rudimentary auto extrusion, needs correction for g2/g3

Author: rmeno12

src/gcodepy/gcode.py

@@ -1,7 +1,9 @@
 from typing import Callable, Tuple, Union
+from . import util
 
-# flow calculations
+# circumference calcs for arcs
 # minimize feedrate output
+# draw absolute
 class Gcode:
     def __init__(
         self,
@@ -10,13 +12,17 @@ def __init__(
         line_width: float = 0.4,
         filament_width: float = 1.75,
         home_position: Tuple[float, float, float] = (0, 0, 0),
+        extrusion_length_calculator: Callable[
+            [float, float, float, float], float
+        ] = util.calculate_extrusion_length,
     ) -> None:
         self.filename = filename
         self.file = open(filename, "w")
         self.layer_height = layer_height
         self.line_width = line_width
         self.filament_width = filament_width
         self.home_pos = home_position
+        self.extrusion_length_calculator = extrusion_length_calculator
         self.pos = [None] * 3
         self.e = None
 
@@ -39,6 +45,15 @@ def get_z(self) -> float:
     def get_e(self) -> float:
         return self.e
 
+    def set_layer_height(self, layer_height: float):
+        self.layer_height = layer_height
+
+    def set_line_width(self, line_width: float):
+        self.line_width = line_width
+
+    def set_filament_width(self, filament_width: float):
+        self.filament_width = filament_width
+
     def zero_extruder(self):
         self.file.write("G92 E0\n")
         self.e = 0
@@ -114,7 +129,12 @@ def draw(
         self, delta: Tuple[float, float, float], e: float = None, feedrate: int = 2400
     ):
         if e is None:
-            e = 0  # REPLACE
+            e = self.extrusion_length_calculator(
+                util.dist(delta),
+                self.line_width,
+                self.layer_height,
+                self.filament_width,
+            )
         self.pos[0] += delta[0]
         self.pos[1] += delta[1]
         self.pos[2] += delta[2]
@@ -133,7 +153,12 @@ def draw_arc(
         feedrate: int = 2400,
     ):
         if e is None:
-            e = 0  # REPLACE
+            e = self.extrusion_length_calculator(
+                util.dist(delta),  # REPLACE
+                self.line_width,
+                self.layer_height,
+                self.filament_width,
+            )
         out = "G2" if clockwise else "G3"
         out += f" F{feedrate}"
         self.pos[0] += delta[0]
@@ -158,7 +183,12 @@ def draw_arc_r(
         feedrate: int = 2400,
     ):
         if e is None:
-            e = 0  # REPLACE
+            e = self.extrusion_length_calculator(
+                util.dist(delta),  # REPLACE
+                self.line_width,
+                self.layer_height,
+                self.filament_width,
+            )
         if delta[0] == 0.0 and delta[1] == 0.0:
             raise ValueError("Both x and y cannot be 0. Make sure to set at least one!")
         out = "G2" if clockwise else "G3"

src/gcodepy/util.py

@@ -0,0 +1,20 @@
+import math
+from typing import Tuple
+
+
+def dist(delta: Tuple[float, float, float]) -> float:
+    return math.sqrt(sum(i ** 2 for i in delta))
+
+
+def calculate_extrusion_length(
+    path_length: float,
+    line_width: float,
+    layer_height: float,
+    filament_width: float,
+) -> float:
+    # uses math from https://manual.slic3r.org/advanced/flow-math
+    flat_area = (line_width - layer_height) * layer_height
+    round_area = math.pi * (layer_height / 2) ** 2
+    ext_area = flat_area + round_area
+    ext_volume = ext_area * path_length
+    return ext_volume / (math.pi * (filament_width / 2) ** 2)