From 673e9c13aea6cd1b11f5ca3e1f6edd474bbb1a19 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Fri, 31 Mar 2023 17:17:27 -0500
Subject: implement nice map grid

---
 src/MapView.js | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 src/MapView.js

(limited to 'src/MapView.js')

diff --git a/src/MapView.js b/src/MapView.js
new file mode 100644
index 0000000..a08d6b7
--- /dev/null
+++ b/src/MapView.js
@@ -0,0 +1,62 @@
+import Canvas from './Canvas.js';
+import { Mat3, Vec3, Point, Shape } from './Geometry.js';
+
+
+const yAxis = new Vec3(0, 1, 0);
+const zAxis = new Vec3(0, 0, 1);
+
+
+function radians(degrees) {
+	return degrees * (Math.PI/180);
+}
+
+function Circle(p0, axis, subdiv) {
+	const rotationMatrix = new Mat3().rotation(axis, 2*Math.PI/(subdiv-1));
+	const points = [p0];
+	for (let i=0; i<subdiv-1; i++) {
+		const point = rotationMatrix.mulv(points[i]);
+		points.push(point);
+	}
+	return new Shape(points);
+}
+
+export class MapGrid {
+	constructor(latDiv, longDiv, circleDiv=50) {
+		// create latitudes
+		this.latitudes = [];
+		// equator
+		this.latitudes.push(Circle(
+			new Point(0, radians(0)).normal(), yAxis, circleDiv
+		));
+		for (let angle=latDiv; angle<90; angle += latDiv) {
+			// positive (north)
+			this.latitudes.push(Circle(
+				new Point(0, radians(angle)).normal(), yAxis, circleDiv
+			));
+			// negative (south)
+			this.latitudes.push(Circle(
+				new Point(0, radians(-angle)).normal(), yAxis, circleDiv
+			));
+		}
+
+		// create longitudes
+		this.longitudes = [];
+		for (let angle=0; angle<180; angle += longDiv) {
+			console.log(angle);
+			const point = new Point(radians(angle), 0).normal();
+			const axis = point.cross(yAxis).normalize();
+			this.longitudes.push(Circle(
+				point, axis, circleDiv
+			));
+		}
+	}
+
+	render(ct, view) {
+		for (let latitude of this.latitudes) {
+			latitude.render(ct, view);
+		}
+		for (let longitude of this.longitudes) {
+			longitude.render(ct, view);
+		}
+	}
+}
-- 
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