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/* 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 *tankBody, *tankControlBody;
static void
update(cpSpace *space, double dt)
{
// turn the control body based on the angle relative to the actual body
cpVect mouseDelta = cpvsub(ChipmunkDemoMouse, cpBodyGetPosition(tankBody));
cpFloat turn = cpvtoangle(cpvunrotate(cpBodyGetRotation(tankBody), mouseDelta));
cpBodySetAngle(tankControlBody, cpBodyGetAngle(tankBody) - turn);
// drive the tank towards the mouse
if(cpvnear(ChipmunkDemoMouse, cpBodyGetPosition(tankBody), 30.0)){
cpBodySetVelocity(tankControlBody, cpvzero); // stop
} else {
cpFloat direction = (cpvdot(mouseDelta, cpBodyGetRotation(tankBody)) > 0.0 ? 1.0 : -1.0);
cpBodySetVelocity(tankControlBody, cpvrotate(cpBodyGetRotation(tankBody), cpv(30.0f*direction, 0.0f)));
}
cpSpaceStep(space, dt);
}
static cpBody *
add_box(cpSpace *space, cpFloat size, cpFloat mass)
{
cpFloat radius = cpvlength(cpv(size, size));
cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForBox(mass, size, size)));
cpBodySetPosition(body, cpv(frand()*(640 - 2*radius) - (320 - radius), frand()*(480 - 2*radius) - (240 - radius)));
cpShape *shape = cpSpaceAddShape(space, cpBoxShapeNew(body, size, size, 0.0));
cpShapeSetElasticity(shape, 0.0f);
cpShapeSetFriction(shape, 0.7f);
return body;
}
static cpSpace *
init(void)
{
ChipmunkDemoMessageString = "Use the mouse to drive the tank, it will follow the cursor.";
cpSpace *space = cpSpaceNew();
cpSpaceSetIterations(space, 10);
cpSpaceSetSleepTimeThreshold(space, 0.5f);
cpBody *staticBody = cpSpaceGetStaticBody(space);
cpShape *shape;
// Create segments around the edge of the screen.
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(-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);
for(int i=0; i<50; i++){
cpBody *body = add_box(space, 20, 1);
cpConstraint *pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(staticBody, body, cpvzero, cpvzero));
cpConstraintSetMaxBias(pivot, 0); // disable joint correction
cpConstraintSetMaxForce(pivot, 1000.0f); // emulate linear friction
cpConstraint *gear = cpSpaceAddConstraint(space, cpGearJointNew(staticBody, body, 0.0f, 1.0f));
cpConstraintSetMaxBias(gear, 0); // disable joint correction
cpConstraintSetMaxForce(gear, 5000.0f); // emulate angular friction
}
// We joint the tank to the control body and control the tank indirectly by modifying the control body.
tankControlBody = cpSpaceAddBody(space, cpBodyNewKinematic());
tankBody = add_box(space, 30, 10);
cpConstraint *pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(tankControlBody, tankBody, cpvzero, cpvzero));
cpConstraintSetMaxBias(pivot, 0); // disable joint correction
cpConstraintSetMaxForce(pivot, 10000.0f); // emulate linear friction
cpConstraint *gear = cpSpaceAddConstraint(space, cpGearJointNew(tankControlBody, tankBody, 0.0f, 1.0f));
cpConstraintSetErrorBias(gear, 0); // attempt to fully correct the joint each step
cpConstraintSetMaxBias(gear, 1.2f); // but limit it's angular correction rate
cpConstraintSetMaxForce(gear, 50000.0f); // emulate angular friction
return space;
}
static void
destroy(cpSpace *space)
{
ChipmunkDemoFreeSpaceChildren(space);
cpSpaceFree(space);
}
ChipmunkDemo Tank = {
"Tank",
1.0/60.0,
init,
update,
ChipmunkDemoDefaultDrawImpl,
destroy,
};
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