Spawning help

[Nisheeth]

I wanted to spawn a circle on collision that was slightly transparent and of Grey color and would fly in the sky.
I used the following code :

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(e)=>{
    scene.my.addcircle({
        pos := e.pos;
        density := 0.0001;
        color := [0.27, 0.24567446, 0.19845001, 0.645];
        radius := 0.01;
        collideSet := 64;
        collideWater := false;
        drawCake := false
    })
}

But when I play the scene, the circles fall down rather than float up (as they should since they have such a low density.)

Please help

[Kilinich]

maybe you just turn off air?

[Nisheeth]

Ah. Thanks. It worked. By the way is there a way to make those circles spread out after they spawn rather than go in a straight line?
Thanks in advance.

[Someone Else]

Try the following:

Make sure Air is turned on. You may need to expand the menu with Play/Pause, Undo, and Redo.
Make the density := 0.001. This, I think, is the smallest positive number Algodoo will accept in that field.
If this causes the circles to float too slowly for you, try adding this bit of code to the spawning code:

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airFrictionMult = 0.01

This will have the effect of making the circles thinner, so air friction has less effect. And the circles will float faster. The lower the number, the faster it will float.

Note: I started typing the above before I saw Kilinich's post.

As for making them go in different directions, try either setting vel to a random function (Kilinich can show you one). Or, spawn two circles by doubling the code-

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scene.addCircle ({ blahblah});
scene.addCircle ({blahblah})

And for random velocity, use

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vel := [scene.my.rnd, scene.my.rnd]

[TC42]

Umm... SE, I think you have to define the scene.my.rnd function before you can use it.

[Kilinich]

Ah. Thanks. It worked. By the way is there a way to make those circles spread out after they spawn rather than go in a straight line?
Thanks in advance.

set initial speed to "flow" spawned circles
vel := [sin(time),0]

[Nisheeth]

Could you please explain it? I didn't understand it. I have just started using thyme.

[Kilinich]

vel is initial velocity [Vx,Vy]
sin(time) is just a function that set velocity depends on simulation time. You can use any function here.

[Nisheeth]

It didn't workout for some reason. I put it in the scene.addcircle.
It was:

Code: Select all

(e)=>{
    scene.my.addcircle({
        pos := e.pos;
        density := 0.001;
        color := [0.27, 0.24567446, 0.19845001, 0.645];
        radius := 0.03;
        collideSet := 64;
        collideWater := false;
        drawCake := false;
        vel := [sin(time), 0]
    })

By the way I wanted to simulate dense smoke.

[Someone Else]

@TC42: I knew that.

Try vel := [math.sin(sim.time), 0].

And for dense smoke, you probably want to set collideSet := 0 and use "random" velocity. And low airFrictionMult.
Or perhaps collideSet := 64;
heteroCollide = true.

[Nisheeth]

Is there a way to set a timer so that after a set amount of time it falls down rather than go up?

[Someone Else]

Umm... Spawn a laser on the circle that gradually increases e.geom.density over time?

Try this:

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    scene.addCircle({
        geomID := 3141;
        pos := e.pos;
        airFrictionMult := 0.1;
        density := 0.001;
        color := [0.27, 0.24567446, 0.19845001, 0.645];
        radius := 1.0;
        collideSet := 64;
        collideWater := false;
        heteroCollide = true;
        drawCake := false;
        onHitByLaser := (e)=>{};
        vel := [(math.sin(sim.time * 100)) * 10, 0]
    });
    scene.addLaserPen({
        pos := e.pos;
        geom := 3141;
        maxRays := 1;
        collideSet := 64;
        onLaserHit := (e)=>{};
        size := 0.3
    })

It spawns circles significantly bigger than the original circles, but in such a way as to make it actually look like dense fog. Every single circle also has a small laser attached. However, I have not figured out how to make it actually change density more than once.

[Nisheeth]

Thanks. Its now behaving like smoke. But it is not dense. I was making a volcano. No the smoke was the one that accompanied the eruption. It is dense enough to fall down after the force that threw it up dies out. So it is supposed to be thick smoke, but it is too thin smoke.

By the way I did try using the code multiple times (as you suggested before). But apparently there was no effect.

[Someone Else]

I added to that code (the scene.addCircle part) a bit that makes the circles not collide with each other. That's what heteroCollide does. If you want something more volcanic ash-like, try this:

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        scene.addCircle({
            pos := e.pos;
            airFrictionMult := 0.1;
            density := 0.011;
            color := [0.27, 0.24567446, 0.19845001, 0.645];
            radius := 1.0;
            collideSet := 64;
            collideWater := false;
            heteroCollide = true;
            drawCake := false;
            onHitByLaser := (e)=>{};
            vel := [(math.sin(sim.time * 100)) * 10, 50]
        })

This will spawn the circles with a constant upward velocity (I think) and they will be a bit denser than air.
If they spawn moving downward, change the vel(1) from 50 to -50.

[Nisheeth]

It worked. Thanks. Just one final problem. They are too large for my scene, actually larger than my volcano!
I tried reducing the radius to 0.3 (the correct size), but it didn't seem like smoke any more. I couldn't increase the size of the Volcano as well because it was using large amounts of water in a small place to cause the eruption.

[Someone Else]

Decrease the velocities.

Try vel := [(math.sin(sim.time * 100)) * 3, 15]

This should be correctly scaled.

On the other hand, I think you will really like this. I figured out how to change density over time.

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    scene.addCircle({
        geomID := 3141;
        pos := e.pos;
        airFrictionMult := 0.1;
        density := 0.001;
        color := [0.27, 0.24567446, 0.19845001, 0.645];
        radius := 0.3;
        collideSet := 64;
        collideWater := false;
        heteroCollide = true;
        drawCake := false;
        onHitByLaser := (e)=>{e.geom.density = e.geom.density + 0.0003};
        vel := [(math.sin(sim.time * 124)) * 3, 0]
    });
    scene.addLaserPen({
        pos := e.pos;
        geom := 3141;
        maxRays := 1;
        collideSet := 64;
        onLaserHit := (e)=>{};
        size := 0.03
    })

[Nisheeth]

Thanks a lot It worked perfectly. But what did you do to increase its density?

And here is the volcano I had been making:

A volcano [Algodoo Only]

Nisheeth

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[Someone Else]

The density increasing code is in the circle's onLaserHit. Or is it onHitByLaser? I can't remember.... It's onHitByLaser.

And I made some tweaks on the volcano:

Another Volcano

Someone Else

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Very interesting using tracers to thicken smoke without lag.

[Nisheeth]

What didn't you understand?
Basically the codes here create the smoke from the volcano, that will go to a height and then begin to fall down.

[Someone Else]

Who didn't understand what?