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Introduce test scenes that demonstrates conflation artifacts
Added two scenes that demonstrate conflation artifacts as described in https://github.com/linebender/vello/issues/49. The first scene demonstrates adjacent triangles and rects that belong to the same path and use opposite winding. The second scene demonstrates strokes with overlapping square caps (these strokes are currently expressed as rects painted with the NonZero fill rule).
This commit is contained in:
Arman Uguray
parent
020a7f5c01
commit
dc2e6690c4
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@ -30,6 +30,8 @@ pub fn test_scenes() -> SceneSet {
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scene!(animated_text: animated),
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scene!(brush_transform: animated),
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scene!(blend_grid),
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scene!(conflation_artifacts),
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scene!(labyrinth),
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];
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#[cfg(target_arch = "wasm32")]
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scenes.push(ExampleScene {
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@ -403,6 +405,169 @@ fn blend_square(blend: BlendMode) -> SceneFragment {
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fragment
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}
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fn conflation_artifacts(sb: &mut SceneBuilder, _: &mut SceneParams) {
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use PathEl::*;
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const N: f64 = 50.0;
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const S: f64 = 4.0;
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let scale = Affine::scale(S);
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let x = N + 0.5; // Fraction pixel offset reveals the problem on axis-aligned edges.
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let mut y = N;
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// Two adjacent triangles touching at diagonal edge with opposing winding numbers
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sb.fill(
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Fill::NonZero,
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Affine::translate((x, y)) * scale,
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Color::RED,
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None,
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&[
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// triangle 1
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MoveTo((0.0, 0.0).into()),
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LineTo((N, N).into()),
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LineTo((0.0, N).into()),
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LineTo((0.0, 0.0).into()),
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// triangle 2
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MoveTo((0.0, 0.0).into()),
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LineTo((N, N).into()),
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LineTo((N, 0.0).into()),
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LineTo((0.0, 0.0).into()),
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],
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);
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// Adjacent rects, opposite winding
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y += S * N + 10.0;
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sb.fill(
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Fill::EvenOdd,
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Affine::translate((x, y)) * scale,
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Color::RED,
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None,
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&Rect::new(0.0, 0.0, N, N),
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);
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sb.fill(
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Fill::EvenOdd,
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Affine::translate((x, y)) * scale,
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Color::GREEN,
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None,
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&[
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// left rect
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MoveTo((0.0, 0.0).into()),
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LineTo((0.0, N).into()),
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LineTo((N * 0.5, N).into()),
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LineTo((N * 0.5, 0.0).into()),
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// right rect
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MoveTo((N * 0.5, 0.0).into()),
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LineTo((N, 0.0).into()),
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LineTo((N, N).into()),
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LineTo((N * 0.5, N).into()),
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],
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);
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// Adjacent rects, same winding
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y += S * N + 10.0;
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sb.fill(
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Fill::EvenOdd,
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Affine::translate((x, y)) * scale,
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Color::RED,
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None,
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&Rect::new(0.0, 0.0, N, N),
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);
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sb.fill(
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Fill::EvenOdd,
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Affine::translate((x, y)) * scale,
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Color::GREEN,
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None,
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&[
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// left rect
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MoveTo((0.0, 0.0).into()),
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LineTo((0.0, N).into()),
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LineTo((N * 0.5, N).into()),
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LineTo((N * 0.5, 0.0).into()),
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// right rect
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MoveTo((N * 0.5, 0.0).into()),
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LineTo((N * 0.5, N).into()),
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LineTo((N, N).into()),
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LineTo((N, 0.0).into()),
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],
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);
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}
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fn labyrinth(sb: &mut SceneBuilder, _: &mut SceneParams) {
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use PathEl::*;
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let rows: &[[u8; 12]] = &[
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[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
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[0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1],
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[0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1],
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[1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0],
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[0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1],
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[1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0],
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[0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0],
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[1, 0, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1],
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[0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1],
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[0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0],
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[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
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];
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let cols: &[[u8; 10]] = &[
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[1, 1, 1, 1, 0, 1, 1, 1, 1, 1],
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[0, 0, 1, 0, 0, 0, 1, 1, 1, 0],
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[0, 1, 1, 0, 1, 1, 1, 0, 0, 1],
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[1, 1, 0, 0, 0, 0, 1, 0, 1, 0],
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[0, 0, 1, 0, 1, 0, 0, 0, 0, 1],
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[0, 0, 1, 1, 1, 0, 0, 0, 1, 0],
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[0, 1, 0, 1, 1, 1, 0, 0, 0, 0],
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[1, 1, 1, 0, 1, 1, 1, 0, 1, 0],
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[1, 1, 0, 1, 1, 0, 0, 0, 1, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 1],
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[0, 0, 1, 1, 0, 0, 0, 0, 1, 0],
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[0, 0, 0, 0, 0, 0, 1, 0, 0, 1],
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[1, 1, 1, 1, 1, 1, 0, 1, 1, 1],
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];
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let mut path = BezPath::new();
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for (y, row) in rows.iter().enumerate() {
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for (x, flag) in row.iter().enumerate() {
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let x = x as f64;
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let y = y as f64;
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if *flag == 1 {
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path.push(MoveTo((x - 0.1, y + 0.1).into()));
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path.push(LineTo((x + 1.1, y + 0.1).into()));
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path.push(LineTo((x + 1.1, y - 0.1).into()));
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path.push(LineTo((x - 0.1, y - 0.1).into()));
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// The above is equivalent to the following stroke with width 0.2 and square
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// caps.
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//path.push(MoveTo((x, y).into()));
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//path.push(LineTo((x + 1.0, y).into()));
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}
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}
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}
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for (x, col) in cols.iter().enumerate() {
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for (y, flag) in col.iter().enumerate() {
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let x = x as f64;
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let y = y as f64;
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if *flag == 1 {
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path.push(MoveTo((x - 0.1, y - 0.1).into()));
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path.push(LineTo((x - 0.1, y + 1.1).into()));
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path.push(LineTo((x + 0.1, y + 1.1).into()));
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path.push(LineTo((x + 0.1, y - 0.1).into()));
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// The above is equivalent to the following stroke with width 0.2 and square
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// caps.
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//path.push(MoveTo((x, y).into()));
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//path.push(LineTo((x, y + 1.0).into()));
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}
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}
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}
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// Note the artifacts are clearly visible at a fractional pixel offset/translation. They
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// disappear if the translation amount below is a whole number.
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sb.fill(
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Fill::NonZero,
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Affine::translate((20.5, 20.5)) * Affine::scale(80.0),
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Color::rgba8(0x70, 0x80, 0x80, 0xff),
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None,
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&path,
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)
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}
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fn around_center(xform: Affine, center: Point) -> Affine {
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Affine::translate(center.to_vec2()) * xform * Affine::translate(-center.to_vec2())
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}
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