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// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.
//! Commands that the GPU will execute (includes draw commands).
//!
//! With Vulkan, before the GPU can do anything you must create a `CommandBuffer`. A command buffer
//! is a list of commands that will executed by the GPU. Once a command buffer is created, you can
//! execute it. A command buffer must always be created even for the most simple tasks.
//!
//! # Primary and secondary command buffers.
//!
//! There are three types of command buffers:
//!
//! - **Primary command buffers**. They can contain any command. They are the only type of command
//! buffer that can be submitted to a queue.
//! - **Secondary "graphics" command buffers**. They can only contain draw and clear commands.
//! They can only be called from a primary command buffer when inside a render pass.
//! - **Secondary "compute" command buffers**. They can only contain non-render-pass-related
//! commands (ie. everything but drawing, clearing, etc.) and cannot enter a render pass. They
//! can only be called from a primary command buffer outside of a render pass.
//!
//! Using secondary command buffers leads to slightly lower performances on the GPU, but they have
//! two advantages on the CPU side:
//!
//! - Building a command buffer is a single-threaded operation, but by using secondary command
//! buffers you can build multiple secondary command buffers in multiple threads simultaneously.
//! - Secondary command buffers can be kept alive between frames. When you always repeat the same
//! operations, it might be a good idea to build a secondary command buffer once at
//! initialization and then reuse it afterwards.
//!
//! # The `AutoCommandBufferBuilder`
//!
//! The most basic (and recommended) way to create a command buffer is to create a
//! [`AutoCommandBufferBuilder`](struct.AutoCommandBufferBuilder.html). Then use the
//! [`CommandBufferBuilder` trait](trait.CommandBufferBuilder.html) to add commands to it.
//! When you are done adding commands, use
//! [the `CommandBufferBuild` trait](trait.CommandBufferBuild.html) to obtain a
//! `AutoCommandBuffer`.
//!
//! Once built, use [the `CommandBuffer` trait](trait.CommandBuffer.html) to submit the command
//! buffer. Submitting a command buffer returns an object that implements the `GpuFuture` trait and
//! that represents the moment when the execution will end on the GPU.
//!
//! ```
//! use vulkano::command_buffer::AutoCommandBufferBuilder;
//! use vulkano::command_buffer::CommandBuffer;
//!
//! # let device: std::sync::Arc<vulkano::device::Device> = return;
//! # let queue: std::sync::Arc<vulkano::device::Queue> = return;
//! let cb = AutoCommandBufferBuilder::new(device.clone(), queue.family()).unwrap()
//! // TODO: add an actual command to this example
//! .build().unwrap();
//!
//! let _future = cb.execute(queue.clone());
//! ```
//!
//! # Internal architecture of vulkano
//!
//! The `commands_raw` and `commands_extra` modules contain structs that correspond to various
//! commands that can be added to command buffer builders. A command can be added to a command
//! buffer builder by using the `AddCommand<C>` trait, where `C` is the command struct.
//!
//! The `AutoCommandBufferBuilder` internally uses a `UnsafeCommandBufferBuilder` wrapped around
//! multiple layers. See the `cb` module for more information.
//!
//! Command pools are automatically handled by default, but vulkano also allows you to use
//! alternative command pool implementations and use them. See the `pool` module for more
//! information.
pub use AutoCommandBuffer;
pub use AutoCommandBufferBuilder;
pub use AutoCommandBufferBuilderContextError;
pub use BeginRenderPassError;
pub use BlitImageError;
pub use BuildError;
pub use ClearColorImageError;
pub use CopyBufferError;
pub use CopyBufferImageError;
pub use DispatchError;
pub use DrawError;
pub use DrawIndexedError;
pub use DrawIndirectError;
pub use ExecuteCommandsError;
pub use FillBufferError;
pub use UpdateBufferError;
pub use StateCacher;
pub use StateCacherOutcome;
pub use CommandBuffer;
pub use CommandBufferBuild;
pub use CommandBufferExecError;
pub use CommandBufferExecFuture;
use Scissor;
use Viewport;
/// The dynamic state to use for a draw command.
// TODO: probably not the right location