From 80b9aacea7bccb62775b09fe1667087393a0945a Mon Sep 17 00:00:00 2001 From: Claude Date: Tue, 27 Oct 2026 15:34:34 -0500 Subject: [PATCH] G1: Turbulent Displace Evolution changes the output (#943) Turbulent Displace read its noise through value_noise, whose quintic fade also eased the evolution axis. Near every whole revolution the pattern hardly moved: Evolution 0 and 37 degrees (or 360 and 400) differed by well under a hundredth of the frame, so different Evolution values looked identical, and the motion sped up and slowed down within each revolution (the #1816 symptom). Add value_noise_linear_z (x and y keep the fade, z is linear) on the CPU and in the WGSL kernels and use it for Turbulent Displace on both paths. value_noise is unchanged, so the other effects and the pinned simulation goldens are unaffected. Tests: CPU test that non-equivalent Evolution values (fractional, past 360, past 720) all differ and that Cycle Evolution still matches 0/360; unit test of the linear z axis; GPU-vs-CPU cases at small and large Evolution. Co-Authored-By: Claude Sonnet 5.5 Claude-Session: https://claude.ai/code/session_01FYXhNN7W7nB6sKjwwU7CDM --- crates/effects/src/distort2.rs | 45 ++++++++++++++++++++++++-- crates/effects/src/generate.rs | 37 +++++++++++++++++++-- crates/gpu/src/shaders/fx_distort.wgsl | 2 +- crates/gpu/src/shaders/kernels.wgsl | 15 ++++++++- crates/gpu/src/tests/fx_distort.rs | 5 +++ 5 files changed, 98 insertions(+), 6 deletions(-) diff --git a/crates/effects/src/distort2.rs b/crates/effects/src/distort2.rs index 10ec59735..db413544b 100644 --- a/crates/effects/src/distort2.rs +++ b/crates/effects/src/distort2.rs @@ -19,7 +19,7 @@ use effectcraft_project::ParamUi; use effectcraft_raster::{Image, Px}; use rayon::prelude::*; -use crate::generate::value_noise; +use crate::generate::value_noise_linear_z; use crate::util::{SRC_NAMES, Src, fit_layer, layer_cover_pad, layer_rect, lerp4, map_xy, pick, premul, remap, smoothstep, src_at, unpremul}; use crate::{Buf, EffectCtx, EffectSpec, col, num, p, popup, slider}; @@ -37,13 +37,15 @@ fn pct(max: f64) -> ParamUi { // ---------------------------------------------------------------- Turbulent Displace +/// Fractional-octave fBm of value noise in 0..1. Evolution (`z`) is linear: with the eased z of +/// plain value noise a few degrees of Evolution barely moved the pattern (#943). fn fbm(u: f64, v: f64, z: f64, seed: u32, octaves: f64, falloff: f32) -> f32 { let n = octaves.ceil().max(1.0) as usize; let frac = (octaves - octaves.floor()) as f32; let (mut sum, mut norm, mut amp, mut f) = (0.0f32, 0.0f32, 1.0f32, 1.0f32); for o in 0..n { let w = if o + 1 == n && frac > 0.0 { frac } else { 1.0 }; - sum += value_noise(u as f32 * f, v as f32 * f, z as f32 + o as f32 * 5.17, seed.wrapping_add(o as u32 * 101)) * amp * w; + sum += value_noise_linear_z(u as f32 * f, v as f32 * f, z as f32 + o as f32 * 5.17, seed.wrapping_add(o as u32 * 101)) * amp * w; norm += amp * w; amp *= falloff; f *= 2.0; @@ -1115,6 +1117,45 @@ mod tests { assert_eq!(TURBULENT_PINNING[11], "Pin Left Locked"); } + /// #943: every non-equivalent Evolution value renders a visibly different frame. The eased + /// evolution axis left 0 and 37 degrees (or 360 and 400) within a hundredth of each other. + #[test] + fn turbulent_displace_evolution_changes_the_output() { + // A smooth ramp (red = x, green = y) with Pin All Locked, so the frame stays opaque and + // the difference is purely how far the pattern moved. + let mut ramp = Image::new(64, 64); + for y in 0..64u32 { + for x in 0..64u32 { + ramp.set(x, y, [x as f32 / 63.0, y as f32 / 63.0, 0.25, 1.0]); + } + } + let render = |evo: f64, extra: &[(&str, Value)]| { + let base = [("evolution", num(evo)), ("size", num(10.0)), ("pinning", Value::Enum(8))]; + run("ec.distort.turbulentdisplace", &[base.as_slice(), extra].concat(), ramp.clone()).img + }; + let evolutions = [0.0, 37.0, 90.5, 180.0, 360.0, 400.25, 725.0, 1000.5]; + let frames: Vec = evolutions.iter().map(|&e| render(e, &[])).collect(); + for (i, a) in frames.iter().enumerate() { + for (j, b) in frames.iter().enumerate().skip(i + 1) { + let d = max_diff(a, b); + assert!(d > 0.01, "evolution {} and {} differ by only {d}", evolutions[i], evolutions[j]); + } + } + // Constant rate: 20 degrees next to a whole revolution (from either side) is a visible + // step, not the rounding-error size the eased axis gave (under 0.001). + assert!(max_diff(&frames[0], &render(20.0, &[])) > 0.02); + assert!(max_diff(&render(340.0, &[]), &frames[4]) > 0.02); + // 0 and 360 degrees are different frames without Cycle Evolution, and the same frame with + // Cycle (in Revolutions) = 1, at any starting angle. + assert!(max_diff(&frames[0], &frames[4]) > 0.01); + let cycle = [("evolutionOptions/cycleEvolution", Value::Bool(true)), ("evolutionOptions/cycle", num(1.0))]; + assert!(max_diff(&render(0.0, &cycle), &render(360.0, &cycle)) < 1e-4); + assert!(max_diff(&render(37.0, &cycle), &render(397.0, &cycle)) < 1e-4); + assert!(max_diff(&render(0.0, &cycle), &render(37.0, &cycle)) > 0.01); + // Random Seed still gives a different pattern at the same Evolution. + assert!(max_diff(&frames[1], &render(37.0, &[("evolutionOptions/randomSeed", num(5.0))])) > 0.01); + } + #[test] fn magnify_blending_none_and_scaling() { let img = test_img(32, 32); diff --git a/crates/effects/src/generate.rs b/crates/effects/src/generate.rs index 637cc428e..ae0d61861 100644 --- a/crates/effects/src/generate.rs +++ b/crates/effects/src/generate.rs @@ -292,10 +292,22 @@ pub(crate) fn fade(t: f32) -> f32 { t * t * t * (t * (t * 6.0 - 15.0) + 10.0) } -/// 3D value noise in 0..1 (z = evolution). +/// 3D value noise in 0..1 (z = evolution). The quintic fade applies on all three axes, so z +/// eases in and out of every integer. pub fn value_noise(x: f32, y: f32, z: f32, seed: u32) -> f32 { + value_noise_z(x, y, z, seed, true) +} + +/// [`value_noise`] with the evolution axis z interpolated linearly (x and y keep the quintic +/// fade). The fade's zero slope at every integer z made a small Evolution change almost invisible +/// next to a whole revolution (#943, #1816); linear z moves the pattern at a constant rate. +pub fn value_noise_linear_z(x: f32, y: f32, z: f32, seed: u32) -> f32 { + value_noise_z(x, y, z, seed, false) +} + +fn value_noise_z(x: f32, y: f32, z: f32, seed: u32, ease_z: bool) -> f32 { let (x0, y0, z0) = (x.floor(), y.floor(), z.floor()); - let (fx, fy, fz) = (fade(x - x0), fade(y - y0), fade(z - z0)); + let (fx, fy, fz) = (fade(x - x0), fade(y - y0), if ease_z { fade(z - z0) } else { z - z0 }); let (ix, iy, iz) = (x0 as i32, y0 as i32, z0 as i32); let l = |a: f32, b: f32, t: f32| a + (b - a) * t; let c = |dx: i32, dy: i32, dz: i32| lattice(ix + dx, iy + dy, iz + dz, seed); @@ -414,6 +426,27 @@ mod generator_tests { Image::filled(32, 32, [1.0, 0.0, 0.0, 1.0]) } + /// #943: the evolution axis is linear, so z moves the noise at a constant rate, while the + /// classic `value_noise` keeps its eased z (other effects and their pinned goldens use it). + #[test] + fn linear_z_value_noise_moves_at_a_constant_rate() { + for (x, y, seed) in [(0.3f32, 0.7f32, 5u32), (2.4, -1.6, 11), (-3.1, 4.9, 0)] { + let a = value_noise_linear_z(x, y, 0.0, seed); + let b = value_noise_linear_z(x, y, 1.0, seed); + for z in [0.1f32, 0.25, 0.5, 0.75, 0.9] { + let want = a + (b - a) * z; + let got = value_noise_linear_z(x, y, z, seed); + assert!((got - want).abs() < 1e-5, "({x}, {y}) z {z}: {got} vs {want}"); + } + // Same lattice values at whole z, and x / y are untouched. + assert_eq!(value_noise_linear_z(x, y, 2.0, seed), value_noise(x, y, 2.0, seed)); + } + // The eased version still has the old shape: at z = 0.25 it lags the linear one. + let (a, b) = (value_noise(0.3, 0.7, 0.0, 5), value_noise(0.3, 0.7, 1.0, 5)); + let eased = value_noise(0.3, 0.7, 0.25, 5); + assert!((eased - (a + (b - a) * 0.25)).abs() > 1e-3); + } + #[test] fn gradient_ramp_stays_inside_the_layer_alpha() { // #1063: a shape's transparent pixels stay transparent; the ramp fills only the shape. diff --git a/crates/gpu/src/shaders/fx_distort.wgsl b/crates/gpu/src/shaders/fx_distort.wgsl index 5fbc76b4b..5e9e20a12 100644 --- a/crates/gpu/src/shaders/fx_distort.wgsl +++ b/crates/gpu/src/shaders/fx_distort.wgsl @@ -238,7 +238,7 @@ fn dst_fbm(u: f32, v: f32, z: f32, seed: u32) -> f32 { if (o + 1u == n && frac > 0.0) { w = frac; } - sum += value_noise(u * f, v * f, z + f32(o) * 5.17, seed + o * 101u) * amp * w; + sum += value_noise_linear_z(u * f, v * f, z + f32(o) * 5.17, seed + o * 101u) * amp * w; norm += amp * w; amp *= falloff; f *= 2.0; diff --git a/crates/gpu/src/shaders/kernels.wgsl b/crates/gpu/src/shaders/kernels.wgsl index 5bb69693e..81c82bcf1 100644 --- a/crates/gpu/src/shaders/kernels.wgsl +++ b/crates/gpu/src/shaders/kernels.wgsl @@ -509,12 +509,25 @@ fn fade(t: f32) -> f32 { } fn value_noise(x: f32, y: f32, z: f32, seed: u32) -> f32 { + return value_noise_z(x, y, z, seed, true); +} + +// effects::generate::value_noise_linear_z: z (evolution) interpolates linearly, x and y keep the +// quintic fade (Turbulent Displace, #943). +fn value_noise_linear_z(x: f32, y: f32, z: f32, seed: u32) -> f32 { + return value_noise_z(x, y, z, seed, false); +} + +fn value_noise_z(x: f32, y: f32, z: f32, seed: u32, ease_z: bool) -> f32 { let x0 = floor(x); let y0 = floor(y); let z0 = floor(z); let fx = fade(x - x0); let fy = fade(y - y0); - let fz = fade(z - z0); + var fz = z - z0; + if (ease_z) { + fz = fade(fz); + } let ix = i32(x0); let iy = i32(y0); let iz = i32(z0); diff --git a/crates/gpu/src/tests/fx_distort.rs b/crates/gpu/src/tests/fx_distort.rs index 19cdcd605..1b8621408 100644 --- a/crates/gpu/src/tests/fx_distort.rs +++ b/crates/gpu/src/tests/fx_distort.rs @@ -55,6 +55,11 @@ fn turbulent_displace_and_cc_lens() { ], ); effect_case("ec.distort.turbulentdisplace", &[("displacement", e(8)), ("size", n(15.0)), ("pinning", e(6))]); + // #943: Evolution moves the pattern at a constant rate on both paths, including steps of a + // few degrees and angles past a whole revolution, where an eased evolution axis diverges. + for evolution in [10.0, 37.0, 400.0, 725.5] { + effect_case("ec.distort.turbulentdisplace", &[("evolution", n(evolution)), ("size", n(12.0)), ("amount", n(30.0))]); + } effect_case("ec.distort.cclens", &[("size", n(70.0))]); effect_case("ec.distort.cclens", &[("size", n(45.0)), ("convergence", n(60.0)), ("center", Value::Vec2([30.0, 20.0]))]); effect_case("ec.distort.cclens", &[("convergence", n(-70.0))]);