Irrlicht 1.3 crashing your custom scene nodes?
Posted on:April 12 2007
Maybe you've just switched to Irrlicht 1.3 and your custom scene nodes are crashing in the getMaterial method. That's because we've changed the single parameter from a s32 to an u32, so your overridden method won't get called. Solution: change your parameter in getMaterial to u32 as well.
Unfortunately, C++ doesn't have a Override keyword such as C# or Java 5 have, which would have prevented that problem. Sorry to write this specific thing here, but a lot of people kept asking this. Maybe I should add this into the wiki.
Unfortunately, C++ doesn't have a Override keyword such as C# or Java 5 have, which would have prevented that problem. Sorry to write this specific thing here, but a lot of people kept asking this. Maybe I should add this into the wiki.
Comments:
halan
Quote2007-04-12 08:57:00
Really? Could anyone tell me what override does?
Matthias
Quote2007-04-12 10:12:00
Matthias, override tells the compiler to override a specifiy method ;) if there is no such method to override (like in this case: getMaterial(s32) ) than the compiler will throw errors.
In C++ the compiler does not know if you want to override a function or create a new one.
In C++ the compiler does not know if you want to override a function or create a new one.
sanjin
Quote2007-04-12 10:23:00
it will not trow errors because in C++ theres no "override" keyword as niko said. instead both functoins will exist getMaterial(s32) and getMaterial(u32)
if so the getMaterial(u32) (the new one) is only defined as empty "interface"-function and produces a crash when called...
if so the getMaterial(u32) (the new one) is only defined as empty "interface"-function and produces a crash when called...
halan
Quote2007-04-12 10:55:00
well, "empty interface function" ^^
actualy it is defined that way:
virtual video::SMaterial& getMaterial(u32 num)
{
return *((video::SMaterial*)0);
}
casting a nullpointer to a reference :D
i mean, if that doesn't produce a crash i don't know ^^
hmm, maybe it should be pure virtual since if someone wants to code a scenenode which doesn't have any material than he shall write something dangerous like this on his own so he knows what the code is doing.
actualy it is defined that way:
virtual video::SMaterial& getMaterial(u32 num)
{
return *((video::SMaterial*)0);
}
casting a nullpointer to a reference :D
i mean, if that doesn't produce a crash i don't know ^^
hmm, maybe it should be pure virtual since if someone wants to code a scenenode which doesn't have any material than he shall write something dangerous like this on his own so he knows what the code is doing.
sanjin
Quote2007-04-12 12:40:00
yeah virtual is a good way to prevent such problems, nice idea!
halan
Quote2007-04-12 19:17:00
Yeah, proper pure virtuals should be used.
BTW: Also annoying is the wrong instruction for renaming Pre/PostRender which should be named OnRegisterSceneNode and onAnimate, repectively.
BTW: Also annoying is the wrong instruction for renaming Pre/PostRender which should be named OnRegisterSceneNode and onAnimate, repectively.
hybrid
Quote2007-04-14 00:24:00
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Topic: well C++ has its problems too :)