add an example for intersection plane

crates/parry3d/Cargo.toml

@@ -22,11 +22,23 @@ workspace = true
 [features]
 default = ["required-features", "std"]
 required-features = ["dim3", "f32"]
-std = ["nalgebra/std", "slab", "rustc-hash", "simba/std", "arrayvec/std", "spade", "thiserror"]
+std = [
+    "nalgebra/std",
+    "slab",
+    "rustc-hash",
+    "simba/std",
+    "arrayvec/std",
+    "spade",
+    "thiserror",
+]
 dim3 = []
 f32 = []
 serde-serialize = ["serde", "nalgebra/serde-serialize", "bitflags/serde"]
-rkyv-serialize = ["rkyv/validation", "nalgebra/rkyv-serialize", "simba/rkyv-serialize"]
+rkyv-serialize = [
+    "rkyv/validation",
+    "nalgebra/rkyv-serialize",
+    "simba/rkyv-serialize",
+]
 bytemuck-serialize = ["bytemuck", "nalgebra/convert-bytemuck"]
 
 simd-stable = ["simba/wide", "simd-is-enabled"]
@@ -76,3 +88,4 @@ obj = { version = "0.10.2", optional = true }
 oorandom = "11"
 ptree = "0.4.0"
 rand = { version = "0.8" }
+macroquad = "0.4"

crates/parry3d/examples/plane_intersection.rs

@@ -0,0 +1,141 @@
+use macroquad::models::Vertex;
+use macroquad::prelude::*;
+use nalgebra::{Point3, UnitVector3, Vector3};
+use parry3d::math::{Isometry, Real};
+use parry3d::query::IntersectResult;
+use parry3d::shape::TriMesh;
+
+fn build_diamond(position: &Isometry<Real>) -> (Vec<Point3<Real>>, Vec<[u32; 3]>) {
+    // Two tetrahedrons sharing a face
+    let points = vec![
+        position * Point3::new(0.0, 2.0, 0.0),
+        position * Point3::new(-2.0, -1.0, 0.0),
+        position * Point3::new(0.0, 0.0, 2.0),
+        position * Point3::new(2.0, -1.0, 0.0),
+        position * Point3::new(0.0, 0.0, -2.0),
+    ];
+
+    let indices = vec![
+        [0u32, 1, 2],
+        [0, 2, 3],
+        [1, 2, 3],
+        [0, 1, 4],
+        [0, 4, 3],
+        [1, 4, 3],
+    ];
+
+    (points, indices)
+}
+
+#[macroquad::main("parry3d::query::PlaneIntersection")]
+async fn main() {
+    //
+    // This is useful to test for https://github.com/dimforge/parry/pull/248
+    let _points = vec![
+        Point3::from([0.0, 0.0, 0.0]),
+        Point3::from([0.0, 0.0, 1.0]),
+        Point3::from([1.0, 0.0, 0.0]),
+        Point3::from([1.0, 0.0, 1.0]),
+    ];
+    let _indices: Vec<[u32; 3]> = vec![[0, 1, 2], [1, 3, 2]];
+    //
+    //
+
+    let (points, indices) = build_diamond(&Isometry::identity());
+
+    let mesh = Mesh {
+        vertices: points
+            .iter()
+            .map(|p| Vertex {
+                position: mquad_from_na(*p),
+                uv: Vec2::new(p.x, p.y),
+                color: WHITE,
+            })
+            .collect(),
+        indices: indices.iter().flatten().map(|v| *v as u16).collect(),
+        texture: None,
+    };
+    let trimesh = TriMesh::new(points, indices);
+
+    for _i in 1.. {
+        clear_background(BLACK);
+
+        let elapsed_time = get_time();
+
+        let bias = -2.0 * (elapsed_time as f32 / 3f32).sin();
+        let rotation = Quat::from_axis_angle(Vec3::Z, (elapsed_time as f32 * 50f32).to_radians());
+        let up_plane_vector = rotation * Vec3::Y;
+        let intersection_result = trimesh.intersection_with_local_plane(
+            &UnitVector3::new_normalize(Vector3::<Real>::new(
+                up_plane_vector.x,
+                up_plane_vector.y,
+                up_plane_vector.z,
+            )),
+            bias,
+            0.0005,
+        );
+
+        // Going 3d!
+        set_camera(&Camera3D {
+            position: Vec3::new(0f32, 3f32, -3f32),
+            up: Vec3::new(0f32, 1f32, 0f32),
+            target: Vec3::new(0.5f32, 0f32, 0.5f32),
+            ..Default::default()
+        });
+
+        let plane_center = up_plane_vector * bias;
+        draw_line_3d(plane_center, plane_center + up_plane_vector, GREEN);
+        draw_mesh(&mesh);
+        draw_grid_ex(10, 0.333, BLUE, RED, plane_center, rotation);
+
+        /*
+         *
+         * Render the intersection
+         *
+         */
+        match intersection_result {
+            IntersectResult::Intersect(points) => {
+                draw_polyline(
+                    points
+                        .segments()
+                        .map(|s| (mquad_from_na(s.a), mquad_from_na(s.b)))
+                        .collect(),
+                    Color::new(0f32, 1f32, 0f32, 1f32),
+                );
+            }
+            IntersectResult::Negative => {
+                set_default_camera();
+                draw_text(
+                    format!("No intersection found, the shape is below the plane.").as_str(),
+                    10.0,
+                    48.0 + 18.0,
+                    30.0,
+                    WHITE,
+                );
+            }
+            IntersectResult::Positive => {
+                set_default_camera();
+                draw_text(
+                    format!("No intersection found, the shape is above the plane.").as_str(),
+                    10.0,
+                    48.0 + 18.0,
+                    30.0,
+                    WHITE,
+                );
+            }
+        }
+        next_frame().await
+    }
+}
+
+fn draw_polyline(polygon: Vec<(Vec3, Vec3)>, color: Color) {
+    for i in 0..polygon.len() {
+        let a = polygon[i].0;
+        let b = polygon[i].1;
+        draw_line_3d(a, b, color);
+    }
+}
+
+fn mquad_from_na(a: Point3<Real>) -> Vec3 {
+    Vec3::new(a.x, a.y, a.z)
+}