implemented adaptive DropCutter positioning

 * see a blog post of Anders Wallin for more details: http://www.anderswallin.net/2010/10/adaptive-sampling-drop-cutter/
simplified the "max_height" detection


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@815 bbaffbd6-741e-11dd-a85d-61de82d9cad9

Changelog

 Version 0.4.1 - UNRELEASED
  * added support for EPS/PS contour files
+ * added adaptive positioning for DropCutter strategy (improves precision)
+
+Version 0.4.0.1 - 2010-10-24
+ * disabled parallel processing for Windows standalone executable
+   (a real fix will follow later)
 
 Version 0.4 - 2010-10-19
  * use all available CPU cores for parallel processing

src/pycam/PathGenerators/DropCutter.py

@@ -23,7 +23,7 @@ along with PyCAM.  If not, see <http://www.gnu.org/licenses/>.
 
 from pycam.Geometry.Point import Point
 from pycam.Geometry.utils import INFINITE, ceil
-from pycam.PathGenerators import get_max_height_triangles, get_max_height_ode
+from pycam.PathGenerators import get_max_height_dynamic
 from pycam.Utils import ProgressCounter
 from pycam.Utils.threading import run_in_parallel
 import pycam.Utils.log
@@ -33,24 +33,12 @@ log = pycam.Utils.log.get_logger()
 
 # We need to use a global function here - otherwise it does not work with
 # the multiprocessing Pool.
-def _process_one_grid_line((positions, minz, maxz, model, cutter,
-        physics, safety_height)):
-    # for now only used for triangular collision detection
-    last_position = None
-    points = []
-    height_exceeded = False
-    for x, y in positions:
-        if physics:
-            result = get_max_height_ode(physics, x, y, minz, maxz)
-        else:
-            result = get_max_height_triangles(model, cutter, x, y, minz, maxz,
-                    last_pos=last_position)
-        if result:
-            points.extend(result)
-        else:
-            points.append(Point(x, y, safety_height))
-            height_exceeded = True
-    return points, height_exceeded
+def _process_one_grid_line((positions, minz, maxz, model, cutter, physics)):
+    """ This function assumes, that the positions are next to each other.
+    Otherwise the dynamic over-sampling (in get_max_height_dynamic) is
+    pointless.
+    """
+    return get_max_height_dynamic(model, cutter, positions, minz, maxz, physics)
 
 
 class Dimension:
@@ -95,76 +83,58 @@ class DropCutter:
         self.pa = path_processor
         self.physics = physics
         # remember if we already reported an invalid boundary
-        self._boundary_warning_already_shown = False
 
     def GenerateToolPath(self, motion_grid, minz, maxz, draw_callback=None):
         quit_requested = False
 
         # Transfer the grid (a generator) into a list of lists and count the
         # items.
-        num_of_grid_positions = 0
         lines = []
         # there should be only one layer for DropCutter
         for layer in motion_grid:
             for line in layer:
-                lines.append(list(line))
-                num_of_grid_positions += len(lines[-1])
+                lines.append(line)
             # ignore any other layers
             break
 
         num_of_lines = len(lines)
-        progress_counter = ProgressCounter(num_of_grid_positions, draw_callback)
+        progress_counter = ProgressCounter(len(lines), draw_callback)
         current_line = 0
 
         self.pa.new_direction(0)
 
-        self._boundary_warning_already_shown = False
-
         args = []
         for one_grid_line in lines:
             # simplify the data (useful for remote processing)
             xy_coords = [(pos.x, pos.y) for pos in one_grid_line]
             args.append((xy_coords, minz, maxz, self.model, self.cutter,
-                    self.physics, self.model.maxz))
-        # ODE does not work with multi-threading
+                    self.physics))
+        # ODE does not work with multi-threading (TODO: check this)
         disable_multiprocessing = not self.physics is None
-        for points, height_exceeded in run_in_parallel(_process_one_grid_line,
+        for points in run_in_parallel(_process_one_grid_line,
                 args, disable_multiprocessing=disable_multiprocessing):
-            if height_exceeded and not self._boundary_warning_already_shown:
-                log.warn("DropCutter: exceed the height of the " \
-                        + "boundary box: using a safe height instead." \
-                        + " This warning is reported only once.")
-                self._boundary_warning_already_shown = True
-
             self.pa.new_scanline()
-
             if draw_callback and draw_callback(text="DropCutter: processing " \
                         + "line %d/%d" % (current_line + 1, num_of_lines)):
                 # cancel requested
                 quit_requested = True
                 break
-
             for p in points:
                 self.pa.append(p)
                 # "draw_callback" returns true, if the user requested to quit
                 # via the GUI.
                 # The progress counter may return True, if cancel was requested.
-                if (draw_callback and draw_callback(tool_position=p,
-                        toolpath=self.pa.paths)) \
-                        or (progress_counter.increment()):
+                if draw_callback and draw_callback(tool_position=p,
+                        toolpath=self.pa.paths):
                     quit_requested = True
                     break
-
+            progress_counter.increment()
             self.pa.end_scanline()
-
             # update progress
             current_line += 1
-
             if quit_requested:
                 break
-
         self.pa.end_direction()
-
         self.pa.finish()
         return self.pa.paths
 

src/pycam/PathGenerators/EngraveCutter.py

@@ -23,9 +23,10 @@ along with PyCAM.  If not, see <http://www.gnu.org/licenses/>.
 
 import pycam.PathProcessors.PathAccumulator
 from pycam.Geometry.Point import Point
-from pycam.Geometry.utils import INFINITE, ceil
-from pycam.PathGenerators import get_max_height_triangles, get_max_height_ode, \
-        get_free_paths_ode, get_free_paths_triangles
+from pycam.Geometry.utils import ceil
+from pycam.PathGenerators import get_max_height_dynamic
+from pycam.PathGenerators import get_max_height_dynamic, get_free_paths_ode, \
+        get_free_paths_triangles
 from pycam.Utils import ProgressCounter
 import pycam.Utils.log
 
@@ -35,7 +36,7 @@ log = pycam.Utils.log.get_logger()
 class EngraveCutter:
 
     def __init__(self, cutter, trimesh_models, contour_model, path_processor,
-            physics=None, safety_height=INFINITE):
+            physics=None):
         self.cutter = cutter
         self.models = trimesh_models
         # combine the models (if there is more than one)
@@ -51,8 +52,6 @@ class EngraveCutter:
         # This path processor does not need to be configurable.
         self.pa_drop = pycam.PathProcessors.PathAccumulator()
         self.physics = physics
-        self.safety_height = safety_height
-        self._boundary_warning_already_shown = False
 
     def GenerateToolPath(self, minz, maxz, horiz_step, dz, draw_callback=None):
         quit_requested = False
@@ -178,6 +177,11 @@ class EngraveCutter:
             draw_callback=None):
         pa.new_direction(0)
         pa.new_scanline()
+        if not self.combined_model:
+            # no obstacle -> minimum height
+            points = [Point(line.p1.x, line.p1.y, minz),
+                    Point(line.p2.x, line.p2.y, minz)]
+        else:
             p1 = Point(line.p1.x, line.p1.y, minz)
             p2 = Point(line.p2.x, line.p2.y, minz)
             distance = line.len
@@ -189,35 +193,14 @@ class EngraveCutter:
             x_steps = [(p1.x + i * x_step) for i in range(num_of_steps)]
             y_steps = [(p1.y + i * y_step) for i in range(num_of_steps)]
             step_coords = zip(x_steps, y_steps)
-
-        last_position = None
-
-        for x, y in step_coords:
-            if not self.combined_model:
-                # no obstacle -> minimum height
-                points = [Point(x, y, minz)]
-            elif self.physics:
-                points = get_max_height_ode(self.physics, x, y, minz, maxz)
-            else:
-                points = get_max_height_triangles(self.combined_model, self.cutter,
-                        x, y, minz, maxz, last_pos=last_position)
-
-            if points:
+            points = get_max_height_dynamic(self.combined_model, self.cutter,
+                    step_coords, minz, maxz, self.physics)
         for p in points:
             pa.append(p)
-            else:
-                p = Point(x, y, self.safety_height)
-                pa.append(p)
-                if not self._boundary_warning_already_shown:
-                    log.warn("EngraveCutter: exceed the height " \
-                            + "of the boundary box: using a safe height " \
-                            + "instead. This warning is reported only once.")
-                self._boundary_warning_already_shown = True
         # "draw_callback" returns true, if the user requested quitting via
         # the GUI.
-            if draw_callback \
-                    and draw_callback(tool_position=p, toolpath=pa.paths):
-                break
+        if draw_callback and points:
+                draw_callback(tool_position=points[-1], toolpath=pa.paths)
         pa.end_scanline()
         pa.end_direction()
 

src/pycam/PathGenerators/__init__.py

@@ -215,30 +215,14 @@ def get_max_height_ode(physics, x, y, minz, maxz):
             safe_z = current_z
         trips -= 1
     if safe_z is None:
-        # no safe position was found - let's check the upper bound
-        physics.set_drill_position((x, y, maxz))
-        if physics.check_collision():
-            # the object fills the whole range of z0..z1 -> no safe height
-            pass
+        # return maxz as the collision height
+        return Point(x, y, maxz)
     else:
-            # at least the upper bound is collision free
-            safe_z = maxz
-    if safe_z is None:
-        return []
-    else:
-        return [Point(x, y, safe_z)]
+        return Point(x, y, safe_z)
 
-def get_max_height_triangles(model, cutter, x, y, minz, maxz, last_pos=None):
-    result = []
-    if last_pos is None:
-        last_pos = {}
-    for key in ("triangle", "cut"):
-        if not key in last_pos:
-            last_pos[key] = None
+def get_max_height_triangles(model, cutter, x, y, minz, maxz):
     p = Point(x, y, maxz)
     height_max = None
-    cut_max = None
-    triangle_max = None
     box_x_min = cutter.get_minx(p)
     box_x_max = cutter.get_maxx(p)
     box_y_min = cutter.get_miny(p)
@@ -251,61 +235,61 @@ def get_max_height_triangles(model, cutter, x, y, minz, maxz, last_pos=None):
         cut = cutter.drop(t, start=p)
         if cut and ((height_max is None) or (cut.z > height_max)):
             height_max = cut.z
-            cut_max = cut
-            triangle_max = t
     # don't do a complete boundary check for the height
     # this avoids zero-cuts for models that exceed the bounding box height
-    if not cut_max or cut_max.z < minz + epsilon:
-        cut_max = Point(x, y, minz)
-    if last_pos["cut"] and \
-            ((triangle_max and not last_pos["triangle"]) \
-            or (last_pos["triangle"] and not triangle_max)):
-        if minz - epsilon <= last_pos["cut"].z <= maxz + epsilon:
-            result.append(Point(last_pos["cut"].x, last_pos["cut"].y,
-                    cut_max.z))
+    if (height_max is None) or (height_max < minz + epsilon):
+        height_max = minz
+    # check if we need more points in between (for better accuracy)
+    return Point(x, y, height_max)
+
+def _check_deviance_of_adjacent_points(p1, p2, p3, min_distance):
+    straight = p3.sub(p1)
+    added = p2.sub(p1).norm + p3.sub(p2).norm
+    # compare only the x/y distance of p1 and p3 with min_distance
+    if straight.x ** 2 + straight.y ** 2 < min_distance ** 2:
+        # the points are too close together
+        return True
     else:
-            result.append(Point(cut_max.x, cut_max.y, last_pos["cut"].z))
-    elif (triangle_max and last_pos["triangle"] and last_pos["cut"] and \
-            cut_max) and (triangle_max != last_pos["triangle"]):
-        # TODO: check if this path is ever in use (e.g. "intersect_lines" is not
-        # defined)
-        nl = range(3)
-        nl[0] = -getattr(last_pos["triangle"].normal, order[0])
-        nl[2] = last_pos["triangle"].normal.z
-        nm = range(3)
-        nm[0] = -getattr(triangle_max.normal, order[0])
-        nm[2] = triangle_max.normal.z
-        last = range(3)
-        last[0] = getattr(last_pos["cut"], order[0])
-        last[2] = last_pos["cut"].z
-        mx = range(3)
-        mx[0] = getattr(cut_max, order[0])
-        mx[2] = cut_max.z
-        c = range(3)
-        (c[0], c[2]) = intersect_lines(last[0], last[2], nl[0], nl[2], mx[0],
-                mx[2], nm[0], nm[2])
-        if c[0] and last[0] < c[0] < mx[0] and (c[2] > last[2] or c[2] > mx[2]):
-            c[1] = getattr(last_pos["cut"], order[1])
-            if (c[2] < minz - 10) or (c[2] > maxz + 10):
-                print "^", "%sl=%s" % (order[0], last[0]), \
-                        ", %sl=%s" % ("z", last[2]), \
-                        ", n%sl=%s" % (order[0], nl[0]), \
-                        ", n%sl=%s" % ("z", nl[2]), \
-                        ", %s=%s" % (order[0].upper(), c[0]), \
-                        ", %s=%s" % ("z".upper(), c[2]), \
-                        ", %sm=%s" % (order[0], mx[0]), \
-                        ", %sm=%s" % ("z", mx[2]), \
-                        ", n%sm=%s" % (order[0], nm[0]), \
-                        ", n%sm=%s" % ("z", nm[2])
+        # allow 0.1% deviance - this is an angle of around 2 degrees
+        return (added / straight.norm) < 1.001
 
+def get_max_height_dynamic(model, cutter, positions, minz, maxz, physics=None):
+    max_depth = 8
+    # the points don't need to get closer than 1/1000 of the cutter radius
+    min_distance = cutter.distance_radius / 1000
+    result = []
+    if physics:
+        get_max_height = lambda x, y: get_max_height_ode(physics, x, y, minz,
+                maxz)
     else:
-                if order[0] == "x":
-                    result.append(Point(c[0], c[1], c[2]))
+        get_max_height = lambda x, y: get_max_height_triangles(model, cutter,
+                x, y, minz, maxz)
+    # add one point between all existing points
+    for index in range(len(positions)):
+        p = positions[index]
+        result.append(get_max_height(p[0], p[1]))
+    # Check if three consecutive points are "flat".
+    # Add additional points if necessary.
+    index = 0
+    depth_count = 0
+    while index < len(result) - 2:
+        p1 = result[index]
+        p2 = result[index + 1]
+        p3 = result[index + 2]
+        if not _check_deviance_of_adjacent_points(p1, p2, p3, min_distance) \
+                and (depth_count < max_depth):
+            # distribute the new point two before the middle and one after
+            if depth_count % 3 != 2:
+                # insert between the 1st and 2nd point
+                middle = ((p1.x + p2.x) / 2, (p1.y + p2.y) / 2)
+                result.insert(index + 1, get_max_height(middle[0], middle[1]))
             else:
-                    result.append(Point(c[1], c[0], c[2]))
-    result.append(cut_max)
-
-    last_pos["cut"] = cut_max
-    last_pos["triangle"] = triangle_max
+                # insert between the 2nd and 3rd point
+                middle = ((p2.x + p3.x) / 2, (p2.y + p3.y) / 2)
+                result.insert(index + 2, get_max_height(middle[0], middle[1]))
+            depth_count += 1
+        else:
+            index += 1
+            depth_count = 0
     return result
 

src/pycam/Toolpath/Generator.py

@@ -265,8 +265,8 @@ def generate_toolpath(model, tool_settings=None,
     if path_generator == "PushCutter":
         step_width = None
     else:
-        # TODO: the step_width should be configurable
-        step_width = tool_settings["tool_radius"] / 10.0
+        # the step_width is only used for the DropCutter
+        step_width = tool_settings["tool_radius"] / 4
     if path_generator == "DropCutter":
         layer_distance = None
     else: