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-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)