orx/orx-keyframer/README.md

orx-keyframer

A highly reusable keyframer.

This POC relies on JSON files, but that's not a hard dependency, it can be replaced with any deserializer scheme.

What this allows you to do:

1. Create a keyframed animation in a json file.

[
  {
    "time": 0.0,
    "easing": "cubic-in-out",
    "x": 3.0,
    "y": 4.0,
    "z": 9.0,
    "r": 0.1,
    "g": 0.5,
    "b": 0.2,
    "radius": 50
  },
  {
    "time": 2.0,
    "easing": "cubic-in-out",
    "r": 0.6,
    "g": 0.5,
    "b": 0.1
  },
  {
    "time": 4.0,
    "easing": "cubic-in-out",
    "x": 10.0,
    "y": 4.0,
    "radius": 400
  },
  {
    "time": 5.0,
    "easing": "cubic-in-out",
    "x": 100.0,
    "y": 320.0,
    "radius": 400
  },
  {
    "time": 5.3,
    "easing": "cubic-in-out",
    "x": 100.0,
    "y": 320.0,
    "radius": 40
  }
]

2. Map the animation data to Kotlin types:

class Animation : Keyframer() {
    val position by Vector2Channel(arrayOf("x", "y"))
    val radius by DoubleChannel("radius")
    val color by RGBChannel(arrayOf("r", "g", "b"))
}

val animation = Animation()
animation.loadFromJson(File("data/keyframes/animation.json"))

3. Animate! (from an OPENRNDR program)

extend {
    animation(seconds)
    drawer.fill = animation.color
    drawer.circle(animation.position, animation.radius)
}

Advanced features

orx-keyframer uses two file formats. A SIMPLE format and a FULL format. For reference check the example full format .json and the example program. The full format adds a parameters block and a prototypes block.

Repeats, simple key repeating mechanism

Expressions, expression mechanism. Currently uses values r to indicate repeat index and t the last used key time, v the last used value (for the animated attribute).

Supported functions in expressions:

• min(x, y), max(x, y)
• cos(x), sin(x), acos(x), asin(x), tan(x), atan(x), atan2(y, x)
• abs(x), saturate(x)
• degrees(x), radians(x)
• pow(x,y), sqrt(x), exp(x)
• mix(left, right, x)
• smoothstep(t0, t1, x)
• map(leftBefore, rightBefore, leftAfter, rightAfter, x)
• random(), random(min, max)

Parameters and prototypes