Name: 2.2 品質和加速度--代碼的性質 (2.2 Mass and Acceleration - The Nature of Code)
Uploaded: 2021-01-14T10:43:14.000Z
Duration: 12 min 13 s
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In the previous video in this section on forces,

I built this particular example where there

a gravity force that's always being applied to the mover

look at how I might consider this mover object

that might affect how the gravity and wind forces behave.

And in truth, for me to be able to demonstrate this

if I have two objects with different masses,

because if I just have one, scaling the mass

scale the strength, the relative strength, of those forces.

So let's quickly add a second object to this example.

Now, you might already be thinking to yourself, ugh,

If you're going to have more than one object,

Or isn't there a different way of doing this?

And ultimately, what I want to do with these examples is build

and sort of add and subtract them from the canvas itself.

I'm going to leave these as two separate variables, mover

A and mover B. I'm going to apply both forces to them

and call update edges and show on both of them.

You can see how they're kind of in lockstep together.

So both are bouncing and responding to the wind force.

Now let's think about where I want to add mass.

And r is a property that is tied to the size

Let's just add mass as its own property for a moment.

or restated as acceleration equals force divided by mass.

And remember, the way that I'm implementing

this is all of the forces divided by mass

are being accumulated into the object's acceleration.

So first and foremost, I need to incorporate this divide by mass

Right here, I can then say force.div by this.mass.

Before I add the force into the acceleration, divide by mass,

I should see the acceleration-- the force remains the same.

I spent all this time talking about static functions?

like, this function, mult for multiply, which is called on v,

And that reason, that moment is right now.

I want to divide force by mass but not the actual force vector

I just want to take that vector, get a copy of it,

divide it by mass, and then add that to the acceleration.

The reason is because out here, I'm taking this wind vector

and applying it to A and B. And I don't want A to mess

with it because wind should stay the same when it applies to B.

taking that force vector and dividing it by 2

I could make a copy of it and then divide it.

But I could also use the static version of divide.

and I need a new vector to store the result in.

So here I am saying, take that force, divide it by mass,

And then that vector f is what gets applied

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2.2 品質和加速度--代碼的性質 (2.2 Mass and Acceleration - The Nature of Code)

ultimately

demonstrate

scale

arbitrary