126 lines
4.2 KiB
Rust
126 lines
4.2 KiB
Rust
// pathfinder/content/src/dilation.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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use crate::orientation::Orientation;
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use crate::outline::Contour;
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use pathfinder_geometry::vector::{Vector2F, vec2f};
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pub struct ContourDilator<'a> {
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contour: &'a mut Contour,
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amount: Vector2F,
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orientation: Orientation,
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}
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impl<'a> ContourDilator<'a> {
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pub fn new(
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contour: &'a mut Contour,
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amount: Vector2F,
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orientation: Orientation,
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) -> ContourDilator<'a> {
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ContourDilator {
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contour,
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amount,
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orientation,
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}
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}
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pub fn dilate(&mut self) {
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// Determine orientation.
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let scale = self.amount * (match self.orientation {
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Orientation::Ccw => vec2f( 1.0, -1.0),
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Orientation::Cw => vec2f(-1.0, 1.0),
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});
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// Find the starting and previous positions.
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let first_position = self.contour.position_of(0);
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let mut prev_point_index = 0;
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let mut prev_position;
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loop {
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prev_point_index = self.contour.prev_point_index_of(prev_point_index);
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prev_position = self.contour.position_of(prev_point_index);
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if prev_point_index == 0 || prev_position != first_position {
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break;
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}
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}
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// Initialize our loop.
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let first_point_index = self.contour.next_point_index_of(prev_point_index);
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let mut current_point_index = first_point_index;
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let mut position = first_position;
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let mut prev_vector = (position - prev_position).normalize();
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loop {
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// Find the next non-degenerate position.
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let mut next_point_index = current_point_index;
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let mut next_position;
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loop {
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next_point_index = self.contour.next_point_index_of(next_point_index);
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if next_point_index == first_point_index {
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next_position = first_position;
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break;
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}
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next_position = self.contour.position_of(next_point_index);
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if next_point_index == current_point_index || next_position != position {
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break;
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}
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}
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let next_vector = (next_position - position).normalize();
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debug!(
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"prev={} cur={} next={}",
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prev_point_index, current_point_index, next_point_index
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);
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// Calculate new position by moving the point by the bisector.
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let bisector = prev_vector.yx() + next_vector.yx();
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let bisector_length = bisector.length();
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let scaled_bisector = if bisector_length == 0.0 {
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Vector2F::zero()
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} else {
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bisector * scale * (1.0 / bisector_length)
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};
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let new_position = position - scaled_bisector;
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debug!(
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"dilate(): prev={}({:?}) cur={}({:?}) next={}({:?}) bisector={:?}({:?}, {:?})",
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prev_point_index,
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prev_position,
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current_point_index,
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position,
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next_point_index,
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next_position,
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bisector,
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bisector_length,
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scaled_bisector
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);
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// Update all points.
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let mut point_index = current_point_index;
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while point_index != next_point_index {
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self.contour.points[point_index as usize] = new_position;
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debug!("... updating {:?}", point_index);
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point_index = self.contour.next_point_index_of(point_index);
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}
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// Check to see if we're done.
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if next_point_index == first_point_index {
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break;
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}
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// Continue.
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prev_vector = next_vector;
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position = next_position;
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current_point_index = next_point_index;
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}
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}
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}
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