summaryrefslogtreecommitdiff
path: root/lib/ray.cpp
blob: f9e33118b2cfb7f7cde5b3d4943721e6f111c1af (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
#include "ray.hpp"
#include <algorithm>

Ray
Ray::fromPoints(glm::vec3 start, glm::vec3 p)
{
	return {start, glm::normalize(p - start)};
}

float
Ray::distanceToLine(const glm::vec3 & p1, const glm::vec3 & e1) const
{
	// https://en.wikipedia.org/wiki/Skew_lines
	const auto diff = p1 - e1;
	const auto d1 = glm::normalize(diff);
	const auto &p2 = start, &d2 = direction;
	const auto n = glm::cross(d1, d2);
	const auto n2 = glm::cross(d2, n);
	const auto c1 = p1 + (glm::dot((p2 - p1), n2) / glm::dot(d1, n2)) * d1;
	const auto difflength = glm::length(diff);
	if (glm::length(c1 - p1) > difflength || glm::length(c1 - e1) > difflength) {
		return std::numeric_limits<float>::infinity();
	}
	return glm::abs(glm::dot(n, p1 - p2));
}

bool
Ray::passesCloseToEdges(const std::span<const glm::vec3> positions, float distance) const
{
	return std::adjacent_find(positions.begin(), positions.end(),
				   [this, distance](const glm::vec3 & a, const glm::vec3 & b) {
					   return distanceToLine(a, b) <= distance;
				   })
			!= positions.end();
}