Simulation differs after deleting and readding objects
Posted: Sat Feb 09, 2008 1:17 am
Hi,
I'm making a wrapper library for chipmunk (more for my use than anyone else).
I'm surprised how well it's working, really. It is lacking quite a many features of chipmunk (eg. joints), but it is in a working condition, as far as I can tell.
I've made a test demo that makes stacks of circles and a controllable square (its lots of fun). The problem is, when pushing 'v' to reset the objects, which are removed, freed then re-added, sometimes a few of the stacks don't form a line. This especially happens when the circles are in the middle of being knocked about. I can't find an explanation, as I would have thought it used new memory, etc.
I've included the source to the demo which you can build with "g++ -Wall *.cpp -o main -lchipmunk -lglut", assuming you have gcc, glut and libchipmunk.a wherever you keep your libraries.
Demo instructions:
Move with arrows
Create circles with 'c'
Reset with 'v'
Create a large block with space.
You can use the library if you want, but who knows why you would:D It's pretty self-explanatory.
Here are the functions that would create the error if there was a bug:
I'm making a wrapper library for chipmunk (more for my use than anyone else).
I'm surprised how well it's working, really. It is lacking quite a many features of chipmunk (eg. joints), but it is in a working condition, as far as I can tell.
I've made a test demo that makes stacks of circles and a controllable square (its lots of fun). The problem is, when pushing 'v' to reset the objects, which are removed, freed then re-added, sometimes a few of the stacks don't form a line. This especially happens when the circles are in the middle of being knocked about. I can't find an explanation, as I would have thought it used new memory, etc.
I've included the source to the demo which you can build with "g++ -Wall *.cpp -o main -lchipmunk -lglut", assuming you have gcc, glut and libchipmunk.a wherever you keep your libraries.
Demo instructions:
Move with arrows
Create circles with 'c'
Reset with 'v'
Create a large block with space.
You can use the library if you want, but who knows why you would:D It's pretty self-explanatory.
Here are the functions that would create the error if there was a bug:
Code: Select all
/*Note:
Memory management is automatic if you use the Physics::AddObject function
*/
void Physics::ClearObjects(void) {
for (unsigned int j = 0; j < objects.size(); j++) {
PhysicsObject *object = objects[j];
for (unsigned int i = 0; i < object->shapes.size(); i++) cpSpaceRemoveShape(space, object->shapes[i]);
cpSpaceRemoveBody(space, object->body);
delete object;
}
objects.clear();
}
void addObjects(void) {
PhysicsObject *staticObject = physics->CreateStaticObject();
staticObject->AddLineShape(cpv(0, 0), cpv(SCREEN_WIDTH, 0));
staticObject->AddLineShape(cpv(SCREEN_WIDTH, 0), cpv(SCREEN_WIDTH, SCREEN_HEIGHT));
staticObject->AddLineShape(cpv(SCREEN_WIDTH, SCREEN_HEIGHT), cpv(0, SCREEN_HEIGHT));
staticObject->AddLineShape(cpv(0, SCREEN_HEIGHT), cpv(0, 0));
physics->InitObject(staticObject);
man = physics->CreateObject(cpv(5, 500), 45);
//man is the user's square
man->AddSquareShape(15, 15);
physics->InitObject(man);
for (int j = 0; j < 20; j++) {
for (int i = 0; i < 10; i++) {
PhysicsObject *obj = physics->CreateObject(cpv(50+j*40, 100+i), 0.001f);
obj->AddCircleShape(5);
physics->InitObject(obj);
}
}
}
PhysicsObject *CreateObject(cpVect pos = cpv(0, 0), cpFloat mass = 10, cpFloat frict = 0.5f, cpFloat elast = 0.0f, cpFloat rot = 0.0f, bool infinteMoment = false);
PhysicsObject *CreateStaticObject(cpVect pos = cpv(0, 0), cpFloat frict = 0.5f, cpFloat elast = 0.0f, cpFloat rot = 0.0f);
void InitObject(PhysicsObject *object); //add the object+shapes to the space
void AddCircleShape(cpFloat radius, cpVect offset = cpv(0, 0));
void AddSquareShape(cpFloat width, cpFloat height, cpVect offset = cpv(0, 0));
void AddLineShape(cpVect start, cpVect end, cpFloat thickness = 1.0f);
void AddShape(int numVerts, cpVect *verts, cpVect offset = cpv(0, 0));