1/*
2 * Copyright 2016-2017 Uber Technologies, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16/** @file vec2d.c
17 * @brief 2D floating point vector functions.
18 */
19
20#include "vec2d.h"
21#include <math.h>
22#include <stdio.h>
23
24/**
25 * Calculates the magnitude of a 2D cartesian vector.
26 * @param v The 2D cartesian vector.
27 * @return The magnitude of the vector.
28 */
29double _v2dMag(const Vec2d* v) { return sqrt(v->x * v->x + v->y * v->y); }
30
31/**
32 * Finds the intersection between two lines. Assumes that the lines intersect
33 * and that the intersection is not at an endpoint of either line.
34 * @param p0 The first endpoint of the first line.
35 * @param p1 The second endpoint of the first line.
36 * @param p2 The first endpoint of the second line.
37 * @param p3 The second endpoint of the second line.
38 * @param inter The intersection point.
39 */
40void _v2dIntersect(const Vec2d* p0, const Vec2d* p1, const Vec2d* p2,
41 const Vec2d* p3, Vec2d* inter) {
42 Vec2d s1, s2;
43 s1.x = p1->x - p0->x;
44 s1.y = p1->y - p0->y;
45 s2.x = p3->x - p2->x;
46 s2.y = p3->y - p2->y;
47
48 float t;
49 t = (s2.x * (p0->y - p2->y) - s2.y * (p0->x - p2->x)) /
50 (-s2.x * s1.y + s1.x * s2.y);
51
52 inter->x = p0->x + (t * s1.x);
53 inter->y = p0->y + (t * s1.y);
54}
55
56/**
57 * Whether two 2D vectors are equal. Does not consider possible false
58 * negatives due to floating-point errors.
59 * @param v1 First vector to compare
60 * @param v2 Second vector to compare
61 * @return Whether the vectors are equal
62 */
63bool _v2dEquals(const Vec2d* v1, const Vec2d* v2) {
64 return v1->x == v2->x && v1->y == v2->y;
65}
66