[Proposal] Modification to Phizix - Chipmunk

[MechatheSlag]

I've had some ideas for improvements with the Phizix extensions. I heard that Daniel Rehn won't modify anything to the actual chipmunk engine, but these improvements I have in mind are really important.

1) When two objects have a slider joint, and one is on a floor, the other in the air, the one in the air will obviously stop falling if the maximum length is met. However, even though the object stops, the velocity is intact which will make some objects fall through it even though it stands completely still.

2) The ablity to freeze. It'd be really useful if you could freeze either x/y positions, angles or velocities. The always condition just isn't enough to make sure these values keep the same.

3) Individual gravity. Sometimes the gravity just isn't the same for all objects, say, one object is a gravity-negative compared to the other objects, yet are in the same room as the others.

4) Objects goes through walls. When a object with high vertical velocity lands on a floor, the object goes around 1-10 pixels into the floor, and if the wall and object is thin enough, go completely through. (This may be unfixable due to it being a part of the chipmunk core physics?)


Although some of these can't be fixed (or can be done in another way), I'd really like to see some of these improvements.

[DanielRehn]

Most of what you suggest would require some serious changes in the chipmunk core.. I won't add any of these in Phizix - Chipmunk Engine.. But I can tell you all that a new Physics extension has been planned.. it will (hopefully) support tons of new features

Cheers!

[DizzyDoo]

Most of what you suggest would require some serious changes in the chipmunk core.. I won't add any of these in Phizix - Chipmunk Engine.. But I can tell you all that a new Physics extension has been planned.. it will (hopefully) support tons of new features

Cheers!

So soon after the release of the first one? And if it's going to be better than the first... phizix 2 is going to be pretty cool indeed.

[danjo]

is the new one going to be done by you guys daniel? if so, are you changing to something else rather than chipmunk?

[DanielRehn]

We are switching engine to the new version of Box2D, it has become an awesome physics engine.. The making of a new extension will start as soon as box2d 2.0 is released

[Werbad]

We can probably start working anytime now... The only thing left for 2.0 seems to be documentation.

Edit:
Uploaded a compiled version of the latest TestBed if anyone wants to see what Box2D can do.
http://www.mediafire.com/?dgl91smciwz

[Nifflas]

As Daniel won't be adding new features to the Chipmunk engine, here's some workarounds to use.

2) The ablity to freeze. It'd be really useful if you could freeze either x/y positions, angles or velocities. The always condition just isn't enough to make sure these values keep the same.

Locking x/y positions can be done by attaching the object to a static one with a pivot joint. Make the pivot point position the same as the non-static object.

3) Individual gravity. Sometimes the gravity just isn't the same for all objects, say, one object is a gravity-negative compared to the other objects, yet are in the same room as the others.

Store the 'gravity offsets' as two alterable values in the images that represents the physical objects. Loop through them and add those values to the x/y speeds.

4) Objects goes through walls. When a object with high vertical velocity lands on a floor, the object goes around 1-10 pixels into the floor, and if the wall and object is thin enough, go completely through. (This may be unfixable due to it being a part of the chipmunk core physics?)

Increase the number of iterations. For even more accurate results, decrease the timestep and compensate by triggering the 'update' action several times per main loop. This will result in physical objects being pushed out of walls a whole lot faster than if you would only have increased the number of iterations per timestep. It eats more CPU though, but it's well worth it. Oh, and don't increase the number of iterations if you're going for this method.

[Dynamite]

When will the Physics extension be compatible with HWA? I really want smooth rotations for my games

[MechatheSlag]

When will the Physics extension be compatible with HWA? I really want smooth rotations for my games

It is already, but it doesn't support decimal values as of yet.

[Nifflas]

It does output decimal values for angles, with the exception of the 'attach active' feature. Simply don't use that, a single event can fix all object positions/angles to the physical bodies anyway. That will enable it to work nicely with the current HWA betas including smooth rotations. Another great advantage of this method is that you'll store the physical body ID within an alterable value of each active object. As you'll refer to bodies as ID( "Active" ) instead of ActiveBodyID( "Phizix - Chipmunk Engine", Fixed( "Active" )) all physics related expressions will be nicer and shorter too.

Afaik the reason why the new version of Phizix that's more HWA friendly is delayed is that 'attach active' won't be compatible with the non-HWA versions. They can't just release a version of the extension that does not work with the latest non-beta build.