LocomotionClass.cs

using Microsoft.VisualStudio.OLE.Interop;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace PatcherYRpp
{
    [StructLayout(LayoutKind.Explicit, Size = 24)]
    public struct LocomotionClass
    {
        private static IntPtr _pGUIDs = new IntPtr(0x7E9A30);
        private static Pointer<Guid> pGUIDs => _pGUIDs.Convert<Guid>();
        public static Guid Drive { get => pGUIDs[0]; set => pGUIDs[0] = value; }/* 0x7E9A30;*/
        public static Guid Hover { get => pGUIDs[1]; set => pGUIDs[1] = value; }/* 0x7E9A40;*/
        public static Guid Tunnel { get => pGUIDs[2]; set => pGUIDs[2] = value; }/* 0x7E9A50;*/
        public static Guid Walk { get => pGUIDs[3]; set => pGUIDs[3] = value; }/* 0x7E9A60;*/
        public static Guid Droppod { get => pGUIDs[4]; set => pGUIDs[4] = value; }/* 0x7E9A70;*/
        public static Guid Fly { get => pGUIDs[5]; set => pGUIDs[5] = value; }/* 0x7E9A80;*/
        public static Guid Teleport { get => pGUIDs[6]; set => pGUIDs[6] = value; }/* 0x7E9A90;*/
        public static Guid Mech { get => pGUIDs[7]; set => pGUIDs[7] = value; }/* 0x7E9AA0;*/
        public static Guid Ship { get => pGUIDs[8]; set => pGUIDs[8] = value; }/* 0x7E9AB0;*/
        public static Guid Jumpjet { get => pGUIDs[9]; set => pGUIDs[9] = value; }/* 0x7E9AC0;*/
        public static Guid Rocket { get => pGUIDs[10]; set => pGUIDs[10] = value; } /*0x7E9AD0;*/

        public Guid GUID => GetClassID();

        public static void ChangeLocomotorTo(Pointer<FootClass> pFoot, Guid clsid)
        {
            // remember the current one
            ILocomotion Original = pFoot.Ref.Locomotor;

            // create a new locomotor and link it
            ILocomotion NewLoco = COMHelpers.CreateInstance<ILocomotion>(clsid);
            NewLoco.Link_To_Object(pFoot);

            // get piggy interface and piggy original
            if (NewLoco is IPiggyback Piggy)
            {
                Piggy.Begin_Piggyback(Original);
            }

            // replace the current locomotor
            pFoot.Ref.Locomotor = NewLoco;
        }

        public static void ChangeLocomotorTo<TLocomotion>(Pointer<FootClass> pFoot)
        {
            ChangeLocomotorTo(pFoot, typeof(TLocomotion).GUID);
        }

        public Guid GetClassID()
        {
            IPersistStream.GetClassID(out Guid guid);
            return guid;
        }

        [FieldOffset(0)] public int Vfptr_IPersistStream;
        public IPersistStream IPersistStream => Marshal.GetObjectForIUnknown(this.GetThisPointer()) as IPersistStream;
        [FieldOffset(4)] public int Vfptr_ILocomotion;
        public ILocomotion ILocomotion => Marshal.GetObjectForIUnknown(this.GetThisPointer()) as ILocomotion;
        [FieldOffset(8)] public Pointer<FootClass> Owner;
        [FieldOffset(12)] public Pointer<FootClass> LinkedTo;
        [FieldOffset(16)] public Bool Powered;
        [FieldOffset(17)] public Bool Dirty;
        [FieldOffset(20)] public int RefCount;
    }

    public static class LocomotionHelpers
    {
        public static Pointer<LocomotionClass> ToLocomotionClass(this ILocomotion locomotion)
        {
            Pointer<IntPtr> ptr = Marshal.GetIUnknownForObject(locomotion);
            Marshal.Release(ptr);
            ptr -= 1;

            return ptr.Convert<LocomotionClass>();
        }

        public static Pointer<TLocomotionClass> ToLocomotionClass<TLocomotionClass>(this ILocomotion locomotion)
        {
            return locomotion.ToLocomotionClass().Convert<TLocomotionClass>();
        }

        public static void Load(this IPersistStream persistStream, System.Runtime.InteropServices.ComTypes.IStream stream)
        {
            persistStream.Load(stream as IStream);
        }
        public static void Save(this IPersistStream persistStream, System.Runtime.InteropServices.ComTypes.IStream stream, int fClearDirty)
        {
            persistStream.Save(stream as IStream, fClearDirty);
        }
        public static int SaveSize(this IPersistStream persistStream)
        {
            var tmp = new ULARGE_INTEGER[1];
            persistStream.GetSizeMax(tmp);
            return (int)tmp[0].QuadPart;
        }
    }
}