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2d improved perlin

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a dinosaur
2024-09-01 18:19:42 +10:00
parent 64fcebf4e5
commit cb0e7bb232
1 changed files with 38 additions and 11 deletions
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49
Sources/Voxelotl/Random/PerlinNoiseGenerator.swift
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@ -1,6 +1,6 @@
import Foundation
public struct ImprovedPerlin<T: BinaryFloatingPoint & SIMDScalar>: CoherentNoise3D {
public struct ImprovedPerlin<T: BinaryFloatingPoint & SIMDScalar>: CoherentNoise2D, CoherentNoise3D {
private let p: [Int16]
public init(permutation: [Int16]) {
@ -12,6 +12,31 @@ public struct ImprovedPerlin<T: BinaryFloatingPoint & SIMDScalar>: CoherentNoise
self.p = (0..<0x100).map { Int16($0) }.shuffled(using: &random)
}
public func get(_ point: SIMD2<T>) -> T {
// Find unit square
let idx = SIMD2(Int(floor(point.x)), Int(floor(point.y))) & 0xFF
// Find relative point in square
let inner = point - SIMD2(floor(point.x), floor(point.y))
// Compute fade curves for each axis
let u = inner.x.smootherStep()
let v = inner.y.smootherStep()
// Compute hash of the coordinates of the 4 square corners
let a = idx.y + perm(idx.x), b = idx.y + perm(idx.x + 1)
let aa = perm(a), ab = perm(a + 1)
let ba = perm(b), bb = perm(b + 1)
// Add blended results
return v.mlerp(
u.mlerp(
grad(perm(aa), inner),
grad(perm(ba), .init(inner.x - 1, inner.y))),
u.mlerp(
grad(perm(ab), .init(inner.x, inner.y - 1)),
grad(perm(bb), inner - .init(repeating: 1))))
}
public func get(_ point: SIMD3<T>) -> T {
// Find unit cube containg point
let idx = SIMD3(Int(floor(point.x)), Int(floor(point.y)), Int(floor(point.z))) & 0xFF
@ -45,17 +70,19 @@ public struct ImprovedPerlin<T: BinaryFloatingPoint & SIMDScalar>: CoherentNoise
u.mlerp(
grad(perm(ab + 1), .init(inner.x, inner.y - 1, inner.z - 1)),
grad(perm(bb + 1), inner - .init(repeating: 1)))))
}
@inline(__always) func perm(_ x: Int) -> Int { Int(self.p[x & 0xFF]) }
@inline(__always) fileprivate func perm(_ x: Int) -> Int { Int(self.p[x & 0xFF]) }
func grad(_ hash: Int, _ point: SIMD3<T>) -> T {
// Convert low 4 bits of hash code into 12 gradient directions
let low4 = hash & 0xF
var u = low4 < 8 ? point.x : point.y
var v = low4 < 4 ? point.y : (low4 == 0b1100 || low4 == 0b1110 ? point.x : point.z)
u = (low4 & 0x1) == 0 ? u : -u
v = (low4 & 0x2) == 0 ? v : -v
return u + v
}
@inline(__always) fileprivate func grad(_ hash: Int, _ point: SIMD2<T>) -> T { grad(hash, SIMD3(point, 0)) }
fileprivate func grad(_ hash: Int, _ point: SIMD3<T>) -> T {
// Convert low 4 bits of hash code into 12 gradient directions
let low4 = hash & 0xF
var u = low4 < 8 ? point.x : point.y
var v = low4 < 4 ? point.y : (low4 == 0b1100 || low4 == 0b1110 ? point.x : point.z)
u = (low4 & 0x1) == 0 ? u : -u
v = (low4 & 0x2) == 0 ? v : -v
return u + v
}
}