physics/test.md

## Slide 1

```drawing
title Test Drawing!
caption This is a test
scale 2.0
buttons
frame 0 0 200 100
axes 200 100
point p1 _.oscillatingPoint([20, 20], [80, 20], 3000)
fill cyan
square p1 1000
point p2 [100, 30]
fill red
circle p2
point p3 [ _.oscillatingValue(20, 80, 3000), 
  _.oscillatingValue(20, 80, 3000, Math.PI/2) ]
fill green
circle p3 1000
start
```

---

## Slide 2

```drawing
title Sine Wave
caption `y = sin(x)`
scale 64
frame 0 -1 2*Math.PI 1
stroke black 4
eval _.line([0, -1], [0, 1])
eval _.line([0, 0], [2*Math.PI, 0])
stroke red 2
func Math.sin(x)
``` 

---

## Slide 3

```drawing
title Oscillating Sine Wave
caption `y = sin(x) * sin(t)`
scale 64
frame 0 -1 2*Math.PI 1
stroke black 4
eval _.line([0, -1], [0, 1])
eval _.line([0, 0], [2*Math.PI, 0])
stroke red 2
func Math.sin(x) * _.oscillatingValue(-1, 1, 500)
start
``` 

---

## Slide 4

```drawing
title Travelling Sine Wave
caption `y = sin(x + t)`
scale 64
frame 0 -1 2*Math.PI 1
stroke black 4
eval _.line([0, -1], [0, 1])
eval _.line([0, 0], [2*Math.PI, 0])
stroke red 2
func Math.sin(x + 2*Math.PI*_.t / 1000)
start
``` 

---

## Slide 5

```drawing
title Projectile
caption `y = v_(0y) * t - g * t^2`<br>`x = v_(0x) * t`
scale 2
frame 0 0 300 100
stroke black 4
eval _.polyline([0, 100], [0, 0], [300, 0]);
value v0 75
value angle Math.PI / 4
value v0x _.getValue('v0') * Math.cos(_.getValue('angle'))
value v0y _.getValue('v0') * Math.sin(_.getValue('angle'))
point p1 (function() {
  const t = _.t / 1000;
  const x = _.getValue('v0x') * t;
  const y = _.getValue('v0y') * t - 9.81 * t**2;
  if (t > 0 && (y <= 0 || x >= _.frame[1][0])) {
    _.stop();
    _.t = 0;
  }
  return [x, y];
 })()
stroke green 1
eval _.line([0, 0], [_.getValue('v0x'), _.getValue('v0y')])
fill blue
eval const projectile = d.circle('p1', {trace: {age: -1}});
  d.onStart(() => {
    if (d.t == 0) {
      projectile.reset();
    }
  })
start
```