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Perlin noise with dot product.

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This commit is contained in:
Bill Thiede 2018-09-23 09:51:46 -07:00
parent 697d056a9d
commit 415cb7be9a
2 changed files with 36 additions and 26 deletions
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56
rtiow/src/perlin.rs
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@ -3,6 +3,7 @@ use rand::Rng;
//use rand::SeedableRng;
//use rand::XorShiftRng;
use vec3::dot;
use vec3::Vec3;
lazy_static! {
@ -11,16 +12,23 @@ lazy_static! {
//const SEED: [u8; 16] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
pub struct Perlin {
ranfloat: Vec<f32>,
ran_vec: Vec<Vec3>,
perm_x: Vec<usize>,
perm_y: Vec<usize>,
perm_z: Vec<usize>,
}
fn perlin_generate() -> Vec<f32> {
fn perlin_generate() -> Vec<Vec3> {
//let mut rng: XorShiftRng = SeedableRng::from_seed(SEED);
let mut rng = rand::thread_rng();
(0..256).map(|_| rng.gen_range::<f32>(0., 1.)).collect()
(0..256)
.map(|_| {
Vec3::new(
rng.gen_range::<f32>(-1., 1.),
rng.gen_range::<f32>(-1., 1.),
rng.gen_range::<f32>(-1., 1.),
).unit_vector()
}).collect()
}
fn permute(p: &mut Vec<usize>, n: usize) {
@ -41,18 +49,25 @@ fn perlin_generate_perm() -> Vec<usize> {
p
}
fn trilinear_interp(c: [[[f32; 2]; 2]; 2], u: f32, v: f32, w: f32) -> f32 {
fn perlin_interp(c: [[[Vec3; 2]; 2]; 2], u: f32, v: f32, w: f32) -> f32 {
// Hermite cubic to round off interpolation and attempt to address 'mach bands'.
let uu = u * u * (3. - 2. * u);
let vv = v * v * (3. - 2. * v);
let ww = w * w * (3. - 2. * w);
let mut accum = 0.;
for i in 0..2 {
for j in 0..2 {
for k in 0..2 {
let fi = i as f32;
let fj = j as f32;
let fk = k as f32;
accum += (fi * u + (1. - fi) * (1. - u))
* (fj * v + (1. - fj) * (1. - v))
* (fk * w + (1. - fk) * (1. - w))
* c[i][j][k];
let weight_v = Vec3::new(u - i as f32, v - j as f32, w - k as f32);
let i = i as f32;
let j = j as f32;
let k = k as f32;
accum += (i * uu + (1. - i) * (1. - uu))
* (j * vv + (1. - j) * (1. - vv))
* (k * ww + (1. - k) * (1. - ww))
* dot(c[i as usize][j as usize][k as usize], weight_v);
}
}
}
@ -62,7 +77,7 @@ fn trilinear_interp(c: [[[f32; 2]; 2]; 2], u: f32, v: f32, w: f32) -> f32 {
impl Perlin {
fn new() -> Perlin {
Perlin {
ranfloat: perlin_generate(),
ran_vec: perlin_generate(),
perm_x: perlin_generate_perm(),
perm_y: perlin_generate_perm(),
perm_z: perlin_generate_perm(),
@ -70,29 +85,24 @@ impl Perlin {
}
pub fn noise(&self, p: Vec3) -> f32 {
let mut u = p.x - p.x.floor();
let mut v = p.y - p.y.floor();
let mut w = p.z - p.z.floor();
// Hermite cubic to round off interpolation and attempt to address 'mach bands'.
u = u * u * (3. - 2. * u);
v = v * v * (3. - 2. * v);
w = w * w * (3. - 2. * w);
let u = p.x - p.x.floor();
let v = p.y - p.y.floor();
let w = p.z - p.z.floor();
let i = p.x.floor() as usize;
let j = p.y.floor() as usize;
let k = p.z.floor() as usize;
let mut c: [[[f32; 2]; 2]; 2] = Default::default();
let mut c: [[[Vec3; 2]; 2]; 2] = Default::default();
for di in 0..2 {
for dj in 0..2 {
for dk in 0..2 {
c[di][dj][dk] = self.ranfloat[self.perm_x[(i + di) & 255]
c[di][dj][dk] = self.ran_vec[self.perm_x[(i + di) & 255]
^ self.perm_y[(j + dj) & 255]
^ self.perm_z[(k + dk) & 255]]
}
}
}
trilinear_interp(c, u, v, w)
perlin_interp(c, u, v, w)
}
}

2
rtiow/src/texture.rs
View File

@ -58,6 +58,6 @@ impl NoiseTexture {
impl Texture for NoiseTexture {
fn value(&self, _u: f32, _v: f32, p: Vec3) -> Vec3 {
Vec3::new(1., 1., 1.) * GENERATOR.noise(self.scale * p)
Vec3::new(1., 1., 1.) * 0.5 * (1. + GENERATOR.noise(self.scale * p))
}
}