This is a very simple collision by sparky's (I added a few touches myself) it works well for dbo worlds and any other type of world.

Hopefully it is easy enough for begginers to understand (i'm a begginer myself). remember you need to position the your player object above the world or else the collision won't work.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    rem make the player object
make object sphere your player object I used a sphere,20
Sc_setupobject 16,0,2

rem setup your world
load object "your world.dbo",world num
Sc_setupcomplexobject world num,1,2


rem collision for the person
   oldx# = object position x(your object)
   oldy# = object position y(your object)
   oldz# = object position z(your object)

rem move the player
   if keystate(17)=1 then move object your object,3
   if keystate(31)=1 then move object your object,-3
   if keystate(30)=1 then move object left your object,3
   if keystate(32)=1 then move object right your object,3


rem if player isn't pressing a key apply simple gravity
   if keystate(17)=0 then position object your object, object position x(your object),object position y(your object)-0.4, object position z(your object)
   if keystate(31)=0 then position object your object, object position x(your object),object position y(your object)-0.4, object position z(your object)
   if keystate(30)=0 then position object your object, object position x(your object),object position y(your object)-0.4, object position z(your object)
   if keystate(32)=0 then position object your object, object position x(your object),object position y(your object)-0.4, object position z(your object)



   x# = object position x(your object)
   y# = object position y(your object)
   z# = object position z(your object)


   collide = sc_SphereSlideGroup(1,oldx#,oldy#,oldz#,x#,y#,z#,100,0)

   if collide>0
      x# = sc_getCollisionSlideX()
      y# = sc_getCollisionSlideY()
      z# = sc_getCollisionSlideZ()

position object your player object,x#,y#,z#

endif

rem position the camera
position camera object position x(yourobject),object position y(your object),object position z(your object)


rem camera control/player movement
rotate camera camera angle x(0)+(mousemovey()/2.0),camera angle y(0)+(mousemovex()/2.0),0
cx#=camera angle x(0) : cy#=camera angle y(0)
if wrapvalue(camera angle x(0))>40 and wrapvalue(camera angle x(0))<180 then xrotate camera 0,40
if wrapvalue(camera angle x(0))>180 and wrapvalue(camera angle x(0))<280 then xrotate camera 0,280