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Ian-ChegeandClaude Opus 5.5
5270eab095
Expansion was a fill plus a stroke 2·|expansion| wide, blended per pixel. Once the expansion passed the shape's curvature radius the stroke's inner edge inverted: a 20 px circle expanded by 60 left a ring with the layer showing through the middle, +600 cut only the original dot, and negative values left islands. The outline is now offset with Offset Paths' geometry (round joins) and filled. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
83 lines
4.0 KiB
Rust
83 lines
4.0 KiB
Rust
//! Mask Expansion grows or shrinks the mask outline by its distance, however large: past the
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//! shape's curvature radius it must still cover everything within the distance of the path,
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//! never leave a ring around an uncovered middle.
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use effectcraft_color::Label;
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use effectcraft_keyframe::{ShapePath, Value};
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use effectcraft_project::build::{self, Ids};
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use effectcraft_project::{Comp, ItemId, ItemKind, LayerSource, MaskMode, Node, Project, Solid};
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use effectcraft_time::{FrameRate, Tick};
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use crate::{NoFootage, RenderOpts, Renderer};
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const W: u32 = 400;
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const H: u32 = 300;
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/// A white 400×300 solid with one mask of `shape` in `mode` expanded by `expansion` pixels.
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fn project(shape: ShapePath, mode: MaskMode, expansion: f64) -> (Project, ItemId) {
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let mut p = Project::default();
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let comp = Comp::new(W, H, FrameRate::FPS_30, Tick::from_seconds_f64(1.0));
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let sid = p.add_item("S", Label::Red, None, ItemKind::Solid(Solid { color: [1.0; 3], width: W, height: H, pixel_aspect: 1.0 }));
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let mut l = build::layer(&mut p, &comp, "S", LayerSource::Solid { item: sid }, (W, H), None);
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let mut next = p.next_id;
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let mut m = build::mask(&mut Ids(&mut next), "Mask 1", shape, mode, [255, 0, 0]);
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p.next_id = next;
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m.get_mut("expansion").unwrap().value = Value::Scalar(expansion);
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l.props.sub_mut("masks").unwrap().children.push(Node::Group(m));
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let cid = p.add_item("C", Label::Sandstone, None, ItemKind::Comp(comp.into()));
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p.comp_mut(cid).unwrap().layers.push(l);
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(p, cid)
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}
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/// Alpha at each of `points` for a Subtract mask on a 40 px circle at the centre (the hole).
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fn hole(expansion: f64, points: &[(i64, i64)]) -> Vec<f32> {
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let (p, cid) = project(ShapePath::ellipse([200.0, 150.0], 40.0, 40.0), MaskMode::Subtract, expansion);
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let img = Renderer::new(&p, &NoFootage, RenderOpts::default()).comp_frame(cid, Tick::ZERO);
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points.iter().map(|&(x, y)| img.get(x, y)[3]).collect()
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}
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#[test]
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fn no_expansion_cuts_the_circle() {
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let a = hole(0.0, &[(200, 150), (215, 150), (225, 150)]);
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assert!(a[0] < 0.01 && a[1] < 0.01, "inside the 20 px radius is cut: {a:?}");
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assert!(a[2] > 0.99, "outside it is kept: {a:?}");
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}
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#[test]
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fn expansion_past_the_radius_grows_a_solid_hole() {
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// +60 on a 20 px radius: a solid hole of radius 80. The fill + stroke blend left a ring
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// from 40 to 80 px with the layer showing at 21–39 px.
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let a = hole(60.0, &[(200, 150), (230, 150), (200, 120), (275, 150), (285, 150)]);
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assert!(a[..4].iter().all(|&v| v < 0.01), "everything within 80 px is cut: {a:?}");
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assert!(a[4] > 0.99, "beyond 80 px is kept: {a:?}");
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}
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#[test]
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fn huge_expansion_cuts_the_whole_frame() {
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// +600 reaches every pixel; the blend left only the 20 px circle cut.
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let a = hole(600.0, &[(200, 150), (230, 150), (0, 0), (399, 299), (399, 0)]);
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assert!(a.iter().all(|&v| v < 0.01), "{a:?}");
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}
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#[test]
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fn negative_expansion_shrinks_then_removes_the_hole() {
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let a = hole(-15.0, &[(200, 150), (210, 150)]);
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assert!(a[0] < 0.01, "a 5 px hole remains: {a:?}");
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assert!(a[1] > 0.99, "shrunk away from 10 px out: {a:?}");
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let a = hole(-25.0, &[(200, 150), (190, 150)]);
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assert!(a.iter().all(|&v| v > 0.99), "shrunk past its radius, nothing is cut: {a:?}");
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}
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#[test]
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fn expanded_rect_add_mask_has_round_corners() {
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// A 100 px square mask (Add) grown by 30: the sides move out 30 px, the corners round off.
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let (p, cid) = project(ShapePath::rect([200.0, 150.0], 100.0, 100.0), MaskMode::Add, 30.0);
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let img = Renderer::new(&p, &NoFootage, RenderOpts::default()).comp_frame(cid, Tick::ZERO);
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assert!(img.get(275, 150)[3] > 0.99, "25 px past the right side is inside");
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assert!(img.get(285, 150)[3] < 0.01, "35 px past it is outside");
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// 25 px diagonally out from the corner (250,100) is within 30 px: inside.
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assert!(img.get(267, 82)[3] > 0.99);
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// The square's bounding corner (280,70) is 42 px from the corner: a miter would cover it.
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assert!(img.get(277, 73)[3] < 0.01);
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}
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