src/geometry.h

Wed, 25 May 2022 20:36:34 +0300

author
Teemu Piippo <teemu@hecknology.net>
date
Wed, 25 May 2022 20:36:34 +0300
changeset 199
6988973515d2
parent 187
30204975694a
child 200
ca23936b455b
permissions
-rw-r--r--

Fix pick() picking from weird places on the screen with high DPI scaling

glReadPixels reads data from the frame buffer, which contains data after
high DPI scaling, so any reads to that need to take this scaling into account

#pragma once
#include <QPolygonF>
#include "basics.h"

namespace geom
{
	struct Plane
	{
		glm::vec3 normal;
		glm::vec3 anchor;
	};

	template<int N, typename T = float, glm::qualifier Q = glm::defaultp>
	struct Line
	{
		glm::vec<N, T, Q> direction;
		glm::vec<N, T, Q> anchor;
	};

	template<int N, typename T = float, glm::qualifier Q = glm::defaultp>
	struct Ray
	{
		glm::vec<N, T, Q> direction;
		glm::vec<N, T, Q> anchor;
	};

	template<int N>
	struct Polygon
	{
		std::array<glm::vec3, N> points;
	};

	template<int N>
	struct Polygon2D
	{
		glm::vec2 points[N];
	};

	inline const glm::vec3 origin = {0, 0, 0};
	inline const Plane XY = {{0, 0, 1}, origin};
	inline const Plane XZ = {{0, 1, 0}, origin};
	inline const Plane YZ = {{1, 0, 0}, origin};
	using Triangle = Polygon<3>;
	using LineSegment2D = Polygon2D<2>;

	/**
	 * @brief Computes a line from two points
	 * @param point_1
	 * @param point_2
	 * @return line
	 */
	template<int N, typename T, glm::qualifier Q>
	Line<N, T, Q> lineFromPoints(const glm::vec<N, T, Q>& point_1, const glm::vec<N, T, Q>& point_2)
	{
		return {point_2 - point_1, point_1};
	}

	template<int N, typename T, glm::qualifier Q>
	Ray<N, T, Q> rayFromPoints(const glm::vec<N, T, Q>& point_1, const glm::vec<N, T, Q>& point_2)
	{
		return {point_2 - point_1, point_1};
	}

	template<int N, typename T, glm::qualifier Q>
	Line<N, T, Q> rayToLine(const Ray<N, T, Q>& ray)
	{
		return {ray.direction, ray.anchor};
	}

	enum class RectangleSide
	{
		Top,
		Left,
		Bottom,
		Right
	};

	struct PointOnRectagle
	{
		glm::vec2 position;
		RectangleSide side;
	};

	std::optional<glm::vec2> lineLineIntersection(const Line<2>& line_1, const Line<2>& line_2);
	std::optional<glm::vec2> rayLineSegmentIntersection(const Ray<2>& ray, const LineSegment2D& line);
	std::optional<PointOnRectagle> rayRectangleIntersection(const Ray<2>& ray, const QRectF& rectangle);
	Plane planeFromTriangle(const Triangle& triangle);
	glm::vec3 normalVector(const Triangle& triangle);
	std::optional<glm::vec3> linePlaneIntersection(
		const Line<3>& line,
		const Plane& plane, const float epsilon = 1e-6f);
	glm::vec3 scalingVector(const glm::mat4 matrix);
	LineSegment2D top(const QRectF& rectangle);
	LineSegment2D bottom(const QRectF& rectangle);
	LineSegment2D left(const QRectF& rectangle);
	LineSegment2D right(const QRectF& rectangle);
	bool isConvex(const std::vector<glm::vec3>& polygon);
	Winding winding(const QPolygonF& polygon);
	struct ScalingExtract
	{
		glm::vec3 scaling;
		glm::mat4 unscaled;
	};
	ScalingExtract extractScaling(const glm::mat4& matrix);

	struct NPolygon
	{
		std::vector<glm::vec3> points;
	};

	inline constexpr bool isclose(const glm::vec3& a, const glm::vec3& b)
	{
		return qFuzzyCompare(a.x, b.x)
			and qFuzzyCompare(a.y, b.y)
			and qFuzzyCompare(a.z, b.z);
	}

	struct CircleF
	{
		QPointF center;
		qreal radius;
	};

	/**
	 * @brief Inscribes a circle
	 * @param circle
	 * @return a QRectF that inscribes the specified circle
	 */
	inline constexpr QRectF inscribe(const CircleF& circle)
	{
		return {
			circle.center.x() - circle.radius,
			circle.center.y() - circle.radius,
			circle.radius * 2,
			circle.radius * 2
		};
	}

	struct BezierCurve
	{
		glm::vec3 points[4];
		const glm::vec3& operator[](int x) const
		{
			Q_ASSERT(x >= 0 and x < 4);
			return this->points[x];
		}
		glm::vec3& operator[](int x)
		{
			Q_ASSERT(x >= 0 and x < 4);
			return this->points[x];
		}
	};

	glm::vec3 pointOnCurve(const BezierCurve& curve, float t);
	glm::vec3 derivativeOnCurve(const BezierCurve& curve, float t);
}

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