Hyperbolic Asteroids, first commit. Rendering Poincare disk, circles, and lines.

src/lib.rs

@@ -0,0 +1,213 @@
+use std::f64;
+
+use wasm_bindgen::prelude::*;
+use wasm_bindgen::JsCast;
+use web_sys::{CanvasRenderingContext2d, HtmlCanvasElement};
+//use web_sys::console;
+
+mod cga;
+use cga::CGA;
+
+const PI: f64 = f64::consts::PI;
+const TWO_PI: f64 = 2.*PI;
+const ERROR: f64 = 0.0001;
+
+const WIDTH: f64 = 600.;
+const HEIGHT: f64 = 600.;
+const CENTER_X: f64 = 300.;
+const CENTER_Y: f64 = 300.;
+const RADIUS: f64 = 250.;
+
+const BACKGROUND: &str = "#ffffff";
+const BLACK: &str      = "#000000";
+const RED: &str        = "#ff0000";
+const GREEN: &str      = "#00ff00";
+const _BLUE: &str       = "#0000ff";
+
+const SCALAR: usize = 0; 
+const E1: usize = 1;
+const E2: usize = 2;
+//const E3: usize = 3;
+//const E4: usize = 4;
+//const E5: usize = 5;
+//const E12: usize = 6;
+//const E13: usize = 7;
+//const E14: usize = 8;
+//const E15: usize = 9;
+//const E23: usize = 10;
+//const E24: usize = 11;
+//const E25: usize = 12;
+//const E34: usize = 13;
+//const E35: usize = 14;
+//const E45: usize = 15;
+//const E123: usize = 16;
+//const E124: usize = 17;
+//const E125: usize = 18;
+//const E134: usize = 19;
+//const E135: usize = 20;
+//const E145: usize = 21;
+//const E234: usize = 22;
+//const E235: usize = 23;
+//const E245: usize = 24;
+//const E345: usize = 25;
+//const E1234: usize = 26;
+//const E1235: usize = 27;
+//const E1245: usize = 28;
+//const E1345: usize = 29;
+//const E2345: usize = 30;
+//const E12345: usize = 31;
+
+struct Ship {
+    _pos: CGA,
+    _vel: CGA,
+    _orientation: CGA,
+}
+
+fn point_to_cga(x: f64, y: f64) -> CGA {
+    let x_vec = CGA::e1();
+    let y_vec = CGA::e2();
+    let _z_vec =CGA::e3();
+    let e_vec = CGA::e4();
+    let e_bar = CGA::e5();
+    let n_vec = &e_vec + &e_bar;
+    let n_bar = &e_vec - &e_bar;
+
+    let mut ux = x;
+    let mut uy = y;
+    let mut mag_sqr = ux*ux + uy*uy;
+    if mag_sqr > 1. {
+        ux /= mag_sqr.sqrt();
+        uy /= mag_sqr.sqrt();
+        mag_sqr = 1.;
+    }
+
+    0.5*mag_sqr*n_vec + ux*x_vec + uy*y_vec - 0.5*n_bar
+}
+
+fn draw_point(context: &CanvasRenderingContext2d, point: &CGA) {
+    //Naively assume we are given a valid point
+    let x = point[1]*RADIUS + CENTER_X;
+    let y = point[2]*RADIUS + CENTER_Y;
+
+    context.begin_path();
+    context.set_fill_style_str(RED);
+    context.arc(x, y, 2., 0., TWO_PI).unwrap();
+    context.fill();
+}
+
+fn draw_line(context: &CanvasRenderingContext2d, line: &CGA) {
+    context.begin_path();
+    context.set_stroke_style_str(GREEN);
+
+    //Naively assume we are given a valid line/circle
+    let n_bar = CGA::e4() - CGA::e5();
+    let n_vec = CGA::e4() + CGA::e5();
+    let dual = line.Dual();
+
+    let lambda = -(&dual | &n_vec)[SCALAR];
+    let mu = (&dual | &n_bar)[SCALAR];
+    let x = dual[E1];
+    let y = dual[E2];
+
+
+    if lambda.abs() < ERROR {
+        //Line
+        let norm_sqr = x*x+y*y;
+        if norm_sqr < ERROR {
+            return;
+        } else {
+            let norm = norm_sqr.sqrt();
+            let px = mu * 0.5 * x / norm_sqr;
+            let py = mu * 0.5 * y / norm_sqr;
+            let tx = -y / norm;
+            let ty = x / norm;
+            let p1x = px + tx * 1000.;
+            let p1y = py + ty * 1000.;
+            let p2x = px - tx * 1000.;
+            let p2y = py - ty * 1000.;
+            context.move_to(p1x*RADIUS + CENTER_X, p1y*RADIUS + CENTER_Y);
+            context.line_to(p2x*RADIUS + CENTER_X, p2y*RADIUS + CENTER_Y);
+
+        }
+    } else {
+        //Extract Center and Radius
+        let c_x = x/lambda;
+        let c_y = y/lambda;
+        let r_sqr = c_x*c_x + c_y*c_y - mu/lambda;
+        let r = r_sqr.sqrt();
+
+        //draw_point(context, &point_to_cga(c_x, c_y));
+
+        //Convert into Canvas Space
+        let canvas_cx = c_x*RADIUS + CENTER_X;
+        let canvas_cy = c_y*RADIUS + CENTER_Y;
+        let canvas_r = r*RADIUS;
+
+        //Draw
+        context.arc(canvas_cx, canvas_cy, canvas_r, 0., TWO_PI).unwrap();
+    }
+    context.stroke();
+}
+
+// Start entry point
+#[wasm_bindgen(start)]
+pub fn start() -> Result<(), JsValue> {
+    let _ship = Ship { _pos: point_to_cga(0.,0.), _vel: CGA::zero(), _orientation: CGA::zero() };
+
+    // Grab document and canvas
+    let window = web_sys::window().unwrap();
+    let document = window.document().unwrap();
+    let canvas = document
+        .get_element_by_id("game-canvas")
+        .unwrap()
+        .dyn_into::<HtmlCanvasElement>()?;
+
+    canvas.set_width(WIDTH as u32);
+    canvas.set_height(HEIGHT as u32);
+
+    let context = canvas
+        .get_context("2d")?
+        .unwrap()
+        .dyn_into::<CanvasRenderingContext2d>()?;
+
+    //Set up play area.
+    context.begin_path();
+    context.set_fill_style_str(BACKGROUND);
+    context.fill_rect(0.0, 0.0, WIDTH, HEIGHT);
+    context.fill();
+    context.set_stroke_style_str(BLACK);
+    context.arc(CENTER_X, CENTER_Y, RADIUS, 0., TWO_PI).unwrap();
+    context.stroke();
+
+    let point = point_to_cga(0.,0.);
+    draw_point(&context, &point);
+
+    let p1 = point_to_cga(0.9, 0.0);
+    draw_point(&context, &p1);
+    let p2 = point_to_cga(0.0, 0.9);
+    draw_point(&context, &p2);
+    let p3 = point_to_cga(0.7, 0.6);
+    draw_point(&context, &p3);
+    let circle = &p1 ^ &p2 ^ &p3 ^ &CGA::e3();
+    draw_line(&context, &circle);
+
+    let p1 = point_to_cga(0.9, 0.2);
+    draw_point(&context, &p1);
+    let p2 = point_to_cga(-0.9, -0.);
+    draw_point(&context, &p2);
+    let p3 = point_to_cga(0., 0.1);
+    draw_point(&context, &p3);
+    let circle = &p1 ^ &p2 ^ &p3 ^ &CGA::e3();
+    draw_line(&context, &circle);
+
+    let p1 = point_to_cga(0.9, 0.1);
+    draw_point(&context, &p1);
+    let p2 = point_to_cga(-0.9, -0.1);
+    draw_point(&context, &p2);
+    let p3 = point_to_cga(0., 0.0);
+    draw_point(&context, &p3);
+    let circle = &p1 ^ &p2 ^ &p3 ^ &CGA::e3();
+    draw_line(&context, &circle);
+
+    Ok(())
+}