feat: add to and from homogenous

src/projection.ts

@@ -1,6 +1,6 @@
 import { Angle, Rad } from "./angle.ts";
 import { Matrix4 } from "./matrix4.ts";
-import { absDiffEq, absDiffNe } from "./util.ts";
+import { absDiffEq } from "./util.ts";
 
 export class Perspective {
   left: number;

src/vector3.ts

@@ -1,4 +1,6 @@
 import { Vector } from "./vector.ts";
+import { Vector2 } from "./vector2.ts";
+import { Vector4 } from "./vector4.ts";
 
 export class Vector3 extends Vector<Vector3> {
   #internal = new Float32Array(3);
@@ -91,6 +93,10 @@ export class Vector3 extends Vector<Vector3> {
     return new Vector3(0, 0, 1);
   }
 
+  static fromHomogeneous(vector: Vector4): Vector3 {
+    return vector.trunc().mul(1 / vector.w)
+  }
+
   constructor();
   constructor(x: number);
   constructor(x: number, y: number, z: number);
@@ -126,6 +132,18 @@ export class Vector3 extends Vector<Vector3> {
     return this.div(this.mag());
   }
 
+  truncN(n: 0 | 1 | 2): Vector2 {
+    switch(n) {
+      case 0: return new Vector2(this.y, this.z);
+      case 1: return new Vector2(this.x, this.z);
+      case 2: return new Vector2(this.x, this.y);
+    }
+  }
+
+  trunc(): Vector2 {
+    return new Vector2(this.x, this.y);
+  }
+
   clamp(length: number): Vector3 {
     return this.normal().mul(length);
   }
@@ -200,6 +218,10 @@ export class Vector3 extends Vector<Vector3> {
     return isFinite(this.x) && isFinite(this.y) && isFinite(this.z);
   }
 
+  toHomogeneous(): Vector4 {
+    return new Vector4(this.x, this.y, this.z, 1);
+  }
+
   toString(): string {
     return `Vector3 { x: ${this[0]}, y: ${this[1]}, z: ${this[2]} }`;
   }

src/vector4.ts

@@ -1,4 +1,5 @@
 import { Vector } from "./vector.ts";
+import { Vector3 } from "./vector3.ts";
 
 export class Vector4 extends Vector<Vector4> {
   #internal = new Float32Array(4);
@@ -113,6 +114,19 @@ export class Vector4 extends Vector<Vector4> {
     return this.div(this.mag());
   }
 
+  truncN(n: 0 | 1 | 2 | 3): Vector3 {
+    switch(n) {
+      case 0: return new Vector3(this.y, this.z, this.w);
+      case 1: return new Vector3(this.x, this.z, this.w);
+      case 2: return new Vector3(this.x, this.y, this.w);
+      case 3: return new Vector3(this.x, this.y, this.z);
+    }
+  }
+
+  trunc(): Vector3 {
+    return new Vector3(this.x, this.y, this.z);
+  }
+
   clamp(length: number): Vector4 {
     return this.normal().mul(length);
   }