found work around for compound assembly issues, #42400

New Issue

Jacob Merrill · 2014-10-26T02:06:38+02:00

Jacob Merrill commented

2014-10-26 02:06:38 +02:00

when assembling a compound body inside a function the objects physics bound was incorrect, also the objects physics bound (child) was left where the object was when assembled,

a work around was to do

(calculations for assembling)

assembling function (center of mass etc)

function(create mesh libNew and parent children and assign mass of "centroid")

for all parts in assembly
removeParent()
disableRigidBody()
suspendPhysics()
setParent(centroid libNew host)

however after doing this, once the object is removed from the assembly with "removeParent" it still had the complex compound shape bounds in physics,

so

for removed objects:
add new copy of object
set properties
end old object

works around all issues.

when assembling a compound body inside a function the objects physics bound was incorrect, also the objects physics bound (child) was left where the object was when assembled, a work around was to do (calculations for assembling) assembling function (center of mass etc) function(create mesh libNew and parent children and assign mass of "centroid") for all parts in assembly removeParent() disableRigidBody() suspendPhysics() setParent(centroid libNew host) however after doing this, once the object is removed from the assembly with "removeParent" it still had the complex compound shape bounds in physics, so for removed objects: add new copy of object set properties end old object works around all issues.

Jacob Merrill commented

2014-10-26 02:06:38 +02:00

Changed status to: 'Open'

Jacob Merrill commented

2014-10-26 02:06:38 +02:00

Added subscriber: @JacobMerrill-1

Jacob Merrill commented

2014-10-26 02:14:40 +02:00

https://www.youtube.com/watch?v=EZFewOI_nCY

working assembly system in game

https://www.youtube.com/watch?v=EZFewOI_nCY working assembly system in game

Bastien Montagne commented

2014-10-26 09:27:38 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2014-10-26 09:27:38 +01:00

I can’t I understand what’s the issue nor topic really here… is it about GE? Blender itself? Is it a bug report? something else?

Please follow our submission template and instructions, it really helps sorting things out…

I can’t I understand what’s the issue nor topic really here… is it about GE? Blender itself? Is it a bug report? something else? Please follow our submission template and instructions, it really helps sorting things out…

Jacob Merrill commented

2014-10-26 19:24:35 +01:00

There was a bug in the game engine, "ending object crashes game engine" that was related to ending the child of a compound object,

another bug, related to this was about the shape bounds not moving when a object was assembled (it left the physics bound of the child where it was when parented)

I found workarounds for both of these issues,

ending compound object child not crashing game

object.removeParent()
object.disableRigidBody()
object.suspendDynamics()
object.endObject()

as for the shape bounds,
I did a similar thing
for objects in new assembly:
object['Root']=parent
object.removeParent()
object.disableRigidBody()
object.suspendDynamics()
object.setParent(object['Root'],1,0)

so, this updated bullets shape bounds on the compound object right after assembly.....

basically I found my own problem and it was related to rigid body assembly, incorrect shape bounds, "ghosts" of objects physics bounds,
and when a object was disassembled it would have "ghosts" in it's physics bounds....

issues I found and worked around
1.in physics visualization shape bound was not correct for my rigid body assemblies

if you ended a child of a compound shape/rigid body it crashed the engine
if you removed a compound assembly object it carried with it "junk" (it could not be moved but could rotate....)

solutions
1 = reparented same objects after disabling rigid body and dynamics (after initial assembly)

2 = remove parent remove rigid body remove dynamics then remove object

3= add in new copy of component , copy properties from old object - end old object

There was a bug in the game engine, "ending object crashes game engine" that was related to ending the child of a compound object, another bug, related to this was about the shape bounds not moving when a object was assembled (it left the physics bound of the child where it was when parented) I found workarounds for both of these issues, ending compound object child not crashing game object.removeParent() object.disableRigidBody() object.suspendDynamics() object.endObject() as for the shape bounds, I did a similar thing for objects in new assembly: object['Root']=parent object.removeParent() object.disableRigidBody() object.suspendDynamics() object.setParent(object['Root'],1,0) so, this updated bullets shape bounds on the compound object right after assembly..... basically I found my own problem and it was related to rigid body assembly, incorrect shape bounds, "ghosts" of objects physics bounds, and when a object was disassembled it would have "ghosts" in it's physics bounds.... **issues I found and worked around** 1.in physics visualization shape bound was not correct for my rigid body assemblies 2. if you ended a child of a compound shape/rigid body it crashed the engine 3. if you removed a compound assembly object it carried with it "junk" (it could not be moved but could rotate....) **solutions** 1 = reparented same objects after disabling rigid body and dynamics (after initial assembly) 2 = remove parent remove rigid body remove dynamics then remove object 3= add in new copy of component , copy properties from old object - end old object

Bastien Montagne commented

2014-10-27 08:27:09 +01:00

Thanks for the clarifications.

Jorge Bernal commented

2015-05-24 11:25:37 +02:00

Added subscriber: @JorgeBernalMartinez

Jorge Bernal commented

2015-05-24 11:25:37 +02:00

Jacob, we need blends for the both issues that you commented. This way we can check the possible bugs.

thanks.

Jacob, we need blends for the both issues that you commented. This way we can check the possible bugs. thanks.

Jacob Merrill commented

2015-05-24 20:25:12 +02:00

ok

File

Assemblysimplified(1) {F179643}= Problem (press P, then press space) see the floating white cube?)

AssemblySimplified2 = work around

turns out it has to do with applyMovment + setParent in the same frame.

setParent then apply movement does not update the physics of the child shape bound.

(I lost most of my old files so I don't know if the other problems I ran into were user error or?)

AssemblieSimplified2.blend

ok File Assemblysimplified(1) {[F179643](https://archive.blender.org/developer/F179643/AssemblieSimplified__1_.blend)}= Problem (press P, then press space) see the floating white cube?) AssemblySimplified2 = work around **turns out it has to do with applyMovment + setParent in the same frame.** setParent then apply movement does not update the physics of the child shape bound. (I lost most of my old files so I don't know if the other problems I ran into were user error or?) [AssemblieSimplified2.blend](https://archive.blender.org/developer/F179640/AssemblieSimplified2.blend)

Jacob Merrill commented

2015-05-29 02:41:02 +02:00

https://youtu.be/fpS9mygynRk

video of exposing the undesired activity,
and the work around,

1 when a object is compound parented, if it is moved after parenting, it leaves the physics mesh, and only moves the graphics mesh.

2 If applyMovement is done, in a frame before parenting, the movment never happens (at least in this case)

a work around for number 2 = use object.worldPosition, and get the world vector you need for local movment using

desired=object.worldPosition+(object.worldOrientation*Vector([x,y,z]))

https://youtu.be/fpS9mygynRk video of exposing the undesired activity, and the work around, # 1 when a object is compound parented, if it is moved after parenting, it leaves the physics mesh, and only moves the graphics mesh. # 2 If applyMovement is done, in a frame before parenting, the movment never happens (at least in this case) a work around for number 2 = use object.worldPosition, and get the world vector you need for local movment using desired=object.worldPosition+(object.worldOrientation*Vector([x,y,z]))

Jorge Bernal commented

2015-06-07 02:23:20 +02:00

Closed as duplicate of #40427

Jorge Bernal closed this issue

2015-06-07 02:23:20 +02:00

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found work around for compound assembly issues, #42400

1 when a object is compound parented, if it is moved after parenting, it leaves the physics mesh, and only moves the graphics mesh.

2 If applyMovement is done, in a frame before parenting, the movment never happens (at least in this case)