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maras

Member

Registered: 2021-04-25

Posts: 28

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draw_curve_cb (cubic bezier)

Expand/// draw_curve_cb(p1, p2, p3, p4, prec)
//
//    p1    start point, array [x, y]
//    p2    curvature point 1, array [x, y]
//    p3    curvature point 2, array [x, y]
//    p4    end point, array [x, y]
//    prec     precision, number of segments, real
//
/// GMLscripts.com/license

function draw_curve_cb(p1, p2, p3, p4, prec) {
	
	prec = round(prec);
	var prev_cb = p1;
	for(var i = 0; i < prec; i++) {
		var cb = cubic_bezier(p1, p2, p3, p4, i / prec);
		draw_line(cb[0], cb[1], prev_cb[0], prev_cb[1]);
		prev_cb = cb;
	}
	draw_line(prev_cb[0], prev_cb[1], p4[0], p4[1]);
}

/// cubic_bezier(p1, p2, p3, p4, t)
//
// returns array [x, y], a single point on the curve depending on t
//
//    p1    start point, array [x, y]
//    p2    curvature point 1, array [x, y]
//    p3    curvature point 2, array [x, y]
//    p4    end point, array [x, y]
//    t     curve position, real
//
/// GMLscripts.com/license

function cubic_bezier(p1, p2, p3, p4, t) {
    t = clamp(t, 0, 1);
    return [
        p1[0] * power(1-t, 3) + 3 * p2[0] * power(1-t, 2) * t + 3 * p3[0] * (1-t) * power(t, 2) + p4[0] * power(t, 3),
        p1[1] * power(1-t, 3) + 3 * p2[1] * power(1-t, 2) * t + 3 * p3[1] * (1-t) * power(t, 2) + p4[1] * power(t, 3)
    ];
}

Last edited by maras (2022-12-27 07:42:01)

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