Implement bezier library's De Casteljau points function (#715)

* pre-rebase

* broken wasm

* hull lines

* update rust lib description

* update comments, handle match statement better, pass Point type to vue

* cleanup

* add linear case

* More idiomatic code

* Further simplifications to the algorithm and removal of more heap allocations

* Rename to de_casteljau_points and use colors for the iterations

* Small comment changes

* Improve colors

Co-authored-by: Jackie Chen <jackiechen73>
Co-authored-by: Keavon Chambers <keavon@keavon.com>
Co-authored-by: Hannah Li <hannahli2010@gmail.com>

bezier-rs/docs/interactive-docs/src/App.vue

@@ -281,6 +281,29 @@ export default defineComponent({
 						],
 					},
 				},
+				{
+					name: "De Casteljau Points",
+					callback: (canvas: HTMLCanvasElement, bezier: WasmBezierInstance, options: Record<string, number>): void => {
+						const hullPoints: Point[][] = JSON.parse(bezier.de_casteljau_points(options.t));
+						hullPoints.reverse().forEach((iteration: Point[], iterationIndex) => {
+							const colorLight = `hsl(${90 * iterationIndex}, 100%, 50%)`;
+
+							iteration.forEach((point: Point, index) => {
+								// Skip the anchor and handle points which are already drawn in black
+								if (iterationIndex !== hullPoints.length - 1) {
+									drawPoint(getContextFromCanvas(canvas), point, 4, colorLight);
+								}
+
+								if (index !== 0) {
+									const prevPoint: Point = iteration[index - 1];
+									drawLine(getContextFromCanvas(canvas), point, prevPoint, colorLight);
+								}
+							});
+						});
+					},
+					template: markRaw(SliderExample),
+					templateOptions: { sliders: [tSliderOptions] },
+				},
 				{
 					name: "Rotate",
 					callback: (canvas: HTMLCanvasElement, bezier: WasmBezierInstance, options: Record<string, number>): void => {

bezier-rs/docs/interactive-docs/wasm/src/lib.rs

@@ -138,4 +138,14 @@ impl WasmBezier {
 		let bezier_points: Vec<Vec<Point>> = self.0.reduce(None).into_iter().map(bezier_to_points).collect();
 		to_js_value(bezier_points)
 	}
+
+	pub fn de_casteljau_points(&self, t: f64) -> JsValue {
+		let hull = self
+			.0
+			.de_casteljau_points(t)
+			.iter()
+			.map(|level| level.iter().map(|&point| Point { x: point.x, y: point.y }).collect::<Vec<Point>>())
+			.collect::<Vec<Vec<Point>>>();
+		to_js_value(hull)
+	}
 }