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Octahedron normals #18

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Octahedron normals #18

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07940fe
small refactor, fix test angle calculation
CptPotato Jun 4, 2023
8f4e186
WIP octahedron normal encoding
CptPotato Jun 8, 2023
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146 changes: 56 additions & 90 deletions src/normals.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ impl NormalPrecisionMode {
/// let dev_5_deg = NormalPrecisionMode::from_deg_dev(5.0);
/// ```
pub fn from_deg_dev(deg: FloatType) -> Self {
// TODO: use correct calculation here
let prec = ((90.0 / deg).log2().ceil() as u8).max(1);
Self(prec)
}
Expand All @@ -34,6 +35,7 @@ impl NormalPrecisionMode {
/// let dev_0_point_05_rad = NormalPrecisionMode::from_rad_dev(0.05);
/// ```
pub fn from_rad_dev(rad: FloatType) -> Self {
// TODO: use correct calculation here
let prec = (FRAC_PI_2 / rad).log2().ceil() as u8;
Self(prec)
}
Expand Down Expand Up @@ -64,73 +66,40 @@ pub fn normalize_arr(normals: &mut [Vector3]) {
*normal = normalize(*normal);
}
}
pub(crate) fn normal_to_encoding(
normal: Vector3,
precision: &NormalPrecisionMode,
) -> (u64, u64, bool, bool, bool) {
pub(crate) fn normal_to_encoding(normal: Vector3, precision: &NormalPrecisionMode) -> (u64, u64) {
let multiplier = ((1 << precision.0) - 1) as FloatType;
//Calculate asine
let xy = (normal.0.abs(), normal.1.abs());
let xy_mag = (xy.0 * xy.0 + xy.1 * xy.1).sqrt();
let xy = (xy.0 / xy_mag, xy.1 / xy_mag);
let asine = xy.0.asin();

let asine = asine / (PI / 2.0);
//
let asine = (asine * multiplier) as u64;
let z = (normal.2.abs() * multiplier) as u64;
let sx = normal.0 < 0.0;
let sy = normal.1 < 0.0;
let sz = normal.2 < 0.0;
(asine, z, sx, sy, sz)
let norm = normal.0.abs() + normal.1.abs() + normal.2.abs();
let mut nx = normal.0 / norm;
let mut ny = normal.1 / norm;
if !normal.2.is_sign_positive() {
// fold over negative z
(nx, ny) = ((1.0 - ny.abs()) * nx.signum(),
(1.0 - nx.abs()) * ny.signum());
}
nx = (nx * 0.5 + 0.5) * multiplier;
ny = (ny * 0.5 + 0.5) * multiplier;
(nx as u64, ny as u64)
}
pub(crate) fn normal_from_encoding(
asine: u64,
z: u64,
sx: bool,
sy: bool,
sz: bool,
precision: NormalPrecisionMode,
) -> Vector3 {
pub(crate) fn normal_from_encoding(a: u64, b: u64, precision: NormalPrecisionMode) -> Vector3 {
let divisor = ((1_u64 << precision.0) - 1) as FloatType;
//Read raw asine
let asine = (asine as FloatType) / divisor;
//Convert asine form 0-1 to 0-tau
let asine = asine * (PI / 2.0);
//Read xyz component
let z = (z as FloatType) / divisor;
#[cfg(feature = "fast_trig")]
let x = fsin(asine as fprec) as FloatType;
#[cfg(feature = "fast_trig")]
let y = (1.0 - x * x).sqrt();
#[cfg(not(feature = "fast_trig"))]
let (x, y) = asine.sin_cos();
// Calculate XY magnitude
let xy_mag = (1.0 - z * z).sqrt();
// Adjust x an y
let y = y * xy_mag;
let x = x * xy_mag;
// Set signs
let x = if sx { -x } else { x };
let y = if sy { -y } else { y };
let z = if sz { -z } else { z };
(x, y, z)
let mut x = (a as FloatType) / divisor * 2.0 - 1.0;
let mut y = (b as FloatType) / divisor * 2.0 - 1.0;
let z = 1.0 - x.abs() - y.abs();
x += x.signum() * z.min(0.0);
y += y.signum() * z.min(0.0);
normalize((x, y, z))
}
const PI: FloatType = std::f64::consts::PI as FloatType;
#[inline(always)]
fn save_normal<W: Write>(
normal: Vector3,
precision: NormalPrecisionMode,
writer: &mut UnalignedWriter<W>,
) -> std::io::Result<()> {
let (asine, z, sx, sy, sz) = normal_to_encoding(normal, &precision);
let (a, b) = normal_to_encoding(normal, &precision);
let main_prec = UnalignedRWMode::precision_bits(precision.0);

writer.write_bit(sx)?;
writer.write_bit(sy)?;
writer.write_bit(sz)?;
writer.write_unaligned(main_prec, asine)?;
writer.write_unaligned(main_prec, z)?;
writer.write_unaligned(main_prec, a)?;
writer.write_unaligned(main_prec, b)?;

Ok(())
}
Expand All @@ -140,12 +109,8 @@ fn read_normal<R: Read>(
reader: &mut UnalignedReader<R>,
) -> std::io::Result<Vector3> {
let main_prec = UnalignedRWMode::precision_bits(precision.0);
// Get signs of x y z component
let sx = reader.read_bit()?;
let sy = reader.read_bit()?;
let sz = reader.read_bit()?;
let (asine, z) = reader.read2_unaligned(main_prec)?;
Ok(normal_from_encoding(asine, z, sx, sy, sz, precision))
let (a, b) = reader.read2_unaligned(main_prec)?;
Ok(normal_from_encoding(a, b, precision))
}
pub(crate) fn save_normal_array<W: Write>(
normals: &[Vector3],
Expand Down Expand Up @@ -184,25 +149,43 @@ pub(crate) fn read_normal_array<R: Read>(reader: &mut R) -> Result<Box<[Vector3]
#[cfg(test)]
mod test_normal {
use super::*;
pub const NORM_PREC_HIGH: NormalPrecisionMode = NormalPrecisionMode(13);
const NORM_PREC_HIGH: NormalPrecisionMode = NormalPrecisionMode(13);
const PI: FloatType = std::f64::consts::PI as FloatType;
fn dot(a: Vector3, b: Vector3) -> FloatType {
a.0 * b.0 + a.1 * b.1 + a.2 * b.2
}
/// Angle between two vectors in degrees.
fn ang_between(a: Vector3, b: Vector3) -> FloatType {
dot(a, b).clamp(0.0, 1.0).acos() * 180.0 / PI
}
fn test_save(normal: Vector3) {
let mut res = Vec::with_capacity(64);
let precision = NormalPrecisionMode(14);
let precision = NormalPrecisionMode::from_deg_dev(0.01);
{
let mut writter = UnalignedWriter::new(&mut res);
save_normal(normal, precision, &mut writter).unwrap();
let mut writer = UnalignedWriter::new(&mut res);
save_normal(normal, precision, &mut writer).unwrap();
}
let mut reader = UnalignedReader::new(&res as &[u8]);
let r_normal = read_normal(precision, &mut reader).unwrap();
let n_dot = (1.0 - dot(r_normal, normal)) * 180.0;
let ang_diff = ang_between(r_normal, normal);
assert!(
n_dot < 0.01,
"expected:{normal:?} != read:{r_normal:?} angle:{n_dot}"
ang_diff < 0.01,
"expected:{normal:?} != read:{r_normal:?} angle:{ang_diff}"
);
}
/// Generator function for random normals (normalized).
fn random_normals() -> impl Iterator<Item = Vector3> {
use rand::{thread_rng, Rng};
let mut rng = thread_rng();
std::iter::from_fn(move || {
Some((
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
))
})
.map(normalize)
}
#[test]
fn x_axis_rw() {
test_save((1.0, 0.0, 0.0));
Expand All @@ -220,15 +203,7 @@ mod test_normal {
}
#[test]
fn random_axis_rw() {
use rand::{thread_rng, Rng};
let mut rng = thread_rng();
for _ in 0..100_000 {
let norm = (
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
);
let norm = normalize(norm);
for norm in random_normals().take(100_000) {
test_save(norm);
}
}
Expand All @@ -238,25 +213,16 @@ mod test_normal {
let mut rng = thread_rng();
let count = ((rng.gen::<crate::IndexType>() % 0x800) + 0x800) as usize;
let mut res = Vec::with_capacity(count);
let mut normals = Vec::with_capacity(count);
for _ in 0..count {
let norm = (
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
rng.gen::<FloatType>() * 2.0 - 1.0,
);
let norm = normalize(norm);
normals.push(norm);
}
let normals: Vec<_> = random_normals().take(count).collect();
save_normal_array(&normals, &mut res, NORM_PREC_HIGH).unwrap();
let r_normals = read_normal_array(&mut (&res as &[u8])).unwrap();
for i in 0..count {
let r_normal = r_normals[i];
let normal = normals[i];
let n_dot = (1.0 - dot(r_normal, normal)) * 180.0;
let ang_diff = ang_between(r_normal, normal);
assert!(
n_dot < 0.1,
"expected:{normal:?} != read:{r_normal:?} angle:{n_dot}"
ang_diff < 0.1,
"expected:{normal:?} != read:{r_normal:?} angle:{ang_diff}"
);
}
}
Expand Down
46 changes: 12 additions & 34 deletions src/tangents.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,25 +42,13 @@ fn ht_from_bool(src: bool) -> HandednessType {
}
/// A representation of a Tangent.
pub type Tangent = (crate::Vector3, HandednessType);
fn tangent_to_encoding(
tangent: Tangent,
prec: TangentPrecisionMode,
) -> (u64, u64, bool, bool, bool, bool) {
fn tangent_to_encoding(tangent: Tangent, prec: TangentPrecisionMode) -> (u64, u64, bool) {
let normal = crate::normals::normal_to_encoding(tangent.0, &prec.normal_precision());
let handeness = ht_to_bool(tangent.1);
(normal.0, normal.1, normal.2, normal.3, normal.4, handeness)
}
fn tangent_from_encoding(
asine: u64,
z: u64,
sx: bool,
sy: bool,
sz: bool,
handenes: bool,
prec: TangentPrecisionMode,
) -> Tangent {
let normal =
crate::normals::normal_from_encoding(asine, z, sx, sy, sz, prec.normal_precision());
(normal.0, normal.1, handeness)
}
fn tangent_from_encoding(a: u64, b: u64, handenes: bool, prec: TangentPrecisionMode) -> Tangent {
let normal = crate::normals::normal_from_encoding(a, b, prec.normal_precision());
let handeness = ht_from_bool(handenes);
(normal, handeness)
}
Expand All @@ -76,13 +64,10 @@ pub(crate) fn save_tangents<W: std::io::Write>(
let mut writer = UnalignedWriter::new(target);
let bits_prec = UnalignedRWMode::precision_bits(bits_prec);
for tangent in tangents {
let (asine, z, sx, sy, sz, handeness) = tangent_to_encoding(*tangent, prec);
let (a, b, handeness) = tangent_to_encoding(*tangent, prec);
writer.write_bit(handeness)?;
writer.write_bit(sx)?;
writer.write_bit(sy)?;
writer.write_bit(sz)?;
writer.write_unaligned(bits_prec, asine)?;
writer.write_unaligned(bits_prec, z)?;
writer.write_unaligned(bits_prec, a)?;
writer.write_unaligned(bits_prec, b)?;
}
writer.flush()?;
Ok(())
Expand All @@ -96,23 +81,16 @@ pub(crate) fn read_tangents<R: std::io::Read>(src: &mut R) -> std::io::Result<Bo
let mut tangents = Vec::with_capacity(count as usize);
for _ in 0..count {
let handeness = reader.read_bit()?;
let sx = reader.read_bit()?;
let sy = reader.read_bit()?;
let sz = reader.read_bit()?;
let asine = reader.read_unaligned(prec)?;
let z = reader.read_unaligned(prec)?;
tangents.push(tangent_from_encoding(
asine, z, sx, sy, sz, handeness, tan_prec,
));
let a = reader.read_unaligned(prec)?;
let b = reader.read_unaligned(prec)?;
tangents.push(tangent_from_encoding(a, b, handeness, tan_prec));
}
Ok(tangents.into())
}
#[cfg(test)]
fn test_tangent(tangent: Tangent, prec: TangentPrecisionMode) -> FloatType {
let encoded = tangent_to_encoding(tangent, prec);
let decoded = tangent_from_encoding(
encoded.0, encoded.1, encoded.2, encoded.3, encoded.4, encoded.5, prec,
);
let decoded = tangent_from_encoding(encoded.0, encoded.1, encoded.2, prec);
assert_eq!(ht_to_bool(tangent.1), ht_to_bool(decoded.1));
(1.0 - crate::utilis::dot(decoded.0, tangent.0)) * 180.0
}
Expand Down