ARROW.sml

#############################################################
#
#	SML Script layer to draw a north arrow.
#
#	NOTE!  This script assumes that the SML layer is in some
#	coordinate system other than Lat/Lon (Which is unfortunately
#  what the SML layer seems to default to).  You MUST change
#	the coordinate system of the layer to State Plane or UTM
#  or something that uses feet or meters for coordinates.
#  If you try to draw this using degrees, you'll get a very
#  tall and thin arrow.
#
###############################################################
# Fill in parameters here...
# Angles are in degrees from vertical.  Positive is to
#	the left, negative is to the right

numeric mn_angle = -7.2;		# Degrees to magnetic north
numeric gn_angle;

###############################################################
#	Get the angle to true north from a map group.
#  This code may have to be tweaked for another layout.
#  It assumes that the group you want is the one just
#  before the group with this script (in drawing order).
class Group group;
group = ThisLayer.group.PrevGroup;
gn_angle = -group.AngleToNorth;

##############################################################
# Generate the strings.  Would like to have this produce
# Degrees, Minutes, Seconds, but decimal degrees is ok for now

string mn_anglestr$ = sprintf("%.1f", abs(mn_angle));
string gn_anglestr$ = sprintf("%.1f", abs(gn_angle));

numeric mn_theta = mn_angle + 90;		# Drawing wants angle from x-axis
numeric gn_theta = gn_angle + 90;

array numeric xs[6]; 
array numeric ys[6];
proc DrawStar(numeric cx, numeric cy, numeric size) {
	local numeric i, th;
	for i = 0 to 5 {
		th = 144 * i + 90;
		xs[i+1] = size * cosd(th) + cx;
		ys[i+1] = size * sind(th) + cy;
		}
	FillPolyLine(xs, ys, 5);
	# Even/Odd winding rule leaves a hole in the middle
	# of our star.  Fill it with a circle whose radius
	# is computed to intersect with the corners of the
	# pentagon shaped hole.  Could do this a different
	# color if we wanted.  Maybe do it before the actual
	# polygon fill to get a different colored hole.
	FillCircle(cx, cy, size * cosd(36) / 2);
	}

#============================================
# Draw a vertical line with a star above it.

numeric r;
SetColorName("black");
r = 200;

MoveTo(0,0);
DrawTo(0,r);
DrawStar(0, r+20, 20);

#============================================
# Draw arrow pointing to Magnetic north

numeric x, y;
r = r * .9;
x = r * cosd(mn_theta);
y = r * sind(mn_theta);
MoveTo(0, 0);
DrawTo(x, y);

# Draw a triangle at the top of it
FillArcWedge(x, y, 20, 20, 270 + mn_angle, 30);

SetColorName("gray");

DrawArc(0, 0, r, r, 90, mn_angle);
SetColorName("black");

DrawTextSetFont("Times.ttf");
DrawTextSetHeight(30);
MoveTo(x + 10, r/2);
DrawTextSimple(mn_anglestr$);
MoveTo(x, y + 5);
DrawTextSimple("MN");

#========================================================
# Draw Grid North

if (gn_angle) {
	r = r * .9;
	x = r * cosd(gn_theta);
	y = r * sind(gn_theta);
	MoveTo(0,0);
	SetColorName("black");
	DrawTo(x, y);
	SetColorName("gray");
	DrawArc(0, 0, r, r, 90, gn_angle);
	SetColorName("black");
	MoveTo(-50, y - 15);
	DrawTextSimple("GN");
	MoveTo(-55, r/2);
	DrawTextSimple(gn_anglestr$);
	}

#=========================================================
# Dump some text about what Grid north is.

numeric yh;
DrawTextSetHeight(20);
x = 100; y = r * .8; yh = 20;

MoveTo(x, y);
DrawTextSimple(group.Projection.System);
y = y - yh;

# Don't bother printing out the name if the system contains
# the name.  Example: "Universal Transverse Mercator"
# contains the name "Transverse Mercator"
if (!(group.Projection.System contains group.Projection.Name)) {
	MoveTo(x,y);
	DrawTextSimple(group.Projection.Name);
	y = y - yh;
	}

if (group.Projection.Zone != "") {
	MoveTo(x, y);
	DrawTextSimple(sprintf("Zone: %s", group.Projection.Zone));
	y = y - yh;
	}

MoveTo(x, y);
DrawTextSimple(group.Projection.Datum);
y = y - yh;

MoveTo(x, y);
DrawTextSimple(sprintf("Ellipsoid: %s", group.Projection.Ellipsoid));