speedscope/math.ts

export function clamp(x: number, minVal: number, maxVal: number) {
  if (x < minVal) return minVal
  if (x > maxVal) return maxVal
  return x
}

export class Vec2 {
  constructor(readonly x = 0, readonly y = 0) {}
  withX(x: number) { return new Vec2(x, this.y) }
  withY(y: number) { return new Vec2(this.x, y) }

  plus(other: Vec2) { return new Vec2(this.x + other.x, this.y + other.y) }
  minus(other: Vec2) { return new Vec2(this.x - other.x, this.y - other.y) }
  times(scalar: number) { return new Vec2(this.x * scalar, this.y * scalar) }
  timesPointwise(other: Vec2) { return new Vec2(this.x * other.x, this.y * other.y) }
  dot(other: Vec2) { return this.x * other.x + this.y * other.y }
  length2() { return this.dot(this) }
  length() { return Math.sqrt(this.length2()) }

  static min(a: Vec2, b: Vec2) {
    return new Vec2(Math.min(a.x, b.x), Math.min(a.y, b.y))
  }

  static max(a: Vec2, b: Vec2) {
    return new Vec2(Math.max(a.x, b.x), Math.max(a.y, b.y))
  }

  flatten(): [number, number] { return [this.x, this.y] }
}

export class AffineTransform {
  constructor(
    readonly m00 = 1, readonly m01 = 0, readonly m02 = 0,
    readonly m10 = 0, readonly m11 = 1, readonly m12 = 0
  ) {}

  withScale(s: Vec2) {
    let {
      m00, m01, m02,
      m10, m11, m12
    } = this
    m00 = s.x
    m11 = s.y
    return new AffineTransform(m00, m01, m02, m10, m11, m12)
  }
  static withScale(s: Vec2) {
    return (new AffineTransform).withScale(s)
  }
  scaledBy(s: Vec2) { return AffineTransform.withScale(s).times(this) }
  getScale() { return new Vec2(this.m00, this.m11) }

  withTranslation(t: Vec2) {
    let {
      m00, m01, m02,
      m10, m11, m12
    } = this
    m02 = t.x
    m12 = t.y
    return new AffineTransform(m00, m01, m02, m10, m11, m12)
  }
  static withTranslation(t: Vec2) {
    return (new AffineTransform).withTranslation(t)
  }
  getTranslation() { return new Vec2(this.m02, this.m12) }
  translatedBy(t: Vec2) { return AffineTransform.withTranslation(t).times(this) }

  static betweenRects(from: Rect, to: Rect) {
    return AffineTransform
      .withTranslation(from.origin.times(-1))
      .scaledBy(new Vec2(
        to.size.x / from.size.x,
        to.size.y / from.size.y
      ))
      .translatedBy(to.origin)
  }

  times(other: AffineTransform) {
    const m00 = this.m00 * other.m00 + this.m01 * other.m10
    const m01 = this.m00 * other.m01 + this.m01 * other.m11
    const m02 = this.m00 * other.m02 + this.m01 * other.m12 + this.m02

    const m10 = this.m10 * other.m00 + this.m11 * other.m10
    const m11 = this.m10 * other.m01 + this.m11 * other.m11
    const m12 = this.m10 * other.m02 + this.m11 * other.m12 + this.m12
    return new AffineTransform(m00, m01, m02, m10, m11, m12)
  }

  timesScalar(s: number) {
    const {m00, m01, m02, m10, m11, m12} = this
    return new AffineTransform(s*m00, s*m01, s*m02, s*m10, s*m11, s*m12)
  }

  det() {
    const {m00, m01, m02, m10, m11, m12} = this
    const m20 = 0
    const m21 = 0
    const m22 = 1

    return (
      m00 * (m11 * m22 - m12 * m21) -
      m01 * (m10 * m22 - m12 * m20) +
      m02 * (m10 * m21 - m11 * m20)
    )
  }

  adj() {
    const {m00, m01, m02, m10, m11, m12} = this
    const m20 = 0
    const m21 = 0
    const m22 = 1

    // Adjugate matrix (a) is the transpose of the
    // cofactor matrix (c).
    //
    // 00 01 02
    // 10 11 12
    // 20 21 22

    const a00 = /* c00 = */ +(m11 * m22 - m12 * m21)
    const a01 = /* c10 = */ -(m01 * m22 - m02 * m21)
    const a02 = /* c20 = */ +(m01 * m12 - m02 * m11)
    const a10 = /* c01 = */ -(m10 * m22 - m12 * m20)
    const a11 = /* c11 = */ +(m00 * m22 - m02 * m20)
    const a12 = /* c21 = */ -(m00 * m12 - m02 * m10)

    return new AffineTransform(a00, a01, a02, a10, a11, a12)
  }

  inverted(): AffineTransform | null {
    const det = this.det()
    if (det === 0) return null
    const adj = this.adj()
    return adj.timesScalar(1 / det)
  }

  transformVector(v: Vec2) {
    return new Vec2(
      v.x * this.m00 + v.y * this.m01,
      v.x * this.m10 + v.y * this.m11
    )
  }

  inverseTransformVector(v: Vec2): Vec2 | null {
    const inv = this.inverted()
    if (!inv) return null
    return inv.transformVector(v)
  }

  transformPosition(v: Vec2) {
    return new Vec2(
      v.x * this.m00 + v.y * this.m01 + this.m02,
      v.x * this.m10 + v.y * this.m11 + this.m12
    )
  }

  inverseTransformPosition(v: Vec2): Vec2 | null {
    const inv = this.inverted()
    if (!inv) return null
    return inv.transformPosition(v)
  }

  transformRect(r: Rect) {
    return new Rect(
      this.transformPosition(r.origin),
      this.transformVector(r.size)
    )
  }

  flatten(): [number, number, number, number, number, number, number, number, number] {
    // Flatten into GLSL format
    return [
      this.m00, this.m10, 0,
      this.m01, this.m11, 0,
      this.m02, this.m12, 1,
    ]
  }
}

export class Rect {
  constructor(
    readonly origin = new Vec2(),
    readonly size = new Vec2()
  ) {}

  width() { return this.size.x }
  height() { return this.size.y }

  left() { return this.origin.x }
  right() { return this.left() + this.width() }
  top() { return this.origin.y }
  bottom() { return this.top() + this.height() }

  topLeft() { return this.origin }
  topRight() { return this.origin.plus(new Vec2(this.width(), 0)) }

  bottomRight() { return this.origin.plus(this.size) }
  bottomLeft() { return this.origin.plus(new Vec2(0, this.height())) }

  withOrigin(origin: Vec2) { return new Rect(origin, this.size) }
  withSize(size: Vec2) { return new Rect(this.origin, size) }

  closestPointTo(p: Vec2) {
    return new Vec2(
      clamp(p.x, this.left(), this.right()),
      clamp(p.y, this.top(), this.bottom())
    )
  }
}