Physics of a Fish.

[JackFalcon]

QUESTION: How to make a fish tail move?

So this is a (brief) STUDY in FISH PHYSICS

Hoping this helps others with fish.

Here goes...

 

[Pryme8]

((what)=>{return 'thehell';})();

?

[JackFalcon]

DESIGN #1:

      3 parts:

            middle: side-to-side, front and back: rotate y, at different rates. Head less, tail more...

[Pryme8]

Ohh your gonna post more stuff about it ok, now Im a little less confused!

was not sure if this was a question or a statement...

[JackFalcon]

Study is a question looking for a statement .. idk.

-> Good to see you again master ninja.

+1 to the efficiency of fat-arrow for single-line expressions!

QUESTION: How to make a fish wiggle?

In progress...

[Pryme8]

Blend meshs and or a rig with animations.

I would do blend meshes, and have like a sin or cos algorithm that is based off of fish speed and make it bounce between 3 mesh variants: idle, maxleft, maxright.

Sorry I'm at work and this is rushed hope that makes since

 

[JackFalcon]

That is awesome Mr. @Pryme8. Likes the approach... tomorrow (out of likes today [once again]). So, looks forward to it!

The search is for the simplest & fastest implementation of --> Low-Perfection-Fish-Physics.

[JackFalcon]

UPDATE:

Ready to wiggle....

            var createAFish = function () {
                var aBox = BABYLON.Mesh.CreateBox("box", 1, scene);
                aBox.position = new BABYLON.Vector3(0,1,1);
                var aSphere = BABYLON.MeshBuilder.CreateSphere('', {diameter: 1}, scene);
                aSphere.position = new BABYLON.Vector3(0,1,0);
                var aRect = BABYLON.Mesh.CreateBox("box", 1, scene);
                aRect.scaling = new BABYLON.Vector3(0.2,0.6, 1);
                aRect.position = new BABYLON.Vector3(0,1,-1);
            }

Will it work? We'll see!

 

[Pryme8]

http://www.babylonjs-playground.com/#5LGGZJ

Just need to make it smooth blending now.

[BitOfGold]

Wiggle in vertex shader, with no physics? Just an idea  

 

[Pryme8]

That actually sounds like the best solution, but I figured he was doing this to include collision detection.

[JackFalcon]

Yes - collision detection.

@BitOfGold oh really? Hmmm... vertex shader, didn't think of that. Interesting...

 @Pryme8 -> really gr8!

Double-likes ... and how did you do that? <looking>

Thank you for intro to 

mrFish._blend();

 

Wow!

[Pryme8]

13 minutes ago, aFalcon said:

Yes - collision detection.

@BitOfGold oh really? Hmmm... vertex shader, didn't think of that. Interesting...

 @Pryme8 -> really gr8!

Double-likes (tomorrow)... and how did you do that? <looking>

Thank you for intro to 

_blend

 

Wow!

Keep in mind that is really rudimentary and can be done in a way better manor, but that can serve as an example to make something cool.

If you really want to make it sing, a animation blending algorithm needs to be implemented which will smooth all this up.

[Pryme8]

http://www.babylonjs-playground.com/#5LGGZJ#2

Super crappy structure, but yeah...

The blending is based off of this algo: x*(1-a)+y*a

[JackFalcon]

Oh yeah, whoooooah!

 

making sense....

[BitOfGold]

First I read the topic title as "Phil Fish" 

[Pryme8]

@BitOfGold I'll let you "phil" my fish   

[JackFalcon]

This thread is about fish-physics!!!

c'mon ppl, Lol...

Here was the result of Design #1 - using lookAt():

https://www.babylonjs-playground.com/#PHMP7X

@Pryme8 wins bigtime! afalcon... learning.

 

[JackFalcon]

@Pryme8 really cool tracking through the use of animationMeshs, of 3 different poses to newDat.applyToMesh(this.mesh);. Cool.

QUESTION: is _blend also morph target? 

Havn't dug into that 1 yet either...

Thx!

 

[Pryme8]

That function is technically a method for morphing yes.  When I get home and have a second (hopefully this evening). I’ll make a better demo for you with a real fish model, and maybe some controls.

[JackFalcon]

Hey @Pryme8 thank you. All good on this. Although, happy to see solution, like your style.

[Pryme8]

^_^, I was thinking about this the other day... and I think @BitOfGold was on the right path wanting to do it with a shader.

I was thinking you could do a sin algo to displace the vertices from a point on the fish (behind the head) and use a texture weightmap to control the intensity in locations.

[JackFalcon]

Hey yeah, you nailed it @Pryme8, here's low-fidelity solution (for now, until morphin-power-ranger skills gained...):

                scene.registerBeforeRender(function() {
                        wiggleSpeed1+=0.18;
                        body.position.x += (Math.sin(wiggleSpeed1)*0.025);
                        head.lookAt(merphbugbody.position)
                        tail.lookAt(merphbugbody.position)
                    }
                });

https://www.babylonjs-playground.com/#PHMP7X

Oh, but sine displacement, cool... yeah?

[Pryme8]

@aFalcon

http://pryme8.github.io/fish/

All this needs is the weight map, and then to shift the sin oscillation down the fish instead of keeping it in place. 
@BitOfGold <- ALL GPU just for you buddy <3

And there are definitively some fixes that need to happen because as this is it "stretches" the fish, so the displacement side to side needs to have a displacement forward as well to make it look like the fish is swishing and not just magically making new skin.

A fade of the intensity of the sin wave from the head is needed as well.


*edit* 
Added the fade from the head, and made some adjustments.  Now I need to make the sin wave "move" down the fish instead of just oscillate.

@jerome or @NasimiAsl how would I make the sin do that?  Im kinda drawing a blank, I was thinking maybe just adding a offset to the position (using the same time algo) that is then moded into range?

[BitOfGold]

@Pryme8 Cooooooooooooooooool!

distance(p.z, fishHead);

 :D:D:D