glm/gtx/polar_coordinates: polar function computes distance using normalized vector to position

[papasitopapi]

Current implementation:

	template<typename T, qualifier Q>
	GLM_FUNC_QUALIFIER vec<3, T, Q> polar
	(
		vec<3, T, Q> const& euclidean
	)
	{
		T const Length(length(euclidean));
		vec<3, T, Q> const tmp(euclidean / Length);
		T const xz_dist(sqrt(tmp.x * tmp.x + tmp.z * tmp.z));

		return vec<3, T, Q>(
			asin(tmp.y),	// latitude
			atan(tmp.x, tmp.z),		// longitude
			xz_dist);				// xz distance
	}

The third coordinate is calculated using the normalized tmp vector, which makes glm::polar(vec3) map all points situated on the same direction from the origin to the same polar coordinates, regardless of distance.

#include <glm/gtx/polar_coordinates.hpp>
#include <glm/gtx/string_cast.hpp>

#include <iostream>

int main() {
    glm::vec3 position1 = {1.0f, 2.0f, 3.0f};
    glm::vec3 position2 = 100.0f * position1;

    std::cout << glm::to_string(glm::polar(position1)) << std::endl;
    std::cout << glm::to_string(glm::polar(position2)) << std::endl;
}

Output:

vec3(0.563943, 0.321751, 0.845154)
vec3(0.563943, 0.321751, 0.845154)

Also I'm not sure what xz_distance is supposed to be, but I find it bizarre to use that instead of distance to origin.