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use crate::math::Vector;
#[cfg(feature = "dim3")]
use crate::shape::{Cone, Cylinder, PackedFeatureId};
use crate::shape::{Cuboid, PolygonalFeature, Segment, SupportMap, Triangle};
/// Trait implemented by convex shapes with features with polyhedral approximations.
pub trait PolygonalFeatureMap: SupportMap {
/// Compute the support polygonal face of `self` towards the `dir`.
fn local_support_feature(&self, dir: Vector, out_feature: &mut PolygonalFeature);
// TODO: this is currently just a workaround for https://github.com/dimforge/rapier/issues/417
// until we get a better way to deal with the issue without breaking internal edges
// handling.
/// Is this shape a `ConvexPolyhedron`?
fn is_convex_polyhedron(&self) -> bool {
false
}
}
impl PolygonalFeatureMap for Segment {
fn local_support_feature(&self, _: Vector, out_feature: &mut PolygonalFeature) {
*out_feature = PolygonalFeature::from(*self);
}
}
impl PolygonalFeatureMap for Triangle {
fn local_support_feature(&self, dir: Vector, out_feature: &mut PolygonalFeature) {
*out_feature = self.support_face(dir);
}
}
impl PolygonalFeatureMap for Cuboid {
fn local_support_feature(&self, dir: Vector, out_feature: &mut PolygonalFeature) {
*out_feature = self.support_face(dir);
}
}
#[cfg(feature = "dim3")]
impl PolygonalFeatureMap for Cylinder {
fn local_support_feature(&self, dir: Vector, out_features: &mut PolygonalFeature) {
use crate::math::Vector2;
// About feature ids.
// At all times, we consider our cylinder to be approximated as follows:
// - The curved part is approximated by a single segment.
// - Each flat cap of the cylinder is approximated by a square.
// - The curved-part segment has a feature ID of 0, and its endpoint with negative
// `y` coordinate has an ID of 1.
// - The bottom cap has its vertices with feature ID of 1,3,5,7 (in counter-clockwise order
// when looking at the cap with an eye looking towards +y).
// - The bottom cap has its four edge feature IDs of 2,4,6,8, in counter-clockwise order.
// - The bottom cap has its face feature ID of 9.
// - The feature IDs of the top cap are the same as the bottom cap to which we add 10.
// So its vertices have IDs 11,13,15,17, its edges 12,14,16,18, and its face 19.
// - Note that at all times, one of each cap's vertices are the same as the curved-part
// segment endpoints.
let dir2 = Vector2::new(dir.x, dir.z)
.try_normalize()
.unwrap_or(Vector2::X);
if dir.y.abs() < 0.5 {
// We return a segment lying on the cylinder's curved part.
out_features.vertices[0] = Vector::new(
dir2.x * self.radius,
-self.half_height,
dir2.y * self.radius,
);
out_features.vertices[1] =
Vector::new(dir2.x * self.radius, self.half_height, dir2.y * self.radius);
out_features.eids = PackedFeatureId::edges([0, 0, 0, 0]);
out_features.fid = PackedFeatureId::face(0);
out_features.num_vertices = 2;
out_features.vids = PackedFeatureId::vertices([1, 11, 11, 11]);
} else {
// We return a square approximation of the cylinder cap.
let y = self.half_height.copysign(dir.y);
out_features.vertices[0] = Vector::new(dir2.x * self.radius, y, dir2.y * self.radius);
out_features.vertices[1] = Vector::new(-dir2.y * self.radius, y, dir2.x * self.radius);
out_features.vertices[2] = Vector::new(-dir2.x * self.radius, y, -dir2.y * self.radius);
out_features.vertices[3] = Vector::new(dir2.y * self.radius, y, -dir2.x * self.radius);
if dir.y < 0.0 {
out_features.eids = PackedFeatureId::edges([2, 4, 6, 8]);
out_features.fid = PackedFeatureId::face(9);
out_features.num_vertices = 4;
out_features.vids = PackedFeatureId::vertices([1, 3, 5, 7]);
} else {
out_features.eids = PackedFeatureId::edges([12, 14, 16, 18]);
out_features.fid = PackedFeatureId::face(19);
out_features.num_vertices = 4;
out_features.vids = PackedFeatureId::vertices([11, 13, 15, 17]);
}
}
}
}
#[cfg(feature = "dim3")]
impl PolygonalFeatureMap for Cone {
fn local_support_feature(&self, dir: Vector, out_features: &mut PolygonalFeature) {
use crate::math::Vector2;
// About feature ids. It is very similar to the feature ids of cylinders.
// At all times, we consider our cone to be approximated as follows:
// - The curved part is approximated by a single segment.
// - The flat cap of the cone is approximated by a square.
// - The curved-part segment has a feature ID of 0, and its endpoint with negative
// `y` coordinate has an ID of 1.
// - The bottom cap has its vertices with feature ID of 1,3,5,7 (in counter-clockwise order
// when looking at the cap with an eye looking towards +y).
// - The bottom cap has its four edge feature IDs of 2,4,6,8, in counter-clockwise order.
// - The bottom cap has its face feature ID of 9.
// - Note that at all times, one of the cap's vertices are the same as the curved-part
// segment endpoints.
let dir2 = Vector2::new(dir.x, dir.z)
.try_normalize()
.unwrap_or(Vector2::X);
if dir.y > 0.0 {
// We return a segment lying on the cone's curved part.
out_features.vertices[0] = Vector::new(
dir2.x * self.radius,
-self.half_height,
dir2.y * self.radius,
);
out_features.vertices[1] = Vector::new(0.0, self.half_height, 0.0);
out_features.eids = PackedFeatureId::edges([0, 0, 0, 0]);
out_features.fid = PackedFeatureId::face(0);
out_features.num_vertices = 2;
out_features.vids = PackedFeatureId::vertices([1, 11, 11, 11]);
} else {
// We return a square approximation of the cone cap.
let y = -self.half_height;
out_features.vertices[0] = Vector::new(dir2.x * self.radius, y, dir2.y * self.radius);
out_features.vertices[1] = Vector::new(-dir2.y * self.radius, y, dir2.x * self.radius);
out_features.vertices[2] = Vector::new(-dir2.x * self.radius, y, -dir2.y * self.radius);
out_features.vertices[3] = Vector::new(dir2.y * self.radius, y, -dir2.x * self.radius);
out_features.eids = PackedFeatureId::edges([2, 4, 6, 8]);
out_features.fid = PackedFeatureId::face(9);
out_features.num_vertices = 4;
out_features.vids = PackedFeatureId::vertices([1, 3, 5, 7]);
}
}
}