Triangle example panics when minimizing the window

[jedel1043]

Issue

Running the triangle example and minimizing the window makes the program crash with the message:

thread 'main' panicked at 'assertion failed: image_extent[0] != 0 || image_extent[1] != 0'

The stacktrace points to the Swapchain::validate method as the culprit:

vulkano/vulkano/src/swapchain/swapchain.rs

Lines 394 to 396 in 5c6bbe0

	// VUID-VkSwapchainCreateInfoKHR-imageExtent-01689
	// Shouldn't be possible with a properly behaving device
	assert!(image_extent[0] != 0 || image_extent[1] != 0);

System Info

• Version of vulkano: 0.29.0 and 5c6bbe0
• OS: Windows 10
• GPU (the selected PhysicalDevice): NVIDIA GeForce GTX 1050
• GPU Driver: Nvidia driver 511.65
• Vulkan Runtime: 1.0.33.0
• Vulkan SDK: 1.3.211.0
• Upload of a reasonably minimal complete main.rs file that demonstrates the issue: https://github.com/vulkano-rs/vulkano/blob/master/examples/src/bin/triangle.rs

[ryco117]

@jedel1043 I can reaffirm that this is the behavior when minimizing on Windows, which coincidentally is why my new example from yesterday contains the check

let dimensions = surface.window().inner_size();
if dimensions.width == 0 && dimensions.height == 0 {
    return; // On Windows, minimizing sets surface to 0x0. Do not draw frame.
}

I'd be willing to shotgun this into the other examples so they don't crash on minimize.

@Rua @AustinJ235 I'm also curious if it makes sense to change the above assert into returning SwapchainCreationError::ImageExtentNotSupported since there is a plausible runtime condition for someone to pass a zero by zero dimensions. I will concede that it is still the callers responsibility to not attempt to create a zero by zero swapchain.

[AustinJ235]

It might be more ergonomic to return an error in this case. Basalt has had this check in place for a while now, but from a new user perspective it might be confusing why their program panics.

[Rua]

I think turning this into a proper error makes sense, and adding it to the other examples. Do you want to make a PR for it?

[ryco117]

@AustinJ235 @Rua Thanks for the quick responses.

Curious. The assert statement references VUID-VkSwapchainCreateInfoKHR-imageExtent-01689, but the language of "width and height must both be non-zero" (emphasis theirs) suggests that neither dimension can be zero, whereas the code asserts at least one non-zero dim. Whoops.

Will make the appropriate validation and code-sample changes. Cheers