Physics fixed update function?

[Andy Gilbert]

Hi, Im wanting to put all my physics calculations into a physics fixed update function based on the callback that the document present im a but unsure how i do this as it has a parameter for an entity?

 

Can i not have a single function that does all the physics routines every physics update?

 

Thanks

Andy

[Flexman]

I don't think there's a global physics update callback. the Entity callback is your best bet. This is called during UpdateWorld(). Assign it to every entity then branch off for specific types in a single function. But you probably did this already.

 

' INITIALISING ENTITYS IN A LOOP, SET THE PHYSICS CALLBACK '
...
SetEntityCallback(newEntity, UpdatePhysicsCallback, ENTITYCALLBACK_UPDATEPHYSICS) ;
...
...
' CALLED 60 FPS REGARDLESS OF FRAMERATE '
Function UpdatePhysicsCallback(entity:TEntity)
  if (entity <> Null)
     if (game.LocalPlayer.entity = entity)
        UpdateLocalPlayerPhysics(entity) ;
     Else
        UpdateRemoteEntityPhysics(entity);
     End If
  End If
End Function

 

If you have to do this for lots of entities, but have many of a specific type, it would make sense to use caching to your advantage by having specific callback functions for them.

[Rick]

To build off of what Flexman has shown, you could fake 1 update call by having an EntityManager class that stores an entity and a list of entities. Whenever you make an entity you add it to this list. Then you only register the callback to the 1 entity in this class. When that entity update gets called, you cycle through the list of all other entities.

 

class EntityManager
{
private:
TEntity _entity;
list<TEntity> _entities;
public:
EntityManager()
{
 SetEntityCallback(_entity, UpdatePhysicsCallback, ENTITYCALLBACK_UPDATEPHYSICS);
 SetEntityUserData(_entity, (byte*)this);
}
list<TEntity>& GetEntities() { return _entities; }
void AddEntity(TEntity e) { _entities.push_back(e); }
};

void _stdcall UpdatePhysicsCallback(TEntity ent)
{
EntityManager* mgr = (EntityManager*)GetEntityUserData(ent);
// now you can call mgr->GetEntities() and loop over them all to process or maybe just call a function in the EntityManager class that will loop so that yo don't have to expose the list of entities to anything else.
}

[Andy Gilbert]

Thanks for this, i actually only have 1 physics entity, so should be to big a problem to impliment.

 

Thanks

Andy

[Andy Gilbert]

Hi, just wondering how this can be done with lua?

 

Cant seem to get the command to work?

 

Thanks

Andy

[Andy Gilbert]

Does anyone know if the above command works in lua, or is meant to work?

 

Thanks

Andy

[DaDonik]

Since the Callback functions are only documented for C/C++ and Blitzmax, i don't think it's possible to do that from LUA.

To be honest i also never tried...

[Rick]

No clue, but in LE Lua a model with a script attached to it that is structured in the template that is in the Script folder has a physics update function callback in it. If you just have the 1 model then attached this script to it, put the script in the same dir and name it the same as the model, and then those functions will be automatically called.

[Canardia]

You can use the UpdatePhysics hook:

require("Scripts/constants/keycodes") 
require("Scripts/console") 

local bonks=0
local frames=0

function MyPhysicsHook()
bonks=bonks+1
AddConsoleText("PhysicsUpdates: "..bonks.."    Frame: "..frames)
end

--Register abstract path 
RegisterAbstractPath("") 

--Set graphics mode 
if Graphics(1024,768)==0 then 
Notify("Failed to set graphics mode.",1) 
return 
end 

world=CreateWorld() 
if world==nil then 
Notify("Failed to initialize engine.",1)   return 
end 

fw=CreateFramework()

camera=fw.main.camera
camera:SetPosition(Vec3(0,0,-2)) 

light=CreateSpotLight(10) 
light:SetRotation(Vec3(45,55,0)) 
light:SetPosition(Vec3(5,5,-5)) 

model=LoadModel("abstract::oildrum.gmf") 

ground=CreateBodyBox(10,1,10)
groundmesh=CreateCube(ground)
groundmesh:SetScale(Vec3(10.0,1.0,10.0))
ground:SetPosition(Vec3(0.0,-2.0,0.0)) 
groundmesh:Paint(LoadMaterial("abstract::cobblestones.mat"))
ground:SetCollisionType(1)

Collisions(1,1,1)
--DebugPhysics(1)
SetStats(0)

light=CreateDirectionalLight() 
light:SetRotation(Vec3(45,45,45)) 

local timer=AppTime()+1000
consolemode=1
AddHook("UpdatePhysics",MyPhysicsHook)
while AppTerminate()==0 do 

if KeyHit(KEY_ESCAPE)==1 then
break
end 

if timer<AppTime() then
timer=AppTime()+1000;
model=CopyEntity(model)
model:SetPosition(Vec3(0,10,0))
end

fw:Update()
fw:Render()

frames=frames+1

DrawText("FPS: "..UPS(),300,0)
Flip(0)

end

[Andy Gilbert]

ahh that seems good, so does this go back to my original question?

 

All the physics code can go inside that physicshook function?

 

Thanks

Andy