src/ldrawalgorithm.h

#pragma once
#include "src/basics.h"
#include "src/model.h"

namespace ldraw
{
	/// Determines how quadrilaterals are split into triangles
	enum class Diagonal
	{
		Diagonal_13,
		Diagonal_24
	};

	std::pair<Triangle, Triangle> splitTriangles(
		const Quadrilateral& q,
		ldraw::Diagonal diagonal);

	std::vector<ModelAction> makeUnofficial(const Model *model);

	constexpr float circleAngle(unsigned int divisions, unsigned int i)
	{
		constexpr float ofs = 0.5 * pi;
		float factor = -2.0f * pi / static_cast<float>(divisions);
		return static_cast<float>(i) * factor + ofs;
	}

	constexpr glm::vec2 rimpoint(unsigned int divisions, unsigned int i)
	{
		const float angle = circleAngle(divisions, i);
		return glm::vec2{std::sin(angle), std::cos(angle)};
	}

	template<typename Fn>
	void circleAngles(unsigned int segments, unsigned int divisions, Fn&& fn)
	{
		for (unsigned int i = 0; i < segments; i += 1)
		{
			const float a1 = circleAngle(divisions, i - 1);
			const float a2 = circleAngle(divisions, i);
			const float a3 = circleAngle(divisions, i + 1);
			fn(a1, a2, a3);
		}
	}

	template<typename Fn>
	void circle(unsigned int segments, unsigned int divisions, Fn&& fn)
	{
		circleAngles(segments, divisions, [&fn](
			const float a1,
			const float a2,
			const float a3
		){
			fn(
				glm::vec2{std::sin(a1), std::cos(a1)},
				glm::vec2{std::sin(a2), std::cos(a2)},
				glm::vec2{std::sin(a3), std::cos(a3)}
			);
		});
	}
}

ModelElement inverted(const ModelElement &element);