added support for automatically distributed support bridges at corners or at edges

git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@959 bbaffbd6-741e-11dd-a85d-61de82d9cad9

Changelog

@@ -21,6 +21,7 @@ Version 0.4.1 - UNRELEASED
  * visibility of 3D view items is now configurable in the 3D window
   * via a button and via the context menu
  * improved stability of remote processing: disconnected nodes should not cause problems anymore
+ * automatically distributed support bridges can now be placed at corners or edges
 
 Version 0.4.0.1 - 2010-10-24
  * disabled parallel processing for Windows standalone executable

share/ui/pycam-project.ui

@@ -216,7 +216,10 @@
         <col id="0" translatable="yes">grid pattern</col>
       </row>
       <row>
-        <col id="0" translatable="yes">automatic distribution</col>
+        <col id="0" translatable="yes">automatic distribution (edges)</col>
+      </row>
+      <row>
+        <col id="0" translatable="yes">automatic distribution (corners)</col>
       </row>
     </data>
   </object>

src/pycam/Geometry/Polygon.py

@@ -142,6 +142,7 @@ class Polygon(TransformableContainer):
         Currently this works only for line groups in an xy-plane.
         Returns zero for empty line groups or for open line groups.
         Returns negative values for inner hole.
+        TODO: "get_area" is wrong by some factor - check the result!
         """
         if not self._points:
             return 0
@@ -163,6 +164,55 @@ class Polygon(TransformableContainer):
             self._area_cache = result / 2
         return self._area_cache
 
+    def get_barycenter(self):
+        area = self.get_area()
+        if not area:
+            return None
+        # TODO: for now we just calculate the "middle of the outline" - the "barycenter" code below needs to be fixed
+        return Point((self.maxx + self.minx) / 2, (self.maxy + self.miny) / 2,
+                (self.maxz + self.minz) / 2)
+        # see: http://stackoverflow.com/questions/2355931/compute-the-centroid-of-a-3d-planar-polygon/2360507
+        # first: calculate cx and y
+        cxy, cxz, cyx, cyz, czx, czy = (0, 0, 0, 0, 0, 0)
+        for index in range(len(self._points)):
+            p1 = self._points[index]
+            p2 = self._points[(index + 1) % len(self._points)]
+            cxy += (p1.x + p2.x) * (p1.x * p2.y - p1.y * p2.x)
+            cxz += (p1.x + p2.x) * (p1.x * p2.z - p1.z * p2.x)
+            cyx += (p1.y + p2.y) * (p1.y * p2.x - p1.x * p2.y)
+            cyz += (p1.y + p2.y) * (p1.y * p2.z - p1.z * p2.y)
+            czx += (p1.z + p2.z) * (p1.z * p2.x - p1.x * p2.z)
+            czy += (p1.z + p2.z) * (p1.z * p2.y - p1.y * p2.z)
+        if self.minz == self.maxz:
+            return Point(cxy / (6 * area), cyx / (6 * area), self.minz)
+        elif self.miny == self.maxy:
+            return Point(cxz / (6 * area), self.miny, czx / (6 * area))
+        elif self.minz == self.maxz:
+            return Point(self.minx, cyz / (6 * area), czy / (6 * area))
+        else:
+            # calculate area of xy projection
+            area_xy = self.get_plane_projection(Plane(Point(0, 0, 0),
+                    Point(0, 0, 1))).get_area()
+            area_xz = self.get_plane_projection(Plane(Point(0, 0, 0),
+                    Point(0, 1, 0))).get_area()
+            area_yz = self.get_plane_projection(Plane(Point(0, 0, 0),
+                    Point(1, 0, 0))).get_area()
+            if 0 in (area_xy, area_xz, area_yz):
+                log.info("Failed assumtion: zero-sized projected area - " + \
+                        "%s / %s / %s" % (area_xy, area_xz, area_yz))
+                return Point(0, 0, 0)
+            if abs(cxy / area_xy - cxz / area_xz) > epsilon:
+                log.info("Failed assumption: barycenter xy/xz - %s / %s" % \
+                        (cxy / area_xy, cxz / area_xz))
+            if abs(cyx / area_xy - cyz / area_yz) > epsilon:
+                log.info("Failed assumption: barycenter yx/yz - %s / %s" % \
+                        (cyx / area_xy, cyz / area_yz))
+            if abs(czx / area_xz - czy / area_yz) > epsilon:
+                log.info("Failed assumption: barycenter zx/zy - %s / %s" % \
+                        (czx / area_xz, cyz / area_yz))
+            return Point(cxy / (6 * area_xy), cyx / (6 * area_xy),
+                    czx / (6 * area_xz))
+
     def get_length(self):
         """ add the length of all lines within the polygon
         """
@@ -306,6 +356,7 @@ class Polygon(TransformableContainer):
             self.minz = min(self.minz, point.z)
             self.maxz = max(self.maxz, point.z)
         self._lines_cache = None
+        self._area_cache = None
 
     def reset_cache(self):
         self._cached_offset_polygons = {}

src/pycam/Gui/Project.py

@@ -145,7 +145,7 @@ PREFERENCES_DEFAULTS = {
 """ the listed items will be loaded/saved via the preferences file in the
 user's home directory on startup/shutdown"""
 
-GRID_TYPES = {"none": 0, "grid": 1, "automatic": 2}
+GRID_TYPES = {"none": 0, "grid": 1, "automatic_edge": 2, "automatic_corner": 3}
 POCKETING_TYPES = ["none", "holes", "enclosed"]
 MAX_UNDO_STATES = 10
 
@@ -1185,11 +1185,13 @@ class ProjectGui:
 
     @gui_activity_guard
     def update_support_grid_controls(self, widget=None):
-        controls = {"GridProfileExpander": ("grid", "automatic"),
+        controls = {"GridProfileExpander": ("grid", "automatic_edge",
+                    "automatic_corner"),
                 "GridPatternExpander": ("grid", ),
                 "GridPositionExpander": ("grid", ),
                 "GridManualShiftExpander": ("grid", ),
-                "GridAverageDistanceExpander": ("automatic", ),
+                "GridAverageDistanceExpander": ("automatic_edge",
+                    "automatic_corner"),
         }
         grid_type = self.settings.get("support_grid_type")
         if grid_type == GRID_TYPES["grid"]:
@@ -1202,9 +1204,8 @@ class ProjectGui:
                         self.settings.get("support_grid_distance_x"))
             self.update_support_grid_manual_model()
             self.switch_support_grid_manual_selector()
-        elif grid_type == GRID_TYPES["automatic"]:
-            pass
-        elif grid_type == GRID_TYPES["none"]:
+        elif grid_type in (GRID_TYPES["automatic_edge"],
+                GRID_TYPES["automatic_corner"], GRID_TYPES["none"]):
             pass
         elif grid_type < 0:
             # not initialized
@@ -1246,7 +1247,8 @@ class ProjectGui:
                         offset_y=s.get("support_grid_offset_y"),
                         adjustments_x=self.grid_adjustments_x,
                         adjustments_y=self.grid_adjustments_y)
-        elif grid_type == GRID_TYPES["automatic"]:
+        elif grid_type in (GRID_TYPES["automatic_edge"],
+                GRID_TYPES["automatic_corner"]):
             if (s.get("support_grid_thickness") > 0) \
                     and (s.get("support_grid_height") > 0) \
                     and (s.get("support_grid_average_distance") > 0) \
@@ -1258,13 +1260,15 @@ class ProjectGui:
                 if not bounds is None:
                     minz = bounds.get_absolute_limits(
                             reference=self.model.get_bounds())[0][2]
+                    corner_start = (grid_type == GRID_TYPES["automatic_corner"])
                     support_grid = pycam.Toolpath.SupportGrid.get_support_distributed(
                             s.get("model"), minz,
                             s.get("support_grid_average_distance"),
                             s.get("support_grid_minimum_bridges"),
                             s.get("support_grid_thickness"),
                             s.get("support_grid_height"),
-                            s.get("support_grid_length"))
+                            s.get("support_grid_length"),
+                            start_at_corners=corner_start)
         elif grid_type == GRID_TYPES["none"]:
             pass
         s.set("support_grid", support_grid)
@@ -3605,13 +3609,16 @@ class ProjectGui:
                     offset_y=self.settings.get("support_grid_offset_y"),
                     adjustments_x=self.grid_adjustments_x,
                     adjustments_y=self.grid_adjustments_y)
-        elif grid_type == GRID_TYPES["automatic"]:
+        elif grid_type in (GRID_TYPES["automatic_edge"],
+                GRID_TYPES["automatic_corner"]):
+            corner_start = (grid_type == GRID_TYPES["automatic_corner"])
             toolpath_settings.set_support_distributed(
                     self.settings.get("support_grid_average_distance"),
                     self.settings.get("support_grid_minimum_bridges"),
                     self.settings.get("support_grid_thickness"),
                     self.settings.get("support_grid_height"),
-                    self.settings.get("support_grid_length"))
+                    self.settings.get("support_grid_length"),
+                    start_at_corner=corner_start)
         elif grid_type == GRID_TYPES["none"]:
             pass
         else:

src/pycam/Gui/Settings.py

@@ -582,6 +582,7 @@ class ToolpathSettings:
             "average_distance": float,
             "minimum_bridges": int,
             "length": float,
+            "start_at_corner": bool,
         },
         "Program": {
             "unit": str,
@@ -660,13 +661,14 @@ class ToolpathSettings:
         self.support_grid["adjustments_y"] = adjustments_y
 
     def set_support_distributed(self, average_distance, minimum_bridges,
-            thickness, height, length):
+            thickness, height, length, start_at_corner=False):
         self.support_grid["type"] = "distributed"
         self.support_grid["average_distance"] = average_distance
         self.support_grid["minimum_bridges"] = minimum_bridges
         self.support_grid["thickness"] = thickness
         self.support_grid["height"] = height
         self.support_grid["length"] = length
+        self.support_grid["start_at_corner"] = start_at_corner
 
     def get_support_grid(self):
         result = {}

src/pycam/Toolpath/SupportGrid.py

@@ -26,6 +26,7 @@ from pycam.Geometry.Triangle import Triangle
 from pycam.Geometry.Plane import Plane
 from pycam.Geometry.Model import Model
 from pycam.Geometry.utils import number
+import pycam.Geometry
 
 
 def _get_triangles_for_face(pts):
@@ -151,12 +152,8 @@ def get_support_grid(minx, maxx, miny, maxy, z_plane, dist_x, dist_y, thickness,
     return grid_model
 
 def get_support_distributed(model, z_plane, average_distance,
-        min_bridges_per_polygon, thickness, height, length):
-    def is_near_list(point_list, point, distance):
-        for p in point_list:
-            if p.sub(point).norm <= distance:
-                return True
-        return False
+        min_bridges_per_polygon, thickness, height, length,
+        start_at_corners=False):
     if (average_distance == 0) or (length == 0) or (thickness == 0) \
             or (height == 0):
         return
@@ -166,62 +163,159 @@ def get_support_distributed(model, z_plane, average_distance,
     else:
         polygons = model.get_waterline_contour(Plane(Point(0, 0, z_plane),
                 Vector(0, 0, 1))).get_polygons()
-    bridge_positions = []
     # minimum required distance between two bridge start points
     avoid_distance = 1.5 * (abs(length) + thickness)
+    if start_at_corners:
+        bridge_calculator = _get_corner_bridges
+    else:
+        bridge_calculator = _get_edge_bridges
     for polygon in polygons:
         # no grid for _small_ inner polygons
         # TODO: calculate a reasonable factor (see below)
         if polygon.is_closed and (not polygon.is_outer()) \
                 and (abs(polygon.get_area()) < 25000 * thickness ** 2):
             continue
-        lines = polygon.get_lines()
-        poly_lengths = polygon.get_lengths()
-        num_of_bridges = max(min_bridges_per_polygon,
-                int(round(sum(poly_lengths) / average_distance)))
-        real_average_distance = sum(poly_lengths) / num_of_bridges
-        max_line_index = poly_lengths.index(max(poly_lengths))
-        positions = []
-        current_line_index = max_line_index
-        distance_processed = poly_lengths[current_line_index] / 2
-        positions.append(current_line_index)
-        while len(positions) < num_of_bridges:
+        bridges = bridge_calculator(polygon, z_plane, min_bridges_per_polygon,
+                average_distance, avoid_distance)
+        for pos, direction in bridges:
+            _add_cuboid_to_model(result, pos, direction.mul(length), height,
+                    thickness)
+    return result
+
+
+class _BridgeCorner(object):
+    # currently we only use the xy plane
+    up_vector = Vector(0, 0, 1)
+    def __init__(self, barycenter, location, p1, p2, p3):
+        self.location = location
+        self.position = p2
+        self.direction = pycam.Geometry.get_bisector(p1, p2, p3,
+                self.up_vector).normalized()
+        preferred_direction = p2.sub(barycenter).normalized()
+        # direction_factor: 0..1 (bigger -> better)
+        direction_factor = (preferred_direction.dot(self.direction) + 1) / 2
+        angle = pycam.Geometry.get_angle_pi(p1, p2, p3,
+                self.up_vector, pi_factor=True)
+        # angle_factor: 0..1 (bigger -> better)
+        if angle > 0.5:
+            # use only angles > 90 degree
+            angle_factor = angle / 2.0
+        else:
+            angle_factor = 0
+        # priority: 0..1 (bigger -> better)
+        self.priority = angle_factor * direction_factor
+    def get_position_priority(self, other_location, average_distance):
+        return self.priority / (1 + self.get_distance(other_location) / \
+                average_distance)
+    def get_distance(self, other_location):
+        return min(abs(other_location - self.location),
+                abs(1 + other_location - self.location))
+    def __str__(self):
+        return "%s (%s) - %s" % (self.position, self.location, self.priority)
+        
+
+def _get_corner_bridges(polygon, z_plane, min_bridges, average_distance, avoid_distance):
+    """ try to place support bridges at corners of a polygon
+    Priorities:
+        - bigger corner angles are preferred
+        - directions pointing away from the center of the polygon are preferred
+    """
+    center = polygon.get_barycenter()
+    points = polygon.get_points()
+    lines = polygon.get_lines()
+    poly_lengths = polygon.get_lengths()
+    outline = sum(poly_lengths)
+    rel_avoid_distance = avoid_distance / outline
+    corner_positions = []
+    length_sum = 0
+    for l in poly_lengths:
+        corner_positions.append(length_sum / outline)
+        length_sum += l
+    num_of_bridges = int(max(min_bridges, round(outline / average_distance)))
+    rel_average_distance = 1.0 / num_of_bridges
+    corners = []
+    for index in range(len(polygon.get_points())):
+        p1 = points[(index - 1) % len(points)]
+        p2 = points[index % len(points)]
+        p3 = points[(index + 1) % len(points)]
+        corner = _BridgeCorner(center, corner_positions[index], p1, p2, p3)
+        if corner.priority > 0:
+            # ignore sharp corners
+            corners.append(corner)
+    bridge_corners = []
+    for index in range(num_of_bridges):
+        preferred_position = index * rel_average_distance
+        suitable_corners = []
+        for corner in corners:
+            if corner.get_distance(preferred_position) < rel_average_distance:
+                # check if the corner is too close to neighbouring corners
+                if (not bridge_corners) or \
+                        ((bridge_corners[-1].get_distance(corner.location) >= rel_avoid_distance) and \
+                            (bridge_corners[0].get_distance(corner.location) >= rel_avoid_distance)):
+                    suitable_corners.append(corner)
+        get_priority = lambda corner: corner.get_position_priority(
+                preferred_position, rel_average_distance)
+        suitable_corners.sort(key=get_priority, reverse=True)
+        if suitable_corners:
+            bridge_corners.append(suitable_corners[0])
+            corners.remove(suitable_corners[0])
+    return [(c.position, c.direction) for c in bridge_corners]
+
+def _get_edge_bridges(polygon, z_plane, min_bridges, average_distance, avoid_distance):
+    def is_near_list(point_list, point, distance):
+        for p in point_list:
+            if p.sub(point).norm <= distance:
+                return True
+        return False
+    lines = polygon.get_lines()
+    poly_lengths = polygon.get_lengths()
+    num_of_bridges = max(min_bridges,
+            int(round(sum(poly_lengths) / average_distance)))
+    real_average_distance = sum(poly_lengths) / num_of_bridges
+    max_line_index = poly_lengths.index(max(poly_lengths))
+    positions = []
+    current_line_index = max_line_index
+    distance_processed = poly_lengths[current_line_index] / 2
+    positions.append(current_line_index)
+    while len(positions) < num_of_bridges:
+        current_line_index += 1
+        current_line_index %= len(poly_lengths)
+        # skip lines that are not at least twice as long as the grid width
+        while (distance_processed + poly_lengths[current_line_index] \
+                < real_average_distance):
+            distance_processed += poly_lengths[current_line_index]
             current_line_index += 1
             current_line_index %= len(poly_lengths)
-            # skip lines that are not at least twice as long as the grid width
-            while (distance_processed + poly_lengths[current_line_index] \
-                    < real_average_distance):
-                distance_processed += poly_lengths[current_line_index]
-                current_line_index += 1
-                current_line_index %= len(poly_lengths)
-            positions.append(current_line_index)
-            distance_processed += poly_lengths[current_line_index]
-            distance_processed %= real_average_distance
-        for line_index in positions:
-            position = polygon.get_middle_of_line(line_index)
-            # skip bridges that are close to another existing bridge
-            if is_near_list(bridge_positions, position, avoid_distance):
-                line = polygon.get_lines()[line_index]
-                # calculate two alternative points on the same line
-                position1 = position.add(line.p1).div(2)
-                position2 = position.add(line.p2).div(2)
-                if is_near_list(bridge_positions, position1, avoid_distance):
-                    if is_near_list(bridge_positions, position2,
-                            avoid_distance):
-                        # no valid alternative - we skip this bridge
-                        continue
-                    else:
-                        # position2 is OK
-                        position = position2
+        positions.append(current_line_index)
+        distance_processed += poly_lengths[current_line_index]
+        distance_processed %= real_average_distance
+    result = []
+    bridge_positions = []
+    for line_index in positions:
+        position = polygon.get_middle_of_line(line_index)
+        # skip bridges that are close to another existing bridge
+        if is_near_list(bridge_positions, position, avoid_distance):
+            line = polygon.get_lines()[line_index]
+            # calculate two alternative points on the same line
+            position1 = position.add(line.p1).div(2)
+            position2 = position.add(line.p2).div(2)
+            if is_near_list(bridge_positions, position1, avoid_distance):
+                if is_near_list(bridge_positions, position2,
+                        avoid_distance):
+                    # no valid alternative - we skip this bridge
+                    continue
                 else:
-                    # position1 is OK
-                    position = position1
-            # append the original position (ignoring z_plane)
-            bridge_positions.append(position)
-            # move the point to z_plane
-            position = Point(position.x, position.y, z_plane)
-            bridge_dir = lines[line_index].dir.cross(
-                    polygon.plane.n).normalized().mul(length)
-            _add_cuboid_to_model(result, position, bridge_dir, height, thickness)
+                    # position2 is OK
+                    position = position2
+            else:
+                # position1 is OK
+                position = position1
+        # append the original position (ignoring z_plane)
+        bridge_positions.append(position)
+        # move the point to z_plane
+        position = Point(position.x, position.y, z_plane)
+        bridge_dir = lines[line_index].dir.cross(
+                polygon.plane.n).normalized()
+        result.append((position, bridge_dir))
     return result