Sphere fall to slow - GameCreators Forum

Author

Message

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 21st Mar 2008 21:14

Link

Hi
I make a sphere and use Physics for c++ but the sphere falling very slow.How i can change the gravity?

Back to top

Profile PM

Fusspawn

16

Years of Service

User Offline

Joined: 19th Feb 2008

Location:

Posted: 21st Mar 2008 23:22

Link

What Physics library are you using ?

Stuck in the land of the confused! and loving it!

Back to top

Profile PM

Codger

21

Years of Service

User Offline

Joined: 23rd Nov 2002

Location:

Posted: 22nd Mar 2008 03:27

Link

Assuming you are using DarkPhysics the default gravity is 9.8 M/ Second^2

This means that all object should fall 9.8 meters in a second. If your object is huge it will "appear" to fall slow. To verify check the Y value over time

Codger

System
PIV 2.8 MZ 512 Mem
FX 5600 256 mem

Back to top

Profile PM Email

Rye

21

Years of Service

User Offline

Joined: 30th May 2003

Location: United Kingdom, Blackrod

Posted: 22nd Mar 2008 04:44

Link

he might be using his own physics.

In which case, you need to make sure that the time step is correct.

Look at the equations of motion

v = u + at velocity = initial Velocity + acceleration X Time

this is probably the one you want. If so, the current velocity will become the initial velocity of the next loop.

So the only thing you need to know is the time that has passed since the last calculation. This can be done in several ways.

1) Either set the number of loops per second, and have a constant for Time.

2) Subtract the old time from the current time. giving the time difference between loops. Store this in some fasion so that it can be accessed wherever it is needed.

3) some other.

Personnally i'd use a combination of 1 and 2. Set the Tick rate for your game, so a tick rate of 40 means 40 game loops per second. And then STILL calculate the time taken, and then only use the calculated version if it is bigger than the time for 1 tick.

This way, if for some reason a loop takes a bit longer, loading an object etc.. then it is still accounted for. You would still need
some varying delay so that the tick rate is constant. and you dont get more that 40 per second. Also, have the tick rate variable. So Faster computers can have faster ticks, producing more accurate calculations.

Probably gone a little off topic here, oh well. it might help some1.

Back to top

Profile PM Email

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 22nd Mar 2008 17:39 Edited at: 22nd Mar 2008 17:40

Link

I use Dark Physics for Darkgdk .net

No funktion to Control the gravity?

In the sample Vehicle the boxes falling faster.

Back to top

Profile PM

Codger

21

Years of Service

User Offline

Joined: 23rd Nov 2002

Location:

Posted: 22nd Mar 2008 18:10

Link

How fast is your object falling? Make its diameter 10 and it should travel through its own diameter every second

You need to time it or post some code so that some can help you time the program.

System
PIV 2.8 MZ 512 Mem
FX 5600 256 mem

Back to top

Profile PM Email

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 22nd Mar 2008 19:18 Edited at: 22nd Mar 2008 19:19

Link

I dont see the time.

I make a objectsphere then i use the kinematic.

No time i have set.

Back to top

Profile PM

Codger

21

Years of Service

User Offline

Joined: 23rd Nov 2002

Location:

Posted: 22nd Mar 2008 22:28

Link

kinomatics are for objects you control directly use dynamic

System
PIV 2.8 MZ 512 Mem
FX 5600 256 mem

Back to top

Profile PM Email

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 23rd Mar 2008 17:32

Link

Here my code from the Sphere:

+ Code Snippet

dbMakeObjectSphere( 100, 20 );
	dbPositionObject( 100, 55, 90, 0 );

	dbPhyMakeRigidBodyDynamicSphere ( 100 );

	dbColorObject( 100, dbRGB( dbRnd( 255 ), dbRnd( 255 ), dbRnd( 255 ) ) );
	dbSetObjectSpecular( 100, dbRGB( dbRnd( 255 ), dbRnd( 255 ), dbRnd( 255 ) ) );

Back to top

Profile PM

Codger

21

Years of Service

User Offline

Joined: 23rd Nov 2002

Location:

Posted: 23rd Mar 2008 21:08

Link

Here is a link to an example I coded some time ago. It is in DBPro but the translation to GDK should be easy
http://forum.thegamecreators.com/?m=forum_view&t=85923&b=30

It has a timer example that should explain what you need

All the best

Codger

System
PIV 2.8 MZ 512 Mem
FX 5600 256 mem

Back to top

Profile PM Email

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 24th Mar 2008 13:56

Link

Cool thx. but startTime is define as??
String?

startTime = Timer()
` and here's our main loop
onetime = 0
do
phy update
sync
Hit = phy get collision data ( )
if (phy get collision object a ( )) > 0 and onetime = 0

onetime = 1
Droptime = Timer()-startTime
Text 10,10, Str$(Droptime)
endif
Text 10,10, Str$(Droptime)
loop

Back to top

Profile PM

theplake

16

Years of Service

User Offline

Joined: 30th Nov 2007

Location:

Posted: 24th Mar 2008 13:56 Edited at: 24th Mar 2008 13:57

Link

Cool thx. but startTime is define as??
String?

+ Code Snippet

startTime = Timer()
   ` and here's our main loop
   onetime = 0
   do
       phy update
       sync
       Hit = phy get collision data ( )
      if (phy get collision object a ( )) > 0 and onetime = 0

         onetime = 1
         Droptime = Timer()-startTime
         Text 10,10, Str$(Droptime)
      endif
      Text 10,10, Str$(Droptime)
   loop

sry for double post

Back to top

Profile PM

jason p sage

17

Years of Service

User Offline

Joined: 10th Jun 2007

Location: Ellington, CT USA

Posted: 24th Mar 2008 16:32

Link

Timer() function returns and integer.