Aquatic macroscale evolution

[stingpie]

I’ve never heard of a convolution surface. do you have a good resource to learn about them?

[hhyyrylainen]

The first post in this thread has an overview:

Convolution Surfaces: A better alternative to metaballs

I saw the metaballs concept on my Facebook feed, and figured I should probably makes this post (about 4 years overdue). One of the things I was working on back in 2016 was figuring out a good solution for 2d and 3d organism editing. There are quite a few constraints that a good editor should meet, but the 3 main ones is that it should be easy to use (you don’t need a 2 hour long course to design a creature), it should be sufficiently powerful (any creature you can come up with should be possible…

[stingpie]

thanks!

[Nunz]

I only have the papers I used to help me program them. There is a thread about them on this forum (there’s even a PyGame demo) but to truly understand you have to read the papers. This is the clearest most basic one: Convolution Surfaces based on Polygonal Curve Skeletons (inria.fr)

[Kemikal]

@stingpie

I know. They’re just difficult. like I said,

@stingpie

it’s just not really a priority in my mind.

You said theyre not a priority not how difficult they are… anyway, i dont think we should let difficulty set us back even so for a more general model.

@stingpie

That was my description of the bone-joint-muscle model. Like I already said,

@stingpie

I was trying to recreate a bone-joint-muscle model, without needing to simulate the forces applied to each bone

Youve confused me here, so in your model the force applied on the bone isnt considered?
If so why would we have even consider it in the first place for the model.

[stingpie]

In a bone-joint-muscle model, the forces to each bone are added together, and then used to calculate the rotational force that the joint can exert. My model skips adding multiple forces, and just assumes the total inline forces adds to zero. The force each muscle applies is considered, but the forces that would contribute to stress on the bone are ignored.

edit:

@Kemikal

i dont think we should let difficulty set us back even so for a more general model.

you’re free to do that. I probably wont be able to implement the model by myself, but you can add stuff if you want to.

[Kemikal]

@stingpie

In a bone-joint-muscle model, the forces to each bone are added together, and then used to calculate the rotational force that the joint can exert

??? Huh? the muscles moves the bone and exerts a force not the joint?

@stingpie

My model skips adding multiple forces, and just assumes the total inline forces adds to zero.

Why would you add multiple bone forces on a single joint for multiple directions? You consider the muscles relevant to that direction you want to move.

@stingpie

The force each muscle applies is considered, but the forces that would contribute to stress on the bone are ignored.

Why would you consider this?

[stingpie]

@Kemikal

??? Huh? the muscles moves the bone and exerts a force not the joint?

Yes, because in animals, joints cannot exert force. A muscle contracts to create the force that turns the joint.

@Kemikal

Why would you add multiple bone forces on a single joint for multiple directions? You consider the muscles relevant to that direction you want to move.

Because joints are turned by an unequal force along the direction of the joint. When a joint turns, it’s because muscles are contracting one one side, and not the other.

@Kemikal

Why would you consider this?

because I add the force the individual muscles can exert to get the total force the muscles can exert.

[Kemikal]

@stingpie

Yes, because in animals, joints cannot exert force. A muscle contracts to create the force that turns the joint.

Thats what i said…though… haha. You said that the joint exerts force xD

@stingpie

Because joints are turned by an unequal force along the direction of the joint

You mean by a force, not an “unequal force”

@stingpie

because I add the force the individual muscles can exert to get the total force the muscles can exert.

Sorry i meant why would you even consider forces stress on the bone.
This can be calculated in-editor, to determine minimum bone strength.

Okay the diagram clears things up a bit, but it shows that you consider the forces between 2 joints and all the joints in between are ignored mathematically and just animated. Did i understand right?
So it only works for fishes not all locomotion types.

In the first part of the picture i dont understand what you mean by forces cancel out.Becaues they dont, they add more movement range to those joints.

[stingpie]

@Kemikal

In the first part of the picture i dont understand what you mean by forces cancel out.Becaues they dont, they add more movement range to those joints.

I’m saying that in terms of forces, the center bone doesn’t contribute to the force, so you can just ignore it, and assume the force is directly transferred from the first to last bone.

[Kemikal]

Ok i understand now, but as i said i think this only works for simple predefined actions and movements. (fishes). The interaction with terain/other objects, will change things…