tree dissolve + instances

src/loaders/mesh.rs

@@ -2,6 +2,26 @@ use bytemuck::{Pod, Zeroable};
 use glam::{Mat4, Quat, Vec3};
 use std::path::Path;
 
+fn compute_aabb(vertices: &[Vertex]) -> (Vec3, Vec3)
+{
+    let mut aabb_min = Vec3::splat(f32::MAX);
+    let mut aabb_max = Vec3::splat(f32::MIN);
+    for v in vertices
+    {
+        let p = Vec3::from(v.position);
+        aabb_min = aabb_min.min(p);
+        aabb_max = aabb_max.max(p);
+    }
+    if vertices.is_empty()
+    {
+        (Vec3::ZERO, Vec3::ZERO)
+    }
+    else
+    {
+        (aabb_min, aabb_max)
+    }
+}
+
 #[repr(C)]
 #[derive(Clone, Copy, Pod, Zeroable)]
 pub struct Vertex
@@ -113,6 +133,10 @@ pub struct Mesh
     pub vertex_buffer: wgpu::Buffer,
     pub index_buffer: wgpu::Buffer,
     pub num_indices: u32,
+    pub aabb_min: Vec3,
+    pub aabb_max: Vec3,
+    pub cpu_positions: Vec<[f32; 3]>,
+    pub cpu_indices: Vec<u32>,
 }
 
 impl Mesh
@@ -121,6 +145,8 @@ impl Mesh
     {
         use wgpu::util::DeviceExt;
 
+        let (aabb_min, aabb_max) = compute_aabb(vertices);
+
         let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
             label: Some("Vertex Buffer"),
             contents: bytemuck::cast_slice(vertices),
@@ -137,6 +163,10 @@ impl Mesh
             vertex_buffer,
             index_buffer,
             num_indices: indices.len() as u32,
+            aabb_min,
+            aabb_max,
+            cpu_positions: vertices.iter().map(|v| v.position).collect(),
+            cpu_indices: indices.to_vec(),
         }
     }