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GPT-4.1 copilot notes on headless GL contexts on windows
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‎Google Keep Document.txt

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Copilot
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Copilot navigation
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Copilot Chat
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GTK4 event handling code adaptation
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You said: The event management code in https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTK4_AdvancedGL.py on
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The event management code in https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTK4_AdvancedGL.py on line 52 to 61 is wrong. Can you change them into their GTK4 corresponding apis?
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2/2
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1 reference
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Copilot said: Here’s what needs to be changed for
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Here’s what needs to be changed for GTK4 event handling in the code block from line 52 to 61. In GTK4, the event mask system and event signals for widgets like Gtk.GLArea have changed:
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add_events() is deprecated/removed in GTK4; event masks are set differently or are simply not needed—the widget is expected to be “event controller” driven.
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Mouse and key events are handled via GtkEventController (for mouse: Gtk.EventControllerMotion and Gtk.GestureClick; for keyboard: Gtk.EventControllerKey).
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Below is the correct replacement for lines 52-61, using GTK4 idioms. This will move the event handling setup to use GTK4 event controllers and gestures:
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SkiaGTK4_AdvancedGL.pyv1
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52| # Setup event controllers for GTK4
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53| self.motion_controller = Gtk.EventControllerMotion.new(self)
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54| self.motion_controller.connect("motion", self.on_motion_notify)
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55|
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56| self.click_gesture = Gtk.GestureClick.new(self)
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57| self.click_gesture.connect("pressed", self.on_button_press)
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You’ll also need to update the signatures of the event handler methods to match the new controller APIs:
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on_motion_notify(self, motion_controller, x, y) (instead of (widget, event))
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on_button_press(self, gesture, n_press, x, y) and on_button_release(self, gesture, n_press, x, y)
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on_key_press(self, key_controller, keyval, keycode, state)
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Summary of changes:
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Remove add_events() and all old-style connect("event-type", ...) calls.
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Use GTK4 event controllers for mouse/keyboard events.
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Would you like a full code patch, including the updated event handler function signatures and logic?
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You said: Yes, i want a full code path
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Yes, i want a full code path
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Copilot said: ```python name=SkiaGTK4_AdvancedGL.py #!/usr/bin/env python3 # Skia + Gtk4 +
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SkiaGTK4_AdvancedGL.pyv2
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#!/usr/bin/env python3
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# Skia + Gtk4 + OpenGL (hardware accelerated, advanced GPU features) example
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import gi
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gi.require_version("Gtk", "4.0")
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from gi.repository import Gtk, Gdk, GLib
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Summary of changes:
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Old event mask and signal-based event handling (lines 52-61) are replaced with GTK4 event controllers (Gtk.EventControllerMotion, Gtk.GestureClick, Gtk.EventControllerKey).
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The handler methods are updated to match the new controller signatures.
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The logic inside each handler is adapted as needed to work with the new API (e.g., using gesture.get_current_button()).
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This patch will make your event handling fully compatible with GTK4.
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You said: Can you improve https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTKGLExample.py ? It seems
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Can you improve https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTKGLExample.py ? It seems to be refreshing excessively.
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1 reference
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Copilot said: The excessive refreshing in this code is
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The excessive refreshing in this code is mainly due to the line in on_realize:
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Python
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GLib.timeout_add(16, self.queue_draw) # ~60fps
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This causes the widget to redraw at ~60fps regardless of whether something actually changed.
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Improvement suggestion:
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Only trigger redraws (queue_draw) when something visual actually changes (e.g., star rotation, mouse drag, or new rect).
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Move the animation timer (GLib.timeout_add) to only run while the star is rotating or a drag is happening.
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When idle (no animation, no drag), stop the timer to avoid unnecessary draws.
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Below is an improved version of the file that only refreshes when needed.
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SkiaGTKGLExample.py
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#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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import gi
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gi.require_version("Gtk", "3.0")
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from gi.repository import Gtk, Gdk, GObject, GLib
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Key improvements:
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The animation timer is not always running; it's started only when the star needs to animate and stopped when not needed.
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Mouse drag events and static UI do not trigger continuous redraws—only queue a draw as needed.
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The UI is now much more efficient and should not refresh excessively.
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Let me know if you want further refinements (e.g., only animating star rotation on user input)!
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You said: Can you improve https://github.com/HinTak/skia-python-examples/blob/main/SkiaTkExample.py? It seems to
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Can you improve https://github.com/HinTak/skia-python-examples/blob/main/SkiaTkExample.py? It seems to be using a lot of CPU time and doing excessive refreshing
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1 reference
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Copilot said: Here's how you can improve `SkiaTkExample.py` to
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Here's how you can improve SkiaTkExample.py to greatly reduce CPU usage and only refresh the UI when needed:
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Problems in the original code:
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The animate method uses root.after(16, self.animate) to refresh at ~60fps, regardless of whether anything is changing (e.g. no interaction, window not visible).
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The draw() method is called on every frame even if nothing has changed.
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The star is always rotating, causing continuous redraws.
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Improvements:
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Only animate the star when the window is focused/visible.
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Only trigger redraws on user interaction (drag, resize, etc.) or when actively animating.
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Pause the animation when the window is not focused or minimized.
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Avoid unnecessary surface recreation.
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Below is an improved version of your file:
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SkiaTkExample.py
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import tkinter as tk
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from skia import *
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import math
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import random
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HELP_MESSAGE = "Click and drag to create rects. Press esc to quit."
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Key Improvements:
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Animation runs only when the window is focused, greatly reducing CPU usage when the app is idle or in the background.
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Redraws occur only on interaction or during animation.
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Surface recreation only happens when the window is resized.
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Avoids unnecessary creation of PhotoImage objects.
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Let me know if you'd like further refinements or explanations!
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You said: https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTKExample.py does not use skia at all,
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https://github.com/HinTak/skia-python-examples/blob/main/SkiaGTKExample.py does not use skia at all, does it?
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Copilot said: You are correct: the file SkiaGTKExample.py in
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You are correct: the file SkiaGTKExample.py in the repository HinTak/skia-python-examples does not use Skia at all.
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Looking at the file's contents, it only uses GTK (via PyGObject), Cairo, and standard Python modules. There is no import or usage of skia or skia-python APIs. All drawing is done via Cairo (the GTK default graphics library), not Skia.
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If you want to update this example to actually use Skia for rendering, let me know—I'm happy to help you rewrite it to use skia-python for drawing!
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You said: Yes, please.
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Yes, please.
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Copilot said: Here is a version of `SkiaGTKExample.py` that
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Here is a version of SkiaGTKExample.py that actually uses skia-python for all drawing, replacing all Cairo usage with Skia rendering. This version creates a GTK drawing area, uses Skia to draw into a raster surface, and then converts the Skia surface to a GdkPixbuf for display in GTK. All interactive rectangle and text drawing will be handled by Skia.
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SkiaGTKExample.pyv1
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#!/usr/bin/env python3
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import gi
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gi.require_version("Gtk", "3.0")
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from gi.repository import Gtk, Gdk, GLib
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from skia import *
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Key points:
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All rendering is done in Skia, not Cairo.
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Drawing events (mouse/key) update Skia state and redraw.
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The Skia surface is converted to a PNG and rendered in GTK via a Pixbuf.
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The UI is interactive and all shapes, text, and the star are rendered using skia-python.
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Let me know if you need a GTK4 version or further features!
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You said: Yes, give me a GTK4 version please.
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Yes, give me a GTK4 version please.
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Copilot said: ```python name=SkiaGTKExample.py #!/usr/bin/env python3 import gi gi.require_version("Gtk", "4.0") from gi.repository import
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SkiaGTKExample.pyv2
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#!/usr/bin/env python3
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import gi
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gi.require_version("Gtk", "4.0")
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from gi.repository import Gtk, Gdk
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from skia import *
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Notes:
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Uses Gtk.DrawingArea with set_draw_func (GTK4 idiom).
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Uses Skia for all rendering; outputs to a PNG, then displays via Gdk.Texture.
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Mouse and key events are handled via GTK4 event controllers.
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All interactive drawing is now Skia-backed, not Cairo.
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Let me know if you want further features or refinements!
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You said: Actually I want you to go back
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Actually I want you to go back a bit, set up GTK3 with a opengl context and do skia drawing through the opengl context.
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Copilot said: ```python name=SkiaGTKExample.py #!/usr/bin/env python3 import gi gi.require_version("Gtk", "3.0") from gi.repository import
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SkiaGTKExample.pyv3
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#!/usr/bin/env python3
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import gi
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gi.require_version("Gtk", "3.0")
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from gi.repository import Gtk, Gdk, GObject
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from OpenGL.GL import *
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from skia import *
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Highlights:
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Uses Gtk.GLArea for OpenGL context in GTK3.
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Skia draws directly into the OpenGL framebuffer via GrDirectContext.
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Interactive drawing with mouse events.
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Drawing is performed by Skia, not Cairo.
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All rendering is hardware accelerated (if supported).
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Let me know if you want further features or refinements!
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You said: How to set up a headless opengl
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How to set up a headless opengl comtext in python for the windows host in github ci?
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Copilot said: To set up a **headless OpenGL context
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To set up a headless OpenGL context in Python on a Windows host in GitHub CI (Actions), you need to use an OpenGL loader that supports offscreen (headless) rendering. Windows does not natively support headless OpenGL contexts, so you typically use OSMesa (from Mesa3D), ANGLE, or EGL if available. However, the most straightforward and cross-platform approach for CI is to use Mesa3D's OSMesa in software mode.
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Below are step-by-step instructions to set up a headless OpenGL context in Python on a Windows runner in GitHub Actions:
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1. Download and Install Mesa3D (OSMesa) DLLs
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You need the osmesa.dll (and sometimes opengl32.dll from Mesa3D). Prebuilt binaries can be found at https://github.com/pal1000/mesa-dist-win/releases.
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Example GitHub Actions Step:
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YAML
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- name: Download Mesa3D
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shell: bash
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run: |
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curl -L -o mesa.7z https://github.com/pal1000/mesa-dist-win/releases/download/24.0.4/mesa3d-24.0.4-release-windows-x64.7z
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7z x mesa.7z -omesa
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echo "${GITHUB_WORKSPACE}/mesa/x64" >> $GITHUB_PATH
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# Or use setx PATH for Windows shell
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2. Add Mesa DLLs to PATH
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Make sure the directory containing osmesa.dll and/or Mesa's opengl32.dll is in your PATH.You can do this in your workflow with:
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YAML
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- name: Add Mesa to PATH
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run: |
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echo "$env:GITHUB_WORKSPACE\\mesa\\x64" | Out-File -Append -FilePath $env:GITHUB_PATH
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shell: pwsh
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3. Use a Python OpenGL context library that supports OSMesa/EGL
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Recommended options:
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pyglet (has headless mode, supports OSMesa)
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moderngl-window (uses EGL on Linux, but not on Windows)
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glcontext (has OSMesa backend)
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osmesa Python bindings
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Example: Using pyglet with OSMesa
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Python
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import pyglet
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pyglet.options['headless'] = True
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import pyglet.gl as gl
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window = pyglet.window.Window(visible=False, width=256, height=256)
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# Now you have an offscreen OpenGL context.
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Example: Using glcontext with OSMesa
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import glcontext
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ctx = glcontext.osmesa.create_context()
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ctx.make_current()
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# You can now use OpenGL calls with PyOpenGL, etc.
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Note: For some libraries, you must set the PYOPENGL_PLATFORM environment variable to osmesa before running Python:
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YAML
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- name: Set PYOPENGL_PLATFORM
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run: |
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echo "PYOPENGL_PLATFORM=osmesa" >> $env:GITHUB_ENV
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Or in Python:
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Python
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import os
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os.environ['PYOPENGL_PLATFORM'] = 'osmesa'
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4. (Optional) Use PyOpenGL for Rendering
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Python
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from OpenGL.GL import *
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glClearColor(1,0,0,1)
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glClear(GL_COLOR_BUFFER_BIT)
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# ... your rendering code ...
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Full GitHub Actions Example YAML Snippet
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YAML
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jobs:
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test-opengl:
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runs-on: windows-latest
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steps:
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- uses: actions/checkout@v4
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- name: Download Mesa3D
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run: |
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curl -L -o mesa.7z https://github.com/pal1000/mesa-dist-win/releases/download/24.0.4/mesa3d-24.0.4-release-windows-x64.7z
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7z x mesa.7z -omesa
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- name: Add Mesa to PATH
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run: |
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echo "$env:GITHUB_WORKSPACE\\mesa\\x64" | Out-File -Append -FilePath $env:GITHUB_PATH
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shell: pwsh
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- name: Set PYOPENGL_PLATFORM
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run: |
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echo "PYOPENGL_PLATFORM=osmesa" | Out-File -Append -FilePath $env:GITHUB_ENV
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shell: pwsh
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- name: Install Python requirements
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run: pip install pyglet PyOpenGL
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- name: Run headless OpenGL test
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run: python your_headless_gl_test.py
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Troubleshooting Tips
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Make sure osmesa.dll and/or Mesa's opengl32.dll are in your PATH before Python starts.
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For pyglet, set pyglet.options['headless'] = True before importing pyglet.gl.
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For PyOpenGL, set PYOPENGL_PLATFORM=osmesa.
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Some OpenGL features may not be available in software (Mesa) implementations.
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Summary:Download Mesa3D, add its DLLs to PATH, set PYOPENGL_PLATFORM=osmesa, and use a Python OpenGL context library that supports OSMesa (e.g., pyglet or glcontext).
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If you want a minimal working Python script for testing, let me know!
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You said: Is there an official source for windows
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Is there an official source for windows mesa3d binaries?
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Copilot said: There is **no official Windows Mesa3D binary
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There is no official Windows Mesa3D binary distribution from the Mesa3D project itself. The Mesa3D project (https://www.mesa3d.org/) does not provide pre-built binaries for Windows on their official website or their GitLab repository.
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However, the most widely used and trusted unofficial source is:
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pal1000/mesa-dist-win GitHub repository:https://github.com/pal1000/mesa-dist-win
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This repository provides regular, up-to-date, and well-documented Windows builds of Mesa3D (including OSMesa, llvmpipe, and more). It is referenced by many open source projects and CI setups as the de facto standard for Windows Mesa binaries.
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Summary:
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The Mesa3D project does not provide official Windows binaries.
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pal1000/mesa-dist-win is the most reputable and widely used source for pre-built Windows Mesa3D binaries.
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References:
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Mesa3D official download page — only source code, no Windows binaries.
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pal1000/mesa-dist-win releases — up-to-date Windows binaries.

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