renderScript.js

function generate_cloth_mesh(x, y, w, h, nx = 10, ny = 10) {

    const base = pointCount;

    const ux = w / (nx - 1);
    const uy = h / (ny - 1);

    for (let r = 0; r < ny; r++) {
        for (let c = 0; c < nx; c++) {

            ADD_POINT(x + ux * c, y + uy * r, r == 0)

        }
    }

    const index = (r, c) => base + r * nx + c;

    for (let r = 0; r < ny; r++) {
        for (let c = 0; c < nx; c++) {

            if (r > 0) {
                ADD_EDGE(index(r - 1, c), index(r, c))
            }

            if (c > 0) {
                ADD_EDGE(index(r, c - 1), index(r, c))
            }

            /*
            if (c > 0 && r > 0) {
                ADD_EDGE(index(r - 1, c - 1), index(r, c))
            }
            */

        }
    }

}

function DRAW_EDGE(i) {
    const p1 = edgeA[i]
    const p2 = edgeB[i]

    const p1x = posX[p1]
    const p1y = posY[p1]

    const p2x = posX[p2]
    const p2y = posY[p2]

    drawLine(p1x, p1y, p2x, p2y)
}

function DRAW_ALL() {
    for (let i = 0; i < edgeCount; i++) {
        DRAW_EDGE(i);
    }
}

function POINT_RECT(px, py, x1, y1, x2, y2, dist = 5) {
    const pad = dist;

    return (
        px >= Math.min(x1, x2) - pad &&
        px <= Math.max(x1, x2) + pad &&
        py >= Math.min(y1, y2) - pad &&
        py <= Math.max(y1, y2) + pad
    );
}

function POINT_SEG_DIST(px, py, ax, ay, bx, by) {
    const dx = bx - ax;
    const dy = by - ay;

    const lenSq = dx * dx + dy * dy;
    if (lenSq === 0) return Infinity;

    let t = ((px - ax) * dx + (py - ay) * dy) / lenSq;
    t = Math.max(0, Math.min(1, t));

    const cx = ax + t * dx;
    const cy = ay + t * dy;

    const ddx = px - cx;
    const ddy = py - cy;

    return ddx * ddx + ddy * ddy; // THIS IS SQUARED
}

function CAN_SLICE_EDGE(i, dist = 5) {
    const p1 = edgeA[i]
    const p2 = edgeB[i]

    const p1x = posX[p1]
    const p1y = posY[p1]

    const p2x = posX[p2]
    const p2y = posY[p2]

    return POINT_RECT(mouseX, mouseY, p1x, p1y, p2x, p2y) && POINT_SEG_DIST(mouseX, mouseY, p1x, p1y, p2x, p2y) <= dist * dist
}

function HANDLE_SLICING_EDGES() {
    const toSplit = [];

    for (let i = 0; i < edgeCount; i++) {
        if (CAN_SLICE_EDGE(i)) {
            toSplit.push(i);
        }
    }

    for (let i = toSplit.length - 1; i >= 0; i--) {
        SPLIT_EDGE(toSplit[i]);
    }
}