Colliders - Rephrased

Blitz3D Forums/Blitz3D Beginners Area/Colliders - Rephrased

Mikorians

(Posted 2013) [#1]

Perhaps I've been asking the wrong questions:

Part 1:I MUST use standard collision detection;
When the slide runs amock and reports that I'm elsewhere when I can see the sphere (as rendered) is in the same spot (or somewhere else), how do I obtain it's REAL entityXYZ?
Since true or false both report the same thing.
I do have two other ellipse pivots (not children) that I could compare with.
Is there some tform thingy for ACTUAL position?

Part 2: Once we've figured that out, I need to snap off slide so I can put it where it's supposed to be and snap it back on again without multiple updateworlds. ?
(Lots of polygons from loadanimmesh)

I'm hoping to come back tomorrow and be able to continue my work.

Mikorians

(Posted 2014) [#2]

RemiD mentioned destroying and recreating them to move them-
Have you all found this to be effective?

RemiD

(Posted 2014) [#3]

If you want to reposition a collider, you need to either :
remove it from the collisions calculation for at least 1 frame, in this case ResetEntity() can help
or
delete the collider and recreate one with the desired orientation/position

I have found that in some cases ResetEntity does not work properly (see : http://www.blitzbasic.com/Community/posts.php?topic=98459 )

Mikorians

(Posted 2014) [#4]

Excellent work, Remi!
I have a test bed application also.

If collisions are so difficult---
We really ought to add this stuff where people can see it
In the codebase and the samples/tutorials.
A banner link to the codebase site would also be helpful...
This would prevent redundant user questions (like ours)

I glanced over it and will attempt deploying your idea.
I noted only a mention of the creation/destruction...

Which order of events?
And what about detecting a position discrepancy?
We both know the entityxyz lies.
It seems to report the "desired target position"

Mikorians

(Posted 2014) [#5]

Here's a sort of sample tester thing, ripped out of my engine.
(I actually load an animmesh and index it to a type array, of course)

Type CamD
	Field Body	  ;Camera parent object
	Field Camera	;ACTUAL Camera - Man to be... (Head)
	Field Head		;Error discrepancy detector
	Field C$			;What we're climbing
	Field P$			;What we're a child of
	Field PIdx		;The parent index value
	Field DY#			;Delta Y (Y velocity for falling/gravity)
	Field OY#			;Offset Y (We must track this for carry catch)
End Type

Global Mde=0		;0=Fork head snagger, 1=Overhead sticker (get stuck)
Global Windowed=1,FirstFlag
;Global B3
;Global C
Graphics3D 800,600,0,1-windowed											;Plane of existence
l=CreateLight()

a=CreateCube()																			;Ground
ScaleMesh a,800,.01,800
PositionEntity a,0,-5,0
cp=CreateBrush(0,90,0)
PaintEntity a,cp

b1=CreateCube()
b2=CreateCube()
b3=CreateCube()
b4=CreateCube()
PositionEntity b1,-20,5,-15
PositionEntity b2,-20,5,15 ;We COULD get one ball pegged!  -Fixed?
ScaleMesh b1,.01,60,11
ScaleMesh b2,.01,60,11
ScaleMesh b3,20,1,20
ScaleMesh b4,40,1,40
PositionEntity b4,80,1,120
cb=CreateBrush(255,0,0)
PaintEntity b1,cb
PaintEntity b2,cb
Global Cam.CamD = New CamD
Cam\Camera=CreateSphere()
Cam\Body=CreateSphere()
Cam\Head=CreateSphere()
ScaleMesh cam\Camera,5,5,5
ScaleMesh cam\Head,8,8,8
ScaleMesh cam\Body,10,22,10
EntityRadius Cam\Body,10,22
EntityRadius Cam\Head,8
EntityRadius Cam\Camera,5
PositionEntity Cam\Camera,-20,22+21,50
PositionEntity Cam\Head,-20,22+21,50
PositionEntity Cam\Body,-20,22,50
EntityType Cam\Body,1
EntityType Cam\Head,1
EntityType Cam\Camera,1
EntityType a,2
EntityType b1,2
EntityType b2,2
EntityType b3,2
EntityType b4,2
c=CreateCamera()
PositionEntity c,-120,55,-60
PointEntity c,b1

Collisions 1,2,2,2 ;Type 1 to 2, Elips-Poly, Slide


TurnEntity Cam\Body,0,90,0
If EntityYaw(Cam\Body)<0 Then TurnEntity Cam\Body,0,360,0
If EntityYaw(Cam\Body)>360 Then TurnEntity Cam\Body,0,-360,0
;RotateEntity Cam\Camera,0,EntityYaw(Cam\Body),0
C=0
While Not KeyHit(1)

If KeyHit(15) Or firstflag=0 Then
	Mde=1-Mde
	If Mde=0 Then
		RotateEntity b2,90,0,0
		PositionEntity b2,-20,50.0122,-15 ;We get stuck on the lift side... ??
	Else
		RotateEntity b2,0,0,0
		PositionEntity b2,-20,5,15
	End If
End If


PositionEntity b3,-20,-2+Abs(Sin(MilliSecs()*.1)*50),50
TurnEntity b4,0,1,0

UpdateInput
CollisionHandling
UpdateWorld
RenderWorld
Flip
firstflag=1
Wend
End


Function UpdateInput()
	;Turn
	mxs=0:mys=0:mdr=0
	If KeyDown(201)	Or KeyDown(73) Then mxs=-3:If Abs(EntityPitch(Cam\Camera)-3)=90 Then mxs=-6	;up
	If KeyDown(209) Or KeyDown(81) Then mxs=3:If Abs(EntityPitch(Cam\Camera)+3)=90 Then mxs=6	;down											;down
	If KeyDown(205) Or KeyDown(77) Then mys=-3															;right
	If KeyDown(203) Or KeyDown(75) Then mys=3
	If KeyDown(82) Then
		PositionEntity Cam\Body,-20,EntityY(Cam\PIdx,False),50,True
	End If
	MoveCamStuff
	
	TurnEntity Cam\Body,0,mys,0
	If EntityYaw(Cam\Body)<0 Then TurnEntity Cam\Body,0,360,0
	If EntityYaw(Cam\Body)>360 Then TurnEntity Cam\Body,0,-360,0
	RotateEntity Cam\Camera,EntityPitch(Cam\Camera)+mxs,EntityYaw(Cam\Body),0
	If EntityPitch(Cam\Camera)<0 Then TurnEntity Cam\Camera,360,0,0
	If EntityPitch(Cam\Camera)>360 Then TurnEntity Cam\Camera,-360,0,0
	
	;Move
	If KeyDown(200)=True Or KeyDown(72)=True Then
			;DebugLog Str(Int(EntityX(Cam\Head,True)))+","+Str(Int(EntityY(Cam\Head,True)-35))+","+Str(Int(EntityZ(Cam\Head,True)))
			mdr=10			;Forward
	End If
	If KeyDown(208)=True Or KeyDown(80)=True Then
			;DebugLog Str(Int(EntityX(Cam\Head,True)))+","+Str(Int(EntityY(Cam\Head,True)-35))+","+Str(Int(EntityZ(Cam\Head,True)))
			mdr=-10			;Backward
	End If

	;Gravity
	If cam\c$<>"" Then cam\DY#=230										;Climbing
	If cam\c$="STOP" Then cam\DY#=194									;Stop climbing - HOLD ALTITUDE
	If cam\c$="STOP" Then cam\c$=""										;Allow fall
	cam\DY#=cam\DY#-14:If cam\DY#<90 Then cam\DY#=90	;Fall velocity increase

	;Jump
	If KeyHit(57) Then										;Jump 310=up, 90=dn
		cam\c$=""
		If CountCollisions(Cam\Body)=1 And CountCollisions(Cam\Head)=0 Then ;Are we sitting on the ground? Nothing touching us?
			If cam\DY#=90 Then cam\DY#=310		;Point accelleration angle/veloc full downward?
		End If
	End If

	S#=-Sin(cam\DY#)*10
	;If Cam\PIdx<>0 Then ;Part of my original engine...
	;If OIdx.ObjD(Cam\PIdx)\DY#>0 Then
	;	S#=0
	;	TFormPoint 0,0,0,Cam\PIdx,0
	;	OY#=TFormedY()
	;	PositionEntity Cam\Body,EntityX(Cam\Body,True),EntityY(Cam\PIdx,True),EntityZ(Cam\Body,True),False
	;	MoveCamStuff
	;End If
	;End If

	;Jumping in progress...
	TranslateEntity Cam\Body,-Sin(EntityYaw(Cam\Body))*mdr,S#,Cos(EntityYaw(Cam\Body))*mdr
	MoveCamStuff
End Function

Function CollisionHandling()
	c=CountCollisions(Cam\Head)
	If c=1 Then cam\DY#=90

	;Body is good for telling what we've touched - Hands are actually only for ladders
	n=CountCollisions(Cam\Body)
	a$="":For t=1 To n;Order collider names by priority below
		If t>CountCollisions(Cam\Body) Then Exit ;watch the index value!
		i=CollisionEntity(Cam\Body,t)			;Relevant because many children have same names
	If t=1 Then If GetParent(cam\body)<>i Then EntityParent Cam\Body,i,True:cam\PIdx=i
	Next
	If c<>0 Then ResetEntity Cam\Head
End Function

Function MoveCamStuff() ;This looked like a global solution, apparently not...
	TFormPoint 0,30,0,Cam\Body,0
	OX#=TFormedX()
	OY#=TFormedY()
	OZ#=TFormedZ()
	PositionEntity Cam\Camera,OX#,OY#,OZ#,True
	TFormPoint 0,35,0,Cam\Body,0
	OX#=TFormedX()
	OY#=TFormedY()
	OZ#=TFormedZ()
	PositionEntity Cam\Head,OX#,OY#,OZ#,True
End Function

RemiD

(Posted 2014) [#6]

And what about detecting a position discrepancy?
We both know the entityxyz lies.

About this, read the documentation and you will see :
EntityX(Entity,True) retrieves the global coordinate
EntityX(Entity,False) retrieves the local coordinate

same thing for EntityY, EntityZ, EntityPitch, EntityYaw, EntityRoll

Mikorians

(Posted 2014) [#7]

What I meant was it sometimes seems (when a collider is pinned), it reports the position you set the entity to go to rather than its physical position.
True or false.