Collision problem: getting stuck

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Allanon Shadeslayer

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Posted: 23rd Feb 2007 23:56

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'Lo all!

I am making a tank game and I am trying out some basic collision to keep my tank inside the boundaries i set.
But here's the problem: you get stuck if you run into something while moving forward or backward and turning at the same time.

Here is my code:

+ Code Snippet

if keystate(72) then move object down 1,5
if keystate(76) then move object up 1,5
if keystate(75) then yrotate object 1,object angle y(1)-2
if keystate(77) then yrotate object 1,object angle y(1)+2

for A=3 to 15

if object collision(1,A) and keystate(72) then move object up 1,5
if object collision(1,A) and keystate(76) then move object down 1,5
if object collision(1,A) and keystate(75) then yrotate object 1,object angle y(1)+2
if object collision(1,A) and keystate(77) then yrotate object 1,object angle y(1)-2

next A

If at first you don't succeed, lower your expectations.

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Sasuke

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Posted: 24th Feb 2007 01:25 Edited at: 24th Feb 2007 01:27

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When you press a key, your code tells the object to for example move up 5. If theres a collision your code tells the object to move up and down 5, so if you work it out, it equals 0. The same for rotation, it won't rotate if theres a collision. The best way to do it is if theres a collision, position the object where that collision happen.

+ Code Snippet

ox# = object position x(1)
oy# = object position y(1)
oz# = object position z(1)

if keystate(72) then move object up 1,5
if keystate(76) then move object down 1,5
if keystate(75) then zrotate object 1,object angle z(1)-2
if keystate(77) then zrotate object 1,object angle z(1)+2

`This will position the object at the last position before the collision. 
`So it will position the object at the same position as long a theres a collision, which stops it.
if object collision(1,2) then position object 1,ox#,oy#,oz#

Also, what kind of game are you making, because your rotating in the wrong axis for going up and down. In the code, you'll notice i've changed it to the Z axis. Hope this helps.

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Allanon Shadeslayer

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Posted: 24th Feb 2007 01:28 Edited at: 24th Feb 2007 01:38

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Lol. I'm making a tank game. You can try it out. It's under Work In Progress (Titled tank arena)

I tried your code and my tank just goes right through. I want my tank to stop when there's a collision, but when I maneuver right(or wrong) my tank slowly goes inside the object I'm trying to keep it out of so it gets stuck.

You might want to try out my game to see what I mean by "Getting stuck".

Tyvm!

If at first you don't succeed, lower your expectations.

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Sasuke

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Posted: 24th Feb 2007 02:15

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Can't download it(think the problems on my end, i'll try later). Anyway, heres how I tested your code.

+ Code Snippet

sync on : sync rate 60

make object cube 1,25
position object 1,0,0,0

for x=0 to 5
   make object cube x+2,50
   position object x+2,sin(x*90)*300,cos(x*90)*300,0
next x

autocam off
position camera 0,100,-700

do

ox# = object position x(1)
oy# = object position y(1)
oz# = object position z(1)

if keystate(72) or keystate(17) then move object up 1,5
if keystate(76) or keystate(31) then move object down 1,5
if keystate(75) or keystate(30) then zrotate object 1,object angle z(1)+2
if keystate(77) or keystate(32) then zrotate object 1,object angle z(1)-2

for x=0 to 5
   if object collision(1,x+2) then position object 1,ox#,oy#,oz#
next x

sync
loop

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TDK

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Posted: 24th Feb 2007 14:50

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Spherical collision?

TDK_Man

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Sasuke

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Posted: 24th Feb 2007 15:24

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Do you mean how I position the boxes.

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Allanon Shadeslayer

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Posted: 25th Feb 2007 22:18

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Anymore help?

If at first you don't succeed, lower your expectations.

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TDK

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Posted: 26th Feb 2007 00:20

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Check out the SET OBJECT COLLISION TO SPHERES command.

By default, DB's collision uses boxes rather than spheres.

You don't appear to be using the GET OBJECT COLLISION() functions, so you probably don't need to use spherical collision.

TDK_Man

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Sasuke

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Posted: 26th Feb 2007 00:20

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Ok, Couldn't work out why it was happening but fixed it.

Main loop code:

rem main loop
do

ox# = object position x(1)
oy# = object position y(1)
oz# = object position z(1)
angy# = object angle y(1)

ox2# = object position x(2)
oy2# = object position y(2)
oz2# = object position z(2)
angy2# = object angle y(2)

spd# = 5

rem setting up player 1 and player 2
Health_1=100
text 0,0,str$(Health_1)

if keystate(72) ` forward
   nx#=newxvalue(ox#,angy#,spd#)
   nz#=newzvalue(oz#,angy#,spd#)
   position object 1,nx#,oy#,nz#
endif

if keystate(76) ` backward
   nx#=newxvalue(ox#,wrapvalue(angy#-180),spd#)
   nz#=newzvalue(oz#,wrapvalue(angy#-180),spd#)
   position object 1,nx#,oy#,nz#
endif

`if keystate(72) then move object down 2,5
`if keystate(76) then move object up 2,5
if keystate(75) then yrotate object 1,object angle y(1)-2
if keystate(77) then yrotate object 1,object angle y(1)+2

if returnkey()
position object 16,object position x(1),object position y(1)+40,object position z(1)
yrotate object 16,object angle y(1)
endif

Health_2=100
text 0,384,str$(Health_2)

if keystate(17) ` forward
   nx2#=newxvalue(ox2#,angy2#,spd#)
   nz2#=newzvalue(oz2#,angy2#,spd#)
   position object 2,nx2#,oy2#,nz2#
endif

if keystate(31) ` backward
   nx2#=newxvalue(ox2#,wrapvalue(angy2#-180),spd#)
   nz2#=newzvalue(oz2#,wrapvalue(angy2#-180),spd#)
   position object 2,nx2#,oy2#,nz2#
endif

`if keystate(17) then move object down 2,5
`if keystate(31) then move object up 2,5
if keystate(30) then yrotate object 2,object angle y(2)-2
if keystate(32) then yrotate object 2,object angle y(2)+2

if controlkey()
position object 17,object position x(2),object position y(2)+40,object position z(2)
yrotate object 17,object angle y(2)
endif

rem setting camera to follow players
position camera 1,object position x(1)-300,150,object position z(1)-300
point camera 1,object position x(1),object position y(1),object position z(1)
position camera 2,object position x(2)+300,150,object position z(2)+300
point camera 2,object position x(2),object position y(2),object position z(2)

rem boundaries and physics
if object collision(1,2) then move object up 1,5 : move object up 2,5

for x=3 to 15
   if object collision(1,x) then position object 1,ox#,oy#,oz#
   if object collision(2,x) then position object 2,ox2#,oy2#,oz2#
next x

rem missile properties
if object position y(16)=object position y(1)+40 then move object 16,15
if object position y(17)=object position y(2)+40 then move object 17,15

rem updating screen
sync

rem end loop
loop

+ Code Snippet

rem main loop
do

ox# = object position x(1)
oy# = object position y(1)
oz# = object position z(1)
angy# = object angle y(1)

ox2# = object position x(2)
oy2# = object position y(2)
oz2# = object position z(2)
angy2# = object angle y(2)

spd# = 5

rem setting up player 1 and player 2
Health_1=100
text 0,0,str$(Health_1)

if keystate(72) ` forward
   nx#=newxvalue(ox#,angy#,spd#)
   nz#=newzvalue(oz#,angy#,spd#)
   position object 1,nx#,oy#,nz#
endif

if keystate(76) ` backward
   nx#=newxvalue(ox#,wrapvalue(angy#-180),spd#)
   nz#=newzvalue(oz#,wrapvalue(angy#-180),spd#)
   position object 1,nx#,oy#,nz#
endif

`if keystate(72) then move object down 2,5
`if keystate(76) then move object up 2,5
if keystate(75) then yrotate object 1,object angle y(1)-2
if keystate(77) then yrotate object 1,object angle y(1)+2

if returnkey()
position object 16,object position x(1),object position y(1)+40,object position z(1)
yrotate object 16,object angle y(1)
endif

Health_2=100
text 0,384,str$(Health_2)

if keystate(17) ` forward
   nx2#=newxvalue(ox2#,angy2#,spd#)
   nz2#=newzvalue(oz2#,angy2#,spd#)
   position object 2,nx2#,oy2#,nz2#
endif

if keystate(31) ` backward
   nx2#=newxvalue(ox2#,wrapvalue(angy2#-180),spd#)
   nz2#=newzvalue(oz2#,wrapvalue(angy2#-180),spd#)
   position object 2,nx2#,oy2#,nz2#
endif

`if keystate(17) then move object down 2,5
`if keystate(31) then move object up 2,5
if keystate(30) then yrotate object 2,object angle y(2)-2
if keystate(32) then yrotate object 2,object angle y(2)+2

if controlkey()
position object 17,object position x(2),object position y(2)+40,object position z(2)
yrotate object 17,object angle y(2)
endif

rem setting camera to follow players
position camera 1,object position x(1)-300,150,object position z(1)-300
point camera 1,object position x(1),object position y(1),object position z(1)
position camera 2,object position x(2)+300,150,object position z(2)+300
point camera 2,object position x(2),object position y(2),object position z(2)

rem boundaries and physics
if object collision(1,2) then move object up 1,5 : move object up 2,5

for x=3 to 15
   if object collision(1,x) then position object 1,ox#,oy#,oz#
   if object collision(2,x) then position object 2,ox2#,oy2#,oz2#
next x

rem missile properties
if object position y(16)=object position y(1)+40 then move object 16,15
if object position y(17)=object position y(2)+40 then move object 17,15

rem updating screen
sync

rem end loop
loop

It seemed changing the way they move did the trick. Also changed this:

+ Code Snippet

sw = screen width()
sh = screen height()

set camera view 1,0,0,sw,sh/2
set camera view 2,0,sh/2,sw,sh

It will still split the screen but allow you to change the screen resolution without the cameras going off the screen. Hope this helps.

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DB PROgrammer

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Posted: 26th Feb 2007 00:22

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I'm not on my computer right now so I cant test it for you but try this.

`make collision limbs
make object sphere 9999,0.5
make mesh from object 9999,9999
delete object 9999
make limb 1,10,1
make limb 1,11,1
delete mesh 9999
`you may need to change these so they will not be in the tank
offset limb 1,10,0,0,5
offset limb 1,11,0,0,-5

`start program loop
do

if keystate(72) then move object down 1,5
if keystate(76) then move object up 1,5
if keystate(75) then yrotate object 1,object angle y(1)-2
if keystate(77) then yrotate object 1,object angle y(1)+2

for A=3 to 15
`get limb positions(you could make a loop for this)
frontl#x=limb position x(1,10)
frontl#y=limb position y(1,10)
frontl#z=limb position z(1,10)
backlx#=limb position x(1,11)
backly#=limb position y(1,11)
backlz#=limb position z(1,11)
playerx#=object position x(1)
playery#=object position y(1)
playerz#=object position z(1)

`test to see if anything comes between the limb and the tank
if intersect object (a,playerx#,playery#,playerz#,frontlx#,frontly#,frontlz#)=1
move object up 1,5
endif

if intersect object (a,playerx#,playery#,playerz#,backlx#,backly#,backlz#)=1
move object down 1,5
endif

next A

`end program loop
loop

+ Code Snippet

`make collision limbs
make object sphere 9999,0.5
make mesh from object 9999,9999
delete object 9999
make limb 1,10,1
make limb 1,11,1
delete mesh 9999
`you may need to change these so they will not be in the tank
offset limb 1,10,0,0,5
offset limb 1,11,0,0,-5

`start program loop
do

if keystate(72) then move object down 1,5
if keystate(76) then move object up 1,5
if keystate(75) then yrotate object 1,object angle y(1)-2
if keystate(77) then yrotate object 1,object angle y(1)+2

for A=3 to 15
`get limb positions(you could make a loop for this)
frontl#x=limb position x(1,10)
frontl#y=limb position y(1,10)
frontl#z=limb position z(1,10)
backlx#=limb position x(1,11)
backly#=limb position y(1,11)
backlz#=limb position z(1,11)
playerx#=object position x(1)
playery#=object position y(1)
playerz#=object position z(1)

`test to see if anything comes between the limb and the tank
if intersect object (a,playerx#,playery#,playerz#,frontlx#,frontly#,frontlz#)=1
move object up 1,5
endif

if intersect object (a,playerx#,playery#,playerz#,backlx#,backly#,backlz#)=1
move object down 1,5
endif

next A

`end program loop
loop

Hope this works

.

Working on an FPS Engine.

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Allanon Shadeslayer

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Posted: 26th Feb 2007 22:16

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Sasuke, your code stopped my tanks from slowly sliding into objects but whenever I rotate my tank to where part of it gets inside of an object I can't go out of it because it's always colliding.

Is there a way to divide my tanks into two collision zones? I think that might help a little.

If at first you don't succeed, lower your expectations.

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Sasuke

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Location: Milton Keynes UK

Posted: 26th Feb 2007 23:14 Edited at: 27th Feb 2007 13:15

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I see the problem now. I think best way is to make a sphere the radius of the tank to collide with.

So, first create a collision sphere for the tank.

+ Code Snippet

rem collision body
make object sphere 20,200 `radius of tank
position object 20,425,0,425 `the position of the tank
hide object 20

Then we what to move the sphere and position the tank at sphere position.

`collision object position
ox# = object position x(20)
oy# = object position y(20)
oz# = object position z(20)
angy# = object angle y(20)

`tank position and y angle of the sphere
position object 1,ox#,oy#,oz#
yrotate object 1,angy#

`player speed
spd# = 5

`sphere movement
if keystate(72) ` forward
   nx#=newxvalue(ox#,angy#,spd#)
   nz#=newzvalue(oz#,angy#,spd#)
   position object 20,nx#,oy#,nz#
endif

if keystate(76) ` backward
   nx#=newxvalue(ox#,wrapvalue(angy#-180),spd#)
   nz#=newzvalue(oz#,wrapvalue(angy#-180),spd#)
   position object 20,nx#,oy#,nz#
endif

`if keystate(72) then move object down 20,5
`if keystate(76) then move object up 20,5
if keystate(75) then yrotate object 20,object angle y(1)-2
if keystate(77) then yrotate object 20,object angle y(1)+2

if returnkey()
position object 16,object position x(20),object position y(20)+40,object position z(20)
yrotate object 16,object angle y(20)
endif

rem setting camera to follow players(of the sphere)
position camera 1,object position x(20)-300,150,object position z(20)-300
point camera 1,object position x(20),object position y(20),object position z(20)

rem boundaries and physics
if object collision(20,2) then move object up 1,5 : move object up 2,5

for x=3 to 15
   if object collision(20,x) then position object 20,ox#,oy#,oz#
next x

+ Code Snippet

`collision object position
ox# = object position x(20)
oy# = object position y(20)
oz# = object position z(20)
angy# = object angle y(20)

`tank position and y angle of the sphere
position object 1,ox#,oy#,oz#
yrotate object 1,angy#

`player speed
spd# = 5

`sphere movement
if keystate(72) ` forward
   nx#=newxvalue(ox#,angy#,spd#)
   nz#=newzvalue(oz#,angy#,spd#)
   position object 20,nx#,oy#,nz#
endif

if keystate(76) ` backward
   nx#=newxvalue(ox#,wrapvalue(angy#-180),spd#)
   nz#=newzvalue(oz#,wrapvalue(angy#-180),spd#)
   position object 20,nx#,oy#,nz#
endif

`if keystate(72) then move object down 20,5
`if keystate(76) then move object up 20,5
if keystate(75) then yrotate object 20,object angle y(1)-2
if keystate(77) then yrotate object 20,object angle y(1)+2

if returnkey()
position object 16,object position x(20),object position y(20)+40,object position z(20)
yrotate object 16,object angle y(20)
endif

rem setting camera to follow players(of the sphere)
position camera 1,object position x(20)-300,150,object position z(20)-300
point camera 1,object position x(20),object position y(20),object position z(20)

rem boundaries and physics
if object collision(20,2) then move object up 1,5 : move object up 2,5

for x=3 to 15
   if object collision(20,x) then position object 20,ox#,oy#,oz#
next x

See if that helps. This is only for player 1, but shouldn't be too hard to do the same for player 2.

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Allanon Shadeslayer

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Posted: 28th Feb 2007 02:50

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Beautiful idea Sasuke!!! It worked like magic! That's exactly what I was looking for thank you very much!!!

If at first you don't succeed, lower your expectations.

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