diff --git a/crates/render/src/lib.rs b/crates/render/src/lib.rs index eccaed2f4..8b9671e43 100644 --- a/crates/render/src/lib.rs +++ b/crates/render/src/lib.rs @@ -2420,6 +2420,8 @@ mod tests_mask_blur; #[cfg(test)] mod tests_mask_expansion; #[cfg(test)] +mod tests_mask_feather; +#[cfg(test)] mod tests_nested; #[cfg(test)] mod tests_paint; diff --git a/crates/render/src/masks.rs b/crates/render/src/masks.rs index bb91ef71d..04a6e63e9 100644 --- a/crates/render/src/masks.rs +++ b/crates/render/src/masks.rs @@ -60,6 +60,86 @@ fn coverage(ctx: &EvalCtx, layer: &Layer, g: &effectcraft_project::PropGroup, bu coverage_at(ctx, layer, g, buf) } +/// The largest feather taken, in buffer pixels (larger and non-finite values are clamped). +const MAX_FEATHER_PX: f64 = 1.0e6; +/// Up to this Gaussian sigma (box radius for a linear falloff: twice it) a feather is blurred at +/// the buffer's resolution. A wider one is blurred on a grid coarser per axis by the factor that +/// leaves it about `COARSE_SIGMA` grid pixels (2x for the box radius): a wide blur is smooth, so +/// the coarse grid loses nothing visible, and the padding stays about 50 grid pixels. +const FULL_RES_SIGMA: f64 = 32.0; +const COARSE_SIGMA: f64 = 16.0; +/// The largest padded grid (pixels); a bigger one (only reachable with a huge buffer) falls back +/// to blurring within the buffer. +const MAX_GRID_PX: usize = 1 << 26; +/// Padding for a variable-width feather, which is rasterised at the buffer's resolution. +const MAX_VARIABLE_PAD: usize = 256; + +/// One axis of the grid a feathered mask is rasterised and blurred on: `step` buffer pixels per +/// grid pixel, `pad` grid pixels on each side of the buffer, and the blur in grid pixels. +#[derive(Clone, Copy, Debug, PartialEq)] +struct Axis { + step: usize, + pad: usize, + /// Gaussian sigma, or the box radius of a linear falloff. + blur: f64, +} + +impl Axis { + /// `feather` in buffer pixels. The pad covers the blur's whole support, so the coverage of + /// the path outside the buffer reaches into it as on an unbounded plane. + fn new(feather: f64, linear: bool, full_res_only: bool) -> Axis { + let f = if feather.is_finite() { feather.clamp(0.0, MAX_FEATHER_PX) } else { 0.0 }; + if f <= 0.0 { + return Axis { step: 1, pad: 0, blur: 0.0 }; + } + if linear { + // One box pass: a straight ramp `feather` pixels wide across the edge. + let r = (f / 2.0).round().max(1.0); + let step = if full_res_only || r <= 2.0 * FULL_RES_SIGMA { 1 } else { (r / (2.0 * COARSE_SIGMA)).ceil() as usize }; + let rg = (r / step as f64).round().max(1.0); + let pad = rg as usize; + Axis { step, pad: if full_res_only { pad.min(MAX_VARIABLE_PAD) } else { pad }, blur: rg } + } else { + let sigma = f / 2.0; + let step = if full_res_only || sigma <= FULL_RES_SIGMA { 1 } else { (sigma / COARSE_SIGMA).ceil() as usize }; + let sg = sigma / step as f64; + // Three box passes of radii summing to at most 1.5 * (sqrt(4 sigma^2 + 1) + 1) <= 3 sigma + 3. + let pad = (3.0 * sg).ceil() as usize + 3; + Axis { step, pad: if full_res_only { pad.min(MAX_VARIABLE_PAD) } else { pad }, blur: sg } + } + } + + /// Grid pixels for `n` buffer pixels. + fn len(&self, n: u32) -> Option { + (n as usize).div_ceil(self.step).checked_add(self.pad.checked_mul(2)?) + } +} + +/// Resamples a grid coverage (`gw` wide) back to the `w x h` buffer: bilinear between the grid +/// pixel centres (an exact copy when both steps are 1). +fn crop(grid: &Mask, ax: Axis, ay: Axis, w: u32, h: u32) -> Mask { + let (gw, gh) = (grid.width as usize, grid.height as usize); + let mut out = Mask::new(w, h, 0.0); + let at = |x: usize, y: usize| grid.data.get(y.saturating_mul(gw).saturating_add(x)).copied().unwrap_or(0.0); + // Grid coordinate of a buffer pixel centre, as (index, fraction) on that axis. + let map = |i: u32, a: Axis, n: usize| -> (usize, usize, f32) { + let u = (i as f64 + 0.5) / a.step as f64 + a.pad as f64 - 0.5; + let u = u.clamp(0.0, n.saturating_sub(1) as f64); + let i0 = u.floor() as usize; + (i0, (i0 + 1).min(n.saturating_sub(1)), (u - i0 as f64) as f32) + }; + let xs: Vec<(usize, usize, f32)> = (0..w).map(|x| map(x, ax, gw)).collect(); + out.data.par_chunks_mut(w.max(1) as usize).enumerate().for_each(|(y, row)| { + let (y0, y1, fy) = map(y as u32, ay, gh); + for (o, &(x0, x1, fx)) in row.iter_mut().zip(&xs) { + let top = at(x0, y0) + (at(x1, y0) - at(x0, y0)) * fx; + let bottom = at(x0, y1) + (at(x1, y1) - at(x0, y1)) * fx; + *o = top + (bottom - top) * fy; + } + }); + out +} + fn coverage_at(ctx: &EvalCtx, layer: &Layer, g: &effectcraft_project::PropGroup, buf: &Buf) -> Option { let Value::Path(sp) = ctx.group_value(layer, g, "path")? else { return None }; let path = effectcraft_path::to_kurbo(&sp); @@ -70,29 +150,45 @@ fn coverage_at(ctx: &EvalCtx, layer: &Layer, g: &effectcraft_project::PropGroup, // Variable-width feather (Mask Feather tool points): expansion and the per-point feather // are applied together from the signed distance to the path. let variable = !sp.feather.is_empty(); + let feather = ctx.v2(layer, g, "feather", [0.0; 2]); + // The feather blurs the mask's own edge, also where the path lies outside the layer (After + // Effects: a feathered mask just below a layer still fades into it). So a feathered mask is + // rasterised on a grid padded by the blur's reach, blurred there and cropped to the buffer. + // A variable feather scales its point radii by the mean scale: it stays at full resolution. + let (ax, ay) = (Axis::new(feather[0] * buf.scale, linear, variable), Axis::new(feather[1] * buf.scale, linear, variable)); + let blurred = ax.blur > 0.0 || ay.blur > 0.0; + let grid = match (ax.len(w), ay.len(h)) { + (Some(gw), Some(gh)) if blurred && gw.checked_mul(gh).is_some_and(|n| n <= MAX_GRID_PX) => { + let (Ok(gw), Ok(gh)) = (u32::try_from(gw), u32::try_from(gh)) else { return None }; + Some((gw, gh, ax, ay)) + } + _ => None, + }; + // Without the grid: blurred within the buffer at its resolution (the behaviour before the padding). + let unpadded = |f: f64| Axis { pad: 0, ..Axis::new(f, linear, true) }; + let (gw, gh, gx, gy) = grid.unwrap_or_else(|| (w, h, unpadded(feather[0] * buf.scale), unpadded(feather[1] * buf.scale))); + // Buffer pixels -> grid pixels. + let to_grid = Mat3::scale(vec2(1.0 / gx.step as f64, 1.0 / gy.step as f64)) * Mat3::translate(vec2((gx.pad * gx.step) as f64, (gy.pad * gy.step) as f64)); + let mg = to_grid * m; let mut cov = if variable { - effectcraft_path::feather::variable_feather_coverage(&sp, &m, w, h, exp, linear) + effectcraft_path::feather::variable_feather_coverage(&sp, &mg, gw, gh, exp, linear) } else if exp.abs() > 0.01 { // Expansion offsets the outline itself (round joins). Offset Paths' geometry stays right // when the expansion exceeds a curvature radius, where a fill + stroke blend leaves a // ring around an uncovered middle (growing) or islands (shrinking). let grown = effectcraft_path::offset::offset_path(&path, exp, Join::Round, 4.0); - effectcraft_path::fill_coverage(std::slice::from_ref(&grown), &m, w, h, FillRule::NonZero) + effectcraft_path::fill_coverage(std::slice::from_ref(&grown), &mg, gw, gh, FillRule::NonZero) } else { - effectcraft_path::fill_coverage(std::slice::from_ref(&path), &m, w, h, FillRule::NonZero) + effectcraft_path::fill_coverage(std::slice::from_ref(&path), &mg, gw, gh, FillRule::NonZero) }; - let feather = ctx.v2(layer, g, "feather", [0.0; 2]); - if feather[0] > 0.0 || feather[1] > 0.0 { + if blurred { let img = cov.to_image(); - let b = if linear { - // One box pass: a straight ramp `feather` pixels wide across the edge. - let r = |f: f64| ((f * buf.scale / 2.0).round() as usize).max(if f > 0.0 { 1 } else { 0 }); - box_blur(&img, r(feather[0]), r(feather[1]), 1, false) - } else { - gaussian_blur(&img, feather[0] * buf.scale / 2.0, feather[1] * buf.scale / 2.0, false) - }; + let b = if linear { box_blur(&img, gx.blur as usize, gy.blur as usize, 1, false) } else { gaussian_blur(&img, gx.blur, gy.blur, false) }; cov = Mask::from_alpha(&b); } + if grid.is_some() { + cov = crop(&cov, gx, gy, w, h); + } Some(cov) } @@ -133,7 +229,9 @@ pub fn apply(ctx: &EvalCtx, layer: &Layer, buf: &mut Buf, blur: MaskBlur) -> boo if list.is_empty() { return false; } - // Masks may extend past the source: grow the buffer to cover them when feather/expansion pads. + // Masks may extend past the source: the buffer keeps its size (pixels outside the layer stay + // empty), but a feathered mask is blurred on a padded grid, so the feather of an edge outside + // the buffer still reaches into it (`coverage_at`). let n = (buf.img.width * buf.img.height) as usize; let first_sub = matches!(list[0].kind, GroupKind::Mask { mode: MaskMode::Subtract, .. }); let mut acc = vec![if first_sub { 1.0f32 } else { 0.0 }; n]; diff --git a/crates/render/src/tests_mask_feather.rs b/crates/render/src/tests_mask_feather.rs new file mode 100644 index 000000000..52ad60c61 --- /dev/null +++ b/crates/render/src/tests_mask_feather.rs @@ -0,0 +1,178 @@ +//! A feathered mask blurs its own edge, also where the path lies outside the layer: the feather +//! of a mask partly or wholly outside the layer reaches into it (After Effects), instead of the +//! coverage stopping at the layer edge. + +use effectcraft_color::Label; +use effectcraft_keyframe::{ShapePath, Value}; +use effectcraft_project::build::{self, Ids}; +use effectcraft_project::{BitDepth, Comp, FeatherFalloff, GroupKind, ItemId, ItemKind, Layer, LayerSource, MaskMode, Node, Project, Solid}; +use effectcraft_time::{FrameRate, Tick}; + +use crate::render_frame; + +fn solid(p: &mut Project, comp: &Comp, color: [f32; 3], w: u32, h: u32) -> Layer { + let sid = p.add_item("Solid", Label::Red, None, ItemKind::Solid(Solid { color, width: w, height: h, pixel_aspect: 1.0 })); + build::layer(p, comp, "Solid", LayerSource::Solid { item: sid }, (w, h), None) +} + +fn add_mask(p: &mut Project, l: &mut Layer, rect: ShapePath, feather: [f64; 2], linear: bool) { + let mut next = p.next_id; + let mut m = build::mask(&mut Ids(&mut next), "Mask 1", rect, MaskMode::Add, [255, 255, 0]); + p.next_id = next; + m.get_mut("feather").unwrap().value = Value::Vec2(feather); + if linear && let GroupKind::Mask { feather_falloff, .. } = &mut m.kind { + *feather_falloff = FeatherFalloff::Linear; + } + l.props.sub_mut("masks").unwrap().children.push(Node::Group(m)); +} + +/// The standard normal distribution function (Abramowitz and Stegun 7.1.26, error < 2e-7). +fn phi(x: f64) -> f64 { + let z = x.abs() / std::f64::consts::SQRT_2; + let t = 1.0 / (1.0 + 0.327_591_1 * z); + let poly = t * (0.254_829_592 + t * (-0.284_496_736 + t * (1.421_413_741 + t * (-1.453_152_027 + t * 1.061_405_429)))); + let erf = 1.0 - poly * (-z * z).exp(); + if x >= 0.0 { 0.5 * (1.0 + erf) } else { 0.5 * (1.0 - erf) } +} + +/// Coverage at pixel centre `x` of the span `a..b` blurred by a Gaussian of `sigma` (one axis). +fn span(x: f64, a: f64, b: f64, sigma: f64) -> f64 { + phi((b - x) / sigma) - phi((a - x) / sigma) +} + +/// A white 200×100 solid (32 bpc) with one Add mask. +fn white_with_mask(rect: ShapePath, feather: [f64; 2], linear: bool, scale: f64) -> effectcraft_raster::Image { + let mut p = Project::default(); + p.settings.bit_depth = BitDepth::Bpc32; + let comp = Comp::new(200, 100, FrameRate::FPS_30, Tick::from_seconds_f64(1.0)); + let cid = p.add_item("Comp", Label::Sandstone, None, ItemKind::Comp(comp.clone().into())); + let mut l = solid(&mut p, &comp, [1.0; 3], 200, 100); + add_mask(&mut p, &mut l, rect, feather, linear); + p.comp_mut(cid).unwrap().layers.push(l); + render_frame(&p, cid, Tick::ZERO, scale) +} + +#[test] +fn a_feathered_mask_outside_a_solid_reaches_into_it() { + // The mask spans x 210..260, right of the layer (x 0..200); feather 40 = Gaussian sigma 20. + let img = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [40.0, 40.0], false, 1.0); + for x in [150i64, 180, 199] { + let want = span(x as f64 + 0.5, 210.0, 260.0, 20.0) * span(50.5, -50.0, 150.0, 20.0); + let got = img.get(x, 50)[3] as f64; + assert!((got - want).abs() < 0.01, "x {x}: alpha {got}, the Gaussian gives {want}"); + } + assert!(img.get(199, 50)[3] > 0.25, "the feather reaches the layer edge"); + assert!(img.get(100, 50)[3] < 1e-3); + // Without feather the mask hides the layer. + let hard = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [0.0, 0.0], false, 1.0); + assert!(hard.data.iter().all(|p| p[3] == 0.0)); + // A linear falloff ramps over the feather width: 20 px either side of the edge at x 210. + let lin = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [40.0, 40.0], true, 1.0); + let a = lin.get(199, 50)[3]; + assert!((a - 0.24).abs() < 0.04, "linear: {a}"); + assert!(lin.get(185, 50)[3] < 0.01); + // At half resolution the same layer pixel gets the same coverage. + let half = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [40.0, 40.0], false, 0.5); + assert!((half.get(99, 25)[3] - img.get(198, 50)[3]).abs() < 0.02, "{} {}", half.get(99, 25)[3], img.get(198, 50)[3]); +} + +#[test] +fn a_feathered_mask_larger_than_the_layer_keeps_the_layer_edges() { + // The mask covers the layer and 100 px around it: the layer edges are inside the mask and + // stay opaque (they used to fade, as if the layer edge were the mask edge). + let img = white_with_mask(ShapePath::rect([100.0, 50.0], 400.0, 300.0), [40.0, 40.0], false, 1.0); + for (x, y) in [(0i64, 0i64), (0, 50), (199, 99), (100, 0)] { + assert!(img.get(x, y)[3] > 0.99, "({x}, {y}): {}", img.get(x, y)[3]); + } + // A mask edge inside the layer is feathered as before: half coverage on the edge. + let inner = white_with_mask(ShapePath::rect([100.0, 50.0], 100.0, 400.0), [40.0, 40.0], false, 1.0); + assert!((inner.get(50, 50)[3] - 0.5).abs() < 0.03, "{}", inner.get(50, 50)[3]); + assert!(inner.get(100, 50)[3] > 0.98); +} + +#[test] +fn huge_and_broken_feathers_stay_bounded() { + for f in [1.0e5, 1.0e9, f64::INFINITY, f64::NAN, -5.0] { + let img = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [f, f], false, 1.0); + assert!(img.data.iter().all(|p| p[3].is_finite() && (0.0..=1.0).contains(&p[3])), "feather {f}"); + let img = white_with_mask(ShapePath::rect([235.0, 50.0], 50.0, 200.0), [f, 10.0], true, 1.0); + assert!(img.data.iter().all(|p| p[3].is_finite() && (0.0..=1.0).contains(&p[3])), "linear feather {f}"); + } +} + +/// Case 398 of the .aep corpus, built in EffectCraft's own model: a 1920×1080 comp at 8 bpc, a +/// red solid, above it an adjustment layer of comp size with a Gradient Ramp at its defaults and +/// one Add mask entirely below the layer (1920×200 centred at [960, 1250]) with feather 1000. +fn case_398(with_mask: bool) -> (Project, ItemId) { + let mut p = Project::default(); + assert_eq!(p.settings.bit_depth, BitDepth::Bpc8, "After Effects' default depth"); + let comp = Comp::new(1920, 1080, FrameRate::FPS_30, Tick::from_seconds_f64(5.0)); + let cid = p.add_item("C", Label::Sandstone, None, ItemKind::Comp(comp.clone().into())); + let red = solid(&mut p, &comp, [1.0, 0.0, 0.0], 1920, 1080); + let mut adj = solid(&mut p, &comp, [1.0; 3], 1920, 1080); + adj.switches.adjustment = true; + let spec = effectcraft_effects::find("ec.generate.gradientramp").unwrap(); + let mut next = p.next_id; + let ramp = effectcraft_effects::instantiate(spec, &mut Ids(&mut next), spec.name, [1920.0, 1080.0]); + p.next_id = next; + adj.props.sub_mut("effects").unwrap().children.push(ramp.into()); + if with_mask { + add_mask(&mut p, &mut adj, ShapePath::rect([960.0, 1250.0], 1920.0, 200.0), [1000.0, 1000.0], false); + } + let c = p.comp_mut(cid).unwrap(); + c.layers.push(adj); + c.layers.push(red); + (p, cid) +} + +fn rgb8(img: &effectcraft_raster::Image, x: i64, y: i64) -> [i32; 3] { + let px = img.get(x, y); + [0, 1, 2].map(|c| (px[c].clamp(0.0, 1.0) * 255.0).round() as i32) +} + +#[test] +fn case_398_a_feathered_mask_below_an_adjustment_layer_reaches_into_it() { + let t = Tick::from_seconds_f64(1.0); + let (p, cid) = case_398(true); + let img = render_frame(&p, cid, t, 1.0); + // The ramp alone (no mask): what the adjustment layer mixes in. + let (q, qid) = case_398(false); + let ramp = render_frame(&q, qid, t, 1.0); + // After Effects 2026, 8 bpc, the render of 398 at 1 s. + let ae = [ + ((960, 0), [255, 0, 0]), + ((960, 300), [254, 0, 0]), + ((960, 540), [250, 5, 5]), + ((960, 800), [248, 20, 20]), + ((960, 1000), [252, 40, 40]), + ((960, 1079), [255, 47, 47]), + ((100, 1079), [255, 29, 29]), + ]; + let mut report = Vec::new(); + for ((x, y), want_ae) in ae { + let got = rgb8(&img, x, y); + // 1. The fix: the coverage is the mask's Gaussian (sigma = feather / 2 = 500), blurred from + // the mask edge outside the layer; the result is the red mixed toward the ramp by it. + let c = span(x as f64 + 0.5, 0.0, 1920.0, 500.0) * span(y as f64 + 0.5, 1150.0, 1350.0, 500.0); + let r = ramp.get(x, y); + let want = [0, 1, 2].map(|k| { + let red = if k == 0 { 1.0 } else { 0.0 }; + ((red + (r[k] as f64 - red) * c) * 255.0).round() as i32 + }); + for k in 0..3 { + assert!((got[k] - want[k]).abs() <= 3, "({x}, {y}): {got:?}, the Gaussian coverage {c:.4} gives {want:?}"); + } + // 2. After Effects: the same shape of falloff, the feather reaching ~500 px into the layer. + // Its kernel is narrower than sigma = feather / 2 (the AE values fit sigma ~ 350), so + // near the mask EffectCraft is lower and far from it higher: 12 levels apart at most + // (green at the bottom edge), allowed 14. + for k in 0..3 { + assert!((got[k] - want_ae[k]).abs() <= 14, "({x}, {y}): EffectCraft {got:?}, After Effects {want_ae:?}"); + } + report.push(format!("({x},{y}) ec {got:?} ae {want_ae:?}")); + } + println!("398: {}", report.join("; ")); + // The mask covers nothing of the layer itself, but its feather does: the top stays (nearly) red. + assert!(rgb8(&img, 960, 0)[0] >= 253 && rgb8(&img, 960, 0)[1] == 0); + assert!(rgb8(&img, 960, 1079)[1] > 25, "the feather reaches the bottom edge"); +}