Move and slightly improve get_points_for_thick_line (#2106)

* Remove drawing_support.py

* Move get_points_for_thick_line to draw_commands.py where it belongs

* Remove drawing_support.py module

* Remove drawing_support.py file and quick index script reference

* Stop redoing math in get_points_for_thick_line

* Remove reference in manually written API docs file

Author: pushfoo

arcade/__init__.py

@@ -68,7 +68,6 @@ def configure_logging(level: Optional[int] = None):
 # pyglet.options['win32_gdi_font'] = True
 
 # Imports from modules that don't do anything circular
-from .drawing_support import get_points_for_thick_line
 
 # Complex imports with potential circularity
 from .window_commands import close_window
@@ -109,6 +108,7 @@ def configure_logging(level: Optional[int] = None):
 from .texture import get_default_image
 from .texture import get_default_texture
 
+from .draw_commands import get_points_for_thick_line
 from .draw_commands import draw_arc_filled
 from .draw_commands import draw_arc_outline
 from .draw_commands import draw_circle_filled

arcade/draw_commands.py

@@ -19,12 +19,11 @@
 import pyglet.gl as gl
 
 from arcade.color import WHITE
-from arcade.types import AsFloat, Color, RGBA255, PointList, Point, Point2List
+from arcade.types import AsFloat, Color, RGBA255, PointList, Point, Point2List, Point2
 from arcade.earclip import earclip
 from arcade.types.rect import Rect, LBWH, LRBT, XYWH
 from .math import rotate_point
 from arcade import (
-    get_points_for_thick_line,
     Texture,
     get_window,
 )
@@ -58,10 +57,49 @@
     "draw_scaled_texture_rectangle",
     "draw_texture_rectangle",
     "draw_lbwh_rectangle_textured",
+    "get_points_for_thick_line",
     "get_pixel",
     "get_image"
 ]
 
+
+def get_points_for_thick_line(start_x: float, start_y: float,
+                              end_x: float, end_y: float,
+                              line_width: float) -> Tuple[Point2, Point2,
+                                                          Point2, Point2]:
+    """
+    Function used internally for Arcade. OpenGL draws triangles only, so a thick
+    line must be two triangles that make up a rectangle. This calculates and returns
+    those points.
+    """
+    vector_x = start_x - end_x
+    vector_y = start_y - end_y
+    perpendicular_x = vector_y
+    perpendicular_y = -vector_x
+    length = math.sqrt(vector_x * vector_x + vector_y * vector_y)
+    if length == 0:
+        normal_x = 1.0
+        normal_y = 1.0
+    else:
+        normal_x = perpendicular_x / length
+        normal_y = perpendicular_y / length
+
+    half_width = line_width / 2
+    shift_x = normal_x * half_width
+    shift_y = normal_y * half_width
+
+    r1_x = start_x + shift_x
+    r1_y = start_y + shift_y
+    r2_x = start_x - shift_x
+    r2_y = start_y - shift_y
+    r3_x = end_x + shift_x
+    r3_y = end_y + shift_y
+    r4_x = end_x - shift_x
+    r4_y = end_y - shift_y
+
+    return (r1_x, r1_y), (r2_x, r2_y), (r4_x, r4_y), (r3_x, r3_y)
+
+
 # --- BEGIN ARC FUNCTIONS # # #
 
 

arcade/drawing_support.py

@@ -16,7 +16,6 @@ for the Python Arcade library. See also:
     api/types
     api/drawing_primitives
     api/drawing_batch
-    api/drawing_utilities
     api/sprites
     api/sprite_list
     api/sprite_scenes

doc/api_docs/arcade.rst

@@ -16,7 +16,6 @@
     'application.py': ['Window and View', 'window.rst'],
     'shape_list.py': ['Shape Lists', 'drawing_batch.rst'],
     'context.py': ['OpenGL Context', 'open_gl.rst'],
-    'drawing_support.py': ['Drawing - Utility', 'drawing_utilities.rst'],
     'draw_commands.py': ['Drawing - Primitives', 'drawing_primitives.rst'],
     'geometry.py': ['Geometry Support', 'geometry.rst'],
     'isometric.py': ['Isometric Map Support (incomplete)', 'isometric.rst'],