static void
update(cpSpace *space)
{
cpFloat tolerance = 2.0;
if(ChipmunkDemoRightClick && cpShapeNearestPointQuery(shape, ChipmunkDemoMouse, NULL) > tolerance){
cpBody *body = cpShapeGetBody(shape);
int count = cpPolyShapeGetNumVerts(shape);
// Allocate the space for the new vertexes on the stack.
cpVect *verts = (cpVect *)alloca((count + 1)*sizeof(cpVect));
for(int i=0; i<count; i++){
verts[i] = cpPolyShapeGetVert(shape, i);
}
verts[count] = cpBodyWorld2Local(body, ChipmunkDemoMouse);
// This function builds a convex hull for the vertexes.
// Because the result array is NULL, it will reduce the input array instead.
int hullCount = cpConvexHull(count + 1, verts, NULL, NULL, tolerance);
// Figure out how much to shift the body by.
cpVect centroid = cpCentroidForPoly(hullCount, verts);
// Recalculate the body properties to match the updated shape.
cpFloat mass = cpAreaForPoly(hullCount, verts)*DENSITY;
cpBodySetMass(body, mass);
cpBodySetMoment(body, cpMomentForPoly(mass, hullCount, verts, cpvneg(centroid)));
cpBodySetPos(body, cpBodyLocal2World(body, centroid));
// Use the setter function from chipmunk_unsafe.h.
// You could also remove and recreate the shape if you wanted.
cpPolyShapeSetVerts(shape, hullCount, verts, cpvneg(centroid));
}
int steps = 1;
cpFloat dt = 1.0f/60.0f/(cpFloat)steps;
for(int i=0; i<steps; i++){
cpSpaceStep(space, dt);
}
}
void wrPolyShapeSetVerts(cpShape *shape, int numVerts, cpVect *verts, cpVect *offset) {
cpPolyShapeSetVerts(shape, numVerts, verts, *offset);
}
static void pullControlPoint(cpShape *shape) {
int i;
float origArea, newArea, newMass;
control_point_t *cp;
cpPolyShape *ps;
cpCircleShape *circle;
cpVect lp;
cpVect verts[4];
cpConstraint *mouseJoint;
mouseJoint = atlMouseJoint();
if (!mouseJoint) {
lp = cpBodyWorld2Local(shape->body, atlMouseClickPos());
} else {
/* update joint position */
lp = cpBodyWorld2Local(shape->body, atlMousePos());
atlRemoveMouseJoint(g_Space);
}
atlCreateMouseJoint(g_Space, shape->body, lp);
cp = (control_point_t *)shape->data;
ps = (cpPolyShape *)cp->dom->shape;
control_point_t *circlePoint;
for (i = 0; i < 4; ++i) {
verts[i] = cpPolyShapeGetVert((cpShape *)ps, i);
if (lp.x > 0) {
if (verts[i].x > 0)
verts[i].x = lp.x;
else
verts[i].x = -lp.x;
} else if (lp.x < 0) {
if (verts[i].x < 0)
verts[i].x = lp.x;
else
verts[i].x = -lp.x;
}
if (lp.y > 0) {
if (verts[i].y > 0)
verts[i].y = lp.y;
else
verts[i].y = -lp.y;
} else if (lp.y < 0) {
if (verts[i].y < 0)
verts[i].y = lp.y;
else
verts[i].y = -lp.y;
}
circlePoint = (control_point_t *)cp->dom->pControlPoints[i];
circle = (cpCircleShape *)circlePoint->shape;
cpCircleShapeSetOffset((cpShape *)circle, verts[i]);
}
origArea = (fabs(dominoVerts[0].x)+dominoVerts[3].x) *
(fabs(dominoVerts[0].y)+dominoVerts[1].y);
newArea = (fabs(verts[0].x)+verts[3].x) *
(fabs(verts[0].y)+verts[1].y);
if (newArea > origArea)
newMass = newArea/origArea * 0.05f;
else
newMass = 1.0f;
cpBodySetMass(cp->dom->body, newMass);
cpPolyShapeSetVerts((cpShape *)ps, ps->numVerts, verts, cpvzero);
}
