; BeginTerrainUpdate Example
; --------------------------

Graphics3D 640,480,0,2
SetBuffer BackBuffer()

camera=CreateCamera()
PositionEntity camera,0,6,-40
CameraClsColor camera,110,150,200

light=CreateLight(1)
RotateEntity light,50,-30,0

; Rolling hills built from a sine-wave height field
terrain=CreateTerrain(128)
For z=0 To 127
    For x=0 To 127
        ModifyTerrain terrain,x,z,0.2+Sin(x*10)*Cos(z*10)*0.12
    Next
Next
ScaleEntity terrain,0.5,20,0.5
PositionEntity terrain,-32,-5,-32
TerrainShading terrain,True
TerrainDetail terrain,8000,True

; Plain grass texture drawn in code
grass=CreateTexture(8,8,1+8)
SetBuffer TextureBuffer(grass) : ClsColor 75,135,60 : Cls : SetBuffer BackBuffer()
EntityTexture terrain,grass

phase#=0

While Not KeyDown(1)

    ; Animate a rippling patch: 1024 edits collected into ONE batch,
    ; so the derived chunk data is rebuilt once per frame, not per call
    phase=phase+5
    BeginTerrainUpdate terrain
    For z=48 To 79
        For x=48 To 79
            ripple#=Sin((x-48)*5.8)*Sin((z-48)*5.8)*Sin((x+z)*12+phase)*0.05
            ModifyTerrain terrain,x,z,0.2+Sin(x*10)*Cos(z*10)*0.12+ripple
        Next
    Next
    EndTerrainUpdate terrain

    ; 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,"BeginTerrainUpdate batches 1024 ModifyTerrain calls per frame"
    Text 0,40,"Chunks rebuilt this frame: "+TerrainRebuiltChunks(terrain)

    Flip

Wend

End