2 files changed, 76 insertions, 5 deletions
diff --git a/src/model/size.ts b/src/model/size.ts
new file mode 100644
index 0000000..5e8a778
--- /dev/null
+++ b/src/model/size.ts
@@ -0,0 +1,8 @@
+export interface Size {
+  width: number,
+  height: number,
+}
+
+export function diagonal(size: Size): number {
+  return Math.sqrt(size.width ** 2 + size.height ** 2)
+}
diff --git a/src/model/vec2.ts b/src/model/vec2.ts
index 4bec53d..46ffc7e 100644
--- a/src/model/vec2.ts
+++ b/src/model/vec2.ts
@@ -1,15 +1,78 @@
+import * as Number from 'util/number'
+import * as Size from 'model/size'
+
 export interface Vec2 {
   x: number,
   y: number,
 }
 
-export function zero(): Vec2 {
-  return {
-    x: 0,
-    y: 0,
-  }
+export const zero: Vec2 = {
+  x: 0,
+  y: 0,
 }
 
 export function equals(v1: Vec2, v2: Vec2): boolean {
   return v1.x === v2.x && v1.y === v2.y
 }
+
+export function length(v: Vec2): number {
+  return Math.sqrt(v.x ** 2 + v.y ** 2)
+}
+
+export function normalize(v: Vec2): Vec2 {
+  if (v.x === 0 && v.y === 0) {
+    return zero
+  } else {
+    const im = 1 / length(v)
+    return {
+      x: v.x * im,
+      y: v.y * im
+    }
+  }
+}
+
+export function applyOnLength(f: (n: number) => number, v: Vec2): Vec2 {
+  return scale(normalize(v), f(length(v)))
+}
+
+export function sub(v1: Vec2, v2: Vec2): Vec2 {
+  return {
+    x: v1.x - v2.x,
+    y: v1.y - v2.y
+  }
+}
+
+export function div(v: Vec2, k: number): Vec2 {
+  return {
+    x: v.x / k,
+    y: v.y / k
+  }
+}
+
+export function add(v1: Vec2, v2: Vec2): Vec2 {
+  return {
+    x: v1.x + v2.x,
+    y: v1.y + v2.y
+  }
+}
+
+export function scale(v: Vec2, k: number): Vec2 {
+  return {
+    x: v.x * k,
+    y: v.y * k
+  }
+}
+
+export function clamp(v: Vec2, vMin: Vec2, vMax: Vec2): Vec2 {
+  return {
+    x: Number.clamp(v.x, vMin.x, vMax.x),
+    y: Number.clamp(v.y, vMin.y, vMax.y)
+  }
+}
+
+export function project(from: Size.Size, to: Size.Size, v: Vec2): Vec2 {
+  return {
+    x: v.x / from.width * to.width,
+    y: v.y / from.height * to.height
+  }
+}