; FlipMesh Example
; ----------------

; Triangles are one-sided. FlipMesh reverses every triangle in a mesh
; so it faces the other way - the classic trick for sky domes: flip a
; giant sphere and view it from the inside.

Graphics3D 640,480
SetBuffer BackBuffer()

camera=CreateCamera()

; A huge sphere surrounding the camera, painted with a sky texture
sky=CreateSphere()
ScaleEntity sky,100,100,100
sky_tex=LoadTexture("media/sky.bmp")
EntityTexture sky,sky_tex
EntityFX sky,1

; The documented command: turn the sphere inside-out so its faces
; point INWARDS, towards our camera
FlipMesh sky
flipped=1

While Not KeyDown(1)

    ; Space flips the mesh again - unflipped, the faces point away
    ; from us and the whole sky disappears
    If KeyHit(57) Then FlipMesh sky : flipped=1-flipped

    ; Arrow keys look around
    If KeyDown(200) Then TurnEntity camera,-1,0,0
    If KeyDown(208) Then TurnEntity camera,1,0,0
    If KeyDown(203) Then TurnEntity camera,0,1,0
    If KeyDown(205) Then TurnEntity camera,0,-1,0

    RenderWorld

    Text 0,0,"Space: FlipMesh again   Arrow keys: look around   Esc: exit"
    If flipped Then
        Text 0,20,"Flipped: faces point inwards - a perfect sky dome"
    Else
        Text 0,20,"Not flipped: faces point outwards - invisible from inside!"
    EndIf

    Flip

Wend

End