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Problem with Waterblock

by James Urquhart · in Torque Game Engine Advanced · 09/11/2005 (12:39 pm) · 6 replies

Hi there,

Currently i have flying vehicles going about in TSE.
Recently, i have been getting this strange assert popping up :

"MatrixF::inverse: non-singular matrix, no inverse."

Oddly enough, i have traced it back to the Waterblock render code :

GuiCanvas::renderFrame -> GuiCanvas::updateReflections -> WaterBlock::updateReflections.

To be specific, here is where it all goes wrong :

// store "normal" camera position before changing over to reflected position
   MatrixF camTrans = query.cameraMatrix;
   gClientSceneGraph->mNormCamPos = camTrans.getPosition();

   // update plane
   PlaneF plane;
   Point3F norm;
   getRenderTransform().getColumn( 2, &norm );
   norm.normalize();
   plane.set( getRenderPosition(), norm );
   mReflectPlane.setPlane( plane );

   // set world mat from new camera view
   MatrixF camReflectTrans = mReflectPlane.getCameraReflection( camTrans );
   >> camReflectTrans.inverse(); <<

Now i notice this error always occurs when i am in the vehicle, usually when the camera is pointing upwards. Usually if i mess up the vehicle and make it collide with something bad (an interior or constantly at the terrain), this assert pops up.

Values of relevant variables are as follows :

The Matrix being inverse'd (camReflectTrans):
0
1.742829933e-039
9.302940245e-039
1.347942904e-038
0
0
0
0
-1.3481545e-038
0
-4.622918386e-038
401.2000122
0
0
0
1

camTrans :
0
1.742829933e-039
9.302940245e-039
1.347942904e-038
0
0
0
0
1.3481545e-038
0
4.622918386e-038
1.742862162e-039
7.289827865e-039
0
4.622918386e-038
1.073327642e-038

mReflectPlane :
normal = (0 0 1)
d = -200.6000061


Looking at the plane normal, it seems to me that i am looking directly upwards, but thats only a guess...
Anyone got any ideas?
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Associate James Urquhart
#1
09/11/2005 (2:03 pm)
An update...

I have come to the conclusion that there is a fault with camTrans, or rather, the camera matrix being passed into the CameraQuery data (query.cameraMatrix).

So, i looked around a bit, and came to this function :

bool GameConnection::getControlCameraTransform(F32 dt, MatrixF* mat)
{
   ShapeBase* obj = getCameraObject();
   if(!obj)
      return false;

Now this is interesting... if it can't get the camera object, that function will return false, which will make this function return false :

bool GameProcessCameraQuery(CameraQuery *query)

Then this:
bool GameTSCtrl::processCameraQuery(CameraQuery *camq)
{
   GameUpdateCameraFov();
   return GameProcessCameraQuery(camq);
}
(NOTE: GameUpdateCameraFov could easily crap up too)

And finally, returning to our Waterblock reflection function :
// grab camera transform from tsCtrl
   GuiTSCtrl *tsCtrl;
   tsCtrl = dynamic_cast<GuiTSCtrl*>( Sim::findObject("PlayGui") );
   CameraQuery query;
   tsCtrl->processCameraQuery( &query );

How did this all come about? I have no idea. Its probably something to do with me deleting my vehicle when its "Destroyed", and not returning a proper control state, but thats just a guess :)
And funnily enough, i'm having a slightly hard time reproducing this - just typical :)

However, there really should be extra error checking to prevent this Assert, or extra Assert's to give a clearer idea of what the problem is.

Associate Andy Hawkins
DrewFX
#2
06/12/2007 (5:42 pm)
I get this too. Any one know a fix?

Torque 3D Owner Mary Westmacott
#3
06/13/2007 (10:20 am)
I've had this happen once. I was mounted, probably looking up.

You could try adding a check before the Assert like this:

if(det == 0.0f)
   {
          Con::executef(3, "MessageBoxOK", "For Your Information","Determinant is zero, engine would have preformed an fatal Assert at this point.");
         // Can't invert this matrix, just return
         return;
   }

That will let you know when it happens and let you keep running.

Associate Andy Hawkins
DrewFX
#4
06/14/2007 (3:23 am)
It only happens to me when I run a debug version of TGEA

Torque Owner Josiah Pisciotta
#5
08/15/2007 (10:47 am)
I am currently having this problem happen to me as well... I just put a mounted particle emitter on my char to shoot bubbles all around him but I am getting this matrix inverse problem pop up when i run the debug build. I really have no idea why it is doing this or how to fix it, any of you guys make any progress towards fixing the problem????

Associate Andy Hawkins
DrewFX
#6
08/15/2007 (4:49 pm)
Just wrap some code around it to ignore if you are running debug I suppose????