add demo (cyclical swirl)

Author: Kwasniok

README.md

@@ -44,7 +44,7 @@ python main.py
 ```
 
 ## Demo
-Use the following script to execute the demo script.
+Use the following script to execute any of the demo scripts.
 The results can be found in the directory `images`.
 ```
 #! /usr/bin/bash
@@ -55,11 +55,13 @@ source .venv/bin/activate
 # ensure existence of output directory
 mkdir -p images
 
-# execute demo script
+# execute demo scripts
 cd src
 python demo_1.py
+python demo_2.py
 ```
-This script was used to create the frames of this video:
+
+A similar script was used to create the frames of this video:
 
 https://user-images.githubusercontent.com/7516208/131228594-f264acce-c461-4ec6-891b-0ef9b7262717.mp4
 

src/demo_2.py

@@ -0,0 +1,157 @@
+"""This demo script renders a test scene using cylindrical coordinates."""
+import math
+
+from nerte.values.coordinates import Coordinates3D
+from nerte.values.domain import Domain1D
+from nerte.values.linalg import AbstractVector
+from nerte.values.face import Face
+from nerte.values.manifolds.cylindrical import (
+    Plane as CarthesianPlaneInCylindric,
+)
+from nerte.world.object import Object
+from nerte.world.camera import Camera
+from nerte.world.scene import Scene
+from nerte.geometry.geometry import Geometry
+from nerte.geometry.cylindircal_swirl_geometry import (
+    SwirlCylindricRungeKuttaGeometry,
+)
+from nerte.render.image_renderer import ImageRenderer
+from nerte.util.random_color_generator import RandomColorGenerator
+
+# pseudo-random color generator
+COLOR = RandomColorGenerator()
+
+
+def make_camera(canvas_dimension: int) -> Camera:
+    """Creates a camera with preset values."""
+
+    location = Coordinates3D((0.1, 0.0, -1.3))
+    manifold = CarthesianPlaneInCylindric(
+        b0=AbstractVector((1.0, 0.0, 0.0)),
+        b1=AbstractVector((0.0, 1.0, 0.0)),
+        x0_domain=Domain1D(-1.0, +1.0),
+        x1_domain=Domain1D(-1.0, +1.0),
+        offset=AbstractVector((0.0, 0.0, -1.0)),
+    )
+    camera = Camera(
+        location=location,
+        detector_manifold=manifold,
+        canvas_dimensions=(canvas_dimension, canvas_dimension),
+    )
+    return camera
+
+
+def make_scene(canvas_dimension: int) -> Scene:
+    """
+    Creates a scene with a camera pointing towards an object.
+    """
+
+    camera = make_camera(canvas_dimension)
+    scene = Scene(camera=camera)
+
+    # add all faces of the hollow cube as separate object to enable
+    # individual colors for each triange
+
+    # cylinder
+    # top 1
+    point0 = Coordinates3D((0.0, -math.pi, +1.0))
+    point1 = Coordinates3D((1.0, -math.pi, +1.0))
+    point2 = Coordinates3D((1.0, math.pi, +1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+    # top 2
+    point0 = Coordinates3D((0.0, -math.pi, +1.0))
+    point1 = Coordinates3D((0.0, +math.pi, +1.0))
+    point2 = Coordinates3D((1.0, +math.pi, +1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+    # side 1
+    point0 = Coordinates3D((1.0, -math.pi, -1.0))
+    point1 = Coordinates3D((1.0, -math.pi, +1.0))
+    point2 = Coordinates3D((1.0, +math.pi, +1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+    # side 2
+    point0 = Coordinates3D((1.0, -math.pi, -1.0))
+    point1 = Coordinates3D((1.0, +math.pi, -1.0))
+    point2 = Coordinates3D((1.0, +math.pi, +1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+    # bottom 1
+    point0 = Coordinates3D((0.0, -math.pi, -1.0))
+    point1 = Coordinates3D((1.0, -math.pi, -1.0))
+    point2 = Coordinates3D((1.0, +math.pi, -1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+    # bottom 2
+    point0 = Coordinates3D((0.0, -math.pi, -1.0))
+    point1 = Coordinates3D((0.0, +math.pi, -1.0))
+    point2 = Coordinates3D((1.0, +math.pi, -1.0))
+    tri = Face(point0, point1, point2)
+    obj = Object(color=next(COLOR))  # pseudo-random color
+    obj.add_face(tri)
+    scene.add_object(obj)
+
+    return scene
+
+
+def render(
+    scene: Scene,
+    geometry: Geometry,
+    output_path: str,
+    file_prefix: str,
+    show: bool,
+) -> None:
+    """
+    Renders a preset scene with non-euclidean geometry in orthographic and
+    perspective projection.
+    """
+
+    for mode in ImageRenderer.Mode:
+        # for mode in (ImageRenderer.Mode.PERSPECTIVE,):
+        print(f"rendering {mode.name} projection ...")
+        image_renderer = ImageRenderer(mode=mode)
+        image_renderer.render(scene=scene, geometry=geometry)
+        image = image_renderer.last_image()
+        if image is not None:
+            image.save(f"{output_path}/{file_prefix}_{mode.name}.png")
+            if show:
+                image.show()
+
+
+def main() -> None:
+    """Creates and renders the demo scene."""
+
+    # NOTE: Increase the canvas dimension to improve the image quality.
+    #       This will also increase rendering time!
+    scene = make_scene(canvas_dimension=100)
+    geo = SwirlCylindricRungeKuttaGeometry(
+        max_ray_length=math.inf,
+        step_size=0.1,
+        max_steps=50,
+        # swirl_strength=5.0,
+        swirl_strength=5.0,
+    )
+
+    # NOTE: Set show to False if images cannot be displayed.
+    render(
+        scene=scene,
+        geometry=geo,
+        output_path="../images",
+        file_prefix="demo_2",
+        show=False,
+    )
+
+
+if __name__ == "__main__":
+    main()