Updated code based on Philip Young's camera rotation example. This rotates camera view around a position (initially 0,0,0) view mouse controls.

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*** Camera Rotation Code Around 3D Object with Mouse Controls ***
*** Based on code from Philip Young in codebase ***
*** Modified by Eric Lenhart 5-2004 Please use freely with credit ***
*** ***
*** Controls have been modified to use mouse controls instead ***
*** arrows and added additional stats onscreen ***
*********************************************************************


*** Controls: ***
Hold right mouse button to rotate
Use scroll to zoom
Both mouse buttons enables scroll also
While rotating, cursor will wrap around screen
Holding right mouse and shift will move camera focus point along X and Y (still needs work)
Space bar recenters camera

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    `*********************************************************************
`*** Camera Rotation Code Around 3D Object with Mouse Controls     ***
`*** Based on code from Philip Young in codebase                   ***
`*** Modified by Eric Lenhart 5-2004 Please use freely with credit ***
`***                                                               ***
`*** Controls have been modified to use mouse controls instead     ***
`*** arrows                                                        ***
`*********************************************************************


`*** Controls: ***
`Hold right mouse button to rotate
`Use scroll to zoom
`Both mouse buttons enables scroll also
`While rotating, cursor will wrap around screen
`Holding right mouse and shift will move camera focus point along X and Y (still needs work)
`Space bar recenters camera

sync on

`*** Set display settings ***
SCREENX = 1024
SCREENY = 768

set display mode SCREENX,SCREENY,32

`*** Create objects to view ***
Make Object cube 1, 3
Make object cylinder 2, 2
Make object cube 3, 3

position object 1, 0, 0, 0
position object 2, 0, 2.5, 0
Position object 3, 0, 5, 0

`*** Set object collision for camera ***
automatic camera collision 0, .25, 1

`*** position camera variables ***
x# = 0
y# = 0
z# = -400

`*** point and position camera variables ***
pcx = 0
pcy = 0
pcz = 0

position camera x#, y#, z#
point camera 0, 0, 0, 0

bearing# = 20
azimuth# = 20
distance# = 30

`*** Setup last camera variables ***
LASTMOUSEX = MOUSEX()
LASTMOUSEY = MOUSEY()
LASTMOUSEZ = MOUSEZ()

do
   `*** show the mouse ***
   show mouse

   `*** Reset model to center if SPACE pressed ***
   IF SCANCODE() = 57
      pcx = 0
      pcy = 0
      pcz = 0
      point camera 0, 0, 0, 0
   ENDIF

   `*** Read current mouse coordinates ***
   CURRENTMOUSEX = MOUSEX()
   CURRENTMOUSEY = MOUSEY()
   CURRENTMOUSEZ = MOUSEZ()

   `******************************************************
   If MOUSECLICK() = 2
      `*** Wrap mouse around screen if right mouse button clicked ***
      IF MOUSEX() = 0
         Position mouse SCREENX - 2, MOUSEY()
      ENDIF

      IF MOUSEX() = SCREENX - 1
         position mouse 1, MOUSEY()
      ENDIF

      IF MOUSEY() = 0
         Position mouse MOUSEX(), SCREENY - 2
      ENDIF

      IF MOUSEY() = SCREENY - 1
         position mouse MOUSEX(), 1
      ENDIF

      `*** Move view of object if holding down shift and right mouse ***
      IF SCANCODE() = 42
         IF CURRENTMOUSEX > LASTMOUSEX
            pcx = pcx + 1
         ENDIF

         IF CURRENTMOUSEX < LASTMOUSEX
            pcx = pcx - 1
         ENDIF

         IF CURRENTMOUSEY > LASTMOUSEY
            pcy = pcy + 1
         ENDIF

         IF CURRENTMOUSEY < LASTMOUSEY
            pcy = pcy - 1
         ENDIF
      ENDIF

      `*** Right mouse button clicked and shift not down - rotate camera ***
      if CURRENTMOUSEX < LASTMOUSEX AND SCANCODE() <> 42
         bearing# = wrapvalue(bearing# + 3)
      endif

      if CURRENTMOUSEX > LASTMOUSEX AND SCANCODE() <> 42
         bearing# = wrapvalue(bearing# - 3)
      endif

      if CURRENTMOUSEY < LASTMOUSEY AND SCANCODE() <> 42 and azimuth# < 179
            azimuth# = wrapvalue(azimuth# + 3)
      endif

      if CURRENTMOUSEY > LASTMOUSEY AND SCANCODE() <> 42 AND azimuth# > 2
         azimuth# = wrapvalue(azimuth# - 3)
      endif
   ENDIF

   `*** Zoom with mouse wheel ***
   IF CURRENTMOUSEZ < LASTMOUSEZ
      distance# = distance# + 1
   ENDIF

   IF CURRENTMOUSEZ > LASTMOUSEZ
      distance# = distance# - 1
   ENDIF


   `*** Zoom by holdign both mouse buttons with cursor wrap ***
   IF MOUSECLICK() = 3
      HIDE MOUSE
      `*** wrap mouse during zoom ***
      IF MOUSEX() = 0
         Position mouse SCREENX - 2, MOUSEY()
      ENDIF

      IF MOUSEX() = SCREENX - 1
         position mouse 1, MOUSEY()
      ENDIF

      IF MOUSEY() = 0
         Position mouse MOUSEX(), SCREENY - 2
      ENDIF

      IF MOUSEY() = SCREENY - 1
         position mouse MOUSEX(), 1
      ENDIF

      `*** Perform zoom ***
      IF CURRENTMOUSEY < LASTMOUSEY
         distance# = distance# - .2
      ENDIF

      IF CURRENTMOUSEY > LASTMOUSEY
         distance# = distance# + .2
      ENDIF
   ENDIF

   `*** Set current mouse position as last mouse position ***
   LASTMOUSEX = MOUSEX()
   LASTMOUSEY = MOUSEY()
   LASTMOUSEZ = MOUSEZ()

   `*** Calculate camera position ***
   x# = distance# * sin(azimuth#) * cos(bearing#)
   z# = distance# * sin(azimuth#) * sin(bearing#)
   y# = distance# * cos(azimuth#)

   `*** Position and point camera ***
   position camera x# + pcx, y# + pcy, z#
   point camera 0, pcx, pcy, pcz

   `*** Display various stats ***
   set cursor 0, 0
   print "x: ";x#;" y: ";y#;" z: ";z#
   print "bearing: ";bearing#
   print "azimuth: ";azimuth#
   print "distance: ";distance#
   print "scancode: ";SCANCODE()
   print "mosue x:  ";mousex()
   print "mouse y:  ";mousey()
   print "mouse z:  ";mousez()
   print "fps:      ";screen fps()
   sync

loop