Module vulkan_validation_layers 

Enabling Vulkan Validation Layers

When developing an application it is often useful to enable Vulkan’s validation layers. They can catch errors when you are using the API incorrectly or exceeding device limits. You can read more about validation layers here: https://gpuopen.com/using-the-vulkan-validation-layers/.

Validation layers are a Vulkan-only feature, so they cannot be used with other backends. You can restrict which backends wgpu uses via InstanceDescriptor and Backends.

Installation

For validation layers to work you need to install the Vulkan SDK:

Linux

Visit https://packages.lunarg.com/ to install the Vulkan SDK along with some validation layers. Click the “Latest Supported Release” button (which looks like it’s just a header, but it is in fact a button) and follow the instructions.

Other operating systems

TODO.

Enabling validation layers

wgpu enables validation layers automatically in most cases when the application is compiled in debug mode (that is, if the --release flag is not passed to cargo), because InstanceFlags::DEBUG is set by default in development builds. You can also enable them explicitly with InstanceFlags::VALIDATION, or by setting the environment variable VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation.

The validation layers use normal Rust logging functionality, which also needs to be enabled. The wgpu examples use the env_logger crate for logging, which means you can enable validation-layer logging by setting an environment variable:

env RUST_LOG=trace cargo run --bin wgpu-examples cube

There are several logging levels (see https://docs.rs/log/latest/log/ for more info), with trace being the highest. If you choose a lower level such as info, then fewer messages will be logged.

If you want to enable validation layers in your own application, make sure it has logging configured. The env_logger crate is one possible way to do this.