hellbound/Assets/Sources/Feel/MMTools/Tools/MMPhysics/MMRigidbodyCenterOfMass.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace MoreMountains.Tools
{
    /// <summary>
    /// Add this class to a Rigidbody or Rigidbody2D to be able to edit its center of mass from the inspector directly
    /// </summary>
    public class MMRigidbodyCenterOfMass : MonoBehaviour
    {
        /// the possible modes this class can start on
        public enum AutomaticSetModes { Awake, Start, ScriptOnly }

        [Header("CenterOfMass")]
        /// the offset to apply to the center of mass
        public Vector3 CenterOfMassOffset;

        [Header("Automation")]
        /// whether to set the center of mass on awake, start, or via script only
        public AutomaticSetModes AutomaticSetMode = AutomaticSetModes.Awake;
        /// whether or not this component should auto destroy after a set
        public bool AutoDestroyComponentAfterSet = true;

        [Header("Test")]
        /// the size of the gizmo point to display at the center of mass
        public float GizmoPointSize = 0.05f;
        /// a button to test the set method
        [MMInspectorButton("SetCenterOfMass")]
        public bool SetCenterOfMassButton;

        protected Vector3 _gizmoCenter;
        protected Rigidbody _rigidbody;
        protected Rigidbody2D _rigidbody2D;

        /// <summary>
        /// On Awake we grab our components and set our center of mass if needed
        /// </summary>
        protected virtual void Awake()
        {
            Initialization();

            if (AutomaticSetMode == AutomaticSetModes.Awake)
            {
                SetCenterOfMass();
            }
        }

        /// <summary>
        /// On Start we set our center of mass if needed
        /// </summary>
        protected virtual void Start()
        {
            if (AutomaticSetMode == AutomaticSetModes.Start)
            {
                SetCenterOfMass();
            }
        }

        /// <summary>
        /// Grabs the rigidbody or rigidbody2D components
        /// </summary>
        protected virtual void Initialization()
        {
            _rigidbody = this.gameObject.MMGetComponentNoAlloc<Rigidbody>();
            _rigidbody2D = this.gameObject.MMGetComponentNoAlloc<Rigidbody2D>();
        }

        /// <summary>
        /// Sets the center of mass on the rigidbody or rigidbody2D
        /// </summary>
        public virtual void SetCenterOfMass()
        {
            if (_rigidbody != null)
            {
                _rigidbody.centerOfMass = CenterOfMassOffset;
            }

            if (_rigidbody2D != null)
            {
                _rigidbody2D.centerOfMass = CenterOfMassOffset;
            }

            if (AutoDestroyComponentAfterSet)
            {
                Destroy(this);
            }
        }

        /// <summary>
        /// On DrawGizmosSelected, we draw a yellow point at the position of our center of mass
        /// </summary>
        protected virtual void OnDrawGizmosSelected()
        {
            _gizmoCenter = this.transform.TransformPoint(CenterOfMassOffset);
            MMDebug.DrawGizmoPoint(_gizmoCenter, GizmoPointSize, Color.yellow);
        }
    }
}