Twisted Roses in Logo

twisted-roses.logo

function new() {
	// set default screen, pen and turtle values
	setbg(0, 0, 0);
	setpc(0, 1, 0);
	setpw(1);
	pu();
}

function ang_col(theta) {
	return abs(255 * cos(theta));
}

function spiral(angle, twist) {
	// Twisted Rose Curves
	radius = 180 * sin(4 * angle);
	angle = angle + 20 * sin(twist * angle);
	setpw(width(angle, radius));
	setpc(ang_col(30 + 3 * angle), 0, 255);
	setxy(radius * sin(angle), radius * cos(angle));
	pd();
}

function width(angle, radius) {
	seth2(radius * sin(angle), radius * cos(angle));
	return 2 * (1.5 + sin(45 + 2 * geth()));
}

new();
for (twist = 0 to 24) {}
	for (angle = 0 to 360) {
		spiral(angle, twist);
	}
}