Pointer to pointer array of scene nodes

[robmar]

I just can´t figure out the syntax to do this and not get errors!

irr::scene::ILightSceneNode (*m_pLights)[MAX_LIGHTS]; // Does not work for some reason! Abstract class not allowed!!

This is meant to be a point to an array of pointers, so this pointer can be initialised and passed to the OnSetConstants callback.

I´ve googled and there are lots of threads about this, it works fine with ints, etc., but not with void ptrs or scene node pointers!

Help!!

[polylux]

Well, pretty obvious to me, as you should be omitting the brackets.
Like so:

Code: Select all

scene::ILightSceneNode* m_pLights[MAX_LIGHTS];

Otherwise the compiler tries to dereference m_pLights which won't work at that stage.
Or do I get your intention wrong?

[robmar]

Ahhh ha, think again!!

that makes it an array of pointers, where what I need is a single pointer to an array of pointers!

officially, the brackets separate the left-right array effect, and make it a pointer to an array of pointers.

if you swap the lightscenenode for an int*, it works fine, or I can list say 8 separate pointers to lightscenenodes, but how to do it in a tidy pointer to array?

[polylux]

Well, the above is of type

Code: Select all

scene::ILightSceneNode**

Isn't that what you want?

[robmar]

Its a ptr to a ptr, but not a ptr to a ptr-array!

Like this works, its similar, but its a series of ptrs to ptrs:

irr::scene::ILightSceneNode **m_pLightNode1;
irr::scene::ILightSceneNode **m_pLightNode2;
irr::scene::ILightSceneNode **m_pLightNode3;
...
//irr::scene::ILightSceneNode (*m_pLights)[MAX_LIGHTS]; // Does not work for some reason! Abstract class not allowed!! Works with ints though!

then...

if ( m_pLightNode1 && *m_pLightNode1 )
m_LightPosition = (*m_pLightNode1)->getAbsolutePosition();

but for neatness, and to use it in a while or for loop, I need a ptr to a ptr-array, but how is that done?

[polylux]

Sry, but that thing up there as I posted it is a pointer array. Dunno what else you want. Also I don't really get your latest example.

[robmar]

Tried this:-

irr::scene::ILightSceneNode **m_pLightNodes[MAX_LIGHTS]; // Pointer to an array of ptrs....???

with

m_LightPosition = *(*m_pLightNodes[0])->getAbsolutePosition(); // Intelisense shows all the members!!!

but then get "error C2100: illegal indirection"

[polylux]

Why not do it this:

Code: Select all

scene::ILightSceneNode* m_pLightNodes[MAX_LIGHTS]; //that bugger here _IS_ a pointer array
core::vector3df pos = m_pLightNodes[0]->getAbsolutePosition();

Guess you just have to get your pointer syntax (and arithmetics) right.

[robmar]

The problem is that the array of pointers is in a class that onsetconstants cannot access unless I setup the class headers in onsetconstants, which I didn´t want to do.

So I need to simply pass a pointer to the "array of pointers" that is in my main class, to the onsetconstants class.

How do I pass a pointer to an array of pointers is the question!!

Not how do I create an array of pointers and use it directly... there is.. a difference!!

[Abraxas)]

Unless I misunderstand, a pointer and an array variable are the same thing. If you had an array with 2 members, your pointer variable++ would be the second member.

I'm not 100% sure about pointer arithmetic because I stay away from code grammar that isn't obvious to another person reading it.

[CuteAlien]

Use the declaration as polylux posted and then pass m_pLights or &m_pLights[0] (those are identical). Then you pass the address of m_pLights.

[robmar]

Have you tried to do that with VS? It generates the errors I mentioned.

[serengeor]

Have you tried to do that with VS? It generates the errors I mentioned.

http://msdn.microsoft.com/en-us/library ... s.71).aspx


Is this http://ideone.com/LrlgHP what you want to do?

[jaworekplay]

+1 to polylux .

[robmar]

Thanks, took a look at those links, and its not error c2100, its just that the compiler does not allow ptrs to arrays of ptrs of abstract class, including even a simple void ptr!

Why it disallows a ptr to an array of void ptrs I can not imagine!!!

In the end I just changed to use a ptr to a ptr to an array of vector3df, and that works.