A deeper bevel on lineJoin()?

I'm in the process of animating diagrams to show the design rules behind Wim Crouwel's New Alphabet. The rules themselves can be explained with lines and points; the weight of the strokes and the shape of the joins are stylizations. But to show the rules being used to make Crouwel's letterforms it would be good to recreate what Crouwel showed in his specimens, and I'm running into a problem:
newPage(500, 500) fill(1) rect(0, 0, 500, 500) translate(250, 250) path = BezierPath() path.moveTo((50, 50)) path.lineTo((50, 50)) path.lineTo((50, 50)) stroke(0) strokeWidth(50) lineJoin('bevel') lineCap('square') drawPath(path) saveImage('~/Desktop/crouwel_test.jpg')
gives me:
which is not as deep a bevel as Crouwel used—it essentially makes it look as if Crouwel folded ribbons at 90deg to make his letterforms:
I've tried setting the bevel at a negative number, but no luck. Any ideas?

And, while I'm asking questions: the code I'm writing is drawing segments in a single path. Is there a way to join these segments into a single, sometimes forking, path, where the contiguous parts are joined and capped per lineJoin and lineCap? Here's the code I have so far to sketch out Crouwel's basic structure:
canvas = 720 cellX = canvas/6 cellY = canvas/6 width = cellX/6 * 2 nodes = [ (cellX, cellY * 2), (cellX, cellY * 2), (cellX, cellY), (0, cellY), (cellX, cellY), (cellX, 0), (cellX, 0), (cellX, cellY), (0, cellY), (cellX, cellY), (cellX, cellY * 2), (cellX, cellY * 2)] segs = [ [0, 0], [0, 1], [0, 2], [1, 1], [1, 4], [2, 3], [2, 4], [2, 5], [3, 4], [3, 8], [4, 6], [5, 6], [5, 7], [6, 9], [7, 8], [7, 9], [7, 10], [8, 9], [9, 11], [10, 10], [10, 11], [11, 11] ] for r in range(0, 512): newPage(canvas, canvas) fill(1) rect(0, 0, canvas, canvas) translate(canvas/2, canvas/2) count = bin(r)[2:] count = count.zfill(22) count = count[::1] for n in range(len(nodes)): fill(1, 0, 0) oval(nodes[n][0]  5, nodes[n][1]  5, 10, 10) path = BezierPath() fill(None) strokeWidth(width) stroke(0) lineJoin('bevel') lineCap('square') glyph = [] for d in range(len(count)): if count[d] == '1': path.moveTo(nodes[segs[d][0]]) path.lineTo(nodes[segs[d][1]]) path.closePath() drawPath(path)
and here's an example of what it produces that I'm trying to avoid (the red circles show node locations):

mm, you cannot set the 'dept' of the bevel.
I would encourage you to have a look at the outline pen from the outliner extension
To combine several lines its best to draw them together in a
BezierPath

Frederik, I'll take a look. I wonder if this and the feature requests I just made could be covered if I just learned more about how to use pens … I really don't want DrawBot to wind up like Illustrator, I swear!

I was working on a foldfont system a few years ago. it took some time to get the trigonometry right. but once that was solved the possibilities were endless ...
so the new alphabet could be rendered with different stroke weights
scaling in the x
or y direction
and there could be multiliners
seems like i did not compensate for the stroke weight at the end of a stroke but the system could be used for any collection of xypoints
it is all a bit messy but let me know if you need some bits.

looks awesome!

@jo I'd love to see your code! Like I said, the way Crouwel used the corners was unrelated to the rules he used to construct the letterforms, so I could illustrate his structure without the beveled corners. But it would be nice in a presentation to show audiences the letters as he styled them.

@frederik Are all the import dependencies/paths in the outliner extension only going to make sense if I have RoboFont installed? Because I don't have RoboFont …

@mauricemeilleur I don’t know how Crouwel defined his rules. but to me the cornerrule seems like an integral part of the design.
I had a look at my code and tried to tidy the worst bits. some of the angle calculations seem very inefficient but ¯\(ツ)/¯ here it is:
EDIT 20180528 changed the code to simplify some of the horrible trigonometry and there now is the
sq_cap
bool to have squared linecaps.# Draw a 'folded outline' between a set of points. # TO DO: There should be an error message when two dots are closer to each other and the weight. # There should be a warning if the folding is further than the next points. # There should be a warning for collinear points. import math # Just a bunch of points p01 = (894, 334) p02 = (808, 86) p03 = (274, 792) p04 = (481, 920) p05 = (583, 730) p06 = (85, 430) p07 = (318, 100) p08 = (870, 600) p09 = (720, 690) points = [p01, p02, p03, p04, p05, p06, p07, p08, p09] def get_dist(p1, p2): return sqrt( (p2[0]  p1[0] )**2 + (p2[1]  p1[1])**2 ) def calc_angle(p1, p2): return atan2((p2[1]  p1[1]), (p2[0]  p1[0])) def calc_delta(p1, p2, p3): ''' Returns the angle between three points. ''' return calc_angle(p2, p3)  calc_angle(p2, p1) def calc_offset(weight, p1, p2, p3): ''' Returns the x and y "offset" to be added to the points of the polygon. ''' halfWeight = weight/2 if p1 == p2: alpha = calc_angle(p1, p3) b = sin(alpha) * halfWeight a = cos(alpha) * halfWeight elif p2 == p3: alpha = calc_angle(p1, p3) b = sin(alpha) * halfWeight a = cos(alpha) * halfWeight else: alpha = calc_angle(p2, p3) delta = calc_delta(p1, p2, p3) xx = halfWeight / sin((delta  pi) / 2) delta_f = (2 * alpha  pi  delta ) / 2 a, b = xx * sin(delta_f), xx * cos(delta_f) return a, b def wrap_line(p1, p2, p3, p4, weight): ''' This draws a polygon around a line. Four points (x,y) and a weight parameter are required. The polygon will be drawn around the two middle points. The first and last points define the angles. ''' a, b = calc_offset(weight, p1, p2, p3) # extend first point x1b, y1b = p2[0]  b, p2[1]  a x1c, y1c = p2[0] + b, p2[1] + a # extend second point c, d = calc_offset(weight, p2, p3, p4) x2b, y2b = p3[0]  d, p3[1]  c x2c, y2c = p3[0] + d, p3[1] + c polygon((x1b, y1b), (x1c, y1c), (x2b, y2b), (x2c, y2c)) #  # The actual drawing fill(0, .4) weight = 180 sq_cap = True if len(points) == 1: rect(points[0][0]  weight/2, points[0][1]  weight/2, weight, weight) for i, point in enumerate(points[:1]): # print (get_dist(point, points[i+1])) if len(points) == 2: wrap_line(points[i], points[i], points[i+1], points[i+1], weight) else: if i == 0: aaa = calc_angle(points[i], points[i+1]) if sq_cap: point = point[0]  weight/2 * cos(aaa), point[1]  weight/2 * sin(aaa) wrap_line(point, point, points[i+1], points[i+2], weight) elif i == len(points)2: next_p = points[i+1] aaa = calc_angle(points[i], next_p) if sq_cap: next_p = next_p[0] + weight/2 * cos(aaa), next_p[1] + weight/2 * sin(aaa) wrap_line(points[i1], points[i], next_p, next_p, weight) else: # print ( calc_delta(points[i1], points[i], points[i+1]) ) wrap_line(points[i1], points[i], points[i+1], points[i+2], weight)

and thanks to @gferreira who helped me getting the initial bits!

Thanks for sharing this!—I'll have a look. I agree that Crouwel used that beveled join pretty consistently. It's just that the underlying logic of the letterforms—the grid of nodes, the segments used to make up the glyph paths—is independent of how the strokes are styled. (Thus he had for example a version of the alphabet with dots in the dimensions of his columns and rows.)

@jo good times!

@jo Johannes, thanks again for posting your code. I'm off to a promising start—the code is handling the 90° bends perfectly and capping the ends correctly; these paths all have 3 or more points to them. But it's not handling the 2point segments correctly, as you can see here (the red circles mark the node locations in the grid). I'm digging into the code now, but in case you have any ideas … ?

I can confirm the sq_cap toggle does work and affects the polygon drawn around the bent paths, but not the twosegment paths.

Figured it out, seems obvious: the <if len(points) == 2:> option wasn't adjusting for the square cap. Just took some adapting the code and it all works great, now. Thanks again!

@mauricemeilleur sorry. I made the changes and updated the post. Only after implementing the changes in my local version did I realize that i forgot to adapt the
len(points) == 2
option. but great you figured it out anyway,
good luck!

The last thing will be to provide for the case where the points are in a continuous chain, like the <o>. I'm pretty sure I know what to do, and it shouldn't be that hard, but I have some other problems with the Crouwel code to fix first (all to do with graphing and finding valid paths—this whole project is forcing me to teach myself the basics of computer science as I go). I'll post the revised and extended code here when it's done.