80 lines
1.8 KiB
Rust
80 lines
1.8 KiB
Rust
use mem_arena::MemArena;
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use crate::{
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bbox::BBox,
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math::{Normal, Point, Vector},
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shading::surface_closure::SurfaceClosure,
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};
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use super::LightAccel;
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#[derive(Debug, Copy, Clone)]
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pub struct LightArray<'a> {
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indices: &'a [usize],
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aprx_energy: f32,
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}
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impl<'a> LightArray<'a> {
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#[allow(dead_code)]
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pub fn from_objects<'b, T, F>(
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arena: &'a MemArena,
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objects: &mut [T],
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info_getter: F,
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) -> LightArray<'a>
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where
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F: 'b + Fn(&T) -> (&'b [BBox], f32),
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{
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let mut indices = Vec::new();
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let mut aprx_energy = 0.0;
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for (i, thing) in objects.iter().enumerate() {
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let (_, power) = info_getter(thing);
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if power > 0.0 {
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indices.push(i);
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aprx_energy += power;
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}
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}
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LightArray {
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indices: arena.copy_slice(&indices),
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aprx_energy: aprx_energy,
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}
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}
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}
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impl<'a> LightAccel for LightArray<'a> {
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fn select(
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&self,
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inc: Vector,
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pos: Point,
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nor: Normal,
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nor_g: Normal,
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sc: &SurfaceClosure,
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time: f32,
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n: f32,
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) -> Option<(usize, f32, f32)> {
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let _ = (inc, pos, nor, nor_g, sc, time); // Not using these, silence warnings
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assert!(n >= 0.0 && n <= 1.0);
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if self.indices.is_empty() {
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return None;
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}
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let n2 = n * self.indices.len() as f32;
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let i = if n == 1.0 {
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*self.indices.last().unwrap()
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} else {
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self.indices[n2 as usize]
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};
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let whittled_n = n2 - i as f32;
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let pdf = 1.0 / self.indices.len() as f32;
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Some((i, pdf, whittled_n))
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}
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fn approximate_energy(&self) -> f32 {
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self.aprx_energy
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}
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}
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