flame/lib/vector.dart

library flame.vector_math;

export 'package:vector_math/vector_math_64.dart' show Vector2;

import 'dart:math' as math;
import 'dart:ui' as ui;
import 'package:vector_math/vector_math_64.dart';

class VectorUtil {
  /// Creates converting integers to double.
  ///
  /// Internal representation is still using double, the conversion is made in the constructor only.
  static Vector2 fromInts(int x, int y) => Vector2(x.toDouble(), y.toDouble());

  /// Creates using an [ui.Offset]
  static Vector2 fromOffset(ui.Offset offset) => Vector2(offset.dx, offset.dy);

  /// Creates using an [ui.Size]
  static Vector2 fromSize(ui.Size size) => Vector2(size.width, size.height);

  /// Creates using an [math.Point]
  static Vector2 fromPoint(math.Point point) => Vector2(point.x, point.y);

  static ui.Offset toOffset(Vector2 v) => ui.Offset(v.x, v.y);

  static ui.Size toSize(Vector2 v) => ui.Size(v.x, v.y);

  static math.Point toPoint(Vector2 v) => math.Point(v.x, v.y);

  // Used once in sprite
  static ui.Rect rectFrom(Vector2 topLeft, Vector2 size) {
    return ui.Rect.fromLTWH(topLeft.x, topLeft.y, size.x, size.y);
  }

  static ui.Rect bounds(List<Vector2> pts) {
    final double minx = pts.map((e) => e.x).reduce(math.min);
    final double maxx = pts.map((e) => e.x).reduce(math.max);
    final double miny = pts.map((e) => e.y).reduce(math.min);
    final double maxy = pts.map((e) => e.y).reduce(math.max);
    return ui.Rect.fromPoints(ui.Offset(minx, miny), ui.Offset(maxx, maxy));
  }

  /// Linearly interpolate between two vectors.
  static Vector2 lerp(Vector2 a, Vector2 b, double t) {
    return a + (b - a) * t;
  }

  static void rotate(Vector2 v, double angle) {
    final double sin = math.sin(angle);
    final double cos = math.cos(angle);
    v.setValues(v.x * cos - v.y * sin, v.x * sin + v.y * cos);
  }

  static Vector2 rotated(Vector2 v, double angle) {
    final double sin = math.sin(angle);
    final double cos = math.cos(angle);
    return Vector2(v.x * cos - v.y * sin, v.x * sin + v.y * cos);
  }

  /// Returns a new vector with the [length] scaled to [newLength], without changing direction.
  ///
  /// If you try to scale the zero (empty) vector, it will remain unchanged, and no error will be thrown.
  static Vector2 scaledTo(Vector2 v, double newLength) {
    final l = v.length;
    if (l == 0) {
      return v;
    }
    return v * (newLength.abs() / l);
  }

  /// Changes the [length] of the vector to the length provided, without changing direction.
  ///
  /// If you try to scale the zero (empty) vector, it will remain unchanged, and no error will be thrown.
  static void scaleTo(Vector2 v, double newLength) {
    final l = v.length;
    if (l != 0) {
      v.setFrom(v * (newLength.abs() / l));
    }
  }
}