[LE3]UpdatePhysicsHook

[AggrorJorn]

Having some issues with adding a physics hook to an entity.

 

//.h
void PlayerUpdate(Entity* entity);

// .cpp
void PlayerUpdate(Entity* entity)
{
//update player
}
bool App::Start()
{
//Somewhere in start function
System::AddHook(Entity::UpdatePhysicsHook,PlayerUpdate);

ERROR:

IntelliSense: argument of type "void (App::*)(Leadwerks::Entity *entity)" is incompatible with parameter of type "void *"

[tjheldna]

Hi Aggror,

 

I have this working if the hook is added to the entity itself... I had no need to define it in .h

 

void UpdateMyPhysicsHook(Entity* entity)
{
blah blah
}


entity->AddHook(Entity::UpdatePhysicsHook, UpdateMyPhysicsHook);

[AggrorJorn]

Aha thats it! Thanks Tim.

[MCP]

ERROR:

IntelliSense: argument of type "void (App::*)(Leadwerks::Entity *entity)" is incompatible with parameter of type "void *"

Your compiler is rightfully complaining that your function pointer isn't of the correct type ie "void *".

 

The error lies within the declaration of System::AddHook() which has "void *" as the second parameter. AddHook should expect a function pointer of type void NOT a void pointer as they are in fact two completely different things and this should be classified as a typo bug.

 

The correct declaration for System::AddHook() should have been this....

typdef void (*vFunc)(Leadwerks::Entity *);

AddHook(int hookid, vFunc hook) {
...
}

As a temporary measure you call cast all your function pointers to void pointers but generally speaking this is considered dangerous in the C++ world and some compilers may not allow you even to do that. In a case were compilation has been successful you will often run into instability issues, memory address violations or other runtime errors... Avoid!

 

See this discussion on the subject...

 

http://stackoverflow...er-as-parameter

[Furbolg]

Good explanation, didnt know/realized that AddHook is the real problem.

 

Of course using void* is a bad thing, because void* can be anything. But there are exceptions for example if you know what void* represents, then it shouldnt be a problem to cast it ( beginthread etc. ):

[lukhns]

Will this bug be fixed? or has anyone found a stable solution? I thought maybe it would be fixed in the next build, but im still unable to compile on OSX using AddHook with a void pointer.

[Josh]

Cast the function pointer to a void* and it will work.

[xtreampb]

i tried this and it doesn't run on OS X. It compiles then crashes