add comments + split the transformations

main.py

@@ -6,13 +6,13 @@ from math import cos, sin
 from typing import cast
 import dearpygui.dearpygui as dpg  # pyright: ignore[reportMissingTypeStubs]
 
-RENDER_VERTICES = False
+RENDER_VERTICES = True
 RENDER_EDGES = True
 BEST_EFFORT_PARSE = True
 
 CANVAS_SIZE = 500
 TIMESTEP = 0.01
-CAMERA_DISTANCE = 3.0
+CAMERA_DISTANCE = 2.5
 
 VERTEX_SIZE = 5.0
 VERTEX_COLOR = (27, 188, 104)
@@ -31,6 +31,8 @@ IndexedFaceSet = list[IndexedFace]
 
 
 def to_viewport(verts: Vertex2Set) -> Vertex2Set:
+    """Maps vertices into the [0, WIDTH]x[0, HEIGHT] viewport"""
+
     def transform(vert: Vertex2) -> Vertex2:
         return (
             ((vert[0] + 1.0) / 2.0) * CANVAS_SIZE,
@@ -41,6 +43,8 @@ def to_viewport(verts: Vertex2Set) -> Vertex2Set:
 
 
 def to_imageplane(verts: Vertex3Set) -> Vertex2Set:
+    """Projects vertices onto the [-1, 1]x[-1, 1] imageplane"""
+
     def transform(vert: Vertex3) -> Vertex2:
         return (vert[0] / vert[2], vert[1] / vert[2])
 
@@ -48,6 +52,8 @@ def to_imageplane(verts: Vertex3Set) -> Vertex2Set:
 
 
 def translate(verts: Vertex3Set, distance: float) -> Vertex3Set:
+    """Translates vertices along the forward-axis in 3D space"""
+
     def transform(vert: Vertex3) -> Vertex3:
         return (vert[0], vert[1], vert[2] + distance)
 
@@ -55,6 +61,8 @@ def translate(verts: Vertex3Set, distance: float) -> Vertex3Set:
 
 
 def rotate(verts: Vertex3Set, angle: float) -> Vertex3Set:
+    """Rotates vertices around the up-axis in 3D space"""
+
     def transform(vert: Vertex3) -> Vertex3:
         return (
             vert[0] * cos(angle) - vert[2] * sin(angle),
@@ -86,9 +94,10 @@ def draw(drawlist, vertices: Vertex3Set, faces: IndexedFaceSet, time: float):
             thickness=EDGE_SIZE,
         )
 
-    viewport_vertices: Vertex2Set = to_viewport(
-        to_imageplane(translate(rotate(vertices, time), CAMERA_DISTANCE))
-    )
+    rotated_vertices: Vertex3Set = rotate(vertices, time)
+    translated_vertices: Vertex3Set = translate(rotated_vertices, CAMERA_DISTANCE)
+    imageplane_vertices: Vertex2Set = to_imageplane(translated_vertices)
+    viewport_vertices: Vertex2Set = to_viewport(imageplane_vertices)
 
     if RENDER_VERTICES:
         for v in viewport_vertices:
@@ -147,9 +156,22 @@ def parse_obj_file(path: str) -> tuple[Vertex3Set, IndexedFaceSet]:
 def main():
     parser = argparse.ArgumentParser()
     _ = parser.add_argument("objfile", type=str, help=".obj file to render")
+    _ = parser.add_argument("--vertices", action="store_true", help="render vertices")
+    _ = parser.add_argument("--edges", action="store_true", help="render edges")
+    _ = parser.add_argument(
+        "--strict", action="store_true", help="require complete parsing of .obj file"
+    )
     args = parser.parse_args()
     args.objfile = cast(str, args.objfile)
 
+    global RENDER_VERTICES
+    global RENDER_EDGES
+    global BEST_EFFORT_PARSE
+
+    RENDER_VERTICES = bool(args.vertices)
+    RENDER_EDGES = bool(args.edges)
+    BEST_EFFORT_PARSE = not bool(args.strict)
+
     dpg.create_context()
 
     with dpg.theme() as canvas_theme, dpg.theme_component():