axmol/tests/cpp-tests/Source/ChipmunkTestBed/demo/Joints.c

/* 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/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)));
    cpBodySetPosition(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, 0.0f)));
    cpBodySetPosition(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, 0.0f)));
    cpBodySetPosition(body, cpvadd(pos, boxOffset));

    cpShape* shape = cpSpaceAddShape(space, cpSegmentShapeNew(body, a, b, 5.0f));
    cpShapeSetElasticity(shape, 0.0f);
    cpShapeSetFriction(shape, 0.7f);
    cpShapeSetFilter(shape, cpShapeFilterNew(1, CP_ALL_CATEGORIES, CP_ALL_CATEGORIES));

    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)));
    cpBodySetPosition(body, cpvadd(pos, boxOffset));

    cpShape* shape = cpSpaceAddShape(space, cpCircleShapeNew(body, radius, cpvzero));
    cpShapeSetElasticity(shape, 0.0f);
    cpShapeSetFriction(shape, 0.7f);
    cpShapeSetFilter(shape, cpShapeFilterNew(1, CP_ALL_CATEGORIES, CP_ALL_CATEGORIES));

    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)));
    cpBodySetPosition(body, cpvadd(pos, boxOffset));

    cpShape* shape = cpSpaceAddShape(space, cpBoxShapeNew(body, width, height, 0.0));
    cpShapeSetElasticity(shape, 0.0f);
    cpShapeSetFriction(shape, 0.7f);
    cpShapeSetFilter(shape, cpShapeFilterNew(1, CP_ALL_CATEGORIES, CP_ALL_CATEGORIES));

    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);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320, 120), cpv(320, 120), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320, 0), cpv(320, 0), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320, -120), cpv(320, -120), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320, -240), cpv(320, -240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320, -240), cpv(-320, 240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-160, -240), cpv(-160, 240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(0, -240), cpv(0, 240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(160, -240), cpv(160, 240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(320, -240), cpv(320, 240), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);
    cpShapeSetFriction(shape, 1.0f);
    cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);

    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, -CP_PI / 2.0f, CP_PI / 2.0f));

    // 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, CP_PI / 2.0f));

    // 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, CP_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, double dt)
{
    cpSpaceStep(space, dt);
}

static void destroy(cpSpace* space)
{
    ChipmunkDemoFreeSpaceChildren(space);
    cpSpaceFree(space);
}

ChipmunkDemo Joints = {
    "Joints and Constraints", 1.0 / 60.0, init, update, ChipmunkDemoDefaultDrawImpl, destroy,
};