Original subtitles

All right, so in this lesson we're gonna talk about physics.

And I know that's probably a little intimidating,

but we're going to shortly how to make click Run a real-world collisions,

both with other objects or the ground,

could be something like a bouncing ball,

kind of bouncing up in the air.

It could be something like a building kind of collapsing in itself.

So it can be pretty complex.

We're going to keep it relatively simple for this lesson,

but we're going to show how you can kind of make

real-world gravity and get some realistic collisions going on.

So let's go ahead and start by making our ground plane.

I'm just going to click and hold here, go to plane.

We'll just say 200 by 200.

That should work.

And then we are going to,

let's go ahead and make a sphere for our ball here.

Now it's really, really important that you create things at real-world dimensions.

So if you plan on making a bouncy ball,

make it the size of a bouncy ball.

If you plan on making a hot air balloon,

make at that size.

And you can always look online to find out generally how big those things are.

Either in inches or meters or whatever it is.

But for this array here,

let's just say it's sort of like a beach ball.

So the radius of the beach ball is probably something like,

I don't know, probably nine inches will say.

Alright, so we have our beach ball there and then I'm gonna go ahead and put it up in

the air like this right here.

And we're gonna make it just kind of fall to the ground and bounce on that surface,

that ground surface right there.

Real quick, I'm just going to make a material, put it on here.

Just we kinda see a little bit more of what it's doing in the color slot texture.

I'm going to put a checkerboard pattern on there. And there we go.

So now we can kind of get a better idea of what's happening.

Alright, so the first thing that we have to do in our ground plane here,

we're gonna go into tags, simulation tags.

And we're gonna go ahead and make this a collider body.

And what this is going to say is,

hey, I don't want you to move,

but I want you to collide with objects that will be moving.

And then on the sphere here I'm going to hit tags,

simulation and rigid body.

What this is saying is that it's a hard surface that you want to

be affected by real-world physics.

So we say OK there.

And without touching anything else,

I'm just gonna hit the play button here.

And we see we, just like that.

We get a little physics simulation without

any of the math or any of the really difficult stuff.

So that's pretty cool, right there.

There's a few other things that we can kinda do to this to maybe change the way

it looks or to kind of get a little bit more of what we're looking for.

So for instance here,

let's go into, let's go into collision, the collision tag here.

So again, all our settings are in this little panel R3 here.

Dynamics.

We'll talk about that in just a minute,

but I'm gonna go into collision here and you can see that there's

settings for bounce friction and collision noise.

What I'll do is, let's say we want this thing to be really bouncy and make that a 100%.

Go back to frame one and play that.

You see.

It bounces a lot more than it did before.

And what friction does and it's not going to help us in this case so much.

But that's essentially saying that we want kind of

the collision with the ground to be more sticky basically to where it's,

if it's, if it's rolling object or something like that.

If we turn up the friction,

it'll kind of stick to the ground a little bit more and kind of not move as much.

Sometimes when you have a lot of objects and you have them colliding with the ground.

They're like squares or cubes.

And sometimes they slide for a really long time, like they're on ice.

If you crank up that friction to be like 80 or something like that,

it's going to feel more like

a corporate carpeted surface or hard wood or something like that.

So that's definitely an important setting,

just not so much for what we're doing with this bouncing ball R3 here.

Alright? So sometimes you're like,

maybe I don't want this collision or this ball

to start bouncing or start falling until about frame 30.

Well, to do that,

I'm gonna go ahead and delete that tag.

And I can go ahead and leave it down there.

I'm just going to hit click on that sphere here.

Go over to I am going to delete it.

There you go. Because whenever you have a simulation like that,

and you go to the middle frames and you try and move your object,

it just won't work at all, it'll just be locked.

So let's say I frame 30 here.

I'm gonna make a keyframe.

And then one frame,

it doesn't really matter to somewhere around here, 32.

I'm just gonna make it move just a little bit.

So the animation just looks like that.

And it's just kind of the start of the ball kind of falling.

Now what I can do is add that rigid,

rigid body tag again.

And in dynamics, you see that we have a trigger,

can trigger it, start unframed 0.

We can have it trigger at velocity peak, which is what we're about to do.

You can have it go on collision,

which I'll show you here in a second.

But for this one we're here, let's do velocity peak.

And whenever I go back to frame one and press Play,

you'll see that it finishes off as soon as that

ball's going as fast as it can with the keyframe animation that we made.

It automatically.

The physics simulation automatically kicks in and starts.

So that's how you can animate things at a certain frame.

Alright, so the other thing now is on collision.

So if I go ahead and duplicate this,

just holding Control or Command,

and then I'm just going to

work as a head of animation or I'm just gonna go and delete that.

And I'll make a couple of different shapes here.

555 sounds good.

And I'm gonna make things for the ball to collide with as its kind of falling down.

And we'll get a pretty good idea of how collision works or how starting,

starting physics on simulation we're on collision works, sorry.

That's good right there.

And I'm just gonna select all of these tags here are all of these objects.

And I can add the same tag to all of them at the same time by hitting tags,

simulation tags and the rigid body.

And with all of them selected,

I can change the settings for all of them at the same time.

So trigger on collision.

Okay, so now what should happen is that at about frame 30,

our sphere here will start its physics simulation.

And as it hits each one of these objects,

they will also start

their own physics simulation colliding with each other and with the ground.

So I hit play.

And there it is, just like that.

So that's one of the really cool things that you can do.

Really quick insight of cinema 14.

So I can also,

let's go ahead and I'm gonna go ahead and just make a whole bunch of new objects here.

We'll make a whole bunch of cubes at ten by ten by ten.

And let's go ahead and I'm just going to make a whole bunch of them just holding

control and dragging for each one of these kind of offset them a little bit.

I'll make a couple more.

We're gonna make it rain blocks.

And we'll kind of get a good idea of how

these physics simulations of the cubes can interact with each other.

Almost done here.

Okay?

So we have about 16 there.

So again, clicking and dragging on all of these.

When I hit tags, simulation, rigid body,

and not gonna touch anything,

I'm just gonna go ahead and frame one and press Play.

Wherever I click off of there.

You get a pretty good idea there of,

of some cool stuff that can happen.

So going back to that idea, that friction here,

I'm gonna turn that friction up to 80 or so because you

see that they were sliding like ice, like they were on ice.

Now, that's a lot more realistic right there where, you know, if,

if they're falling off of theirs because they're kind of rolling off more so than

just kind of gliding off of the surface there.

So another thing that I can do is I can change the surface two,

maybe I want these cubes to kinda fall more like it's in a cup.

So I'm gonna go in here and change,

change these to three right here.

And I'm going to make this and editable object beheading C.

And I'm going to grab the faces here

and just going to grab all of these outside ones here.

And let's say we kinda want the cubes to kind of fall

into this little cup kinda thing are here.

So holding control and dragging, i am extruding.

And you see it makes it a little cup right in there.

Alright.

So if I go ahead and start that from frame one,

you can see that's not right at all.

At work, how we wanted it to at all.

It's just kind of floating on the surface there.

Well, what's happening is that if I go into my

My plane collider here,

which is kind of cup right now.

It says for on our collision tag or on our collision tab.

Sorry, for shape.

It says automatic.

Well, it's trying to make the simplest shape that it possibly can for simulation.

Because the simpler the simulation settings,

the quicker it's going to work and the easier it's going to be.

So sometimes automatic isn't exactly what you want.

Sometimes you need to change that to say Static Mesh.

I mean, there's a whole bunch of different options here,

but usually I start with static mesh to see if that kinda fixes things for me,

will start that back at 0, press play.

And this time we get things falling inside of our mesh there.

So that's pretty cool right there.

And that would be if you wanted something to

kind of fall into a cup or something like that,

that would be how to do it.

So another thing that we can do now is,

let's say we wanted these to kind of fall slower.

What we can change gravity, we have that ability.

And that's why it's also important to make things at the right scale.

Because if we made that beach ball in the beginning,

the size of a planet,

it's gonna fall like a planet would.

It's going to look really slow.

It's not going to the speed of it's not going to look right.

And to do that, I can hit control D.

I can get into the project settings here.

And you'll see that there is a dynamics tab.

Whenever I click on that, I can

change a few different things in the general settings here in general tab,

we're going to deal with the expert tab here in just a moment.

But in general, you can see that I have timescale and gravity.

If I change that to a negative number,

we see that it just starts falling upwards.

If I change that to 0, is that it doesn't move at all.

I can change it to ten and starts to slow or slowly, kind of full.

And do a couple of times a second.

Oh, I guess it doesn't work.

Let's go ahead and redo.

All right, so whenever I hit that,

I might have to redo a couple things here.

So it's 393, I think something around there.

There we go. And then I'm just going to press undo just one too many times.

So I'm gonna go back into the shape of the cup there and raise that up a bit again.

And it's always important anytime that you make changes,

that you go back to frame one,

you can't just keep playing it.

And so back to what we wanted there.

So another thing you can do is sometimes whenever you do really complex simulations,

it slows your computer down by a lot.

And what you can do is selecting all of these tags right here.

What you can do is you can cache that simulation to the file so that you're able

to scrub back and forth because you'll see whenever I

do that right now, nothing is happening.

I have to go all the way back to that first frame to kinda see anything.

Well, what I can do with all of those selected,

I can go into cache and then go to bake object or go into bake all.

And I don't have to have any of that stuff selected that.

Fake object.

And whenever I do that and I started scrubbing back and forth,

you can see that it plays it smoother.

I mean, it's pretty simple physics simulation to begin with,

but it definitely makes

things easier to view and we'll see that a little bit more in just a minute.

But so you can see that we can just kinda quickly go back and forth.

But we can't change anything at this point unless we go to clear object cache.

And just like that, we're good.

Alright, so the last thing now is,

and I'm going to delete this whole scenery here and make a new plane.

We're gonna talk about soft body collisions.

So something more like a balloon or something,

something soft to that kinda has some bounce to it and isn't so rigid. And I suppose.

So I'm gonna go into sphere.

Let's go back into that idea that beach balls,

it will say 99 inches radius.

That should be good right here.

Now, I'm going to go into display,

quick shading, see the lines.

Now.

First thing I'm gonna do with this is

you see how there's a ton of points intersecting right here.

Well, with a soft body collision,

this whole thing right here,

we'll just kind of explode and not be good because there's

too many points converging in one area.

So the first thing you need to change is if you were to use

this fear is to go into standard and change that to icosahedron.

And just like that now there's no individual kind of points going into it.

And I'm also going to make it a little bit smoother at,

will say 35 segments.

There we go. Okay, so now with that sphere selected,

Oh, let's do the plane first, the plane,

I'm going to go again and make that a collider body just like we did before.

Sphere, I'm going to go to tags,

simulation and change that to a soft body.

Alright, so now what I can do is go to Frame one or 0 here, press play.

And you'll see that it's sort of working.

But it's not looking too pretty and it's going really slow.

So that's the thing that kinda keep in mind is that

soft body collisions go a lot slower and it's

usually based on the amount of polygons in your object.

So you want to keep them as low as possible.

Because if, if I change that to like a 100 or a 1000 segments instead of 30,

it might just take forever.

And you also see that it's going through the plane here.

So that's not right. Let's fix that problem first.

So starting back at frame 0,

I'm gonna go ahead and go into Control D or the project settings again.

And in the dynamics tab and then go to expert.

And then you see steps per frame.

That's kind of that's always the default right here.

Anytime that you get some weird stuff happening like that,

you can always change this number higher.

But the higher it goes,

the longer the simulations they're gonna take.

So I'm changing the ten and we'll see if that works for us.

And let's go play.

It's not going through the bottom there.

So just like that, we solve that problem.

I don't wanna go into Display and then our normal shading mode here,

just so we can kind of again see.

Now when we play this through,

we see that it is really soft.

It's almost like it's turning into an egg or something splattered.

It's more like a liquid then it is something with actual value.

So to change that,

let's go back to the first frame here.

Go into our soft body tag.

And then I'm going to go into,

Let's see here, let's go into the soft body.

And in here I can go ahead and change the stiffness.

I'll just go ahead and change to ten and we'll see what happens starting from x0,

from 0. Press play.

And all right, now we're getting some pretty cool where it's definitely a soft,

soft ball and it is working pretty well here.

And the other thing that I can change would be the pressure.

I mean, there's obviously a billion different settings here that you can change,

but I'm just going to be with the pressure here.

And let's change that to ten and start from 0.

And you see that it is chugging along quite a bit.

Both that pressure now it kind of gives us a

little bit more kind of buoyancy and everything.

And what I can do to kind of speed that up a little bit now,

like let's say I'm happy with that.

I can go into cache just like we did before.

I'm going to bake object,

and you'll see that it'll kind of bake all of

these frames just like it did with the rigid body tags.

And we're going to let that finish.

And so now I can kind of scrub through here and I can see that we get a pretty cool,

pretty cool animation to physics simulation on there.

Again, this is without making a single keyframe at all.

So it's a really cool way to kind of use this stuff.

And you're gonna make like a 1000 balls falling

here and each kind of having that same soft body tag on it.

I have a definitely slow down the computer,

so you again, gotta be really careful.

Yeah, that's kind of the basics of physics simulations.