Here's a nice and simple one by Norc:
Open in online IDE; norcs 3D Outline demo Graphics3D 640,480,16,2 SetBuffer BackBuffer() camera=CreateCamera() MoveEntity camera,0,0,-3 CameraRange camera,1,2000 CameraClsColor camera,20,50,100 light=CreateLight() RotateEntity light,30,30,30 n=200 Dim cubei(n),cubeo(n),sx#(n),sy#(n),sz#(n),x#(n),y#(n),z#(n) min100=-30 max100=30 For i=0 To n cubei(i)=CreateSphere(7) EntityFX cubei(i),8 Or 4 ; no fog + flat shaded cubeo(i)=CreateSphere(7,cubei(i)) EntityFX cubeo(i),1 ; full bright FlipMesh cubeo(i) ; inverted EntityColor cubeo(i),0,0,0 ; black x(i)=Rnd(min100,max100) : y(i)=Rnd(min100,max100) : z(i)=Rnd(max100) sx(i)=Rnd(.1,.2) : sy(i)=Rnd(.1,.2) : sz(i)=Rnd(.1,.2) EntityColor cubei(i),Rand(20,255),Rand(20,255),Rand(20,255) Next correct=1 While KeyDown(1)=0 If KeyHit(57) correct=correct Xor 1 EndIf For i=0 To n x(i)=x(i)+sx(i) If x(i)>max100 Then sx(i)=-Rnd(.1,.2) If x(i)<min100 Then sx(i)=Rnd(.1,.2) y(i)=y(i)+sy(i) If y(i)>max100 Then sy(i)=-Rnd(.1,.2) If y(i)<min100 Then sy(i)=Rnd(.1,.2) z(i)=z(i)+sz(i) If z(i)>max100 Then sz(i)=-Rnd(.1,.2) If z(i)<1 Then sz(i)=Rnd(.1,.2) PositionEntity cubei(i),x(i),y(i),z(i),1 TurnEntity cubei(i),1,1,1 ; d#=EntityDistance(camera,cubei(i)) ; for a mobile camera d#=Abs(EntityZ(camera)-EntityZ(cubei(i))) ; pretty accureate, but only for a north-pointing camera s#=1.01+(d/80.0) If s>2 Then s=2 If correct=1 ScaleEntity cubeo(i),s,s,s Else ScaleEntity cubeo(i),1.2,1.2,1.2 EndIf Next RenderWorld() Text 0,0,"Hit Space to toggle Scaling Correcture" If correct Text 0,16,"Correcture is on" Else Text 0,16,"Correcture is off" EndIf Flip Wend End