Simple Chipmunk Physics

**Cybermonkey** · 10-07-2011, 08:31 PM

Okay, I guess I can initialize chipmunk, but again... In demo11 the drawing is done by

Code:

  cpDrawSpace( space, TRUE );

which means I have to "break down" the source of ZenGL. What if I would add a "ball" with your procedure

Code:

procedure cpAddBall( x, y, r, mass, e, u : cpFloat );

how do I know where to draw the circle when physics were calculated. Assuming my procedure looks like

Code:

circle (x,y,radius)

and my engine is purely procedural driven which means I have to establish a game loop like

Code:

repeat
  key=getkey();
  //do all the stuff
until key=27;

How can I get the x and y value of my ball?

**Cybermonkey** · 24-07-2011, 04:01 PM

Ok, since no one can answer me, I'll post here an example from Freebasic

Code:

 ''
 ''  My first chipmunk simulation
 ''
 #include "chipmunk/chipmunk.bi"
 #inclib "chipmunk"
 
const as cpFloat mass = 5.0, radius = 10 ' Mass and radius values for our circle - you can play around with these
 const as cpFloat dt = 60.0 / 1.0 ' The delta time for physics calculations
 
dim shared space as cpSpace ptr ' The space where the simulation takes place
 
screenres 800, 600, 16 ' Setup the screen
 
cpInitChipmunk() ' Initialize chipmunk
 
space = cpSpaceNew() ' Create a new space
 space->iterations = 10 ' 10 Iterations per step
 space->gravity = cpv(0, 50) ' Gravity x = 0, y = 50 
 
dim shared circleBody as cpBody ptr ' Circle body
 dim shared circleShape as cpShape ptr ' Circle shape
 
' Create a new circle body
 circleBody = cpBodyNew( mass, cpMomentForCircle( mass, 0.0, radius, cpvzero ) )
 circleBody->p = cpv( 400, 0 ) ' set the circle at the top-middle of the screen
 cpSpaceAddBody( space, circleBody ) ' add the body to the simulation
 
' Crate a new circle shape
 circleShape = cpCircleShapeNew( circleBody, radius, cpvzero )
 cpSpaceAddShape( space, circleShape ) ' add the shape to the simulation
 
do
   screenlock()
     cls
     locate 1, 1: print "The ball should fall down into a bottomless pit"
 
    circle( circleBody->p.x, circleBody->p.y ), radius, rgb( 255, 0, 0 )
   screenunlock()
 
  ' Advance the simulation
   cpSpaceStep( space, dt )
 
  sleep 1, 1
 loop until multikey(&H01) ' Loop until Escape is pressed
 
' Cleans up everything associated with this space
 cpSpaceFreeChildren( space )
 cpSpaceFree( space )
 
end 0

So I will try to port this to FreePascal. (Of course there's still a timer missing but one step after the other ...)