/* Copyright (c) 2007 Scott Lembcke
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "chipmunk.h"
#include "ChipmunkDemo.h"
static cpBody *
addBall(cpSpace *space, cpVect pos, cpVect boxOffset)
{
cpFloat radius = 15.0f;
cpFloat mass = 1.0f;
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForCircle(mass, 0.0f, radius, cpvzero)));
cpBodySetPos(body, cpvadd(pos, boxOffset));
cpShape *shape = cpSpaceAddShape(space, cpCircleShapeNew(body, radius, cpvzero));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
return body;
}
static cpBody *
addLever(cpSpace *space, cpVect pos, cpVect boxOffset)
{
cpFloat mass = 1.0f;
cpVect a = cpv(0, 15);
cpVect b = cpv(0, -15);
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForSegment(mass, a, b)));
cpBodySetPos(body, cpvadd(pos, cpvadd(boxOffset, cpv(0, -15))));
cpShape *shape = cpSpaceAddShape(space, cpSegmentShapeNew(body, a, b, 5.0f));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
return body;
}
static cpBody *
addBar(cpSpace *space, cpVect pos, cpVect boxOffset)
{
cpFloat mass = 2.0f;
cpVect a = cpv(0, 30);
cpVect b = cpv(0, -30);
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForSegment(mass, a, b)));
cpBodySetPos(body, cpvadd(pos, boxOffset));
cpShape *shape = cpSpaceAddShape(space, cpSegmentShapeNew(body, a, b, 5.0f));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
return body;
}
static cpBody *
addWheel(cpSpace *space, cpVect pos, cpVect boxOffset)
{
cpFloat radius = 15.0f;
cpFloat mass = 1.0f;
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForCircle(mass, 0.0f, radius, cpvzero)));
cpBodySetPos(body, cpvadd(pos, boxOffset));
cpShape *shape = cpSpaceAddShape(space, cpCircleShapeNew(body, radius, cpvzero));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
cpShapeSetGroup(shape, 1); // use a group to keep the car parts from colliding
return body;
}
static cpBody *
addChassis(cpSpace *space, cpVect pos, cpVect boxOffset)
{
cpFloat mass = 5.0f;
cpFloat width = 80;
cpFloat height = 30;
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForBox(mass, width, height)));
cpBodySetPos(body, cpvadd(pos, boxOffset));
cpShape *shape = cpSpaceAddShape(space, cpBoxShapeNew(body, width, height));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
cpShapeSetGroup(shape, 1); // use a group to keep the car parts from colliding
return body;
}
static cpSpace *
init(void)
{
cpSpace *space = cpSpaceNew();
cpSpaceSetIterations(space, 10);
cpSpaceSetGravity(space, cpv(0, -100));
cpSpaceSetSleepTimeThreshold(space, 0.5f);
cpBody *staticBody = cpSpaceGetStaticBody(space);
cpShape *shape;
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,240), cpv(320,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,120), cpv(320,120), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,0), cpv(320,0), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,-120), cpv(320,-120), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,-240), cpv(320,-240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,-240), cpv(-320,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-160,-240), cpv(-160,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(0,-240), cpv(0,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(160,-240), cpv(160,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(320,-240), cpv(320,240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
cpVect boxOffset;
cpBody *body1, *body2;
cpVect posA = cpv( 50, 60);
cpVect posB = cpv(110, 60);
#define POS_A cpvadd(boxOffset, posA)
#define POS_B cpvadd(boxOffset, posB)
// Pin Joints - Link shapes with a solid bar or pin.
// Keeps the anchor points the same distance apart from when the joint was created.
boxOffset = cpv(-320, -240);
body1 = addBall(space, posA, boxOffset);
body2 = addBall(space, posB, boxOffset);
cpSpaceAddConstraint(space, cpPinJointNew(body1, body2, cpv(15,0), cpv(-15,0)));
// Slide Joints - Like pin joints but with a min/max distance.
// Can be used for a cheap approximation of a rope.
boxOffset = cpv(-160, -240);
body1 = addBall(space, posA, boxOffset);
body2 = addBall(space, posB, boxOffset);
cpSpaceAddConstraint(space, cpSlideJointNew(body1, body2, cpv(15,0), cpv(-15,0), 20.0f, 40.0f));
// Pivot Joints - Holds the two anchor points together. Like a swivel.
boxOffset = cpv(0, -240);
body1 = addBall(space, posA, boxOffset);
body2 = addBall(space, posB, boxOffset);
cpSpaceAddConstraint(space, cpPivotJointNew(body1, body2, cpvadd(boxOffset, cpv(80,60))));
// cpPivotJointNew() takes it's anchor parameter in world coordinates. The anchors are calculated from that
// cpPivotJointNew2() lets you specify the two anchor points explicitly
// Groove Joints - Like a pivot joint, but one of the anchors is a line segment that the pivot can slide in
boxOffset = cpv(160, -240);
body1 = addBall(space, posA, boxOffset);
body2 = addBall(space, posB, boxOffset);
cpSpaceAddConstraint(space, cpGrooveJointNew(body1, body2, cpv(30,30), cpv(30,-30), cpv(-30,0)));
// Damped Springs
boxOffset = cpv(-320, -120);
body1 = addBall(space, posA, boxOffset);
body2 = addBall(space, posB, boxOffset);
cpSpaceAddConstraint(space, cpDampedSpringNew(body1, body2, cpv(15,0), cpv(-15,0), 20.0f, 5.0f, 0.3f));
// Damped Rotary Springs
boxOffset = cpv(-160, -120);
body1 = addBar(space, posA, boxOffset);
body2 = addBar(space, posB, boxOffset);
// Add some pin joints to hold the circles in place.
cpSpaceAddConstraint(space, cpPivotJointNew(body1, staticBody, POS_A));
cpSpaceAddConstraint(space, cpPivotJointNew(body2, staticBody, POS_B));
cpSpaceAddConstraint(space, cpDampedRotarySpringNew(body1, body2, 0.0f, 3000.0f, 60.0f));
// Rotary Limit Joint
boxOffset = cpv(0, -120);
body1 = addLever(space, posA, boxOffset);
body2 = addLever(space, posB, boxOffset);
// Add some pin joints to hold the circles in place.
cpSpaceAddConstraint(space, cpPivotJointNew(body1, staticBody, POS_A));
cpSpaceAddConstraint(space, cpPivotJointNew(body2, staticBody, POS_B));
// Hold their rotation within 90 degrees of each other.
cpSpaceAddConstraint(space, cpRotaryLimitJointNew(body1, body2, -M_PI_2, M_PI_2));
// Ratchet Joint - A rotary ratchet, like a socket wrench
boxOffset = cpv(160, -120);
body1 = addLever(space, posA, boxOffset);
body2 = addLever(space, posB, boxOffset);
// Add some pin joints to hold the circles in place.
cpSpaceAddConstraint(space, cpPivotJointNew(body1, staticBody, POS_A));
cpSpaceAddConstraint(space, cpPivotJointNew(body2, staticBody, POS_B));
// Ratchet every 90 degrees
cpSpaceAddConstraint(space, cpRatchetJointNew(body1, body2, 0.0f, M_PI_2));
// Gear Joint - Maintain a specific angular velocity ratio
boxOffset = cpv(-320, 0);
body1 = addBar(space, posA, boxOffset);
body2 = addBar(space, posB, boxOffset);
// Add some pin joints to hold the circles in place.
cpSpaceAddConstraint(space, cpPivotJointNew(body1, staticBody, POS_A));
cpSpaceAddConstraint(space, cpPivotJointNew(body2, staticBody, POS_B));
// Force one to sping 2x as fast as the other
cpSpaceAddConstraint(space, cpGearJointNew(body1, body2, 0.0f, 2.0f));
// Simple Motor - Maintain a specific angular relative velocity
boxOffset = cpv(-160, 0);
body1 = addBar(space, posA, boxOffset);
body2 = addBar(space, posB, boxOffset);
// Add some pin joints to hold the circles in place.
cpSpaceAddConstraint(space, cpPivotJointNew(body1, staticBody, POS_A));
cpSpaceAddConstraint(space, cpPivotJointNew(body2, staticBody, POS_B));
// Make them spin at 1/2 revolution per second in relation to each other.
cpSpaceAddConstraint(space, cpSimpleMotorNew(body1, body2, M_PI));
// Make a car with some nice soft suspension
boxOffset = cpv(0, 0);
cpBody *wheel1 = addWheel(space, posA, boxOffset);
cpBody *wheel2 = addWheel(space, posB, boxOffset);
cpBody *chassis = addChassis(space, cpv(80, 100), boxOffset);
cpSpaceAddConstraint(space, cpGrooveJointNew(chassis, wheel1, cpv(-30, -10), cpv(-30, -40), cpvzero));
cpSpaceAddConstraint(space, cpGrooveJointNew(chassis, wheel2, cpv( 30, -10), cpv( 30, -40), cpvzero));
cpSpaceAddConstraint(space, cpDampedSpringNew(chassis, wheel1, cpv(-30, 0), cpvzero, 50.0f, 20.0f, 10.0f));
cpSpaceAddConstraint(space, cpDampedSpringNew(chassis, wheel2, cpv( 30, 0), cpvzero, 50.0f, 20.0f, 10.0f));
return space;
}
static void
update(cpSpace *space)
{
cpSpaceStep(space, 1.0f/60.0f);
}
static void
destroy(cpSpace *space)
{
ChipmunkDemoFreeSpaceChildren(space);
cpSpaceFree(space);
}
ChipmunkDemo Joints = {
"Joints and Constraints",
init,
update,
ChipmunkDemoDefaultDrawImpl,
destroy,
};
