Closed
Description
Since commit 87b0b5e we can generate bootstrap paths multi-threaded. While debugging something else I figured that the generated bootstrap samples differ slightly between the C++ and Rust version. To dig deeper into the problem I modified both versions to print out very specialized information regarding the test scene (assets/scenes/caustic.pbrt) and the resulting bootstrap samples.
In Rust (src/core/sampling.rs):
impl Distribution1D {
pub fn new(f: Vec<Float>) -> Self {
let n: i32 = f.len() as i32;
// compute integral of step function at $x_i$
let mut cdf: Vec<Float> = Vec::with_capacity(n as usize + 1);
cdf.push(0.0 as Float);
for i in 1..(n + 1) {
...
if n == 600000 && f[(i - 1) as usize] > 0.0 as Float {
println!("f[{:?}] = {1:2.8}", i - 1, f[(i - 1) as usize]);
}
}
...
}
...
}In C++ (src/core/sampling.h):
struct Distribution1D {
// Distribution1D Public Methods
Distribution1D(const Float *f, int n) : func(f, f + n), cdf(n + 1) {
// Compute integral of step function at $x_i$
cdf[0] = 0;
for (int i = 1; i < n + 1; ++i) {
if (n == 600000 && f[i - 1] > 0.0) {
printf("f[%d] = %2.8f\n", i - 1, f[i - 1]);
}
...
}
...
};I will attach the resulting difference between both versions to the issue and report on any progress ...