The open source OpenXR runtime
c/main: Read preferred_at_least_image_count from an enviroment variable
Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2452>
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src/xrt/compositor/main/comp_target_swapchain.c
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src/xrt/compositor/main/comp_target_swapchain.c
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#include "util/u_misc.h"
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#include "util/u_pacing.h"
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#include "util/u_debug.h"
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#include "util/u_pretty_print.h"
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#include "vk/vk_surface_info.h"
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* Vulkan functions.
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*
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*/
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/*
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* For all direct mode outputs 2 is what we want since we want to run
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* lockstep with the display. Most direct mode swapchains only supports
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* FIFO mode, and since there is no commonly available Vulkan API to
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* wait for a specific VBLANK event, even just the latest, we can set
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* the number of images to two and then acquire immediately after
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* present. Since the old images are being displayed and the new can't
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* be flipped this will block until the flip has gone through. Crude but
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* works well enough on both AMD(Mesa) and Nvidia(Blob).
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*
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* When not in direct mode and display to a composited window we
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* probably want 3, but most compositors on Linux sets the minImageCount
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* to 3 anyways so we get what we want.
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*/
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DEBUG_GET_ONCE_NUM_OPTION(preferred_at_least_image_count, "XRT_COMPOSITOR_PREFERRED_IMAGE_COUNT", 2)
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static inline struct vk_bundle *
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get_vk(struct comp_target_swapchain *cts)
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extent.height = w2;
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}
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/*
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* For all direct mode outputs 2 is what we want since we want to run
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* lockstep with the display. Most direct mode swapchains only supports
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* FIFO mode, and since there is no commonly available Vulkan API to
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* wait for a specific VBLANK event, even just the latest, we can set
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* the number of images to two and then acquire immediately after
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* present. Since the old images are being displayed and the new can't
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* be flipped this will block until the flip has gone through. Crude but
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* works well enough on both AMD(Mesa) and Nvidia(Blob).
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*
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* When not in direct mode and display to a composited window we
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* probably want 3, but most compositors on Linux sets the minImageCount
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* to 3 anyways so we get what we want.
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*/
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const uint32_t preferred_at_least_image_count = 2;
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const uint32_t preferred_at_least_image_count = debug_get_num_option_preferred_at_least_image_count();
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// Get the image count.
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uint32_t image_count = select_image_count(cts, surface_caps, preferred_at_least_image_count);