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Write in the line segment intersection code in matrix form

This commit is contained in:
Patrick Walton 2019-05-21 14:50:35 -07:00
parent c6fc853579
commit 197f01d56a
1 changed files with 5 additions and 7 deletions
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12
geometry/src/basic/line_segment.rs
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@ -11,6 +11,7 @@
//! Line segment types, optimized with SIMD. //! Line segment types, optimized with SIMD.
use crate::basic::point::Point2DF32; use crate::basic::point::Point2DF32;
use crate::basic::transform2d::Matrix2x2F32;
use crate::util; use crate::util;
use pathfinder_simd::default::F32x4; use pathfinder_simd::default::F32x4;
use std::ops::{Add, Sub}; use std::ops::{Add, Sub};
@ -227,15 +228,12 @@ impl LineSegmentF32 {
// http://www.cs.swan.ac.uk/~cssimon/line_intersection.html // http://www.cs.swan.ac.uk/~cssimon/line_intersection.html
pub fn intersection_t(&self, other: &LineSegmentF32) -> Option<f32> { pub fn intersection_t(&self, other: &LineSegmentF32) -> Option<f32> {
let d0d1 = self.vector().0.concat_xy_xy(other.vector().0); let p0p1 = self.vector();
let offset = other.from() - self.from(); let matrix = Matrix2x2F32(other.vector().0.concat_xy_xy((-p0p1).0));
let factors = d0d1.concat_wz_yx(offset.0); if f32::abs(matrix.det()) < EPSILON {
let terms = d0d1 * factors;
let denom = terms[0] - terms[1];
if f32::abs(denom) < EPSILON {
return None; return None;
} }
return Some((terms[3] - terms[2]) / denom); return Some(matrix.inverse().transform_point(self.from() - other.from()).y());
const EPSILON: f32 = 0.0001; const EPSILON: f32 = 0.0001;
} }