; TFormNormal Example
; -------------------

; TFormNormal works exactly like TFormVector, then scales the result
; to length 1 - just what you want for surface normals. The local
; direction (1,1,0) has length Sqr(2), but after TFormNormal the
; world-space result always has length 1, however the rock tumbles.

Graphics3D 640,480
SetBuffer BackBuffer()

camera=CreateCamera()
PositionEntity camera,0,0,-6

light=CreateLight()
RotateEntity light,30,40,0

; A tumbling rock
rock=CreateSphere()
ScaleMesh rock,1.4,0.9,1.1
EntityColor rock,150,130,110

; A fullbright marker shows where the transformed normal points
marker=CreateSphere()
ScaleEntity marker,0.15,0.15,0.15
EntityColor marker,255,255,0
EntityFX marker,1

While Not KeyDown(1)

    TurnEntity rock,0.3,1,0.7

    ; The documented command: local direction (1,1,0) -> a unit-length
    ; world-space normal
    TFormNormal 1,1,0,rock,0

    ; Place the marker 2.5 units from the rock's centre along the normal
    PositionEntity marker,TFormedX()*2.5,TFormedY()*2.5,TFormedZ()*2.5

    ; Confirm the promise: the result's length is always 1
    length#=Sqr(TFormedX()*TFormedX()+TFormedY()*TFormedY()+TFormedZ()*TFormedZ())

    ; Arrow keys move the camera
    If KeyDown(200) Then MoveEntity camera,0,0,0.1
    If KeyDown(208) Then MoveEntity camera,0,0,-0.1
    If KeyDown(203) Then TurnEntity camera,0,1,0
    If KeyDown(205) Then TurnEntity camera,0,-1,0

    RenderWorld

    Text 0,0,"Arrow keys: move camera   Esc: exit"
    Text 0,20,"TFormNormal 1,1,0,rock,0 = "+TFormedX()+", "+TFormedY()+", "+TFormedZ()
    Text 0,40,"Length of result = "+length+" (always 1)"

    Flip

Wend

End