2019-01-11 18:50:09 -05:00
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// pathfinder/geometry/src/segment.rs
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//
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// Copyright © 2019 The Pathfinder Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Line or curve segments, optimized with SIMD.
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2019-02-04 23:20:32 -05:00
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use crate::basic::line_segment::LineSegmentF32;
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use crate::basic::point::Point2DF32;
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2019-05-08 20:43:06 -04:00
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use crate::util::{self, EPSILON};
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2019-02-01 14:48:10 -05:00
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use pathfinder_simd::default::F32x4;
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2019-01-11 18:50:09 -05:00
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2019-05-08 20:43:06 -04:00
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const MAX_NEWTON_ITERATIONS: u32 = 32;
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2019-01-11 18:50:09 -05:00
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#[derive(Clone, Copy, Debug, PartialEq)]
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pub struct Segment {
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pub baseline: LineSegmentF32,
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pub ctrl: LineSegmentF32,
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pub kind: SegmentKind,
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pub flags: SegmentFlags,
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}
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impl Segment {
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#[inline]
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pub fn none() -> Segment {
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Segment {
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baseline: LineSegmentF32::default(),
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ctrl: LineSegmentF32::default(),
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kind: SegmentKind::None,
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flags: SegmentFlags::empty(),
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}
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}
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#[inline]
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pub fn line(line: &LineSegmentF32) -> Segment {
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Segment {
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baseline: *line,
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ctrl: LineSegmentF32::default(),
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kind: SegmentKind::Line,
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flags: SegmentFlags::empty(),
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}
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}
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#[inline]
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pub fn quadratic(baseline: &LineSegmentF32, ctrl: &Point2DF32) -> Segment {
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Segment {
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baseline: *baseline,
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ctrl: LineSegmentF32::new(ctrl, &Point2DF32::default()),
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kind: SegmentKind::Cubic,
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flags: SegmentFlags::empty(),
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}
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}
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#[inline]
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pub fn cubic(baseline: &LineSegmentF32, ctrl: &LineSegmentF32) -> Segment {
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Segment {
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baseline: *baseline,
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ctrl: *ctrl,
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kind: SegmentKind::Cubic,
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flags: SegmentFlags::empty(),
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}
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}
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#[inline]
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pub fn as_line_segment(&self) -> LineSegmentF32 {
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debug_assert!(self.is_line());
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self.baseline
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}
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#[inline]
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pub fn is_none(&self) -> bool {
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self.kind == SegmentKind::None
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}
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#[inline]
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pub fn is_line(&self) -> bool {
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self.kind == SegmentKind::Line
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}
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#[inline]
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pub fn is_quadratic(&self) -> bool {
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self.kind == SegmentKind::Quadratic
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}
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#[inline]
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pub fn is_cubic(&self) -> bool {
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self.kind == SegmentKind::Cubic
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}
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#[inline]
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pub fn as_cubic_segment(&self) -> CubicSegment {
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debug_assert!(self.is_cubic());
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CubicSegment(self)
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}
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// FIXME(pcwalton): We should basically never use this function.
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// FIXME(pcwalton): Handle lines!
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#[inline]
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pub fn to_cubic(&self) -> Segment {
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if self.is_cubic() {
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return *self;
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}
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let mut new_segment = *self;
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let p1_2 = self.ctrl.from() + self.ctrl.from();
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new_segment.ctrl =
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LineSegmentF32::new(&(self.baseline.from() + p1_2), &(p1_2 + self.baseline.to()))
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.scale(1.0 / 3.0);
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new_segment
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}
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2019-02-02 14:12:54 -05:00
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#[inline]
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pub fn is_monotonic(&self) -> bool {
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// FIXME(pcwalton): Don't degree elevate!
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match self.kind {
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SegmentKind::None | SegmentKind::Line => true,
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SegmentKind::Quadratic => self.to_cubic().as_cubic_segment().is_monotonic(),
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SegmentKind::Cubic => self.as_cubic_segment().is_monotonic(),
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}
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}
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2019-01-11 18:50:09 -05:00
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#[inline]
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pub fn reversed(&self) -> Segment {
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Segment {
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baseline: self.baseline.reversed(),
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ctrl: if self.is_quadratic() {
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self.ctrl
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} else {
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self.ctrl.reversed()
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},
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kind: self.kind,
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flags: self.flags,
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}
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}
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// Reverses if necessary so that the from point is above the to point. Calling this method
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// again will undo the transformation.
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#[inline]
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pub fn orient(&self, y_winding: i32) -> Segment {
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if y_winding >= 0 {
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*self
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} else {
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self.reversed()
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}
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}
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2019-01-28 15:57:15 -05:00
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#[inline]
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pub fn is_tiny(&self) -> bool {
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const EPSILON: f32 = 0.0001;
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self.baseline.square_length() < EPSILON
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}
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2019-01-28 17:58:57 -05:00
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#[inline]
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pub fn split(&self, t: f32) -> (Segment, Segment) {
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// FIXME(pcwalton): Don't degree elevate!
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if self.is_line() {
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let (before, after) = self.as_line_segment().split(t);
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(Segment::line(&before), Segment::line(&after))
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} else {
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self.to_cubic().as_cubic_segment().split(t)
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}
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}
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2019-02-20 21:27:18 -05:00
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#[inline]
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pub fn sample(self, t: f32) -> Point2DF32 {
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// FIXME(pcwalton): Don't degree elevate!
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if self.is_line() {
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self.as_line_segment().sample(t)
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} else {
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self.to_cubic().as_cubic_segment().sample(t)
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}
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}
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2019-01-11 18:50:09 -05:00
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}
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#[derive(Clone, Copy, Debug, PartialEq)]
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#[repr(u8)]
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pub enum SegmentKind {
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None,
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Line,
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Quadratic,
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Cubic,
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}
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bitflags! {
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pub struct SegmentFlags: u8 {
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const FIRST_IN_SUBPATH = 0x01;
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const CLOSES_SUBPATH = 0x02;
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}
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}
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#[derive(Clone, Copy, Debug)]
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2019-01-31 13:12:37 -05:00
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pub struct CubicSegment<'s>(pub &'s Segment);
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2019-01-11 18:50:09 -05:00
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impl<'s> CubicSegment<'s> {
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2019-01-28 23:36:06 -05:00
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// See Kaspar Fischer, "Piecewise Linear Approximation of Bézier Curves", 2000.
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2019-01-11 18:50:09 -05:00
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#[inline]
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2019-01-28 23:36:06 -05:00
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pub fn is_flat(self, tolerance: f32) -> bool {
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2019-04-29 19:46:35 -04:00
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let mut uv = F32x4::splat(3.0) * self.0.ctrl.0
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- self.0.baseline.0
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- self.0.baseline.0
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- self.0.baseline.reversed().0;
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2019-01-28 23:36:06 -05:00
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uv = uv * uv;
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uv = uv.max(uv.zwxy());
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uv[0] + uv[1] <= 16.0 * tolerance * tolerance
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}
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2019-01-12 20:13:58 -05:00
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2019-01-11 18:50:09 -05:00
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#[inline]
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pub fn split(self, t: f32) -> (Segment, Segment) {
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2019-01-31 13:12:37 -05:00
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let (baseline0, ctrl0, baseline1, ctrl1);
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if t <= 0.0 {
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let from = &self.0.baseline.from();
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baseline0 = LineSegmentF32::new(from, from);
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ctrl0 = LineSegmentF32::new(from, from);
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baseline1 = self.0.baseline;
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ctrl1 = self.0.ctrl;
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} else if t >= 1.0 {
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let to = &self.0.baseline.to();
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baseline0 = self.0.baseline;
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ctrl0 = self.0.ctrl;
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baseline1 = LineSegmentF32::new(to, to);
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ctrl1 = LineSegmentF32::new(to, to);
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} else {
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let tttt = F32x4::splat(t);
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2019-01-11 18:50:09 -05:00
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2019-01-31 13:12:37 -05:00
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let (p0p3, p1p2) = (self.0.baseline.0, self.0.ctrl.0);
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2019-02-01 15:16:42 -05:00
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let p0p1 = p0p3.concat_xy_xy(p1p2);
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2019-01-11 18:50:09 -05:00
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2019-01-31 13:12:37 -05:00
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// p01 = lerp(p0, p1, t), p12 = lerp(p1, p2, t), p23 = lerp(p2, p3, t)
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let p01p12 = p0p1 + tttt * (p1p2 - p0p1);
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let pxxp23 = p1p2 + tttt * (p0p3 - p1p2);
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2019-02-01 15:16:42 -05:00
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let p12p23 = p01p12.concat_zw_zw(pxxp23);
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2019-01-12 20:13:58 -05:00
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2019-01-31 13:12:37 -05:00
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// p012 = lerp(p01, p12, t), p123 = lerp(p12, p23, t)
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let p012p123 = p01p12 + tttt * (p12p23 - p01p12);
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let p123 = p012p123.zwzw();
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2019-01-12 20:13:58 -05:00
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2019-01-31 13:12:37 -05:00
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// p0123 = lerp(p012, p123, t)
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let p0123 = p012p123 + tttt * (p123 - p012p123);
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2019-01-12 20:13:58 -05:00
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2019-02-01 15:16:42 -05:00
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baseline0 = LineSegmentF32(p0p3.concat_xy_xy(p0123));
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ctrl0 = LineSegmentF32(p01p12.concat_xy_xy(p012p123));
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baseline1 = LineSegmentF32(p0123.concat_xy_zw(p0p3));
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ctrl1 = LineSegmentF32(p012p123.concat_zw_zw(p12p23));
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2019-01-31 13:12:37 -05:00
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}
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2019-01-12 20:13:58 -05:00
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2019-04-29 19:46:35 -04:00
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(
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Segment {
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baseline: baseline0,
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ctrl: ctrl0,
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kind: SegmentKind::Cubic,
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flags: self.0.flags & SegmentFlags::FIRST_IN_SUBPATH,
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},
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Segment {
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baseline: baseline1,
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ctrl: ctrl1,
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kind: SegmentKind::Cubic,
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flags: self.0.flags & SegmentFlags::CLOSES_SUBPATH,
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},
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)
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2019-01-11 18:50:09 -05:00
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}
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2019-01-31 13:12:37 -05:00
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#[inline]
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pub fn split_before(self, t: f32) -> Segment {
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self.split(t).0
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}
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2019-01-11 18:50:09 -05:00
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#[inline]
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pub fn split_after(self, t: f32) -> Segment {
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self.split(t).1
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}
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2019-01-28 17:58:57 -05:00
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// FIXME(pcwalton): Use Horner's method!
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#[inline]
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pub fn sample(self, t: f32) -> Point2DF32 {
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self.split(t).0.baseline.to()
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}
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2019-02-02 14:12:54 -05:00
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#[inline]
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pub fn is_monotonic(self) -> bool {
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// TODO(pcwalton): Optimize this.
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let (p0, p3) = (self.0.baseline.from_y(), self.0.baseline.to_y());
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let (p1, p2) = (self.0.ctrl.from_y(), self.0.ctrl.to_y());
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(p0 <= p1 && p1 <= p2 && p2 <= p3) || (p0 >= p1 && p1 >= p2 && p2 >= p3)
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}
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2019-01-11 18:50:09 -05:00
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#[inline]
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pub fn y_extrema(self) -> (Option<f32>, Option<f32>) {
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2019-02-02 14:12:54 -05:00
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if self.is_monotonic() {
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2019-04-29 19:46:35 -04:00
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return (None, None);
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2019-02-02 14:12:54 -05:00
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}
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2019-04-29 19:46:35 -04:00
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let p0p1p2p3 = F32x4::new(
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self.0.baseline.from_y(),
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self.0.ctrl.from_y(),
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self.0.ctrl.to_y(),
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self.0.baseline.to_y(),
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);
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2019-01-22 14:46:01 -05:00
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2019-01-12 21:10:18 -05:00
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let pxp0p1p2 = p0p1p2p3.wxyz();
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2019-01-12 20:13:58 -05:00
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let pxv0v1v2 = p0p1p2p3 - pxp0p1p2;
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let (v0, v1, v2) = (pxv0v1v2[1], pxv0v1v2[2], pxv0v1v2[3]);
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2019-05-08 20:43:06 -04:00
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let (t0, t1);
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2019-01-12 20:13:58 -05:00
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let (v0_to_v1, v2_to_v1) = (v0 - v1, v2 - v1);
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2019-05-08 20:43:06 -04:00
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let denom = v0_to_v1 + v2_to_v1;
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if util::approx_eq(denom, 0.0) {
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// Let's not divide by zero (issue #146). Fall back to Newton's method.
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// FIXME(pcwalton): Can we have two roots here?
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let mut t = 0.5;
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for _ in 0..MAX_NEWTON_ITERATIONS {
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let dydt = 3.0 * ((denom * t - v0_to_v1 - v0_to_v1) * t + v0);
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if f32::abs(dydt) <= EPSILON {
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break
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}
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let d2ydt2 = 6.0 * (denom * t - v0_to_v1);
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t -= dydt / d2ydt2;
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}
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t0 = t;
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t1 = 0.0;
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debug!("... t=(newton) {}", t);
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} else {
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|
|
|
// Algebraically compute the values for t.
|
|
|
|
let discrim = f32::sqrt(v1 * v1 - v0 * v2);
|
|
|
|
let denom_recip = 1.0 / denom;
|
2019-01-12 20:13:58 -05:00
|
|
|
|
2019-05-08 20:43:06 -04:00
|
|
|
t0 = (v0_to_v1 + discrim) * denom_recip;
|
|
|
|
t1 = (v0_to_v1 - discrim) * denom_recip;
|
|
|
|
|
|
|
|
debug!("... t=({} +/- {})/{} t0={} t1={}", v0_to_v1, discrim, denom, t0, t1);
|
|
|
|
}
|
2019-01-11 18:50:09 -05:00
|
|
|
|
|
|
|
return match (
|
|
|
|
t0 > EPSILON && t0 < 1.0 - EPSILON,
|
|
|
|
t1 > EPSILON && t1 < 1.0 - EPSILON,
|
|
|
|
) {
|
|
|
|
(false, false) => (None, None),
|
|
|
|
(true, false) => (Some(t0), None),
|
|
|
|
(false, true) => (Some(t1), None),
|
|
|
|
(true, true) => (Some(f32::min(t0, t1)), Some(f32::max(t0, t1))),
|
|
|
|
};
|
|
|
|
}
|
2019-01-22 14:46:01 -05:00
|
|
|
|
|
|
|
#[inline]
|
2019-04-29 19:46:35 -04:00
|
|
|
pub fn min_x(&self) -> f32 {
|
|
|
|
f32::min(self.0.baseline.min_x(), self.0.ctrl.min_x())
|
|
|
|
}
|
2019-01-22 14:46:01 -05:00
|
|
|
#[inline]
|
2019-04-29 19:46:35 -04:00
|
|
|
pub fn min_y(&self) -> f32 {
|
|
|
|
f32::min(self.0.baseline.min_y(), self.0.ctrl.min_y())
|
|
|
|
}
|
2019-01-22 14:46:01 -05:00
|
|
|
#[inline]
|
2019-04-29 19:46:35 -04:00
|
|
|
pub fn max_x(&self) -> f32 {
|
|
|
|
f32::max(self.0.baseline.max_x(), self.0.ctrl.max_x())
|
|
|
|
}
|
2019-01-22 14:46:01 -05:00
|
|
|
#[inline]
|
2019-04-29 19:46:35 -04:00
|
|
|
pub fn max_y(&self) -> f32 {
|
|
|
|
f32::max(self.0.baseline.max_y(), self.0.ctrl.max_y())
|
|
|
|
}
|
2019-01-11 18:50:09 -05:00
|
|
|
}
|