293

README.md

@@ -6,6 +6,16 @@ Hi! I'm [Alexandre Villares](https://abav.lugaralgum.com), let's see if I can ma
 
 If you enjoy this, be a [patreon](https://patreon.com/arteprog) or make a donation [here](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=HCGAKACDMVNV2) 
 
+
+---
+
+![s293](s293/s293.gif)
+
+293: [code](https://github.com/villares/sketch-a-day/tree/master/s293) [[Py.Processing](https://villares.github.io/como-instalar-o-processing-modo-python/index-EN)]
+
+The polygons now are non-self-intersecting, and the hatches are kept inside :)
+White lines in the background are from discarded random polys that self-intersected.
+
 ---
 
 ![s292](s292/s292.gif)
@@ -13,7 +23,6 @@ If you enjoy this, be a [patreon](https://patreon.com/arteprog) or make a donati
 292: [code](https://github.com/villares/sketch-a-day/tree/master/s292) [[Py.Processing](https://villares.github.io/como-instalar-o-processing-modo-python/index-EN)]
 
 
-
 ---
 
 ![s291](s291/s291.gif)

s293/s293.pyde

@@ -0,0 +1,136 @@
+# Alexandre B A Villares - https://abav.lugaralgum.com/sketch-a-day
+SKETCH_NAME = "s293"  # 20181018
+OUTPUT = ".gif"
+
+NUM = 8 
+BORDER = 50
+SPACING = 10
+
+def setup():
+    global previous_points, next_points, points
+    size(500, 500)
+    frameRate(5 )
+    points = previous_points = create_points()
+    next_points = create_points()
+    
+def create_points(non_intersecting=True):
+    background(200)
+    done = False
+    while not done:
+        points = [PVector(random(BORDER, width - BORDER),
+                         random(BORDER, height - BORDER))
+                  for _ in range(NUM)]
+        edges = pairwise(points) + [(points[-1], points[0])]
+        done = True
+        if non_intersecting:
+            for p1, p2 in edges:
+                for p3, p4 in edges:
+                    # test only non consecutive edges
+                    if (p1 != p3) and (p2 != p3) and (p1 != p4):
+                        if line_instersect(Line(p1, p2), Line(p3, p4)):
+                            stroke(255, 51)
+                            strokeWeight(2)
+                            line(p1.x, p1.y, p2.x, p2.y)
+                            done = False
+                            break
+    return points
+    
+        
+
+def draw():  
+
+    stroke(0, 0, 100)
+    for x in range(0, width, SPACING):
+           a = PVector(x, 0)
+           b = PVector(x, height)
+           inter_points = inter_line(points, Line(a, b))
+           draw_inter(inter_points)
+            
+    stroke(100, 0, 0)
+    for y in range(0, height, SPACING):
+           a = PVector(0, y)
+           b = PVector(width, y)
+           inter_points = inter_line(next_points, Line(a, b))
+           draw_inter(inter_points)
+    
+
+
+def inter_line(points, L):                         
+    edges = pairwise(points) + [(points[-1], points[0])]
+    inter_points = []
+    
+    for p1, p2 in edges:
+        strokeWeight(2)
+        line(p1.x, p1.y, p2.x, p2.y)
+        inter = line_instersect(Line(p1, p2), L)
+        if inter:
+            inter_points.append(inter)
+    return inter_points   
+
+def draw_inter(inter_points):
+    if inter_points and len(inter_points) > 1:
+        # strokeWeight(7)
+        # for p in inter_points:
+        #     point(p.x, p.y)
+        strokeWeight(1)
+        inter_points.sort()
+        pairs = zip(inter_points[::2], inter_points[1::2])
+        for p1, p2 in pairs:
+            if p2:
+               line(p1.x, p1.y, p2.x, p2.y)    
+    
+def keyPressed():
+    global points, next_points
+    if key == " ": 
+        points = create_points()
+        next_points = create_points()
+    if key == "s": saveFrame("###.png")
+        
+class Line():
+    """ I should change this to a named tuple... """
+    def __init__(self, p1, p2):
+        self.p1 = p1
+        self.p2 = p2
+    
+def line_instersect(line_a, line_b):     
+    """
+    code adapted from Bernardo Fontes 
+    https://github.com/berinhard/sketches/
+    """
+       
+    x1, y1 = line_a.p1.x, line_a.p1.y
+    x2, y2 = line_a.p2.x, line_a.p2.y
+    x3, y3 = line_b.p1.x, line_b.p1.y
+    x4, y4 = line_b.p2.x, line_b.p2.y
+        
+    try:
+        uA = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
+        uB = ((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
+    except ZeroDivisionError:
+        return 
+        
+    if not(0 <= uA <= 1 and 0 <= uB <= 1):
+        return
+        
+    x = line_a.p1.x + uA * (line_a.p2.x - line_a.p1.x)
+    y = line_a.p1.y + uA * (line_a.p2.y - line_a.p1.y)
+        
+    return PVector(x, y)
+
+
+def pairwise(iterable):
+    import itertools
+    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
+    a, b = itertools.tee(iterable)
+    next(b, None)
+    return zip(a, b) 
+
+# print text to add to the project's README.md             
+def settings():
+    println(
+"""
+![{0}]({0}/{0}{2})
+
+{1}: [code](https://github.com/villares/sketch-a-day/tree/master/{0}) [[Py.Processing](https://villares.github.io/como-instalar-o-processing-modo-python/index-EN)]
+""".format(SKETCH_NAME, SKETCH_NAME[1:], OUTPUT)
+    )