fix(game-env): DOOM (2016) keeps the swapchain image count it asks for (#1987)

DOOM (2016) asks for exactly two swapchain images and stops with "FATAL
ERROR: getSwapchainImagesKHR failed with error (VK_SUCCESS)" when it gets
more. Every game launch gets GAMESCOPE_WSI_MIN_IMAGE_COUNT=8 and
GAMESCOPE_WSI_ENSURE_MIN_IMAGE_COUNT=1, so gamescope's WSI layer gave it 8
images (3 with only the count removed) and the game crashed on start.

When DOOMx64vk.exe sits beside the launched program (DOOMx64.exe for a GOG
install, or DOOMx64vk.exe), both variables are removed and
vk_x11_strict_image_count=true is set, the option Mesa's driconf gives the
game. Other games keep the defaults. A per-game value in the environment
editor still wins.

Tested on an AYANEO Pocket FIT with DroidDeck 0.6.9 and the same values set
per game: the swapchain gets 2 images and the game reaches its main menu at
60 fps; before, it crashed on every launch.

docs/development/game-environment.md

@@ -113,6 +113,13 @@ same WSI layer, and with eight images and no frame limit it drew flat out
 (about 240 frames a second at 120 Hz) and heated the device. Values set in the
 launch options or the environment editor are kept.
 
+DOOM (2016) is the exception (`DOOMx64vk.exe` beside the launched program, which
+is `DOOMx64.exe` for a GOG install). It asks for exactly two images and stops with
+`FATAL ERROR: getSwapchainImagesKHR failed with error (VK_SUCCESS)` when it gets
+more, so its fix removes both variables, also from its launch options, and sets
+`vk_x11_strict_image_count=true`, the option Mesa's driconf gives the game. A
+per-game value in the environment editor still wins.
+
 ## Defaults and available suggestions
 
 The initial configuration enables Mesa shader caching with

tools/linuxfs/overlay/usr/local/bin/droiddeck-game-env

@@ -124,6 +124,17 @@ def arkham_city_x87(game):
 
 
 
+@fix
+def doom_2016_swapchain_images(game):
+    if "doomx64vk.exe" in game.files and game.stem in ("doomx64", "doomx64vk"):
+        images = {
+            "GAMESCOPE_WSI_MIN_IMAGE_COUNT": None,
+            "GAMESCOPE_WSI_ENSURE_MIN_IMAGE_COUNT": None,
+            "vk_x11_strict_image_count": "true",
+        }
+        return images, [], "DOOM (2016): the swapchain keeps the image count the game asks for"
+
+
 @fix
 def teardown_vsync(game):
     if game.stem == "teardown":

tools/tests/test_game_environment.py

@@ -873,6 +873,38 @@ class GameEnvironmentTest(unittest.TestCase):
             (game / "D3DGear64.DLL").unlink()
             self.assertEqual(MODULE["engine_fixes"](str(game / "TheCrew2.exe"), []), ({}, [], []))
 
+    def test_doom_2016_keeps_the_swapchain_image_count_it_asks_for(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            game = Path(tmp) / "DOOM (2016)"
+            game.mkdir()
+            for name in ("DOOMx64.exe", "DOOMx64vk.exe", "Galaxy64.dll"):
+                (game / name).touch()
+            images = {
+                "GAMESCOPE_WSI_MIN_IMAGE_COUNT": None,
+                "GAMESCOPE_WSI_ENSURE_MIN_IMAGE_COUNT": None,
+                "vk_x11_strict_image_count": "true",
+            }
+            for exe in ("DOOMx64.exe", "DOOMx64vk.exe"):
+                env, extra, notes = MODULE["engine_fixes"](str(game / exe), [])
+                self.assertEqual((env, extra), (images, []))
+                self.assertTrue(notes)
+            launched = {"GAMESCOPE_WSI_MIN_IMAGE_COUNT": "8", "GAMESCOPE_WSI_ENSURE_MIN_IMAGE_COUNT": "1"}
+            result = MODULE["apply_config"](launched, {"version": 1}, "3566086475", env)
+            self.assertNotIn("GAMESCOPE_WSI_MIN_IMAGE_COUNT", result)
+            self.assertNotIn("GAMESCOPE_WSI_ENSURE_MIN_IMAGE_COUNT", result)
+            self.assertEqual(result["vk_x11_strict_image_count"], "true")
+            config = {"version": 1, "games": {"3566086475": {"GAMESCOPE_WSI_MIN_IMAGE_COUNT": "3"}}}
+            self.assertEqual(MODULE["apply_config"](launched, config, "3566086475", env)["GAMESCOPE_WSI_MIN_IMAGE_COUNT"], "3")
+            eternal = Path(tmp) / "DOOMEternal"
+            eternal.mkdir()
+            (eternal / "DOOMEternalx64vk.exe").touch()
+            self.assertEqual(MODULE["engine_fixes"](str(eternal / "DOOMEternalx64vk.exe"), []), ({}, [], []))
+            other = Path(tmp) / "Other"
+            other.mkdir()
+            for name in ("Other.exe", "DOOMx64vk.exe"):
+                (other / name).touch()
+            self.assertEqual(MODULE["engine_fixes"](str(other / "Other.exe"), []), ({}, [], []))
+
     def test_dll_overrides_from_several_fixes_are_all_kept(self):
         with tempfile.TemporaryDirectory() as tmp:
             for name in ("Game.exe", "Game.pck", "GodotSharp.dll", "libsentry.windows.release.x86_64.dll", "d3dgear64.dll"):