geometryutils.h

#ifndef GEOMETRYUTILS_H
#define GEOMETRYUTILS_H

#include <QObject>
#include <QQmlEngine>
#include <QPoint>
#include <QVector2D>

class GeometryUtils : public QObject
{
    Q_OBJECT
    QML_ELEMENT
    QML_SINGLETON

public:
    explicit GeometryUtils(QObject *parent = nullptr);

    Q_INVOKABLE static qreal lerp(qreal from, qreal to, qreal t);

    // Calculate a transition between two given points, mapping position onto a nearest perpendicular point on a line between start and end points.
    // Returns a number clamped into [0; 1] range.
    Q_INVOKABLE static qreal linearPosition(QPointF start, QPointF end, QPointF position);

    // Calculate a transition between three given points in normalized coordinates.
    // Returns a Point where both coordinates are clamped into [0; 1] range:
    //  - x corresponds to the position between the start and end points,
    //  - y corresponds to the position on a perpendicular between the third (zero) point and a line between start and end points.
    Q_INVOKABLE static QPointF planarPosition(QPointF start, QPointF end, QPointF zero, QPointF position);

    // If the point is inside the triangle, do nothing and return the point.
    // Otherwise, find the closest vertex or a perpendicular projection on the perimeter.
    Q_INVOKABLE static QPointF snapPointToTriangle(QPointF vertexA, QPointF vertexB, QPointF vertexC, QPointF position);
    Q_INVOKABLE static QVector2D snapVectorToTriangle(QVector2D vertexA, QVector2D vertexB, QVector2D vertexC, QVector2D position);

    // Generate a random triangle (three vertices) whose bounds are a unit square.
    Q_INVOKABLE static QList<QPointF> randomUnitTriangle();

    // Generate an SVG path for an outline of a triangle with rounded corners.
    // Vertices are centers of circles for the rounded corners,
    // so the all edges are offset outward by the radius.
    Q_INVOKABLE static QString roundedTriangleOutlineSvgPath(QPointF vertexA, QPointF vertexB, QPointF vertexC, qreal cornerRadius);

    // Multiply each point by the given scale factor.
    Q_INVOKABLE static QList<QPointF> scaledPoints(const QList<QPointF> &points, QSizeF scale);
};

#endif // GEOMETRYUTILS_H