nightshade 0.10.0

A cross-platform data-oriented game engine.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

use std::collections::HashSet;

use nalgebra_glm::{IVec3, Vec3};

use super::marching_cubes;
use super::resources::SdfWorld;

pub struct SdfCollisionMesh {
    pub chunk_size: f32,
    pub cell_size: f32,
    pub dirty_chunks: HashSet<IVec3>,
    pub max_chunks_per_frame: usize,
    pub terrain_octaves: u32,
}

impl SdfCollisionMesh {
    pub fn new(chunk_size: f32, cell_size: f32) -> Self {
        Self {
            chunk_size,
            cell_size,
            dirty_chunks: HashSet::new(),
            max_chunks_per_frame: 8,
            terrain_octaves: 11,
        }
    }

    pub fn mark_dirty_in_bounds(&mut self, bounds_min: Vec3, bounds_max: Vec3) {
        let chunk_min = IVec3::new(
            (bounds_min.x / self.chunk_size).floor() as i32,
            (bounds_min.y / self.chunk_size).floor() as i32,
            (bounds_min.z / self.chunk_size).floor() as i32,
        );
        let chunk_max = IVec3::new(
            (bounds_max.x / self.chunk_size).ceil() as i32,
            (bounds_max.y / self.chunk_size).ceil() as i32,
            (bounds_max.z / self.chunk_size).ceil() as i32,
        );

        for cz in chunk_min.z..=chunk_max.z {
            for cy in chunk_min.y..=chunk_max.y {
                for cx in chunk_min.x..=chunk_max.x {
                    self.dirty_chunks.insert(IVec3::new(cx, cy, cz));
                }
            }
        }
    }

    pub fn update(
        &mut self,
        sdf_world: &SdfWorld,
        camera_pos: Vec3,
        excluded_edit_indices: &HashSet<usize>,
    ) -> Vec<(IVec3, CollisionChunkResult)> {
        if self.dirty_chunks.is_empty() {
            return Vec::new();
        }

        let count = self.max_chunks_per_frame.min(self.dirty_chunks.len());
        let mut candidates: Vec<IVec3> = self.dirty_chunks.iter().copied().collect();

        if candidates.len() > count {
            candidates.select_nth_unstable_by(count - 1, |a, b| {
                let dist_a = chunk_center_distance(*a, self.chunk_size, camera_pos);
                let dist_b = chunk_center_distance(*b, self.chunk_size, camera_pos);
                dist_a.partial_cmp(&dist_b).unwrap()
            });
            candidates.truncate(count);
        }

        let mut results = Vec::with_capacity(count);
        let octaves = self.terrain_octaves;

        for chunk_coord in candidates {
            self.dirty_chunks.remove(&chunk_coord);

            let region_min = Vec3::new(
                chunk_coord.x as f32 * self.chunk_size,
                chunk_coord.y as f32 * self.chunk_size,
                chunk_coord.z as f32 * self.chunk_size,
            );
            let region_max =
                region_min + Vec3::new(self.chunk_size, self.chunk_size, self.chunk_size);

            let (vertices, indices) = if excluded_edit_indices.is_empty() {
                marching_cubes::extract_mesh(
                    &|point| sdf_world.evaluate_at_lod(point, octaves),
                    region_min,
                    region_max,
                    self.cell_size,
                )
            } else {
                marching_cubes::extract_mesh(
                    &|point| {
                        sdf_world.evaluate_at_lod_excluding(point, octaves, excluded_edit_indices)
                    },
                    region_min,
                    region_max,
                    self.cell_size,
                )
            };

            if vertices.is_empty() || indices.is_empty() {
                results.push((chunk_coord, CollisionChunkResult::Empty));
            } else {
                results.push((
                    chunk_coord,
                    CollisionChunkResult::Mesh { vertices, indices },
                ));
            }
        }

        results
    }

    pub fn clear(&mut self) {
        self.dirty_chunks.clear();
    }
}

pub enum CollisionChunkResult {
    Empty,
    Mesh {
        vertices: Vec<[f32; 3]>,
        indices: Vec<[u32; 3]>,
    },
}

fn chunk_center_distance(chunk_coord: IVec3, chunk_size: f32, camera_pos: Vec3) -> f32 {
    let center = Vec3::new(
        (chunk_coord.x as f32 + 0.5) * chunk_size,
        (chunk_coord.y as f32 + 0.5) * chunk_size,
        (chunk_coord.z as f32 + 0.5) * chunk_size,
    );
    nalgebra_glm::length(&(center - camera_pos))
}