aUCBLogo Demos and Tests / moonphases

to moonphases
   hideTurtle
   setScreenColor 0
   perspective
   setPenColor "grey ;"white
   setLightSpecular RGB 1 1 1
   setMaterialSpecular RGB 1 1 1
   setMaterialShininess 5
   t=Texture loadImage "moon.jpg
   (Sphere 250 400 400)
   rotateScene
end

to rotateScene [dphi 1]   ;a bit modified from the library procedure
   local [eye phi ddphi theta dtheta center upvector r dr]
   eye=Array 3
   theta=0
   dtheta=5
   center={0 0 0}
   upvector={0 1 0}
   phi=0
   ddphi=dphi/3
   r=500
   dr=1.1
   pr [left, right changes rotation speed, uP down set Pitch, ESC exits]
   dispatchMessages
   forever
   [   eye.1=r*(Cos theta)*Sin phi
      eye.2=r* Sin theta
      eye.3=r*(Cos theta)*Cos phi
      setEye eye center upvector
      setLightPos {0 0 1000}
      redraw
      phi=phi+dphi
      if Key?
      [   dispatchMessages
         local [ch]
         ch=readChar
         ifElse ch==Char 255
         [   ch=readCharExt
            if ch==WXK_RIGHT [dphi=dphi+ddphi]
            if ch==WXK_LEFT  [dphi=dphi-ddphi]
            if ch==WXK_UP    [theta=theta+dtheta]
            if ch==WXK_DOWN  [theta=theta-dtheta]
            if ch==WXK_PRIOR [r=r/dr]
            if ch==WXK_NEXT  [r=r*dr]
         ][
            if ch==Char 27 [stop]
            if ch=="+ [r=r-dr]
            if ch=="- [r=r+dr]
         ]
      ]
   ]
end