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authorjaseg <git@jaseg.de>2022-01-30 20:11:38 +0100
committerjaseg <git@jaseg.de>2022-01-30 20:11:38 +0100
commitc3ca4f95bd59f69d45e582a4149327f57a360760 (patch)
tree5f43c61a261698e2f671b5238a7aa9a71a0f6d23 /gerbonara/graphic_primitives.py
parent259a56186820923c78a5688f59bd8249cf958b5f (diff)
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Rename gerbonara/gerber package to just gerbonara
Diffstat (limited to 'gerbonara/graphic_primitives.py')
-rw-r--r--gerbonara/graphic_primitives.py403
1 files changed, 403 insertions, 0 deletions
diff --git a/gerbonara/graphic_primitives.py b/gerbonara/graphic_primitives.py
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+++ b/gerbonara/graphic_primitives.py
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+
+import math
+import itertools
+
+from dataclasses import dataclass, KW_ONLY, replace
+
+
+@dataclass
+class GraphicPrimitive:
+ _ : KW_ONLY
+ polarity_dark : bool = True
+
+
+def rotate_point(x, y, angle, cx=0, cy=0):
+ """ rotate point (x,y) around (cx,cy) clockwise angle radians """
+
+ return (cx + (x - cx) * math.cos(-angle) - (y - cy) * math.sin(-angle),
+ cy + (x - cx) * math.sin(-angle) + (y - cy) * math.cos(-angle))
+
+def min_none(a, b):
+ if a is None:
+ return b
+ if b is None:
+ return a
+ return min(a, b)
+
+def max_none(a, b):
+ if a is None:
+ return b
+ if b is None:
+ return a
+ return max(a, b)
+
+def add_bounds(b1, b2):
+ (min_x_1, min_y_1), (max_x_1, max_y_1) = b1
+ (min_x_2, min_y_2), (max_x_2, max_y_2) = b2
+ min_x, min_y = min_none(min_x_1, min_x_2), min_none(min_y_1, min_y_2)
+ max_x, max_y = max_none(max_x_1, max_x_2), max_none(max_y_1, max_y_2)
+ return ((min_x, min_y), (max_x, max_y))
+
+def rad_to_deg(x):
+ return x/math.pi * 180
+
+@dataclass
+class Circle(GraphicPrimitive):
+ x : float
+ y : float
+ r : float # Here, we use radius as common in modern computer graphics, not diameter as gerber uses.
+
+ def bounding_box(self):
+ return ((self.x-self.r, self.y-self.r), (self.x+self.r, self.y+self.r))
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ return tag('circle', cx=self.x, cy=self.y, r=self.r, style=f'fill: {color}')
+
+
+@dataclass
+class Obround(GraphicPrimitive):
+ x : float
+ y : float
+ w : float
+ h : float
+ rotation : float # radians!
+
+ def to_line(self):
+ if self.w > self.h:
+ w, a, b = self.h, self.w-self.h, 0
+ else:
+ w, a, b = self.w, 0, self.h-self.w
+ return Line(
+ *rotate_point(self.x-a/2, self.y-b/2, self.rotation, self.x, self.y),
+ *rotate_point(self.x+a/2, self.y+b/2, self.rotation, self.x, self.y),
+ w, polarity_dark=self.polarity_dark)
+
+ def bounding_box(self):
+ return self.to_line().bounding_box()
+
+ def to_svg(self, tag, fg, bg):
+ return self.to_line().to_svg(tag, fg, bg)
+
+
+def arc_bounds(x1, y1, x2, y2, cx, cy, clockwise):
+ # This is one of these problems typical for computer geometry where out of nowhere a seemingly simple task just
+ # happens to be anything but in practice.
+ #
+ # Online there are a number of algorithms to be found solving this problem. Often, they solve the more general
+ # problem for elliptic arcs. We can keep things simple here since we only have circular arcs.
+ #
+ # This solution manages to handle circular arcs given in gerber format (with explicit center and endpoints, plus
+ # sweep direction instead of a format with e.g. angles and radius) without any trigonometric functions (e.g. atan2).
+ #
+ # cx, cy are relative to p1.
+
+ # Center arc on cx, cy
+ cx += x1
+ cy += y1
+ x1 -= cx
+ x2 -= cx
+ y1 -= cy
+ y2 -= cy
+ clockwise = bool(clockwise) # bool'ify for XOR/XNOR below
+
+ # Calculate radius
+ r = math.sqrt(x1**2 + y1**2)
+
+ # Calculate in which half-planes (north/south, west/east) P1 and P2 lie.
+ # Note that we assume the y axis points upwards, as in Gerber and maths.
+ # SVG has its y axis pointing downwards.
+ p1_west = x1 < 0
+ p1_north = y1 > 0
+ p2_west = x2 < 0
+ p2_north = y2 > 0
+
+ # Calculate bounding box of P1 and P2
+ min_x = min(x1, x2)
+ min_y = min(y1, y2)
+ max_x = max(x1, x2)
+ max_y = max(y1, y2)
+
+ # North
+ # ^
+ # |
+ # |(0,0)
+ # West <-----X-----> East
+ # |
+ # +Y |
+ # ^ v
+ # | South
+ # |
+ # +-----> +X
+ #
+ # Check whether the arc sweeps over any coordinate axes. If it does, add the intersection point to the bounding box.
+ # Note that, since this intersection point is at radius r, it has coordinate e.g. (0, r) for the north intersection.
+ # Since we know that the points lie on either side of the coordinate axis, the '0' coordinate of the intersection
+ # point will not change the bounding box in that axis--only its 'r' coordinate matters. We also know that the
+ # absolute value of that coordinate will be greater than or equal to the old coordinate in that direction since the
+ # intersection with the axis is the point where the full circle is tangent to the AABB. Thus, we can blindly set the
+ # corresponding coordinate of the bounding box without min()/max()'ing first.
+
+ # Handle north/south halfplanes
+ if p1_west != p2_west: # arc starts in west half-plane, ends in east half-plane
+ if p1_west == clockwise: # arc is clockwise west -> east or counter-clockwise east -> west
+ max_y = r # add north to bounding box
+ else: # arc is counter-clockwise west -> east or clockwise east -> west
+ min_y = -r # south
+ else: # Arc starts and ends in same halfplane west/east
+ # Since both points are on the arc (at same radius) in one halfplane, we can use the y coord as a proxy for
+ # angle comparisons.
+ small_arc_is_north_to_south = y1 > y2
+ small_arc_is_clockwise = small_arc_is_north_to_south == p1_west
+ if small_arc_is_clockwise != clockwise:
+ min_y, max_y = -r, r # intersect aabb with both north and south
+
+ # Handle west/east halfplanes
+ if p1_north != p2_north:
+ if p1_north == clockwise:
+ max_x = r # east
+ else:
+ min_x = -r # west
+ else:
+ small_arc_is_west_to_east = x1 < x2
+ small_arc_is_clockwise = small_arc_is_west_to_east == p1_north
+ if small_arc_is_clockwise != clockwise:
+ min_x, max_x = -r, r # intersect aabb with both north and south
+
+ return (min_x+cx, min_y+cy), (max_x+cx, max_y+cy)
+
+
+def point_line_distance(l1, l2, p):
+ # https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line
+ x1, y1 = l1
+ x2, y2 = l2
+ x0, y0 = p
+ length = math.dist(l1, l2)
+ if math.isclose(length, 0):
+ return math.dist(l1, p)
+ return ((x2-x1)*(y1-y0) - (x1-x0)*(y2-y1)) / length
+
+def svg_arc(old, new, center, clockwise):
+ r = math.hypot(*center)
+ # invert sweep flag since the svg y axis is mirrored
+ sweep_flag = int(not clockwise)
+ # In the degenerate case where old == new, we always take the long way around. To represent this "full-circle arc"
+ # in SVG, we have to split it into two.
+ if math.isclose(math.dist(old, new), 0):
+ intermediate = old[0] + 2*center[0], old[1] + 2*center[1]
+ # Note that we have to preserve the sweep flag to avoid causing self-intersections by flipping the direction of
+ # a circular cutin
+ return f'A {r:.6} {r:.6} 0 1 {sweep_flag} {intermediate[0]:.6} {intermediate[1]:.6} ' +\
+ f'A {r:.6} {r:.6} 0 1 {sweep_flag} {new[0]:.6} {new[1]:.6}'
+
+ else: # normal case
+ d = point_line_distance(old, new, (old[0]+center[0], old[1]+center[1]))
+ large_arc = int((d < 0) == clockwise)
+ return f'A {r:.6} {r:.6} 0 {large_arc} {sweep_flag} {new[0]:.6} {new[1]:.6}'
+
+@dataclass
+class ArcPoly(GraphicPrimitive):
+ """ Polygon whose sides may be either straight lines or circular arcs """
+
+ # list of (x : float, y : float) tuples. Describes closed outline, i.e. first and last point are considered
+ # connected.
+ outline : [(float,)]
+ # must be either None (all segments are straight lines) or same length as outline.
+ # Straight line segments have None entry.
+ arc_centers : [(float,)] = None
+
+ @property
+ def segments(self):
+ ol = self.outline
+ return itertools.zip_longest(ol, ol[1:] + [ol[0]], self.arc_centers or [])
+
+ def bounding_box(self):
+ bbox = (None, None), (None, None)
+ for (x1, y1), (x2, y2), arc in self.segments:
+ if arc:
+ clockwise, (cx, cy) = arc
+ bbox = add_bounds(bbox, arc_bounds(x1, y1, x2, y2, cx, cy, clockwise))
+
+ else:
+ line_bounds = (min(x1, x2), min(y1, y2)), (max(x1, x2), max(y1, y2))
+ bbox = add_bounds(bbox, line_bounds)
+ return bbox
+
+ def __len__(self):
+ return len(self.outline)
+
+ def __bool__(self):
+ return bool(len(self))
+
+ def _path_d(self):
+ if len(self.outline) == 0:
+ return
+
+ yield f'M {self.outline[0][0]:.6} {self.outline[0][1]:.6}'
+
+ for old, new, arc in self.segments:
+ if not arc:
+ yield f'L {new[0]:.6} {new[1]:.6}'
+ else:
+ clockwise, center = arc
+ yield svg_arc(old, new, center, clockwise)
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ return tag('path', d=' '.join(self._path_d()), style=f'fill: {color}')
+
+class Polyline:
+ def __init__(self, *lines):
+ self.coords = []
+ self.polarity_dark = None
+ self.width = None
+
+ for line in lines:
+ self.append(line)
+
+ def append(self, line):
+ assert isinstance(line, Line)
+ if not self.coords:
+ self.coords.append((line.x1, line.y1))
+ self.coords.append((line.x2, line.y2))
+ self.polarity_dark = line.polarity_dark
+ self.width = line.width
+ return True
+
+ else:
+ x, y = self.coords[-1]
+ if self.polarity_dark == line.polarity_dark and self.width == line.width \
+ and math.isclose(line.x1, x) and math.isclose(line.y1, y):
+ self.coords.append((line.x2, line.y2))
+ return True
+
+ else:
+ return False
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ if not self.coords:
+ return None
+
+ (x0, y0), *rest = self.coords
+ d = f'M {x0:.6} {y0:.6} ' + ' '.join(f'L {x:.6} {y:.6}' for x, y in rest)
+ width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+ return tag('path', d=d, style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linejoin: round; stroke-linecap: round')
+
+@dataclass
+class Line(GraphicPrimitive):
+ x1 : float
+ y1 : float
+ x2 : float
+ y2 : float
+ width : float
+
+ def bounding_box(self):
+ r = self.width / 2
+ return add_bounds(Circle(self.x1, self.y1, r).bounding_box(), Circle(self.x2, self.y2, r).bounding_box())
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+ return tag('path', d=f'M {self.x1:.6} {self.y1:.6} L {self.x2:.6} {self.y2:.6}',
+ style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linecap: round')
+
+@dataclass
+class Arc(GraphicPrimitive):
+ x1 : float
+ y1 : float
+ x2 : float
+ y2 : float
+ # absolute coordinates
+ cx : float
+ cy : float
+ clockwise : bool
+ width : float
+
+ def bounding_box(self):
+ r = self.width/2
+ endpoints = add_bounds(Circle(self.x1, self.y1, r).bounding_box(), Circle(self.x2, self.y2, r).bounding_box())
+
+ arc_r = math.dist((self.cx, self.cy), (self.x1, self.y1))
+
+ # extend C -> P1 line by line width / 2 along radius
+ dx, dy = self.x1 - self.cx, self.y1 - self.cy
+ x1 = self.x1 + dx/arc_r * r
+ y1 = self.y1 + dy/arc_r * r
+
+ # same for C -> P2
+ dx, dy = self.x2 - self.cx, self.y2 - self.cy
+ x2 = self.x2 + dx/arc_r * r
+ y2 = self.y2 + dy/arc_r * r
+
+ arc = arc_bounds(x1, y1, x2, y2, self.cx, self.cy, self.clockwise)
+ return add_bounds(endpoints, arc) # FIXME add "include_center" switch
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ arc = svg_arc((self.x1, self.y1), (self.x2, self.y2), (self.cx, self.cy), self.clockwise)
+ width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+ return tag('path', d=f'M {self.x1:.6} {self.y1:.6} {arc}',
+ style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linecap: round; fill: none')
+
+def svg_rotation(angle_rad, cx=0, cy=0):
+ return f'rotate({float(rad_to_deg(angle_rad)):.4} {float(cx):.6} {float(cy):.6})'
+
+@dataclass
+class Rectangle(GraphicPrimitive):
+ # coordinates are center coordinates
+ x : float
+ y : float
+ w : float
+ h : float
+ rotation : float # radians, around center!
+
+ def bounding_box(self):
+ return self.to_arc_poly().bounding_box()
+
+ def to_arc_poly(self):
+ sin, cos = math.sin(self.rotation), math.cos(self.rotation)
+ sw, cw = sin*self.w/2, cos*self.w/2
+ sh, ch = sin*self.h/2, cos*self.h/2
+ x, y = self.x, self.y
+ return ArcPoly([
+ (x - (cw+sh), y - (ch+sw)),
+ (x - (cw+sh), y + (ch+sw)),
+ (x + (cw+sh), y + (ch+sw)),
+ (x + (cw+sh), y - (ch+sw)),
+ ])
+
+ @property
+ def center(self):
+ return self.x + self.w/2, self.y + self.h/2
+
+ def to_svg(self, tag, fg, bg):
+ color = fg if self.polarity_dark else bg
+ x, y = self.x - self.w/2, self.y - self.h/2
+ return tag('rect', x=x, y=y, width=self.w, height=self.h,
+ transform=svg_rotation(self.rotation, self.x, self.y), style=f'fill: {color}')
+
+@dataclass
+class RegularPolygon(GraphicPrimitive):
+ x : float
+ y : float
+ r : float
+ n : int
+ rotation : float # radians!
+
+ def to_arc_poly(self):
+ ''' convert n-sided gerber polygon to normal ArcPoly defined by outline '''
+
+ delta = 2*math.pi / self.n
+
+ return ArcPoly([
+ (self.x + math.cos(self.rotation + i*delta) * self.r,
+ self.y + math.sin(self.rotation + i*delta) * self.r)
+ for i in range(self.n) ])
+
+ def bounding_box(self):
+ return self.to_arc_poly().bounding_box()
+
+ def to_svg(self, tag, fg, bg):
+ return self.to_arc_poly().to_svg(tag, fg, bg)
+