(DBP) CAR MOVEMENT - GameCreators Forum

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CuCuMBeR

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Posted: 20th Jul 2004 21:40

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hi,

can someone explain basics of;
velocity, speed to time relation, acceleration to time relation
briefly basic knowledge to make a car movement simulation...

Thank you

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SandraD

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Posted: 21st Jul 2004 01:33

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--Basic Physics--
Velocity = distance traveled over a given time frame.
1 KPH = 1 kilometer per hour for example.
(This should answer the speed/time relation.)

Acceration = change in velocity over time.
1g = 32 feet per second times number of seconds squared.
V = A * T^2

Total velocity = 1/2 the acceleration times # of seconds applied.
V = 1/2 * A * T^2

For gaming purposes, the maximum velocity is usually a fixed value, say 50 units for every pass through the game loop. Based upon the scale used by the world, this can simulate anything from 50 inches or microns per second to 50 light years per second, but is usually the number of screen pixels the character or object moves per loop.

Acceleration in the gaming sense is the amount of the change of speed for the character, say a car that starts off as stopped and gains 1 unit of speed for every pass in the loop until it reaches the 50 stated above. It then continues at that speed until you hit the brakes, which slow it down at say, 2 units per loop until it stops again.

More complex formulas actually use the above physical formulas, not the simple examples I've given. Look in the 2D forums for the tutorial on gaming physics, or get a physics textbook.

Hope this helps.
S.

Any truly great code should be indisguishable from magic.

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SandraD

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Posted: 21st Jul 2004 07:13

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Oh by the way, I was wrong about the second formula... it's actually the distance traveled, not speed;

D = 1/2 * A * T^2

Used primarily for falling objects or those under a constant acceleration if I remember correctly.
S.

Any truly great code should be indisguishable from magic.

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Ric

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Location: object position x

Posted: 21st Jul 2004 07:35

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Hi,

ah - physics questions - I may be able to help here

It's as Sandra has said, but here's another way of looking at it which doesn't involve any complex equations or physics text books!

Let's say your car is able to move in just one direction first of all (to keep things simple). Its position is given by its x-coordinate, so we'll call it 'x#'

Velocity is the change in this position per unit of time. As you will have a loop in your program, this loop is really the 'time', so velocity just becomes the change in position. We'll call this change in position 'v#' for velocity. Your object's new position will be given, then, by 'x#=x#+v#'

Acceleration is the change in velocity. Let's call it 'a#'. When you accelerate, the velocity is then given by 'v#=v#+a#'

So, your game loop should look something like this:

DO

check input (maybe the arrow keys) for increase or decrease in v#

x#=x#+v#
v#=v#+a#

Show object at position x#

LOOP

That's the basics in one dimension. It's quite easy then to extend into 2 or 3 dimensions by adding y and z coordinates. Let me know if you get stuck.

Richard

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SandraD

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Posted: 21st Jul 2004 13:30

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Thanks Ric!
Maybe between the two of us it'll make sense for him...

Any truly great code should be indisguishable from magic.

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CuCuMBeR

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Posted: 21st Jul 2004 17:49 Edited at: 21st Jul 2004 17:55

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Well, i have managed the x# y# z# positions with friction#, smooth acceleration..
however, ive stucked on turns, here is my well designed but poor explained code hope someone can also learn from this..

Can Anyone implement turning with skiddings to this code?

Im sorry i cant include the 3d model because its a huge file and i spent lots of time creating it..however, any 4 wheels with 3 limbs as follows will do fine:
1st - backwheels
2nd - Front Left Wheel
3rd - Front Right Wheel

Rem Project: Corvette
Rem Created: 20.07.2004 23:30:43

Rem ***** Main Source File *****
type Coordinate
   x As Float
   y As Float
   z As Float
endtype

type Object
   Pos As Coordinate
   Ang As Coordinate
   Size As Coordinate
endtype

`---------------------------------------
`-----------Make Objects----------------
`---------------------------------------
Dim Obj(4) As Object
Dim Players(4) As Object
gosub Cars
`---------------------------------------
`-----------Set Variables---------------
`---------------------------------------
turnFriction# = 0.97
Friction# = 500

`---------------------------------------
`-----------Set Camera Start Pos--------
`---------------------------------------
position camera -200,50,0
point camera 0,50,0

Restart:
`---------------------------------------
`-------Set Time Start Variables--------
`---------------------------------------
milisecond_start = timer()
#constant second_start = milisecond_start / 60
#constant minute_start = second_start / 60
#constant hour_start = minute_start / 60

`---------------------------------------
`-----------Start Main Loop-------------
`---------------------------------------
sync on
do
`---------------------------------------
`-----------Start Time Loop-------------
`---------------------------------------
gosub Game_Time

`---------------------------------------
`-----------Control Speed---------------
`---------------------------------------

if upkey() > 0
   ivme# = ivme# + 0.001
endif
if downkey() > 0
   ivme# = ivme# - 0.001
endif

WheelTurnSpeed# = WheelTurnSpeed# + ivme#
WheelTurnSpeed# = (WheelTurnSpeed# * turnFriction#)
MoveSpeed# = curvevalue (WheelTurnSpeed#, movespeed#, Friction#)
`---------------------------------------
`-----------Control Turning-------------
`---------------------------------------
if leftkey() > 0
   Obj(2).Ang.y = wrapvalue (Obj(2).Ang.y + 0.1)
      if Obj(2).Ang.y > 30 then Obj(2).Ang.y = 30
         Obj(3).Ang.y = wrapvalue (Obj(3).Ang.y + 0.1)
            if Obj(3).Ang.y > 30 then Obj(3).Ang.y = 30
endif
if rightkey() > 0
   Obj(2).Ang.y = wrapvalue (Obj(2).Ang.y - 0.1)
      if Obj(2).Ang.y < -30 then Obj(2).Ang.y = -30
         Obj(3).Ang.y = wrapvalue (Obj(3).Ang.y - 0.1)
            if Obj(3).Ang.y < -30 then Obj(3).Ang.y = -30
endif

` Back Wheels
Obj(1).Ang.x = Obj(1).Ang.x + WheelTurnSpeed#
rotate limb player1, BackW, Obj(1).Ang.x, Obj(1).Ang.y, Obj(1).Ang.z
` Front Right Wheel
Obj(2).Ang.x = Obj(2).Ang.x + WheelTurnSpeed#
rotate limb player1, FrontWR, Obj(2).Ang.x, Obj(2).Ang.y, Obj(2).Ang.z
` Front Left Wheel
Obj(3).Ang.x = Obj(3).Ang.x + WheelTurnSpeed#
rotate limb player1, FrontWL, Obj(3).Ang.x, Obj(3).Ang.y, Obj(3).Ang.z

`---------------------------------------
`-----------Control Positions-----------
`---------------------------------------
Players(1).Pos.x = newxvalue (Players(1).Pos.x, Players(1).Ang.y, MoveSpeed#)
Players(1).Pos.z = newzvalue (Players(1).Pos.z, Players(1).Ang.y, MoveSpeed#)
position object player1, Players(1).Pos.x, Players(1).Pos.y, Players(1).Pos.z

rotate object player1,Players(1).Ang.x, Players(1).Ang.y, Players(1).Ang.z

`---------------------------------------
`-----------Camera Positions------------
`---------------------------------------
set camera to follow Players(1).Pos.x, Players(1).Pos.y, Players(1).Pos.z, 45, 200, 50, 10, 1

`---------------------------------------
`-------Start Information Loop----------
`---------------------------------------
gosub Information

sync
loop
`---------------------------------------
`-----------Start Subroutines-----------
`---------------------------------------
`-------------------------------------------------------------
`--------------------------LOAD CARS--------------------------
`-------------------------------------------------------------
Cars:
make matrix 1,10000,10000,10,10
Rem Load Bicycles
set dir "modelcar1"
player1 = 1
BackW = 1
FrontWL = 2
FrontWR = 3
load object "CorvetteWheels.x", player1
scale object player1, 1000,1000,1000
   position object player1, 0, 0, 0

perform checklist for object limbs player1
`---------------------------------------
`-----------BackW Object----------------
`---------------------------------------
Obj(1).Pos.x = limb position x (player1, BackW)
Obj(1).Pos.y = limb position y (player1, BackW)
Obj(1).Pos.z = limb position z (player1, BackW)
Obj(1).Ang.x = limb angle x (player1, BackW)
Obj(1).Ang.y = limb angle y (player1, BackW)
Obj(1).Ang.z = limb angle z (player1, BackW)
`---------------------------------------
`-----------FrontWL Object--------------
`---------------------------------------
Obj(2).Pos.x = limb position x (player1, FrontWL)
Obj(2).Pos.y = limb position y (player1, FrontWL)
Obj(2).Pos.z = limb position z (player1, FrontWL)
Obj(2).Ang.x = limb angle x (player1, FrontWL)
Obj(2).Ang.y = limb angle y (player1, FrontWL)
Obj(2).Ang.z = limb angle z (player1, FrontWL)
`---------------------------------------
`-----------FrontWR Object--------------
`---------------------------------------
Obj(3).Pos.x = limb position x (player1, FrontWR)
Obj(3).Pos.y = limb position y (player1, FrontWR)
Obj(3).Pos.z = limb position z (player1, FrontWR)
Obj(3).Ang.x = limb angle x (player1, FrontWR)
Obj(3).Ang.y = limb angle y (player1, FrontWR)
Obj(3).Ang.z = limb angle z (player1, FrontWR)
`---------------------------------------
`-----------Player1 Object--------------
`---------------------------------------
Players(1).Pos.x = object position x (player1)
Players(1).Pos.y = object position y (player1)
Players(1).Pos.z = object position z (player1)
Players(1).Ang.x = object angle x (player1)
Players(1).Ang.y = object angle y (player1)
Players(1).Ang.z = object angle z (player1)

set dir ".." : set dir ".."

return
`-------------------------------------------------------------
`--------------------------GAME TIME--------------------------
`-------------------------------------------------------------
Game_Time:
`-------------------------
rem set timer
milisecond = timer ()
second = milisecond / 60
minute = second / 60
hour = minute / 60
`-------------------------
current_milisecond = (milisecond - milisecond_start)
current_second = current_milisecond / 1000
current_minute = current_second / 60
current_hour = current_minute / 60
`-------------------------
return
`-------------------------------------------------------------
`--------------------------INFORMATION------------------------
`-------------------------------------------------------------
Information:
set cursor 0,0
`-------------------------
rem time
Elapsed_milisecond = current_milisecond mod 60
Elapsed_second = current_second mod 60
Elapsed_minute = current_minute mod 60
Elapsed_hour = current_hour mod 60
print "Elapsed Time: ", Elapsed_hour, ":", Elapsed_minute, ":", Elapsed_second, ":", Elapsed_milisecond
`-------------------------
print "Ivme: ", ivme#
print "TurnSpeed: ", WheelTurnSpeed#
print "MoveSpeed: ", MoveSpeed#
print "object y angle: ", Players(1).Ang.y

for t = 1 to 15
if limb exist(player1,t) then print t, " ", limb name$ (player1,t)
next t

return
`-------------------------------------------------------------
`-------------------------------------------------------------

+ Code Snippet

Rem Project: Corvette
Rem Created: 20.07.2004 23:30:43

Rem ***** Main Source File *****
type Coordinate
   x As Float
   y As Float
   z As Float
endtype

type Object
   Pos As Coordinate
   Ang As Coordinate
   Size As Coordinate
endtype

`---------------------------------------
`-----------Make Objects----------------
`---------------------------------------
Dim Obj(4) As Object
Dim Players(4) As Object
gosub Cars
`---------------------------------------
`-----------Set Variables---------------
`---------------------------------------
turnFriction# = 0.97
Friction# = 500

`---------------------------------------
`-----------Set Camera Start Pos--------
`---------------------------------------
position camera -200,50,0
point camera 0,50,0

Restart:
`---------------------------------------
`-------Set Time Start Variables--------
`---------------------------------------
milisecond_start = timer()
#constant second_start = milisecond_start / 60
#constant minute_start = second_start / 60
#constant hour_start = minute_start / 60

`---------------------------------------
`-----------Start Main Loop-------------
`---------------------------------------
sync on
do
`---------------------------------------
`-----------Start Time Loop-------------
`---------------------------------------
gosub Game_Time

`---------------------------------------
`-----------Control Speed---------------
`---------------------------------------

if upkey() > 0
   ivme# = ivme# + 0.001
endif
if downkey() > 0
   ivme# = ivme# - 0.001
endif

WheelTurnSpeed# = WheelTurnSpeed# + ivme#
WheelTurnSpeed# = (WheelTurnSpeed# * turnFriction#)
MoveSpeed# = curvevalue (WheelTurnSpeed#, movespeed#, Friction#)
`---------------------------------------
`-----------Control Turning-------------
`---------------------------------------
if leftkey() > 0
   Obj(2).Ang.y = wrapvalue (Obj(2).Ang.y + 0.1)
      if Obj(2).Ang.y > 30 then Obj(2).Ang.y = 30
         Obj(3).Ang.y = wrapvalue (Obj(3).Ang.y + 0.1)
            if Obj(3).Ang.y > 30 then Obj(3).Ang.y = 30
endif
if rightkey() > 0
   Obj(2).Ang.y = wrapvalue (Obj(2).Ang.y - 0.1)
      if Obj(2).Ang.y < -30 then Obj(2).Ang.y = -30
         Obj(3).Ang.y = wrapvalue (Obj(3).Ang.y - 0.1)
            if Obj(3).Ang.y < -30 then Obj(3).Ang.y = -30
endif

` Back Wheels
Obj(1).Ang.x = Obj(1).Ang.x + WheelTurnSpeed#
rotate limb player1, BackW, Obj(1).Ang.x, Obj(1).Ang.y, Obj(1).Ang.z
` Front Right Wheel
Obj(2).Ang.x = Obj(2).Ang.x + WheelTurnSpeed#
rotate limb player1, FrontWR, Obj(2).Ang.x, Obj(2).Ang.y, Obj(2).Ang.z
` Front Left Wheel
Obj(3).Ang.x = Obj(3).Ang.x + WheelTurnSpeed#
rotate limb player1, FrontWL, Obj(3).Ang.x, Obj(3).Ang.y, Obj(3).Ang.z

`---------------------------------------
`-----------Control Positions-----------
`---------------------------------------
Players(1).Pos.x = newxvalue (Players(1).Pos.x, Players(1).Ang.y, MoveSpeed#)
Players(1).Pos.z = newzvalue (Players(1).Pos.z, Players(1).Ang.y, MoveSpeed#)
position object player1, Players(1).Pos.x, Players(1).Pos.y, Players(1).Pos.z

rotate object player1,Players(1).Ang.x, Players(1).Ang.y, Players(1).Ang.z


`---------------------------------------
`-----------Camera Positions------------
`---------------------------------------
set camera to follow Players(1).Pos.x, Players(1).Pos.y, Players(1).Pos.z, 45, 200, 50, 10, 1





`---------------------------------------
`-------Start Information Loop----------
`---------------------------------------
gosub Information

sync
loop
`---------------------------------------
`-----------Start Subroutines-----------
`---------------------------------------
`-------------------------------------------------------------
`--------------------------LOAD CARS--------------------------
`-------------------------------------------------------------
Cars:
make matrix 1,10000,10000,10,10
Rem Load Bicycles
set dir "modelcar1"
player1 = 1
BackW = 1
FrontWL = 2
FrontWR = 3
load object "CorvetteWheels.x", player1
scale object player1, 1000,1000,1000
   position object player1, 0, 0, 0

perform checklist for object limbs player1
`---------------------------------------
`-----------BackW Object----------------
`---------------------------------------
Obj(1).Pos.x = limb position x (player1, BackW)
Obj(1).Pos.y = limb position y (player1, BackW)
Obj(1).Pos.z = limb position z (player1, BackW)
Obj(1).Ang.x = limb angle x (player1, BackW)
Obj(1).Ang.y = limb angle y (player1, BackW)
Obj(1).Ang.z = limb angle z (player1, BackW)
`---------------------------------------
`-----------FrontWL Object--------------
`---------------------------------------
Obj(2).Pos.x = limb position x (player1, FrontWL)
Obj(2).Pos.y = limb position y (player1, FrontWL)
Obj(2).Pos.z = limb position z (player1, FrontWL)
Obj(2).Ang.x = limb angle x (player1, FrontWL)
Obj(2).Ang.y = limb angle y (player1, FrontWL)
Obj(2).Ang.z = limb angle z (player1, FrontWL)
`---------------------------------------
`-----------FrontWR Object--------------
`---------------------------------------
Obj(3).Pos.x = limb position x (player1, FrontWR)
Obj(3).Pos.y = limb position y (player1, FrontWR)
Obj(3).Pos.z = limb position z (player1, FrontWR)
Obj(3).Ang.x = limb angle x (player1, FrontWR)
Obj(3).Ang.y = limb angle y (player1, FrontWR)
Obj(3).Ang.z = limb angle z (player1, FrontWR)
`---------------------------------------
`-----------Player1 Object--------------
`---------------------------------------
Players(1).Pos.x = object position x (player1)
Players(1).Pos.y = object position y (player1)
Players(1).Pos.z = object position z (player1)
Players(1).Ang.x = object angle x (player1)
Players(1).Ang.y = object angle y (player1)
Players(1).Ang.z = object angle z (player1)

set dir ".." : set dir ".."

return
`-------------------------------------------------------------
`--------------------------GAME TIME--------------------------
`-------------------------------------------------------------
Game_Time:
`-------------------------
rem set timer
milisecond = timer ()
second = milisecond / 60
minute = second / 60
hour = minute / 60
`-------------------------
current_milisecond = (milisecond - milisecond_start)
current_second = current_milisecond / 1000
current_minute = current_second / 60
current_hour = current_minute / 60
`-------------------------
return
`-------------------------------------------------------------
`--------------------------INFORMATION------------------------
`-------------------------------------------------------------
Information:
set cursor 0,0
`-------------------------
rem time
Elapsed_milisecond = current_milisecond mod 60
Elapsed_second = current_second mod 60
Elapsed_minute = current_minute mod 60
Elapsed_hour = current_hour mod 60
print "Elapsed Time: ", Elapsed_hour, ":", Elapsed_minute, ":", Elapsed_second, ":", Elapsed_milisecond
`-------------------------
print "Ivme: ", ivme#
print "TurnSpeed: ", WheelTurnSpeed#
print "MoveSpeed: ", MoveSpeed#
print "object y angle: ", Players(1).Ang.y


for t = 1 to 15
if limb exist(player1,t) then print t, " ", limb name$ (player1,t)
next t

return
`-------------------------------------------------------------
`-------------------------------------------------------------

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CuCuMBeR

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Joined: 11th Jan 2003

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Posted: 21st Jul 2004 17:59

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Also i need some sort of vectors implementing to find the mass position of the car and calculating different forces,
Thanks Very much..

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CuCuMBeR

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Posted: 22nd Jul 2004 01:00

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well, unfortunately ive found out theres nothin to learn from this code..
so nevermind ppl

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