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Merged
merged 3 commits into from
Nov 2, 2025
Merged

examples: Prevent invalid semaphore reuse across frames #1009

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151047d
examples: Have a unique semaphore per swapchain image
MarijnS95 Oct 11, 2025
9dab58e
examples: Wait earlier for command-buffer fence to prevent semaphore …
MarijnS95 Oct 11, 2025
8452dff
examples: Implement triple-buffering
MarijnS95 Oct 11, 2025
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11 changes: 7 additions & 4 deletions ash-examples/src/bin/texture.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -352,8 +352,8 @@ fn main() -> Result<(), Box<dyn Error>> {

record_submit_commandbuffer(
&base.device,
base.setup_command_buffer,
base.setup_commands_reuse_fence,
base.app_setup_command_buffer,
vk::Fence::null(),
base.present_queue,
&[],
&[],
Expand Down Expand Up @@ -711,6 +711,9 @@ fn main() -> Result<(), Box<dyn Error>> {
},
];

let rendering_complete_semaphore =
base.rendering_complete_semaphores[present_index as usize];

let render_pass_begin_info = vk::RenderPassBeginInfo::default()
.render_pass(renderpass)
.framebuffer(framebuffers[present_index as usize])
Expand All @@ -724,7 +727,7 @@ fn main() -> Result<(), Box<dyn Error>> {
base.present_queue,
&[vk::PipelineStageFlags::BOTTOM_OF_PIPE],
&[base.present_complete_semaphore],
&[base.rendering_complete_semaphore],
&[rendering_complete_semaphore],
|device, draw_command_buffer| {
device.cmd_begin_render_pass(
draw_command_buffer,
Expand Down Expand Up @@ -773,7 +776,7 @@ fn main() -> Result<(), Box<dyn Error>> {
);
let present_info = vk::PresentInfoKHR {
wait_semaphore_count: 1,
p_wait_semaphores: &base.rendering_complete_semaphore,
p_wait_semaphores: &rendering_complete_semaphore,
swapchain_count: 1,
p_swapchains: &base.swapchain,
p_image_indices: &present_index,
Expand Down
7 changes: 5 additions & 2 deletions ash-examples/src/bin/triangle.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -373,6 +373,9 @@ fn main() -> Result<(), Box<dyn Error>> {
},
];

let rendering_complete_semaphore =
base.rendering_complete_semaphores[present_index as usize];

let render_pass_begin_info = vk::RenderPassBeginInfo::default()
.render_pass(renderpass)
.framebuffer(framebuffers[present_index as usize])
Expand All @@ -386,7 +389,7 @@ fn main() -> Result<(), Box<dyn Error>> {
base.present_queue,
&[vk::PipelineStageFlags::COLOR_ATTACHMENT_OUTPUT],
&[base.present_complete_semaphore],
&[base.rendering_complete_semaphore],
&[rendering_complete_semaphore],
|device, draw_command_buffer| {
device.cmd_begin_render_pass(
draw_command_buffer,
Expand Down Expand Up @@ -425,7 +428,7 @@ fn main() -> Result<(), Box<dyn Error>> {
device.cmd_end_render_pass(draw_command_buffer);
},
);
let wait_semaphors = [base.rendering_complete_semaphore];
let wait_semaphors = [rendering_complete_semaphore];
let swapchains = [base.swapchain];
let image_indices = [present_index];
let present_info = vk::PresentInfoKHR::default()
Expand Down
65 changes: 35 additions & 30 deletions ash-examples/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,9 +36,7 @@ macro_rules! offset_of {
}
}};
}
/// Helper function for submitting command buffers. Immediately waits for the fence before the command buffer
/// is executed. That way we can delay the waiting for the fences by 1 frame which is good for performance.
/// Make sure to create the fence in a signaled state on the first use.

#[allow(clippy::too_many_arguments)]
pub fn record_submit_commandbuffer<F: FnOnce(&Device, vk::CommandBuffer)>(
device: &Device,
Expand All @@ -51,14 +49,6 @@ pub fn record_submit_commandbuffer<F: FnOnce(&Device, vk::CommandBuffer)>(
f: F,
) {
unsafe {
device
.wait_for_fences(&[command_buffer_reuse_fence], true, u64::MAX)
.expect("Wait for fence failed.");

device
.reset_fences(&[command_buffer_reuse_fence])
.expect("Reset fences failed.");

device
.reset_command_buffer(
command_buffer,
Expand Down Expand Up @@ -161,16 +151,16 @@ pub struct ExampleBase {
pub pool: vk::CommandPool,
pub draw_command_buffer: vk::CommandBuffer,
pub setup_command_buffer: vk::CommandBuffer,
pub app_setup_command_buffer: vk::CommandBuffer,

pub depth_image: vk::Image,
pub depth_image_view: vk::ImageView,
pub depth_image_memory: vk::DeviceMemory,

pub present_complete_semaphore: vk::Semaphore,
pub rendering_complete_semaphore: vk::Semaphore,
pub rendering_complete_semaphores: Vec<vk::Semaphore>,

pub draw_commands_reuse_fence: vk::Fence,
pub setup_commands_reuse_fence: vk::Fence,
}

impl ExampleBase {
Expand All @@ -194,7 +184,21 @@ impl ExampleBase {
} => {
elwp.exit();
}
Event::AboutToWait => f(),
Event::AboutToWait => {
unsafe {
self.device.wait_for_fences(
&[self.draw_commands_reuse_fence],
true,
u64::MAX,
)
}
.expect("Wait for fence failed.");

unsafe { self.device.reset_fences(&[self.draw_commands_reuse_fence]) }
.expect("Reset fences failed.");

f()
}
_ => (),
}
})
Expand Down Expand Up @@ -400,15 +404,16 @@ impl ExampleBase {
let pool = device.create_command_pool(&pool_create_info, None).unwrap();

let command_buffer_allocate_info = vk::CommandBufferAllocateInfo::default()
.command_buffer_count(2)
.command_buffer_count(3)
.command_pool(pool)
.level(vk::CommandBufferLevel::PRIMARY);

let command_buffers = device
.allocate_command_buffers(&command_buffer_allocate_info)
.unwrap();
let setup_command_buffer = command_buffers[0];
let draw_command_buffer = command_buffers[1];
let app_setup_command_buffer = command_buffers[1];
let draw_command_buffer = command_buffers[2];

let present_images = swapchain_loader.get_swapchain_images(swapchain).unwrap();
let present_image_views: Vec<vk::ImageView> = present_images
Expand Down Expand Up @@ -473,14 +478,11 @@ impl ExampleBase {
let draw_commands_reuse_fence = device
.create_fence(&fence_create_info, None)
.expect("Create fence failed.");
let setup_commands_reuse_fence = device
.create_fence(&fence_create_info, None)
.expect("Create fence failed.");

record_submit_commandbuffer(
&device,
setup_command_buffer,
setup_commands_reuse_fence,
vk::Fence::null(),
present_queue,
&[],
&[],
Expand Down Expand Up @@ -533,9 +535,13 @@ impl ExampleBase {
let present_complete_semaphore = device
.create_semaphore(&semaphore_create_info, None)
.unwrap();
let rendering_complete_semaphore = device
.create_semaphore(&semaphore_create_info, None)
.unwrap();
let rendering_complete_semaphores = (0..present_images.len())
.map(|_| {
device
.create_semaphore(&semaphore_create_info, None)
.unwrap()
})
.collect();

Ok(Self {
event_loop: RefCell::new(event_loop),
Expand All @@ -557,12 +563,12 @@ impl ExampleBase {
pool,
draw_command_buffer,
setup_command_buffer,
app_setup_command_buffer,
depth_image,
depth_image_view,
present_complete_semaphore,
rendering_complete_semaphore,
rendering_complete_semaphores,
draw_commands_reuse_fence,
setup_commands_reuse_fence,
surface,
debug_call_back,
debug_utils_loader,
Expand All @@ -578,16 +584,15 @@ impl Drop for ExampleBase {
self.device.device_wait_idle().unwrap();
self.device
.destroy_semaphore(self.present_complete_semaphore, None);
self.device
.destroy_semaphore(self.rendering_complete_semaphore, None);
for &semaphore in &self.rendering_complete_semaphores {
self.device.destroy_semaphore(semaphore, None);
}
self.device
.destroy_fence(self.draw_commands_reuse_fence, None);
self.device
.destroy_fence(self.setup_commands_reuse_fence, None);
self.device.free_memory(self.depth_image_memory, None);
self.device.destroy_image_view(self.depth_image_view, None);
self.device.destroy_image(self.depth_image, None);
for &image_view in self.present_image_views.iter() {
for &image_view in &self.present_image_views {
self.device.destroy_image_view(image_view, None);
}
self.device.destroy_command_pool(self.pool, None);
Expand Down