MDX and collision

[xalcon]

Hi folks,
currently working on geometry parsing. ADT and WMO seem to be quite simple. Getting the collision data (=> bounding vertices) from MDX was not that hard too, but I've noticed that doors as well as characters do have those bounding vertices (which ofc makes sense!)... but how does the client knows which mdx objects can collide with eachother?
e.g. how does the client knows that a tauren can pass "through" a nightelv on a big mount or the cooking campfire, but not through a closed door? Is there a flag which I've just missed or can I expect that all mdx files defined inside a WMO are used for collision?

Thanks for help!

[Jadd]

Check out CGGameObject_C::IsSolidCollidable - 0x0044A820 (5.1.0.16357 x86 [rebased])

[Frosttall]

The model of your character is a simple cylinder.

Here is some code:

        /// <summary>
        /// Collision Height
        /// </summary>
        public float UnitHeight
        {
            get
            {
                return WowMem.Read<float>(MovementFields + MemEnums.MovementsFields.UnitHeightOffset);
            }
        }

        /// <summary>
        /// Collision Radius
        /// </summary>
        public float UnitRadius
        {
            get
            {
                return WowMem.Read<float>(MovementFields + MemEnums.MovementsFields.UnitRadiusOffset);
            }
        }

        private uint MovementFields
        {
            get { return WowMem.Read<uint>(BaseAddress + MemEnums.MovementsFields.MovementField); }
        }

Offsets:

internal enum MovementsFields : uint
        {
            MovementField = 0xE4,
            UnitHeightOffset = 0xD0,
            UnitRadiusOffset = 0xCC
        }

Enjoy

[xalcon]

The model of your character is a simple cylinder.
[...]
Enjoy

Well, that didn't helped really much :P I know how to check if something is colliding. What I don't know is, how to find out if something is collidable.

@Jadd:
I think that could help. Does anyone knows what data is passed to the method? It looks like some kind of flag *not that good with asm*
It seems, when the param does not contain 0x8000, it's not collidable... otherwise, some data at [[this+0xD8]+0x2D] is checked to be > 0
What kind of data can I find at [this+0x21C]? My structs from my older projects aren't that big... maybe I have an idea, but it will take some time to check it.
Anyway, thanks for your help!

[Jadd]

Well, that didn't helped really much :P I know how to check if something is colliding. What I don't know is, how to find out if something is collidable.

@Jadd:
I think that could help. Does anyone knows what data is passed to the method? It looks like some kind of flag *not that good with asm*
It seems, when the param does not contain 0x8000, it's not collidable... otherwise, some data at [[this+0xD8]+0x2D] is checked to be > 0
What kind of data can I find at [this+0x21C]? My structs from my older projects aren't that big... maybe I have an idea, but it will take some time to check it.
Anyway, thanks for your help!

The signature for the function is:

__thiscall DWORD_PTR CGGameObject_C__IsSolidCollidable( CGGameObject_C* pObject, UINT16 wCollisionFlags )

It seems that [[obj+0xD8]+0x2D] is true/false (1 byte) and determines whether it is collidable. The flag parameter (2 bytes) is called with 0x8000 flag depending on how ObjectCollisionProc, the parent function, calls it. If 0x8000 is specified then it will skip the [[obj+0xD8]+0x2D] true/false check and simply return [obj+0x21C].

I assume [obj+0x21C] contains some kind of collision data but I have not looked.

To test collision, I would suggest one of these:
1. Read: IsCollidable = [[obj+0xD8]+0x2D]
2. Call: IsCollidable = CGGameObject_C__IsSolidCollidable( pObject, 0x8000 ) != 0;

Edit: Sorry if this is hard to understand, I have been awake all night.

[xalcon]

No, it's not hard, just not really what I was looking for But I think it might help, will try it out when I have some spare time.
+rep for clarifcation

[hamburger12]

This is for 5.4.2:17688

result = *(_BYTE *)(GameObjectAddress + 0x224);

if the object is collidable it will be 1 else it will be 0. If you write the value to zero, you can go trought the object ^.^


Sorry for pumping such an old thread.