Multicellular Stage - Ciliates and Flagellates

JezzDawga · April 22, 2025, 6:15am

Hi,

I haven’t seen any other posts here or issues in the Github about this but I’m sure this must have been noticed years ago.

There is currently no point in creating dedicated flagellum or cilia cells in the Multicellular stage because speed and turn rate stats are based on the starter cell. Any additional cell just slows the whole organism down, regardless of fluidity or cell contents (however, MORE contents/size equals less speed, as expected).

I’ve confirmed this is happening with ciliates as of 0.8.1.1, but I haven’t tested flagellates yet; past experience with versions from I’d say ~0.5? onwards leads me to believe that flagellates still suffer the same issue too.

hhyyrylainen · April 22, 2025, 6:50am

You mean like the stats shown in the editor? It is extremely likely that the stats just don’t take the entire bodyplan into account whatsoever.

The math for colony movement and rotation speed is something that was written a really long time ago and not really updated. The main focus was to not make cell colonies just totally overpowered and infinitely be able to stack movement speed. But that also means that the balancing is kind of off. There’s a TODO comment in the code about redoing the math:

github.com/Revolutionary-Games/Thrive

src/multicellular_stage/CellBodyPlanInternalCalculations.cs

c821fde73


      
              return ((int)ammoniaCostTotal, (int)phosphatesCostTotal);
          }
          
          public static void ModifyCellSpeedWithColony(ref float speed, int cellCount)
          {
              // Multiplies the movement factor as if the colony has the normal microbe speed
              // Then it subtracts movement speed from 100% up to 75%(soft cap),
              // using a series that converges to 1 , value = (1/2 + 1/4 + 1/8 +.....) = 1 - 1/2^n
              // when specialized cells become a reality the cap could be lowered to encourage cell specialization
              // Note that the multiplier below was added as a workaround for colonies being faster than individual cells
              // TODO: a proper rebalance of the algorithm would be excellent to do
          
              speed *= cellCount * Constants.CELL_COLONY_MOVEMENT_FORCE_MULTIPLIER;
              var seriesValue = 1 - 1 / (float)Math.Pow(2, cellCount - 1);
              speed -= speed * 0.15f * seriesValue;
          }
          
          /// <summary>
          ///   Calculates a colony's rotation speed. The code here should be based on the algorithm in
          ///   <see cref="MicrobeColonyHelpers.CalculateRotationSpeed"/>
          /// </summary>

And that code is used from here where the colony impact on the movement is calculated:

github.com/Revolutionary-Games/Thrive

src/microbe_stage/systems/MicrobeMovementSystem.cs

3f597a23b


      
          
              return movementVector;
          }
          
          private void CalculateColonyImpactOnMovementForce(ref MicrobeColony microbeColony, Vector3 movementDirection,
              bool isBacteria, float delta, ref float force)
          {
              // If this method is updated, the CalculateSpeed() method in CellBodyPlanInternalCalculations.cs
              // also has to be changed
          
              CellBodyPlanInternalCalculations.ModifyCellSpeedWithColony(ref force, microbeColony.ColonyMembers.Length);
          
              // Colony members have their movement update before organelle update, so that the movement organelles
              // see the direction
              // The colony master should be already updated as the movement direction is either set by the
              // player input or microbe AI, neither of which will happen concurrently, so this should always get the
              // up to date value
          
              foreach (var colonyMember in microbeColony.ColonyMembers)
              {
                  // Colony leader processes the normal movement logic so it isn't taken into account here

The situation has not been perfect but good enough for years so that’s likely why no one has done anything. If someone wants to rebalance the math, I’m open to looking at such pull requests.

aah31415 · April 22, 2025, 11:22am

I don’t think we need to worry about this until we enter multicellular development, as like how it was already said, this system does work relatively well.

JezzDawga · April 23, 2025, 1:56am

Thanks for your replies and I hear you in that it’s not on the radar right now.

Apologies if I come across as ignorant but wouldn’t the solution be to just calculate the average speed and turn rate values for all cells that currently compose the organism whenever exiting the Editor and whenever a new cell pops into existence during growth?

I’m sure there’s more to it than that deep down, and again I understand it’s not something to focus on right now, but it seems appropriate to me on face value.

Thank you so much for your efforts and continued development of this wonderful game

aah31415 · April 23, 2025, 4:33am

Since the average colony cell speed isn’t used, I would assume something blocks implementing such a solution…

hhyyrylainen · April 23, 2025, 6:45am

I mean someone could just write the math to do that, but as the game uses movement force to move stuff, it would be complicated to calculate how much extra force is needed to achieve the exactly same movement speed as before.

But that would be highly unrealistic solution, because for example rotation rate of a massive colony should not be the same as a single cell, as you need a ton more angular force to cause the same rate of rotation (with way more mass far away from the center of mass). And anyway the leverage force of cells farther away from the center of mass is much higher on rotation.

aah31415 · April 23, 2025, 7:37am

So I guess it’s just better to leave this aspect for when we have already entered multicellular so that we don’t waste time on recodings that would need to get replaced anyways.