feat: add shape module

Signed-off-by: André Jaenisch <andre.jaenisch@posteo.de>

src/js/shape.js

@@ -0,0 +1,71 @@
+import { gravity } from './constants.js'
+import { Vec2 } from './vector.js'
+
+/** @typedef {import('./vector.js').Vector2D} Vector2D
+
+/**
+ * @typedef {object} Shape
+ * @property {Vector2D} C
+ * @property {number} F
+ * @property {number} R
+ * @property {number} M
+ * @property {Vector2D} V
+ * @property {Vector2D} A
+ * @property {number} G
+ * @property {number} v
+ * @property {number} a
+ * @property {number} B
+ * @property {number} W
+ * @property {number} H
+ * @property {Array<*>} N
+ * @property {Array<Vector2D>} X
+ */
+
+/**
+ * Defines a rigid shape.
+ *
+ * @param {object} config
+ * @param {Vector2D} config.center
+ * @param {number}   config.mass
+ * @param {number}   config.friction
+ * @param {number}   config.restitution
+ * @param {number}   config.bounds
+ * @param {number}   config.width
+ * @param {number}   config.height
+ * @returns {Shape}
+ */
+export function RigidShape ({
+  center,
+  mass,
+  friction,
+  restitution, // bouncing
+  bounds, // radius
+  width,
+  height
+}) {
+  const immobile = 0
+
+  const shape = {
+    C: center,
+    F: friction,
+    R: restitution,
+    M: mass ? 1 / mass : immobile,
+    V: Vec2(0, 0), // velocity, i.e. speed
+    A: mass ? gravity : Vec2(0, 0), // acceleration
+    G: 0, // angle
+    v: 0, // angle velocity
+    a: 0, // angle acceleration
+    B: bounds,
+    W: width,
+    H: height,
+    N: [], // face normals array
+    X: [
+      Vec2(center.x - width / 2, center.y - height / 2), // top-left
+      Vec2(center.x + width / 2, center.y - height / 2), // top-right
+      Vec2(center.x + width / 2, center.y + height / 2), // bottom-right
+      Vec2(center.x - width / 2, center.y + height / 2) // bottom-left
+    ]
+  }
+
+  return shape
+}

test/js/shape.test.js

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+import { expect } from 'chai'
+
+import { RigidShape } from '../../src/js/shape.js'
+import { Vec2 } from '../../src/js/vector.js'
+
+describe('RigidShape', function () {
+  it('should create a rigid shape', function () {
+    // Arrange
+    const center = Vec2(500, 200)
+    const friction = 20
+    const restitution = 0
+    const mass = 400
+    const bounds = 1
+    const width = 5
+    const height = 5
+
+    // Act
+    const shape = RigidShape({
+      center,
+      mass,
+      friction,
+      restitution,
+      bounds,
+      width,
+      height
+    })
+
+    // Assert
+    expect(shape).to.be.an('object')
+  })
+})

types/shape.d.ts

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+/** @typedef {import('./vector.js').Vector2D} Vector2D
+
+/**
+ * @typedef {object} Shape
+ * @property {Vector2D} C
+ * @property {number} F
+ * @property {number} R
+ * @property {number} M
+ * @property {Vector2D} V
+ * @property {Vector2D} A
+ * @property {number} G
+ * @property {number} v
+ * @property {number} a
+ * @property {number} B
+ * @property {number} W
+ * @property {number} H
+ * @property {Array<*>} N
+ * @property {Array<Vector2D>} X
+ */
+/**
+ * Defines a rigid shape.
+ *
+ * @param {object} config
+ * @param {Vector2D} config.center
+ * @param {number}   config.mass
+ * @param {number}   config.friction
+ * @param {number}   config.restitution
+ * @param {number}   config.bounds
+ * @param {number}   config.width
+ * @param {number}   config.height
+ * @returns {Shape}
+ */
+export function RigidShape({ center, mass, friction, restitution, bounds, width, height }: {
+    center: Vector2D;
+    mass: number;
+    friction: number;
+    restitution: number;
+    bounds: number;
+    width: number;
+    height: number;
+}): Shape;
+/**
+ * /**
+ */
+export type Vector2D = import('./vector.js').Vector2D;
+export type Shape = {
+    C: Vector2D;
+    F: number;
+    R: number;
+    M: number;
+    V: Vector2D;
+    A: Vector2D;
+    G: number;
+    v: number;
+    a: number;
+    B: number;
+    W: number;
+    H: number;
+    N: Array<any>;
+    X: Array<Vector2D>;
+};