Implement function to find intersections between a Bezier and a linear line (#708)

* Implement line intersection for quadratics, begin work for cubic

* Implement line intersection for cubic beziers, add tests for cubic root finding

* Rename function and update comments

* Minor refactor and adjust comments

* Address PR comments

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

@@ -250,6 +250,45 @@ export default defineComponent({
 						});
 					},
 				},
+				{
+					name: "Rotate",
+					callback: (canvas: HTMLCanvasElement, bezier: WasmBezierInstance, options: Record<string, number>): void => {
+						const context = getContextFromCanvas(canvas);
+						const rotatedBezier = bezier
+							.rotate((options.angle * Math.PI) / 180)
+							.get_points()
+							.map((p) => JSON.parse(p));
+						drawBezier(context, rotatedBezier, null, { curveStrokeColor: COLORS.NON_INTERACTIVE.STROKE_1, radius: 3.5 });
+					},
+					template: markRaw(SliderExample),
+					templateOptions: {
+						sliders: [
+							{
+								variable: "angle",
+								min: -90,
+								max: 90,
+								step: 5,
+								default: 15,
+							},
+						],
+					},
+				},
+				{
+					name: "Line Intersection",
+					callback: (canvas: HTMLCanvasElement, bezier: WasmBezierInstance): void => {
+						const context = getContextFromCanvas(canvas);
+						const line = [
+							{ x: 150, y: 150 },
+							{ x: 30, y: 30 },
+						];
+						const mappedLine = line.map((p) => [p.x, p.y]);
+						drawLine(context, line[0], line[1], COLORS.NON_INTERACTIVE.STROKE_1);
+						const intersections: Point[] = bezier.line_intersection(mappedLine).map((p) => JSON.parse(p));
+						intersections.forEach((p: Point) => {
+							drawPoint(context, p, 3, COLORS.NON_INTERACTIVE.STROKE_2);
+						});
+					},
+				},
 			],
 		};
 	},

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

@@ -107,4 +107,13 @@ impl WasmBezier {
 		let local_extrema = self.0.local_extrema();
 		JsValue::from_serde(&serde_json::to_string(&local_extrema).unwrap()).unwrap()
 	}
+
+	pub fn rotate(&self, angle: f64) -> WasmBezier {
+		WasmBezier(self.0.rotate(angle))
+	}
+
+	pub fn line_intersection(&self, js_points: &JsValue) -> Vec<JsValue> {
+		let line: [DVec2; 2] = js_points.into_serde().unwrap();
+		self.0.line_intersection(line).iter().map(|&p| vec_to_point(&p)).collect::<Vec<JsValue>>()
+	}
 }