T3D 1.1 Beta3 - debrisShapeName causes hard engine crash due to bad pointer - RESOLVED (THREED-1565)

Build: T3D 1.1 beta 3 pro (and probably earlier)

Platform: Windows Vista

Target: Game


Issues:
Assigning a debrisShapeName to the datablock for a ShapeBase derived object causes the engine to crash when the objects damage state == Destroyed and ShapeBase::blowUp() is invoked. This is due to Debris::prepRenderImage using a bad pointer.


Steps to repeat:
Assign a debrisShapeName to the datablock for a destroyable object, preferably a StaticShape (note, not player, as players override the normal shapebase damage state handling, and ShapeBase::blowUp() doesn't get called for them).
Destroy the object.
Watch the engine crash.


Suggested Fix:
in Debris.cpp, line 837, (debris::prepRenderImage)
change:

if( mPart )
   mShape->setDetailFromDistance( state, dist * invScale );

*this is the crash line, as if mPart is assigned, mShape will be null.

to:

if( mPart )
   {
      // get the shapeInstance that we are using for the debris parts
      TSShapeInstance *si = mPart->getSourceShapeInstance();
         
      // set the correct detail level
      if( si )
         si->setDetailFromDistance( state, dist * invScale );
   }

Further info:
The (virtually undocumented) debrisShapeName field for ShapeBase derived objects is intended to allow the designer to be able to specify a shape which is broken up into its component parts when the object is destroyed. Each of these parts become a separate debris object, thereby allowing the designer to do things like have a robot or spacecraft break into flaming, smoking pieces, or have head, arms, legs and body fly around leaving trails of gibs behind.

The engine documentation for this field reads:
"The DTS or DAE model to use for auto-generated breakups. @note may not be functional."

The FPS example includes a debris shape file for the player in art/shapes/actors/common, and assigns it to the players datablock, but it doesn't actually get used because the player scripts override the normal ShapeBase damage state handling code.

After this fix debrisShapeName will be functional for destroyable shapes: