Unity Raycast Optimization: Efficient Graphic Selection in Canvas

private static void Raycast(Canvas canvas, Camera eventCamera, Vector2 pointerPosition, IList foundGraphics, List results) { // Necessary for the event system int totalCount = foundGraphics.Count; for (int i = 0; i < totalCount; ++i) { Graphic graphic = foundGraphics[i]; if (graphic.depth == -1 || !graphic.raycastTarget) { continue; }

            RectTransform graphicRectTransform = graphic.rectTransform;
            Vector3[] corners = new Vector3[4];
            graphicRectTransform.GetWorldCorners(corners);

            bool isInside = RectTransformUtility.RectangleContainsScreenPoint(graphicRectTransform, pointerPosition, eventCamera);
            if (isInside)
            {
                Vector2 localPosition;
                RectTransformUtility.ScreenPointToLocalPointInRectangle(graphicRectTransform, pointerPosition, eventCamera, out localPosition);

                Vector3[] localCorners = new Vector3[4];
                graphicRectTransform.GetLocalCorners(localCorners);

                if (!RectTransformUtility.RectangleContainsScreenPoint(graphicRectTransform, localPosition, eventCamera))
                {
                    continue;
                }

                float width = corners[2].x - corners[0].x;
                float height = corners[2].y - corners[0].y;

                float x = (localPosition.x - localCorners[0].x) / width;
                float y = (localPosition.y - localCorners[0].y) / height;

                if (graphic.Raycast(new Vector2(x, y), eventCamera))
                {
                    results.Add(graphic);
                }
            }
        }
    }