Have a look at this example...(Warning, Messy code!)
Open in online IDEGraphics3D 640,480,0,2 SetBuffer BackBuffer() AmbientLight 255,255,255 WireFrame True CamScale#=0.1 Global Camera = CreateCamera() PositionEntity Camera,0,0,-50 CameraProjMode Camera,2 CameraZoom Camera,CamScale# CameraClsMode Camera,False,True ClsColor 150,150,150 Global GRIDSTEP#=1.0 ; Size of each GridBlock Global GRIDCOLR=90 Global GRIDCOLG=90 Global GRIDCOLB=90 SeedRnd MilliSecs() mesh1 = CreateCylinder() PositionEntity mesh1,Int(Rnd(-5,5)),Int(Rnd(-5,5)),0 EntityColor mesh1,255,0,0 mesh2 = CreateSphere() PositionEntity mesh2,Int(Rnd(-5,5)),Int(Rnd(-5,5)),0 EntityColor mesh2,0,0,255 While Not KeyDown(1) Select MouseZSpeed () Case -1 CamScale#=CamScale#*0.9 If CamScale#<0.001 Then camScale#=0.001 CameraZoom Camera,CamScale# Case 1 CamScale#=CamScale#*1.1 If CamScale#<0.001 Then camScale#=0.001 CameraZoom Camera,CamScale# End Select ; MousePanning XDiff=-MouseXSpeed() YDiff=MouseYSpeed() If MouseDown(1) Then MoveEntity Camera,XDiff/(400.0*CamScale#),YDiff/(300.0*CamScale#),0 EndIf DrawGrid() Color 0,0,0 RenderWorld Flip False Wend End Function DrawGrid() Cls CenterX#=EntityX#(Camera) CenterY#=EntityY#(Camera) StartDrawX#=Int(CenterX#/GRIDSTEP#)*GRIDSTEP# StartDrawY#=Int(CenterY#/GRIDSTEP#)*GRIDSTEP# ; Vertical lines ;Draw lines center to left CurrPosX#=StartDrawX# Repeat CameraProject(Camera,CurrPosX#,CenterY#,0) Xpos=ProjectedX() If CurrPosX#=0 Then Color 0,0,0 Else Color GRIDCOLR,GRIDCOLG,GRIDCOLB EndIf Line Xpos,0,Xpos,480 CurrPosX#=CurrPosX#-GRIDSTEP# Until Xpos<0 ;Draw lines center to right CurrPosX#=StartDrawX#+GRIDSTEP# Repeat CameraProject(Camera,CurrPosX#,CenterY#,0) Xpos=ProjectedX() If CurrPosX#=0 Then Color 0,0,0 Else Color GRIDCOLR,GRIDCOLG,GRIDCOLB EndIf Line Xpos,0,Xpos,480 CurrPosX#=CurrPosX#+GRIDSTEP# Until Xpos>640 ; Horizontal lines ;Draw lines center to up CurrPosY#=StartDrawY# Repeat CameraProject(Camera,CenterX#,CurrPosY#,0) Ypos=ProjectedY() If CurrPosY#=0 Then Color 0,0,0 Else Color GRIDCOLR,GRIDCOLG,GRIDCOLB EndIf Line 0,Ypos,640,Ypos CurrPosY#=CurrPosY#+GRIDSTEP# Until Ypos<0 ;Draw lines center to down CurrPosY#=StartDrawY#-GRIDSTEP# Repeat CameraProject(Camera,CenterX#,CurrPosY#,0) Ypos=ProjectedY() If CurrPosY#=0 Then Color 0,0,0 Else Color GRIDCOLR,GRIDCOLG,GRIDCOLB EndIf Line 0,Ypos,640,Ypos CurrPosY#=CurrPosY#-GRIDSTEP# Until Ypos>480 End Function