X, Y and Z position bug in absolute

BlitzMax Forums/MiniB3D Module/X, Y and Z position bug in absolute

Bobysait

(Posted 2014) [#1]

I Don't know if it's been reported yet but the "EntityX/Y/Z(true)" (while and entity is a child of another) does not return the good value

Actually, as I finished my own blitzmax 3D engine, I wanted to compare the two engines (performance and precision accuracy) and I realised two major things (about entity) :
- miniB3d uses the invert matrix to compute relative position/scale/rotation but use a slow method for TFormPoint/Vector.

Repeat
	mat.Scale(1.0/ent.sx,1.0/ent.sy,1.0/ent.sz)
	mat.RotateRoll(-ent.rz)
	mat.RotatePitch(-ent.rx)
	mat.RotateYaw(-ent.ry)
	mat.Translate(-ent.px,-ent.py,-ent.pz)																																																																																																																																																																																																																																																																																																																																									
	ent=ent.parent
Until ent=Null

if could (should) be replaced with a more direct computation.

- the second point I noticed is that lots of calculs does not return the same results as Blitz3D. (mine does ... I made it in this way)

So, of course, I can't compare the engines at this state as minib3d is not fully functionnal, but anyway, what matters now is that minib3d needs a fix on the "X", "Y" and "Z" coordinates.

Where I'm sure it's a bug and not a matter of different axis is :

p1 = CreatePivot()
position scale and rotate p1 randomly
p2 = createpivot(p1)
position scale and rotate p2 randomly in absolute

let's say positionentity p2, 0.0,-5.2,14.5

EntityY(p2,true) and EntityZ(p2,true) does not return -5.2 and 14.5.

SuperStrict

Framework sidesign.minib3d

Graphics3D (800,600,0,2);

SeedRnd(1);

Local px1# = Rnd(-50,50), py1# = Rnd(-50,50), pz1# = Rnd(-50,50);
Local rx1# = -180+Rnd(540), ry1# = -180+Rnd(540), rz1# = -180+Rnd(540);
Local sx1# = Rnd(0.1,2.0), sy1# = Rnd(0.1,2.0), sz1# = Rnd(0.1,2.0);

Local px2# = Rnd(-50,50), py2# = Rnd(-50,50), pz2# = Rnd(-50,50);
Local rx2# = -180+Rnd(540), ry2# = -180+Rnd(540), rz2# = -180+Rnd(540);
Local sx2# = Rnd(0.1,2.0), sy2# = Rnd(0.1,2.0), sz2# = Rnd(0.1,2.0);


Local p1:TEntity = CreatePivot();
	PositionEntity	( p1, px1,py1,pz1, True );
	RotateEntity	( p1, rx1,ry1,rz1, True );
	ScaleEntity		( p1, sx1,sy1,sz1, True );
Local p2:TEntity = CreatePivot(p1);
	PositionEntity	( p2, px2,py2,pz2, True );
	RotateEntity	( p2, rx2,ry2,rz2, True );
	ScaleEntity		( p2, sx2,sy2,sz2, True );
	
Print "p1"
Print px1+", "+py1+", "+pz1
Print EntityX(p1, True)+", "+EntityY(p1, True)+", "+EntityZ(p1, True);
Print ""
Print "p2"
Print px2+", "+py2+", "+pz2
Print EntityX(p2, True)+", "+EntityY(p2, True)+", "+EntityZ(p2, True);
Print

my results :

p1
-49.9910088, -9.45895767, 37.1822815
-49.9910088, -9.45895767, 37.1822815

p2
40.4846954, -31.1590710, 9.79907608
40.5032539, -29.9750633, 8.96056747