.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "_gallery/feature_demo/world_map_projection.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download__gallery_feature_demo_world_map_projection.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr__gallery_feature_demo_world_map_projection.py:


World map projection
====================

Example showing a world map using a common map projection.

This uses ``WorldObject.nonlinear_transform`` to convert lon/lat coordinates
to a rectangular map. Code is shown for both the "Mercator" and the
"Winkel Tripel" projections.

.. GENERATED FROM PYTHON SOURCE LINES 14-20

.. note::

  To run this example, you need a model from the source repo's example
  folder. If you are running this example from a local copy of the code (dev
  install) no further actions are needed. Otherwise, you may have to replace
  the path below to point to the location of the model.

.. GENERATED FROM PYTHON SOURCE LINES 20-32

.. code-block:: Python


    import os
    from pathlib import Path

    try:
        # modify this line if your model is located elsewhere
        model_dir = Path(__file__).parents[1] / "data"
    except NameError:
        # compatibility with sphinx-gallery
        model_dir = Path(os.getcwd()).parent / "data"









.. GENERATED FROM PYTHON SOURCE LINES 33-135

.. code-block:: Python



    import numpy as np
    from rendercanvas.auto import RenderCanvas, loop
    import pygfx as gfx


    # Load public domain coastline data from naturalearthdata.com.
    # Original source: https://naturalearth.s3.amazonaws.com/110m_physical/ne_110m_coastline.zip
    # Transformed to a numpy array using geopandas and then stored as npz
    lonlat = np.load(model_dir / "coastlines.npz")["lonlat"]


    WGSL_MERCATOR = """
    fn nonlinear_transform(pos: vec3f) -> vec3f {
        // Source: Wikipedia - this is web-mercator
        let lon = pos.x * PI / 180;
        let lat = pos.y * PI / 180;
        let max_lat: f32 = 1.4844222;  // = 2*atan(e**pi)-pi/2 ≈ 85°
        let clamped_lat = clamp(lat, -max_lat, max_lat);
        let y = log(tan(0.25 * PI + 0.5 * clamped_lat));
        return vec3f(lon, y, pos.z);
    }
    """

    WGSL_WINKEL_TRIPEL = """
    fn nonlinear_transform(pos: vec3f) -> vec3f {
        // Source: Wikipedia
        let lon = pos.x * PI / 180;
        let lat = pos.y * PI / 180;
        let x1 = lon * cos(lat / 2.0);
        let y1 = lat;
        let alpha = acos(cos(lat) * cos(lon / 2.0));
        let sinc = select(1.0, sin(alpha) / alpha, alpha > 1e-6);
        let x2 = 2.0 * cos(lat) * sin(lon / 2.0) / sinc;
        let y2 = sin(lat) / sinc;
        let x = 0.5 * (x1 + x2);
        let y = 0.5 * (y1 + y2);
        return vec3f(x, y, pos.z);
    }
    """

    # Setup visuzaliation

    canvas = RenderCanvas(update_mode="continuous")
    renderer = gfx.WgpuRenderer(canvas)
    scene = gfx.Scene()
    scene.add(gfx.Background.from_color("#000"))

    camera = gfx.OrthographicCamera(maintain_aspect=True)
    camera.show_object((0, 0, 0, 3), up=(0, 0, 1))
    controller = gfx.PanZoomController(camera, register_events=renderer)


    # Add points for the lon/lat lines

    density = 1

    point_positions1 = []
    for lat in range(-90, 90, 10):
        x = np.linspace(-180, 180, 360 * density, dtype=np.float32)
        y = np.full_like(x, lat)
        point_positions1.append(np.column_stack([x, y, np.zeros_like(x)]))
    for lon in range(-180, 180, 10):
        y = np.linspace(-90, 90, 180 * density, dtype=np.float32)
        x = np.full_like(y, lon)
        point_positions1.append(np.column_stack([x, y, np.zeros_like(x)]))
    point_positions1 = np.vstack(point_positions1)

    points1 = gfx.Points(
        gfx.Geometry(positions=point_positions1),
        gfx.PointsMaterial(size=1.0, color="#777"),
    )
    scene.add(points1)


    # Add lines for the coastlines

    lon = lonlat[:, 0]
    lat = lonlat[:, 1]
    point_positions2 = np.column_stack([lon, lat, np.zeros_like(lon)])
    lines2 = gfx.Line(
        gfx.Geometry(positions=point_positions2),
        gfx.LineMaterial(thickness=3.0, color="#aaf"),
    )
    scene.add(lines2)


    # Apply projection (pick one)

    for ob in [points1, lines2]:
        ob.nonlinear_transform = WGSL_WINKEL_TRIPEL
        # ob.nonlinear_transform = WGSL_MERCATOR


    def animate():
        renderer.render(scene, camera)


    if __name__ == "__main__":
        canvas.request_draw(animate)
        loop.run()



.. image-sg:: /_gallery/feature_demo/images/sphx_glr_world_map_projection_001.webp
   :alt: world map projection
   :srcset: /_gallery/feature_demo/images/sphx_glr_world_map_projection_001.webp
   :class: sphx-glr-single-img






.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.304 seconds)


.. _sphx_glr_download__gallery_feature_demo_world_map_projection.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: world_map_projection.ipynb <world_map_projection.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: world_map_projection.py <world_map_projection.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: world_map_projection.zip <world_map_projection.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_