strafe-client/src/bvh.rs

124 lines
3.2 KiB
Rust

use crate::aabb::Aabb;
//da algaritum
//lista boxens
//sort by {minx,maxx,miny,maxy,minz,maxz} (6 lists)
//find the sets that minimizes the sum of surface areas
//splitting is done when the minimum split sum of surface areas is larger than the node's own surface area
//start with bisection into octrees because a bad bvh is still 1000x better than no bvh
//sort the centerpoints on each axis (3 lists)
//bv is put into octant based on whether it is upper or lower in each list
enum BvhNodeContent{
Branch(Vec<BvhNode>),
Leaf(usize),
}
impl Default for BvhNodeContent{
fn default()->Self{
Self::Branch(Vec::new())
}
}
#[derive(Default)]
pub struct BvhNode{
content:BvhNodeContent,
aabb:Aabb,
}
impl BvhNode{
pub fn the_tester<F:FnMut(usize)>(&self,aabb:&Aabb,f:&mut F){
match &self.content{
&BvhNodeContent::Leaf(model)=>f(model),
BvhNodeContent::Branch(children)=>for child in children{
//this test could be moved outside the match statement
//but that would test the root node aabb
//you're probably not going to spend a lot of time outside the map,
//so the test is extra work for nothing
if aabb.intersects(&child.aabb){
child.the_tester(aabb,f);
}
},
}
}
}
pub fn generate_bvh(boxen:Vec<Aabb>)->BvhNode{
generate_bvh_node(boxen.into_iter().enumerate().collect())
}
fn generate_bvh_node(boxen:Vec<(usize,Aabb)>)->BvhNode{
let n=boxen.len();
if n<20{
let mut aabb=Aabb::default();
let nodes=boxen.into_iter().map(|b|{
aabb.join(&b.1);
BvhNode{
content:BvhNodeContent::Leaf(b.0),
aabb:b.1,
}
}).collect();
BvhNode{
content:BvhNodeContent::Branch(nodes),
aabb,
}
}else{
let mut octant=std::collections::HashMap::with_capacity(n);//this ids which octant the boxen is put in
let mut sort_x=Vec::with_capacity(n);
let mut sort_y=Vec::with_capacity(n);
let mut sort_z=Vec::with_capacity(n);
for (i,aabb) in boxen.iter(){
let center=aabb.center();
octant.insert(*i,0);
sort_x.push((*i,center.x()));
sort_y.push((*i,center.y()));
sort_z.push((*i,center.z()));
}
sort_x.sort_by(|tup0,tup1|tup0.1.cmp(&tup1.1));
sort_y.sort_by(|tup0,tup1|tup0.1.cmp(&tup1.1));
sort_z.sort_by(|tup0,tup1|tup0.1.cmp(&tup1.1));
let h=n/2;
let median_x=sort_x[h].1;
let median_y=sort_y[h].1;
let median_z=sort_z[h].1;
for (i,c) in sort_x{
if median_x<c{
octant.insert(i,octant[&i]+1<<0);
}
}
for (i,c) in sort_y{
if median_y<c{
octant.insert(i,octant[&i]+1<<1);
}
}
for (i,c) in sort_z{
if median_z<c{
octant.insert(i,octant[&i]+1<<2);
}
}
//generate lists for unique octant values
let mut list_list=Vec::with_capacity(8);
let mut octant_list=Vec::with_capacity(8);
for (i,aabb) in boxen.into_iter(){
let octant_id=octant[&i];
let list_id=if let Some(list_id)=octant_list.iter().position(|&id|id==octant_id){
list_id
}else{
let list_id=list_list.len();
octant_list.push(octant_id);
list_list.push(Vec::new());
list_id
};
list_list[list_id].push((i,aabb));
}
let mut aabb=Aabb::default();
let children=list_list.into_iter().map(|b|{
let node=generate_bvh_node(b);
aabb.join(&node.aabb);
node
}).collect();
BvhNode{
content:BvhNodeContent::Branch(children),
aabb,
}
}
}