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fix: Create and destroy joints after world has been locked #110

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Merged
luanpotter merged 1 commit into from
Oct 26, 2025
Merged

fix: Create and destroy joints after world has been locked #110

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34 changes: 22 additions & 12 deletions packages/forge2d/lib/src/dynamics/world.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,10 @@ class World {
late ContactManager contactManager;
final List<Body> bodies = <Body>[];
final List<Joint> joints = <Joint>[];
final List<Body> bodiesToCreate = <Body>[];
final List<Body> bodiesToDestroy = <Body>[];
final List<Joint> jointsToCreate = <Joint>[];
final List<Joint> jointsToDestroy = <Joint>[];
final List<Body> _bodiesToCreate = <Body>[];
final List<Body> _bodiesToDestroy = <Body>[];
final List<Joint> _jointsToCreate = <Joint>[];
final List<Joint> _jointsToDestroy = <Joint>[];

final Vector2 _gravity;

Expand Down Expand Up @@ -139,7 +139,7 @@ class World {
Body createBody(BodyDef def) {
final body = Body(def, this);
if (isLocked) {
bodiesToCreate.add(body);
_bodiesToCreate.add(body);
return body;
}
bodies.add(body);
Expand All @@ -153,7 +153,7 @@ class World {
/// Warning: This function is locked during callbacks.
void destroyBody(Body body) {
if (isLocked) {
bodiesToDestroy.add(body);
_bodiesToDestroy.add(body);
return;
}

Expand Down Expand Up @@ -184,7 +184,7 @@ class World {
/// Adding a joint doesn't wake up the bodies.
void createJoint(Joint joint) {
if (isLocked) {
jointsToCreate.add(joint);
_jointsToCreate.add(joint);
return;
}
joints.add(joint);
Expand All @@ -209,7 +209,7 @@ class World {
/// Destroys a joint. This may cause the connected bodies to begin colliding.
void destroyJoint(Joint joint) {
if (isLocked) {
jointsToDestroy.add(joint);
_jointsToDestroy.add(joint);
return;
}

Expand Down Expand Up @@ -308,15 +308,25 @@ class World {

flags &= ~locked;

for (final body in bodiesToCreate) {
for (final body in _bodiesToCreate) {
bodies.add(body);
}
bodiesToCreate.clear();
_bodiesToCreate.clear();

for (final body in bodiesToDestroy) {
for (final body in _bodiesToDestroy) {
destroyBody(body);
}
bodiesToDestroy.clear();
_bodiesToDestroy.clear();

for (final joint in _jointsToCreate) {
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@luanpotter luanpotter Oct 26, 2025

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did this just... never worked? haha

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@spydon spydon Oct 26, 2025

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Haha yeah, but it's quite new

createJoint(joint);
}
_jointsToCreate.clear();

for (final joint in _jointsToDestroy) {
destroyJoint(joint);
}
_jointsToDestroy.clear();

_profile.step.record(_stepTimer.getMilliseconds());
}
Expand Down
29 changes: 29 additions & 0 deletions packages/forge2d/test/dynamics/body_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -83,5 +83,34 @@ void main() {
expect(bodyInitialPosition.y, isNot(equals(body.position.y)));
});
});

test('creation and destruction of body while world is locked', () {
final world = World(Vector2(0.0, -10.0));
final bodyDef = BodyDef();

world.flags = World.locked;

// Attempt to create a body while the world is locked
final body = world.createBody(bodyDef);
expect(world.bodies.contains(body), isFalse);

world.flags = 0;
world.stepDt(1 / 60);

// Verify the body is created after unlocking the world
expect(world.bodies.contains(body), isTrue);

world.flags = World.locked;

// Attempt to destroy the body while the world is locked
world.destroyBody(body);
expect(world.bodies.contains(body), isTrue);

world.flags = 0;
world.stepDt(1 / 60);

// Verify the body is destroyed after unlocking the world
expect(world.bodies.contains(body), isFalse);
});
});
}
47 changes: 47 additions & 0 deletions packages/forge2d/test/dynamics/joints/joint_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -39,5 +39,52 @@ void main() {
expect(body1.joints.length, 0);
expect(body2.joints.length, 0);
});

test('destruction of body with joint while world is locked', () {
final world = World(Vector2(0.0, -10.0));
final bodyDef = BodyDef();
final body1 = world.createBody(bodyDef);
final body2 = world.createBody(bodyDef..position = Vector2.all(2));
final shape = CircleShape(radius: 1.2, position: Vector2.all(10));
final fixtureDef = FixtureDef(
shape,
density: 50.0,
friction: 0.1,
restitution: 0.9,
);

body1.createFixture(fixtureDef);
body2.createFixture(fixtureDef);

world.flags = World.locked;

final revoluteJointDef = RevoluteJointDef()
..initialize(body1, body2, body1.position);
final revoluteJoint = RevoluteJoint(revoluteJointDef);
world.createJoint(revoluteJoint);

expect(body1.joints.length, 0);
expect(body2.joints.length, 0);

world.flags = 0;
world.stepDt(1 / 60);

expect(body1.joints.length, 1);
expect(body2.joints.length, 1);

world.flags = World.locked;

// Attempt to destroy the body while the world is locked
world.destroyBody(body1);
expect(body1.joints.length, 1);
expect(body2.joints.length, 1);

// Step the world again to process the destruction
world.flags = 0;
world.stepDt(1 / 60);

expect(body1.joints.length, 0);
expect(body2.joints.length, 0);
});
});
}