Help with Gravity/Bounce Code...

Blitz3D Forums/Blitz3D Programming/Help with Gravity/Bounce Code...

Rook Zimbabwe
 #1
I made a small change to the vector.bb it is slightly more accurate and realistic change the funtion thus:
Function Vector_Magnitude#(v.Vector)
	Return Sqr((v\x * v\x) + (v\y * v\y) + (v\z * v\z)) / 2
End Function
and run it now!!!
Then I did this to see:
;// Gravity and Bounce Example
Graphics3D 800,600
SetBuffer BackBuffer()

Include "vector.bb"

;// Camera and Lights
camera = CreateCamera()
PositionEntity camera,0,1,-20
light=CreateLight()
RotateEntity light,90,0,0

;// Set Gravity meters per sec
g% = -9 ; changed it to flat number

;// Ball Parameters
ball = CreateSphere()
ScaleEntity ball,0.5,0.5,0.5
mass% = 10

; for a bit of fun
plane=CreatePlane()
grass_tex=LoadTexture( "tmp11.jpg" )
EntityTexture plane,grass_tex
EntityAlpha plane,0.5
PositionEntity plane,0,0,-.5
; make plane a mirror
mirror=CreateMirror()

;// Set Initial Forces and Vectors
vFor.vector = vector()				;force vector
vAcc.vector = vector()				;acceleration vector
vVel.vector = vector()				;velocity vector
vPos.vector = vector(0,15,0)		        ;position vector

NewTime = MilliSecs()
OldTime = NewTime



;// Main Loop
While Not KeyHit(1)
Cls

NewTime = MilliSecs()
delta# = Float (NewTime - OldTime) / 1000
OldTime = NewTime
FPS = 1 / delta

;// Reset Forces to Zero Each Cycle
Vector_Reset vFor

;// Calculate Gravity
grav% = g * mass ; so you can show it
vFor\y = g * mass 

;// Collision
If vPos\y < 0 Then Collided = True
If Collided = True
	speed% = Vector_Magnitude(vVel)
	collided = False
	vFor\y = -vFor\y * speed% / 2  * mass% 
	vVel\y = 0
EndIf

;// Up Arrow Key applies 100 force upwards
If KeyDown(200) Then vFor\y = 100

If KeyHit(57) = True Then 
	vPos.vector = vector(0,15,0)
	;Vector_PositionEntity ball,vPos
EndIf

;// Calc New Acc, Vel, and Pos
Vector_DivideScalar vAcc,vFor,mass
Vector_AddTimeStep vVel,vAcc,delta
Vector_AddTimeStep vPos,vVel,delta

;// Position the Ball
Vector_PositionEntity ball,vPos

UpdateWorld
RenderWorld

;// Show What's Happening
Text 5,5,"FPS=" + FPS
Text 5,30,"Speed=" + Int(Vector_Magnitude(vVel))
Text 5,60,"Grav: "+grav

Vector_Show(vFor,5,100,"Force: ")
Vector_Show(vAcc,5,175,"Acc: ")
Vector_Show(vVel,5,250,"Vel: ")
Vector_Show(vPos,5,325,"Pos: ")

Flip
Wend
End

MASS seems to be a part of the problem... monkey with that and see...

For some reason velocity adds at some point(possibly because of mass be applied wrongly I am uncertain!)... which is why I squelched magnitude a bit...

RZ