57 lines
2.6 KiB
Rust
57 lines
2.6 KiB
Rust
//! Off-centre (focal) radial gradients: the pixels follow the model's gradient parameter, with
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//! and without an aspect ratio, and differ from the centred gradient.
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use vectorcraft_color::{Gradient, GradientGeom, GradientKind, GradientPaint, Paint};
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use vectorcraft_doc::{Appearance, Document};
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use vectorcraft_geom::{Point, Rect, shapes};
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use vectorcraft_testkit::fixtures::DocBuilder;
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use vectorcraft_testkit::raster::{Image, render_view};
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/// A 100 pt square filled with a white-to-black radial on `geom`.
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fn radial(geom: GradientGeom) -> Document {
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let mut gp = GradientPaint::new(Gradient { kind: GradientKind::Radial, ..Gradient::default() });
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gp.geom = Some(geom);
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let mut b = DocBuilder::new(100.0, 100.0);
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b.path(shapes::rectangle(Rect::new(0.0, 0.0, 100.0, 100.0)), Appearance::basic(Paint::Gradient(Box::new(gp)), Paint::None, 0.0), |_| {});
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b.build()
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}
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/// A circle of radius 40 at (50, 50) with its focal point at `focal`.
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fn off_centre(focal: Option<Point>) -> GradientGeom {
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let mut g = GradientGeom { start: Point::new(50.0, 50.0), end: Point::new(90.0, 50.0), aspect: 1.0, focal: None };
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g.set_focal(focal);
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g
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}
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/// Every 7th pixel's red matches white→black at the model's parameter there (pixel centres).
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fn assert_follows_model(img: &Image, geom: &GradientGeom) {
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for y in (3..100).step_by(7) {
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for x in (3..100).step_by(7) {
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let t = geom.param_at(GradientKind::Radial, Point::new(x as f64 + 0.5, y as f64 + 0.5)).clamp(0.0, 1.0);
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let want = ((1.0 - t) * 255.0).round() as u8;
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let got = img.over_white(x, y)[0];
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assert!(got.abs_diff(want) <= 6, "({x},{y}) t={t:.3}: got {got}, want {want}");
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}
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}
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}
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#[test]
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fn an_off_centre_focal_point_renders_as_its_model() {
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let geom = off_centre(Some(Point::new(30.0, 40.0)));
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let img = render_view(&radial(geom), 100, 100);
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assert_follows_model(&img, &geom);
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// White at the focal point, and the light side faces it.
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assert!(img.over_white(30, 40)[0] > 245, "{:?}", img.over_white(30, 40));
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let centred = render_view(&radial(off_centre(None)), 100, 100);
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assert!(img.over_white(35, 50)[0] > centred.over_white(35, 50)[0] + 20);
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assert!(img.over_white(65, 50)[0] + 20 < centred.over_white(65, 50)[0]);
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}
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#[test]
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fn a_focal_point_on_a_squashed_rotated_ellipse_renders_as_its_model() {
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let mut geom = GradientGeom { start: Point::new(50.0, 50.0), end: Point::new(80.0, 75.0), aspect: 0.5, focal: None };
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geom.set_focal(Some(Point::new(60.0, 50.0)));
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assert!(geom.focal.is_some());
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assert_follows_model(&render_view(&radial(geom), 100, 100), &geom);
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}
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