How to implement simple pendulum?
Posted: Thu Oct 29, 2009 1:14 am
Hi, I'm just getting started using chipmunk for the first time and am trying to build a simple pendulum, also using cocos2d. what would the recommended method for this be? My first attempt at this was to do the below, this results in the rope and the weight/box bouncing about all over the place manically.
create a static body:
add a 'rope' and pivotJoint this to the static body:
add a 'box' and pivot joint it to the rope:
is this a sensible way to try to do this? if so what am i doing wrong? if not, what is? the eventual aim is to introduce objects to 'hit' the pendulum to get it to swing. thanks!
create a static body:
Code: Select all
staticBody = cpBodyNew(INFINITY, INFINITY);
staticBody->p = cpv(0, 0);Code: Select all
cpVect rope_verts[] = {
cpv(-5,-70),
cpv(-5, 70),
cpv( 5, 70),
cpv( 5,-70),
};
cpFloat mass = 1;
ropeBody = cpBodyNew(mass, cpMomentForPoly(mass, 4, rope_verts, cpvzero));
ropeBody->p = cpv(240, 250);
cpSpaceAddBody(space, ropeBody);
cpShape *ropeShape = cpPolyShapeNew(ropeBody, 4, rope_verts, cpvzero);
ropeShape->e = 0.0;
ropeShape->u = 0.8;
ropeShape->data = ropeSprite;
ropeShape->collision_type = 1;
cpSpaceAddShape(space, ropeShape);
cpSpaceAddJoint(space, cpPivotJointNew(staticBody, ropeBody, cpv(240,320))); add a 'box' and pivot joint it to the rope:
Code: Select all
cpVect box_verts[] = {
cpv(-100,-90),
cpv(-100, 90),
cpv( 100, 90),
cpv( 100,-90),
};
cpFloat mass = 50.0;
boxBody = cpBodyNew(mass, cpMomentForPoly(mass, 4, box_verts, cpvzero));
boxBody->p = cpv(240, 160);
cpSpaceAddBody(space, boxBody);
cpShape *boxShape = cpPolyShapeNew(boxBody, 4, box_verts, cpvzero);
boxShape->e = 0.5;
boxShape->u = 0.8;
boxShape->data = boxSprite;
boxShape->collision_type = 1;
cpSpaceAddShape(space, boxShape);
cpSpaceAddJoint(space, cpPivotJointNew(boxBody, ropeBody, cpv(240,180)));