From a9e755c29f8ffeda259edc4698ba8ae6f7ad5e13 Mon Sep 17 00:00:00 2001
From: Thierry Berger <contact@thierryberger.com>
Date: Fri, 2 Aug 2024 12:17:40 +0200
Subject: [PATCH] Raycast example using macroquad (#234)
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Co-authored-by: Sébastien Crozet <sebastien@crozet.re>
---
 crates/parry2d/examples/raycasts_animated.rs | 132 +++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 crates/parry2d/examples/raycasts_animated.rs

diff --git a/crates/parry2d/examples/raycasts_animated.rs b/crates/parry2d/examples/raycasts_animated.rs
new file mode 100644
index 00000000..09aa4bd4
--- /dev/null
+++ b/crates/parry2d/examples/raycasts_animated.rs
@@ -0,0 +1,132 @@
+use macroquad::prelude::*;
+use nalgebra::{Isometry2, Point2, UnitComplex, Vector2};
+use parry2d::math::Isometry;
+use parry2d::query::{Ray, RayCast};
+use parry2d::shape::Cuboid;
+
+const RENDER_SCALE: f32 = 30.0;
+
+#[macroquad::main("parry2d::query::RayCast")]
+async fn main() {
+    let animation_scale = 1.4;
+    let animation_rotation = 0.04;
+
+    for i in 1.. {
+        clear_background(BLACK);
+
+        let screen_shift = Point2::new(screen_width() / 2.0, screen_height() / 2.0);
+        /*
+         *
+         * Compute the scaled cuboid.
+         *
+         */
+        let cube =
+            Cuboid::new(Vector2::new(2.0, 2.0) * ((i as f32 / 50.0).sin().abs() * animation_scale));
+        let cube_pose = Isometry2::rotation(0.008 * i as f32);
+        /*
+         *
+         * Prepare a Raycast and compute its result against the shape.
+         *
+         */
+        let ray = Ray::new(
+            Point2::new(2.0, 2.0),
+            UnitComplex::new(animation_rotation * i as f32) * -Vector2::x(),
+        );
+        let toi = cube.cast_ray(&cube_pose, &ray, std::f32::MAX, true);
+
+        /*
+         *
+         * Render the raycast's result.
+         *
+         */
+        if let Some(toi) = toi {
+            if toi == 0f32 {
+                draw_point(ray.origin, RENDER_SCALE, screen_shift, YELLOW);
+            } else {
+                drawline_from_to(
+                    ray.origin,
+                    ray.origin + ray.dir * toi,
+                    RENDER_SCALE,
+                    screen_shift,
+                    GREEN,
+                );
+            }
+        } else {
+            drawline_from_to(
+                ray.origin,
+                ray.origin + ray.dir * 1000f32,
+                RENDER_SCALE,
+                screen_shift,
+                RED,
+            );
+        }
+
+        /*
+         *
+         * Render the cuboid.
+         *
+         */
+        draw_polygon(
+            &cube.to_polyline(),
+            &cube_pose,
+            RENDER_SCALE,
+            screen_shift,
+            GREEN,
+        );
+
+        next_frame().await
+    }
+}
+
+fn draw_polygon(
+    polygon: &[Point2<f32>],
+    pose: &Isometry<f32>,
+    scale: f32,
+    shift: Point2<f32>,
+    color: Color,
+) {
+    for i in 0..polygon.len() {
+        let a = pose * (scale * polygon[i]);
+        let b = pose * (scale * polygon[(i + 1) % polygon.len()]);
+        draw_line(
+            a.x + shift.x,
+            a.y + shift.y,
+            b.x + shift.x,
+            b.y + shift.y,
+            2.0,
+            color,
+        );
+    }
+}
+
+fn draw_point(point: Point2<f32>, scale: f32, shift: Point2<f32>, color: Color) {
+    let edge_len = 0.15;
+    draw_line(
+        (point.x - edge_len) * scale + shift.x,
+        point.y * scale + shift.y,
+        (point.x + edge_len) * scale + shift.x,
+        point.y * scale + shift.y,
+        2.0,
+        color,
+    );
+    draw_line(
+        point.x * scale + shift.x,
+        (point.y - edge_len) * scale + shift.y,
+        point.x * scale + shift.x,
+        (point.y + edge_len) * scale + shift.y,
+        2.0,
+        color,
+    );
+}
+
+fn drawline_from_to(
+    from: Point2<f32>,
+    to: Point2<f32>,
+    scale: f32,
+    shift: Point2<f32>,
+    color: Color,
+) {
+    let from = from * scale + shift.coords;
+    let to = to * scale + shift.coords;
+    draw_line(from.x, from.y, to.x, to.y, 2.0, color);
+}