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.. _offscreen_guide: |
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Offscreen Rendering |
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=================== |
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.. note:: |
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If you're using a headless server, you'll need to use either EGL (for |
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GPU-accelerated rendering) or OSMesa (for CPU-only software rendering). |
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If you're using OSMesa, be sure that you've installed it properly. See |
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:ref:`osmesa` for details. |
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Choosing a Backend |
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------------------ |
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Once you have a scene set up with its geometry, cameras, and lights, |
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you can render it using the :class:`.OffscreenRenderer`. Pyrender supports |
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three backends for offscreen rendering: |
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- Pyglet, the same engine that runs the viewer. This requires an active |
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display manager, so you can't run it on a headless server. This is the |
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default option. |
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- OSMesa, a software renderer. |
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- EGL, which allows for GPU-accelerated rendering without a display manager. |
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If you want to use OSMesa or EGL, you need to set the ``PYOPENGL_PLATFORM`` |
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environment variable before importing pyrender or any other OpenGL library. |
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You can do this at the command line: |
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.. code-block:: bash |
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PYOPENGL_PLATFORM=osmesa python render.py |
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or at the top of your Python script: |
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.. code-block:: bash |
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# Top of main python script |
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import os |
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os.environ['PYOPENGL_PLATFORM'] = 'egl' |
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The handle for EGL is ``egl``, and the handle for OSMesa is ``osmesa``. |
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Running the Renderer |
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-------------------- |
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Once you've set your environment variable appropriately, create your scene and |
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then configure the :class:`.OffscreenRenderer` object with a window width, |
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a window height, and a size for point-cloud points: |
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>>> r = pyrender.OffscreenRenderer(viewport_width=640, |
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... viewport_height=480, |
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... point_size=1.0) |
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Then, just call the :meth:`.OffscreenRenderer.render` function: |
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>>> color, depth = r.render(scene) |
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.. image:: /_static/scene.png |
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This will return a ``(w,h,3)`` channel floating-point color image and |
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a ``(w,h)`` floating-point depth image rendered from the scene's main camera. |
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You can customize the rendering process by using flag options from |
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:class:`.RenderFlags` and bitwise or-ing them together. For example, |
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the following code renders a color image with an alpha channel |
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and enables shadow mapping for all directional lights: |
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>>> flags = RenderFlags.RGBA | RenderFlags.SHADOWS_DIRECTIONAL |
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>>> color, depth = r.render(scene, flags=flags) |
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Once you're done with the offscreen renderer, you need to close it before you |
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can run a different renderer or open the viewer for the same scene: |
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>>> r.delete() |
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Google CoLab Examples |
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--------------------- |
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For a minimal working example of offscreen rendering using OSMesa, |
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see the `OSMesa Google CoLab notebook`_. |
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.. _OSMesa Google CoLab notebook: https://colab.research.google.com/drive/1Z71mHIc-Sqval92nK290vAsHZRUkCjUx |
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For a minimal working example of offscreen rendering using EGL, |
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see the `EGL Google CoLab notebook`_. |
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.. _EGL Google CoLab notebook: https://colab.research.google.com/drive/1rTLHk0qxh4dn8KNe-mCnN8HAWdd2_BEh |
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