFace);
                Vector3 faceNormal    = BoxMath.CalcBoxFaceNormal(modelAABB.Center, modelAABB.Size, Quaternion.identity, modelAABBFace);
                Vector3 overlapCenter = faceCenter - faceNormal * halfOverlapAmount;
                overlapAABBs.Add(new AABB(overlapCenter, overlapAABBSizes[boxFaceIndex]));
            }

            return(overlapAABBs);
        }
        public bool Initialize(GameObject gameObject)
        {
            if (gameObject == null || _gameObject != null)
            {
                return(false);
            }

            Mesh   mesh   = gameObject.GetMesh();
            Sprite sprite = gameObject.GetSprite();

            if (mesh == null && sprite == null)
            {
                return(false);
            }

            bool useMesh = true;

            if (mesh == null)
            {
                useMesh = false;
            }

            RTMesh rtMesh = null;

            if (useMesh)
            {
                Renderer meshRenderer = gameObject.GetMeshRenderer();
                if (meshRenderer == null || !meshRenderer.enabled)
                {
                    useMesh = false;
                }

                rtMesh = RTMeshDb.Get.GetRTMesh(mesh);
                if (rtMesh == null)
                {
                    useMesh = false;
                }
            }
            if (rtMesh == null && sprite == null)
            {
                return(false);
            }

            List <AABB> vertOverlapAABBs = BuildVertOverlapAABBs(gameObject, useMesh ? null : sprite, useMesh ? rtMesh : null);

            if (vertOverlapAABBs.Count == 0)
            {
                return(false);
            }

            AABB modelAABB = useMesh ? rtMesh.AABB : ObjectBounds.CalcSpriteModelAABB(gameObject);
            var  aabbFaces = BoxMath.AllBoxFaces;

            _gameObject = gameObject;
            if (useMesh)
            {
                foreach (var aabbFace in aabbFaces)
                {
                    AABB           overlapAABB     = vertOverlapAABBs[(int)aabbFace];
                    List <Vector3> overlappedVerts = rtMesh.OverlapModelVerts(overlapAABB);
                    Plane          facePlane       = BoxMath.CalcBoxFacePlane(modelAABB.Center, modelAABB.Size, Quaternion.identity, aabbFace);
                    overlappedVerts = facePlane.ProjectAllPoints(overlappedVerts);
                    _snapAreaBounds[(int)aabbFace] = new AABB(overlappedVerts);
                    _snapAreaDesc[(int)aabbFace]   = BoxMath.GetBoxFaceAreaDesc(_snapAreaBounds[(int)aabbFace].Size, aabbFace);
                }
            }
            else
            {
                foreach (var aabbFace in aabbFaces)
                {
                    if (aabbFace != BoxFace.Front && aabbFace != BoxFace.Back)
                    {
                        AABB           overlapAABB     = vertOverlapAABBs[(int)aabbFace];
                        List <Vector3> overlappedVerts = ObjectVertexCollect.CollectModelSpriteVerts(sprite, overlapAABB);
                        Plane          facePlane       = BoxMath.CalcBoxFacePlane(modelAABB.Center, modelAABB.Size, Quaternion.identity, aabbFace);
                        overlappedVerts = facePlane.ProjectAllPoints(overlappedVerts);
                        _snapAreaBounds[(int)aabbFace] = new AABB(overlappedVerts);
                        _snapAreaDesc[(int)aabbFace]   = BoxMath.GetBoxFaceAreaDesc(_snapAreaBounds[(int)aabbFace].Size, aabbFace);
                    }
                    else
                    {
                        _snapAreaBounds[(int)aabbFace] = AABB.GetInvalid();
                        _snapAreaDesc[(int)aabbFace]   = BoxFaceAreaDesc.GetInvalid();
                    }
                }
            }

            return(true);
        }