Code with jumping on a matrix, taken from the DB Sliding Collision Demo. Includes simple gravity and collision with matrix and objects.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    Rem Set up environment
hide mouse
sync on : sync rate 40

Rem Create sphere
make object sphere 1,10
color object 1,rgb(20,100,255)
make object collision box 1,-5,-5,-5,5,5,5,0
position object 1,990,400,670


Rem Create matrix
make matrix 1,10000,10000,25,25
randomize matrix 1,100

Rem Make simple objects for collision
for a = 10 to 20
make object box a,50,8,50
position object a,1300*a/3,100,(a*200)+(a+300)
make object collision box a,-25,-4,-25,25,4,25,0
position object a,1000,4+(a*10),100+(a*50)
color object a,RGB(0,200,0)
next a










Rem _______________________________________________________________________











rem Start off player gravity
playergrav#=2.0

rem Main loop
do

rem User prompts
ink rgb(255,255,0),0
center text 320,20,"USE ARROWS TO MOVE AND SPACE TO JUMP"
center text 320,38,"COLLISION WITH A MATRIX"
center text 320,56,"TAKEN FROM THE DB SLIDING COLLISION DEMO"

rem Store old positions
oldposx#=object position x(1)
oldposy#=object position y(1)
oldposz#=object position z(1)

rem Control player object
if upkey()=1 then move object 1,2
if downkey()=1 then move object 1,-2
if leftkey()=1 then yrotate object 1,wrapvalue(object angle y(1)-3)
if rightkey()=1 then yrotate object 1,wrapvalue(object angle y(1)+3)
if spacekey()=1 and playergrav#=0.0 then playergrav#=2.0

rem Get current object position
posx#=object position x(1)
posy#=object position y(1)
posz#=object position z(1)

rem Handle a touch of gravity
playergrav#=playergrav#-0.1
posy#=posy#+playergrav#

rem Handle sliding collision for player object with other objects
position object 1,posx#,posy#,posz#
if object collision(1,0)>0
   dec posx#,get object collision x()
   dec posy#,get object collision y()
   dec posz#,get object collision z()
   playergrav#=0.0
endif

rem HANDLE COLLISION WITH THE MATRIX
if posy#<get ground height(1,posx#,posz#)+50.0
playergrav#=0.0
posy# = get ground height(1,posx#,posz#)+50.0
endif


rem Set a size for the player object
s#=object size y(1)/2.0

rem Ensure camera stays out of static collision boxes
if get static collision hit(oldposx#-s#,oldposy#-s#,oldposz#-s#,oldposx#+s#,oldposy#+s#,oldposz#+s#,posx#-s#,posy#-s#,posz#-s#,posx#+s#,posy#+s#,posz#+s#)=1
   dec posx#,get static collision x()
   dec posy#,get static collision y()
   dec posz#,get static collision z()
   if get static collision y()<>0.0 then playergrav#=0.0
endif

rem Update with new object position
position object 1,posx#,posy#,posz#

rem Use camera tracker to follow player object
angle#=object angle y(1)
camdist#=25.0 : camhigh#=posy#+10.0 : camfade#=3.5
set camera to follow posx#,posy#,posz#,angle#,camdist#,camhigh#,camfade#,1

rem Tilt camera down a little
xrotate camera 15

rem For fun, slightly move pedastal step
move object 10,0.01

rem Update screen
sync

rem End loop
loop