Separating Axis Theorem Helper Functions

sat_1.js

function buildEdges(vertices) {
    const edges = [];
    if (vertices.length < 3) {
        console.error("Only polygons supported.");
        return edges;
    }
    for (let i = 0; i < vertices.length; i++) {
        const a = vertices[i];
        let b = vertices[0];
        if (i + 1 < vertices.length) {
            b = vertices[i + 1];
        }
        edges.push({
            x: (b.x - a.x),
            y: (b.y - a.y),
        });
    }
    return edges;
}

function intervalDistance(minA, maxA, minB, maxB) {
    if (minA < minB) {
        return (minB - maxA);
    }
    return (minA - maxB);
}