void draw_shape(cpBody* body, cpShape* shape, void* data)
{
// get body info
cpVect v = cpBodyGetPos(body);
cpFloat angle = cpBodyGetAngle(body);
cpVect rot = cpvforangle(angle);
// get vectors
int n = cpPolyShapeGetNumVerts(shape);
SDL_Point* pts = calloc(sizeof(SDL_Point), n+1);
// rotate vectors
int i;
for(i=0; i<n; i++) {
cpVect p = cpPolyShapeGetVert(shape, i);
cpVect vr = cpvrotate(cpv(p.x,p.y), rot);
pts[i] = (SDL_Point) { (vr.x+v.x)*10+50, (vr.y+v.y)*10+50 };
if(i == 0)
pts[n] = pts[i];
}
// draw
SDL_RenderDrawLines(ren, pts, n+1);
free(pts);
}
void PhysicsShapePolygon::updateScale()
{
cpFloat factorX = _newScaleX / _scaleX;
cpFloat factorY = _newScaleY / _scaleY;
auto shape = _cpShapes.front();
int count = cpPolyShapeGetCount(shape);
cpVect* vects = new cpVect[count];
for(int i=0;i<count;++i)
vects[i] = cpPolyShapeGetVert(shape, i);
for (int i = 0; i < count; ++i)
{
vects[i].x *= factorX;
vects[i].y *= factorY;
}
// convert hole to clockwise
if (factorX * factorY < 0)
{
for (int i = 0; i < count / 2; ++i)
{
cpVect v = vects[i];
vects[i] = vects[count - i - 1];
vects[count - i - 1] = v;
}
}
cpPolyShapeSetVertsRaw(shape, count, vects);
CC_SAFE_DELETE_ARRAY(vects);
PhysicsShape::updateScale();
}
static void
draw_poly_shape(struct draw_options opts, cpShape *shape, cpBody *body)
{
int num_verts = cpPolyShapeGetNumVerts(shape);
cpVect first_vert = cpBodyLocal2World(body, cpPolyShapeGetVert(shape, 0));
cpVect prev_vert = first_vert;
cpVect pos = cpBodyGetPos(body);
for (int i = 1; i < num_verts; i++)
{
cpVect vert = cpBodyLocal2World(body, cpPolyShapeGetVert(shape, i));
draw_line(opts, prev_vert, vert);
prev_vert = vert;
}
/* close up the polygon */
draw_line(opts, prev_vert, first_vert);
}
void PhysicsShapePolygon::getPoints(Vec2* outPoints) const
{
auto shape = _cpShapes.front();
int count = cpPolyShapeGetCount(shape);
cpVect* vecs = new cpVect[count];
for(int i=0;i<count;++i)
vecs[i] = cpPolyShapeGetVert(shape, i);
PhysicsHelper::cpvs2points(vecs, outPoints, count);
CC_SAFE_DELETE_ARRAY(vecs);
}
void Slice::ClipPoly(cpSpace *space, cpShape *shape, cpVect n, cpFloat dist)
{
cpBody *body = cpShapeGetBody(shape);
int count = cpPolyShapeGetCount(shape);
int clippedCount = 0;
cpVect *clipped = (cpVect *)alloca((count + 1)*sizeof(cpVect));
for(int i=0, j=count-1; i<count; j=i, i++){
cpVect a = cpBodyLocalToWorld(body, cpPolyShapeGetVert(shape, j));
cpFloat a_dist = cpvdot(a, n) - dist;
if(a_dist < 0.0){
clipped[clippedCount] = a;
clippedCount++;
}
cpVect b = cpBodyLocalToWorld(body, cpPolyShapeGetVert(shape, i));
cpFloat b_dist = cpvdot(b, n) - dist;
if(a_dist*b_dist < 0.0f){
cpFloat t = cpfabs(a_dist)/(cpfabs(a_dist) + cpfabs(b_dist));
clipped[clippedCount] = cpvlerp(a, b, t);
clippedCount++;
}
}
cpVect centroid = cpCentroidForPoly(clippedCount, clipped);
cpFloat mass = cpAreaForPoly(clippedCount, clipped, 0.0f)*DENSITY;
cpFloat moment = cpMomentForPoly(mass, clippedCount, clipped, cpvneg(centroid), 0.0f);
cpBody *new_body = cpSpaceAddBody(space, cpBodyNew(mass, moment));
cpBodySetPosition(new_body, centroid);
cpBodySetVelocity(new_body, cpBodyGetVelocityAtWorldPoint(body, centroid));
cpBodySetAngularVelocity(new_body, cpBodyGetAngularVelocity(body));
cpTransform transform = cpTransformTranslate(cpvneg(centroid));
cpShape *new_shape = cpSpaceAddShape(space, cpPolyShapeNew(new_body, clippedCount, clipped, transform, 0.0));
// Copy whatever properties you have set on the original shape that are important
cpShapeSetFriction(new_shape, cpShapeGetFriction(shape));
}
float PhysicsShapePolygon::calculateArea()
{
auto shape = _cpShapes.front();
int count = cpPolyShapeGetCount(shape);
cpVect* vecs = new cpVect[count];
for(int i=0;i<count;++i)
vecs[i] = cpPolyShapeGetVert(shape, i);
float area = PhysicsHelper::cpfloat2float(cpAreaForPoly(count, vecs, cpPolyShapeGetRadius(shape)));
CC_SAFE_DELETE_ARRAY(vecs);
return area;
}
Vec2 PhysicsShapePolygon::getCenter()
{
auto shape = _cpShapes.front();
int count = cpPolyShapeGetCount(shape);
cpVect* vecs = new cpVect[count];
for(int i=0;i<count;++i)
vecs[i] = cpPolyShapeGetVert(shape, i);
Vec2 center = PhysicsHelper::cpv2point(cpCentroidForPoly(count, vecs));
CC_SAFE_DELETE_ARRAY(vecs);
return center;
}
float PhysicsShapePolygon::calculateDefaultMoment()
{
if(_mass == PHYSICS_INFINITY)
{
return PHYSICS_INFINITY;
}
else
{
auto shape = _cpShapes.front();
int count = cpPolyShapeGetCount(shape);
cpVect* vecs = new cpVect[count];
for(int i=0;i<count;++i)
vecs[i] = cpPolyShapeGetVert(shape, i);
float moment = PhysicsHelper::cpfloat2float(cpMomentForPoly(_mass, count, vecs, cpvzero, cpPolyShapeGetRadius(shape)));
CC_SAFE_DELETE_ARRAY(vecs);
return moment;
}
}
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);
}
}
Vec2 PhysicsShapePolygon::getPoint(int i) const
{
return PhysicsHelper::cpv2point(cpPolyShapeGetVert(_cpShapes.front(), i));
}
Size PhysicsShapeBox::getSize() const
{
cpShape* shape = _cpShapes.front();
return PhysicsHelper::cpv2size(cpv(cpvdist(cpPolyShapeGetVert(shape, 1), cpPolyShapeGetVert(shape, 2)),
cpvdist(cpPolyShapeGetVert(shape, 0), cpPolyShapeGetVert(shape, 1))));
}
Point PhysicsShapePolygon::getPoint(int i) const
{
return PhysicsHelper::cpv2point(cpPolyShapeGetVert(_info->getShapes().front(), i));
}
static int cpPolyShape_getVert (lua_State *L) {
cpPolyShape *ps = check_cpPolyShape(L, 1);
int i = luaL_checkint(L, 2);
push_cpVect(L, cpPolyShapeGetVert((cpShape*)ps, i-1));
return 2;
}
cpBool Buoyancy::WaterPreSolve(cpArbiter *arb, cpSpace *space, void *ptr)
{
CP_ARBITER_GET_SHAPES(arb, water, poly);
cpBody *body = cpShapeGetBody(poly);
// Get the top of the water sensor bounding box to use as the water level.
cpFloat level = cpShapeGetBB(water).t;
// Clip the polygon against the water level
int count = cpPolyShapeGetCount(poly);
int clippedCount = 0;
#ifdef _MSC_VER
// MSVC is pretty much the only compiler in existence that doesn't support variable sized arrays.
cpVect clipped[10];
#else
cpVect clipped[count + 1];
#endif
for(int i=0, j=count-1; i<count; j=i, i++){
cpVect a = cpBodyLocalToWorld(body, cpPolyShapeGetVert(poly, j));
cpVect b = cpBodyLocalToWorld(body, cpPolyShapeGetVert(poly, i));
if(a.y < level){
clipped[clippedCount] = a;
clippedCount++;
}
cpFloat a_level = a.y - level;
cpFloat b_level = b.y - level;
if(a_level*b_level < 0.0f){
cpFloat t = cpfabs(a_level)/(cpfabs(a_level) + cpfabs(b_level));
clipped[clippedCount] = cpvlerp(a, b, t);
clippedCount++;
}
}
// Calculate buoyancy from the clipped polygon area
cpFloat clippedArea = cpAreaForPoly(clippedCount, clipped, 0.0f);
cpFloat displacedMass = clippedArea*FLUID_DENSITY;
cpVect centroid = cpCentroidForPoly(clippedCount, clipped);
cpDataPointer data = ptr;
DrawPolygon(clippedCount, clipped, 0.0f, RGBAColor(0, 0, 1, 1), RGBAColor(0, 0, 1, 0.1f), data);
DrawDot(5, centroid, RGBAColor(0, 0, 1, 1), data);
cpFloat dt = cpSpaceGetCurrentTimeStep(space);
cpVect g = cpSpaceGetGravity(space);
// Apply the buoyancy force as an impulse.
cpBodyApplyImpulseAtWorldPoint(body, cpvmult(g, -displacedMass*dt), centroid);
// Apply linear damping for the fluid drag.
cpVect v_centroid = cpBodyGetVelocityAtWorldPoint(body, centroid);
cpFloat k = k_scalar_body(body, centroid, cpvnormalize(v_centroid));
cpFloat damping = clippedArea*FLUID_DRAG*FLUID_DENSITY;
cpFloat v_coef = cpfexp(-damping*dt*k); // linear drag
// cpFloat v_coef = 1.0/(1.0 + damping*dt*cpvlength(v_centroid)*k); // quadratic drag
cpBodyApplyImpulseAtWorldPoint(body, cpvmult(cpvsub(cpvmult(v_centroid, v_coef), v_centroid), 1.0/k), centroid);
// Apply angular damping for the fluid drag.
cpVect cog = cpBodyLocalToWorld(body, cpBodyGetCenterOfGravity(body));
cpFloat w_damping = cpMomentForPoly(FLUID_DRAG*FLUID_DENSITY*clippedArea, clippedCount, clipped, cpvneg(cog), 0.0f);
cpBodySetAngularVelocity(body, cpBodyGetAngularVelocity(body)*cpfexp(-w_damping*dt/cpBodyGetMoment(body)));
return cpTrue;
}
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);
}
