[Plugin] [Design Stage] Modular Mass Modifier - A better system for modifying part mass

[blowfish]

The current options for modifying a part's mass aren't very good. You can implement IPartMassModifier, but that mass doesn't affect physics at all. You can modify the part's mass, but if you have more than one module trying to do that, you're going to run into trouble. Therefore I am proposing a new system for part mass modification:

• A single module will handle all mass modifications and update part.mass
  
• Other modules that wish to modify a part's mass will implement an interface similar to IPartMassModifier
  
• The part's mass will be automatically updated on part update events, but modules may request a manual update if necessary
  

I've got the basic implementation details worked out in code below. Still a lot of work to be done, but most of the major stuff is there

public interface IPartMassModifier2
{
float GetModuleMass(float baseMass);
}

public class PartMassModifierModule : PartModule, IPartMassModifier
{
public float BaseMass { get; private set; }
public float ModuleMass { get; private set; }
public float Mass { get { return BaseMass + ModuleMass; } }

public override void OnStart(PartModule.StartState state)
{
base.OnStart(state);

BaseMass = part.GetPrefab().mass;

if (state == PartModule.StartState.Editor)
GameEvents.onEditorPartEvent.Add(OnEditorPartUpdate);
else
GameEvents.onVesselUpdate.Add(OnVesselUpdate);
}

private void OnDestroy()
{
GameEvents.onEditorPartEvent.Remove(OnEditorPartUpdate);
GameEvents.onVesselUpdate.Remove(OnVesselUpdate);
}

[KSPEvent]
public void UpdateMass()
{
ModuleMass = 0f;
foreach (PartModule m in part.Modules)
{
if (m is IPartMassModifier2)
ModuleMass += (m as IPartMassModifier2).GetModuleMass(BaseMass);
}

part.mass = Mass;
}

private void OnEditorPartUpdate(ConstructionEventType eventType, Part part)
{
if (object.ReferenceEquals(part, this.part))
UpdateMass();
}

private void OnVesselUpdate(Vessel vessel)
{
if (object.ReferenceEquals(vessel, this.part.vessel))
UpdateMass();
}

public float GetModuleMass(float baseMass)
{
if (baseMass == BaseMass)
return ModuleMass;
else if (baseMass == part.mass)
return 0f;
else
{
Debug.LogWarning("Warning: unrecognized mass detected");
return 0f;
}
}
}

So to all the plugin developers out there, I ask: does this seem like a reasonable system? Would you use it? Is there anything you feel is missing?

[*Aqua*]

You forgot about the resource mass.

wet mass = (dry) part mass + module mass(es) + resource mass

does this seem like a reasonable system?

IMHO you replicate what the game already does. If a programmer wants to add mass, he can just add a module and set a mass attribute. KSP will take care of all calculations.

Would you use it?

Probably not. It's too much of a hassle to search the forums for small things like your interface. If there's a bundle which incorporates all the snippets I'll think about it.

Edited September 13, 2015 by *Aqua*

[blowfish]

You forgot about the resource mass.

wet mass = (dry) part mass + module mass(es) + resource mass

KSP deals with resource mass correctly, so it doesn't need to be added

IMHO you replicate what the game already does. If a programmer wants to add mass, he can just add a module and set a mass attribute. KSP will take care of all calculations.

Currently, you can have multiple modules affecting mass (but that mass won't count toward physics), OR you can affect physics (but only one module can do it). The goal here is to allow both.

[*Aqua*]

Currently, you can have multiple modules affecting mass (but that mass won't count toward physics), OR you can affect physics (but only one module can do it).

I never heard of that. Are you sure?

[blowfish]

I never heard of that. Are you sure?

I'm sure. IPartMassModifier has no effect on physics. You could possibly devise a system where multiple modules would carefully add their mass to part.mass then keep track of changes in that mass, but it would be messy and prone to error.

[Blackline]

Sorry for necro-ing, but is the mass behavior still tihs way? Are there any "new" ways since 1.2 for a module to have its own mass (which counts towards total part.mass)?

Cheers

[blowfish]

On 11/19/2016 at 4:45 PM, Blackline said:

Sorry for necro-ing, but is the mass behavior still tihs way? Are there any "new" ways since 1.2 for a module to have its own mass (which counts towards total part.mass)?

Cheers

There's nothing new in this regard in 1.2, but since 1.0? We have IPartMassModifier (and IPartCostModifier for cost), which, if implemented on a PartModule, will tell KSP to add some mass to the part (or subtract even).

[Blackline]

7 hours ago, blowfish said:

There's nothing new in this regard in 1.2, but since 1.0? We have IPartMassModifier (and IPartCostModifier for cost), which, if implemented on a PartModule, will tell KSP to add some mass to the part (or subtract even).

But are those additional masses used for physics calculations? Because you said in the OP they are not.

[blowfish]

2 hours ago, Blackline said:

But are those additional masses used for physics calculations? Because you said in the OP they are not.

Yes, they are.  This thread is from before they did however.

[Blackline]

I wrote since 1.2, but I get that was not what I meant. sry, non-native. I meant if any changes happened from your OP until now (1.2.x)

I'll try the interfaces. thanks!