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arbiter.go
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arbiter.go
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// Copyright 2014 The Azul3D Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cp
/*
#include "chipmunk/include/chipmunk/chipmunk.h"
*/
import "C"
import (
"unsafe"
)
const (
MAX_CONTACTS_PER_ARBITER = C.CP_MAX_CONTACTS_PER_ARBITER
)
// The Arbiter struct controls pairs of colliding shapes.
//
// They are also used in conjuction with collision handler callbacks allowing
// you to retrieve information on the collision and control it.
type Arbiter struct {
c *C.cpArbiter
contactPointSet *ContactPointSet
userData interface{}
}
func goArbiter(c *C.cpArbiter) *Arbiter {
return &Arbiter{
c: c,
}
}
func (a *Arbiter) Restitution() float64 {
return float64(C.cpArbiterGetRestitution(a.c))
}
func (a *Arbiter) SetRestitution(restitution float64) {
C.cpArbiterSetRestitution(
a.c,
C.cpFloat(restitution),
)
}
func (a *Arbiter) Friction() float64 {
return float64(C.cpArbiterGetFriction(a.c))
}
func (a *Arbiter) SetFriction(friction float64) {
C.cpArbiterSetFriction(
a.c,
C.cpFloat(friction),
)
}
// Get the relative surface velocity of the two shapes in contact.
func (a *Arbiter) SurfaceVelocity() Vect {
return goVect(C.cpArbiterGetSurfaceVelocity(a.c))
}
// Override the relative surface velocity of the two shapes in contact.
//
// By default this is calculated to be the difference of the two surface
// velocities clamped to the tangent plane.
func (a *Arbiter) SetSurfaceVelocity(vr Vect) {
C.cpArbiterSetSurfaceVelocity(a.c, vr.c())
}
// Calculate the total impulse including the friction that was applied by this arbiter.
// This function should only be called from a post-solve, post-step or cpBodyEachArbiter callback.
func (a *Arbiter) TotalImpulse() Vect {
return goVect(C.cpArbiterTotalImpulse(a.c))
}
func (a *Arbiter) UserData() interface{} {
return a.userData
}
func (a *Arbiter) SetUserData(i interface{}) {
a.userData = i
}
// Calculate the amount of energy lost in a collision including static, but not dynamic friction.
// This function should only be called from a post-solve, post-step or cpBodyEachArbiter callback.
func (a *Arbiter) TotalKE() float64 {
return float64(C.cpArbiterTotalKE(a.c))
}
func (a *Arbiter) Ignore() bool {
return goBool(C.cpArbiterIgnore(a.c))
}
// Return the colliding shapes involved for this arbiter.
//
// The order of their cpSpace.collision_type values will match
// the order set when the collision handler was registered.
func (arb *Arbiter) Shapes() (a, b *Shape) {
var ca, cb *C.cpShape
C.cpArbiterGetShapes(
arb.c,
&ca,
&cb,
)
return goShape(ca, nil), goShape(cb, nil)
}
type Int C.int
type ContactPoint struct {
// The position of the contact on the surface of each shape.
Point1, Point2 Vect
// Penetration distance of the two shapes. Overlapping means it will be
// negative.
//
// This value is calculated as Vdot(Vsub(point2, point1), normal) and is
// ignored by arbiter.SetContactPointSet().
Distance float64
}
// A struct that wraps up the important collision data for an arbiter.
type ContactPointSet struct {
// The number of contact points in the set.
Count Int
// The normal of the collision.
Normal Vect
// The array of contact points.
Points [MAX_CONTACTS_PER_ARBITER]ContactPoint
}
// Return a contact set from an arbiter.
func (a *Arbiter) ContactPointSet() *ContactPointSet {
ret := C.cpArbiterGetContactPointSet(a.c)
return (*ContactPointSet)(unsafe.Pointer(&ret))
}
// Replace the contact point set for an arbiter.
//
// This can be a very powerful feature, but use it with caution!
func (a *Arbiter) SetContactPointSet(set *ContactPointSet) {
a.contactPointSet = set
C.cpArbiterSetContactPointSet(
a.c,
(*C.cpContactPointSet)(unsafe.Pointer(set)),
)
}
// Returns true if this is the first step a pair of objects started colliding.
func (a *Arbiter) IsFirstContact() bool {
return goBool(C.cpArbiterIsFirstContact(a.c))
}
// Returns true if in separate callback due to a shape being removed from the space.
func (a *Arbiter) IsRemoval() bool {
return goBool(C.cpArbiterIsRemoval(a.c))
}
// Get the number of contact points for this arbiter.
func (a *Arbiter) Count() int {
return int(C.cpArbiterGetCount(a.c))
}
// Get the normal of the collision.
func (a *Arbiter) GetNormal() Vect {
return goVect(C.cpArbiterGetNormal(a.c))
}
// Get the position of the ith contact point on the surface of the first shape.
func (a *Arbiter) Point1(i int) Vect {
return goVect(C.cpArbiterGetPointA(a.c, C.int(i)))
}
// Get the position of the ith contact point on the surface of the second shape.
func (a *Arbiter) Point2(i int) Vect {
return goVect(C.cpArbiterGetPointB(a.c, C.int(i)))
}
// Get the depth of the ith contact point.
func (a *Arbiter) Depth(i int) float64 {
return float64(C.cpArbiterGetDepth(a.c, C.int(i)))
}
func (a *Arbiter) CallWildcardBeginA(space *Space) bool {
return goBool(C.cpArbiterCallWildcardBeginA(a.c, space.c))
}
func (a *Arbiter) CallWildcardBeginB(space *Space) bool {
return goBool(C.cpArbiterCallWildcardBeginB(a.c, space.c))
}
func (a *Arbiter) CallWildcardPreSolveA(space *Space) bool {
return goBool(C.cpArbiterCallWildcardPreSolveA(a.c, space.c))
}
func (a *Arbiter) CallWildcardPreSolveB(space *Space) bool {
return goBool(C.cpArbiterCallWildcardPreSolveB(a.c, space.c))
}
func (a *Arbiter) CallWildcardPostSolveA(space *Space) {
C.cpArbiterCallWildcardPostSolveA(a.c, space.c)
}
func (a *Arbiter) CallWildcardPostSolveB(space *Space) {
C.cpArbiterCallWildcardPostSolveB(a.c, space.c)
}
func (a *Arbiter) CallWildcardSeparateA(space *Space) {
C.cpArbiterCallWildcardSeparateA(a.c, space.c)
}
func (a *Arbiter) CallWildcardSeparateB(space *Space) {
C.cpArbiterCallWildcardSeparateB(a.c, space.c)
}