wehub-resource-sync
315 lines
10 KiB
Rust
315 lines
10 KiB
Rust
// Copyright (c) 2019-present Dmitry Stepanov and Fyrox Engine contributors.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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use nalgebra::{Vector2, Vector3};
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use std::fmt;
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///
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/// Polygon vertex
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///
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#[derive(Debug)]
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struct Vertex {
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position: Vector2<f32>,
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prev: usize,
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index: usize,
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next: usize,
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}
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///
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/// Linked list of vertices
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///
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struct Polygon {
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vertices: Vec<Vertex>,
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head: usize,
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tail: usize,
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}
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impl Polygon {
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///
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/// Excludes vertex from polygon. Does not remove it from vertices array!
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///
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#[inline]
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fn remove_vertex(&mut self, index: usize) {
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let next_index = self.vertices[index].next;
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let prev_index = self.vertices[index].prev;
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let prev = &mut self.vertices[prev_index];
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prev.next = next_index;
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let next = &mut self.vertices[next_index];
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next.prev = prev_index;
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if index == self.head {
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self.head = next_index;
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}
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if index == self.tail {
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self.tail = prev_index;
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}
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}
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}
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impl fmt::Debug for Polygon {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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let mut i = self.head;
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loop {
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let vertex = &self.vertices[i];
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writeln!(
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f,
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"Vertex {:?}; {} {} {}",
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vertex.position, vertex.prev, vertex.index, vertex.next
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)?;
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i = self.vertices[i].next;
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if i == self.head {
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break;
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}
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}
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Ok(())
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}
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}
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fn is_ear(poly: &Polygon, prev: &Vertex, ear: &Vertex, next: &Vertex) -> bool {
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// Check if other points are inside triangle
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let mut i = poly.head;
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loop {
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let vertex = &poly.vertices[i];
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if i != prev.index
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&& i != ear.index
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&& i != next.index
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&& crate::is_point_inside_2d_triangle(
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vertex.position,
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prev.position,
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ear.position,
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next.position,
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)
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{
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return false;
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}
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i = vertex.next;
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if i == poly.head {
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break;
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}
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}
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true
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}
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///
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/// Triangulates specified polygon.
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///
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pub fn triangulate(vertices: &[Vector3<f32>], out_triangles: &mut Vec<[usize; 3]>) {
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out_triangles.clear();
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if vertices.len() == 3 {
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// Triangulating a triangle?
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out_triangles.push([0, 1, 2]);
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} else if vertices.len() == 4 {
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// Special case for quadrilaterals (much faster than generic)
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let mut start_vertex = 0;
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for i in 0..4 {
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let v = vertices[i];
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let v0 = vertices[(i + 3) % 4];
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if let Some(left) = (v0 - v).try_normalize(f32::EPSILON) {
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let v1 = vertices[(i + 2) % 4];
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if let Some(diag) = (v1 - v).try_normalize(f32::EPSILON) {
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let v2 = vertices[(i + 1) % 4];
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if let Some(right) = (v2 - v).try_normalize(f32::EPSILON) {
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// Check for concave vertex
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let angle = left.dot(&diag).acos() + right.dot(&diag).acos();
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if angle > std::f32::consts::PI {
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start_vertex = i;
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break;
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}
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}
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}
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}
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}
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out_triangles.push([start_vertex, (start_vertex + 1) % 4, (start_vertex + 2) % 4]);
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out_triangles.push([start_vertex, (start_vertex + 2) % 4, (start_vertex + 3) % 4]);
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} else {
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// Ear-clipping for arbitrary polygon (requires one additional memory allocation, so
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// relatively slow)
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if let Ok(normal) = crate::get_polygon_normal(vertices) {
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let plane_class = crate::classify_plane(normal);
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let mut polygon = Polygon {
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vertices: vertices
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.iter()
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.enumerate()
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.map(|(i, point)| Vertex {
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position: crate::vec3_to_vec2_by_plane(plane_class, normal, *point),
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index: i,
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prev: if i == 0 { vertices.len() - 1 } else { i - 1 },
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next: if i == vertices.len() - 1 { 0 } else { i + 1 },
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})
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.collect(),
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head: 0,
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tail: vertices.len() - 1,
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};
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let mut ear_index = polygon.head;
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let mut vertices_left = polygon.vertices.len();
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while vertices_left > 3 {
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let ear = &polygon.vertices[ear_index];
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let prev = &polygon.vertices[ear.prev];
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let next = &polygon.vertices[ear.next];
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if is_ear(&polygon, prev, ear, next) {
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let prev_index = prev.index;
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out_triangles.push([prev_index, ear.index, next.index]);
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polygon.remove_vertex(ear_index);
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ear_index = prev_index;
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vertices_left -= 1;
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} else {
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ear_index = ear.next;
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}
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}
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// Append last triangle.
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if vertices_left > 0 {
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let a = &polygon.vertices[polygon.head];
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let b = &polygon.vertices[a.next];
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out_triangles.push([polygon.head, a.next, b.next]);
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}
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}
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}
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}
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#[cfg(test)]
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mod test {
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use nalgebra::Vector2;
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use crate::triangulator::triangulate;
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use nalgebra::{Point3, Unit, UnitQuaternion, Vector3};
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use super::{Polygon, Vertex};
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#[test]
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fn triangle_triangulation() {
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let polygon = vec![
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Vector3::new(0.0, 0.0, 0.0),
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Vector3::new(1.0, 0.0, 0.0),
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Vector3::new(0.0, 1.0, 0.0),
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];
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let mut ref_indices = Vec::new();
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triangulate(polygon.as_slice(), &mut ref_indices);
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assert_ne!(ref_indices.len(), 0);
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}
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#[test]
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fn quadrilaterals_triangulation_non_concave() {
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let polygon = vec![
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Vector3::new(0.0, 0.0, 1.0),
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Vector3::new(1.0, 2.0, 1.0),
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Vector3::new(2.0, 3.0, 1.0),
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Vector3::new(3.0, 2.0, 1.0),
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];
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let mut ref_indices = Vec::new();
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triangulate(polygon.as_slice(), &mut ref_indices);
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assert_ne!(ref_indices.len(), 0);
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}
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#[test]
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fn quadrilaterals_triangulation_concave() {
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let polygon = vec![
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Vector3::new(0.0, 2.0, 1.0),
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Vector3::new(3.0, 3.0, 1.0),
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Vector3::new(2.0, 2.0, 1.0),
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Vector3::new(3.0, 1.0, 1.0),
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];
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let mut ref_indices = Vec::new();
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triangulate(polygon.as_slice(), &mut ref_indices);
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assert_ne!(ref_indices.len(), 0);
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}
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#[test]
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fn ear_clip_test() {
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let polygon = vec![
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Vector3::new(-22.760103, 29.051392, 1.377507),
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Vector3::new(-24.6454, 29.051392, 1.377507),
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Vector3::new(-24.640476, 24.873882, 1.377506),
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Vector3::new(-24.637342, 22.215763, 1.377506),
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Vector3::new(-22.760103, 22.215763, 1.377506),
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];
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// First test flat case
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let mut ref_indices = Vec::new();
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triangulate(polygon.as_slice(), &mut ref_indices);
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assert_ne!(ref_indices.len(), 0);
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// Then compare previous result with series of rotated versions of the polygon.
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for axis in &[
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Unit::new_normalize(Vector3::new(1.0, 0.0, 0.0)),
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Unit::new_normalize(Vector3::new(0.0, 1.0, 0.0)),
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Unit::new_normalize(Vector3::new(0.0, 0.0, 1.0)),
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Unit::new_normalize(Vector3::new(1.0, 1.0, 1.0)),
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] {
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let mut angle: f32 = 0.0;
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while angle <= 360.0 {
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let mrot =
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UnitQuaternion::from_axis_angle(axis, angle.to_radians()).to_homogeneous();
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let rotated: Vec<Vector3<f32>> = polygon
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.iter()
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.map(|v: &Vector3<f32>| mrot.transform_point(&Point3::from(*v)).coords)
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.collect();
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let mut new_indices = Vec::new();
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triangulate(rotated.as_slice(), &mut new_indices);
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// We just need to ensure that we have the same amount of triangles as reference triangulation.
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assert_eq!(new_indices.len(), ref_indices.len());
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angle += 36.0;
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}
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}
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}
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#[test]
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fn test_debug_for_polygon() {
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let p = Polygon {
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vertices: vec![
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Vertex {
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prev: 2,
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index: 0,
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next: 1,
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position: Vector2::new(0.0, 0.0),
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},
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Vertex {
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prev: 0,
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index: 1,
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next: 2,
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position: Vector2::new(1.0, 0.0),
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},
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Vertex {
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prev: 1,
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index: 2,
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next: 0,
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position: Vector2::new(0.0, 1.0),
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},
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],
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head: 0,
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tail: 2,
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};
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assert_eq!(
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format!("{p:?}"),
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r"Vertex [[0.0, 0.0]]; 2 0 1
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Vertex [[1.0, 0.0]]; 0 1 2
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Vertex [[0.0, 1.0]]; 1 2 0
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"
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);
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}
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}
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