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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. //! Location in memory that contains data. //! //! All buffers are guaranteed to be accessible from the GPU. //! //! # High-level wrappers //! //! The low level implementation of a buffer is `UnsafeBuffer`. However, the vulkano library //! provides high-level wrappers around that type that are specialized depending on the way you //! are going to use it: //! //! - `CpuAccessBuffer` designates a buffer located in RAM and whose content can be directly //! written by your application. //! - `DeviceLocalBuffer` designates a buffer located in video memory and whose content can't be //! written by your application. Accessing this buffer from the GPU is usually faster than the //! `CpuAccessBuffer`. //! - `ImmutableBuffer` designates a buffer in video memory and whose content can only be //! written once. Compared to `DeviceLocalBuffer`, this buffer requires less processing on the //! CPU because we don't need to keep track of the reads and writes. //! //! If you have data that is modified at every single frame, you are encouraged to use a //! `CpuAccessibleBuffer`. If you have data that is very rarely modified, you are encouraged to //! use an `ImmutableBuffer` or a `DeviceLocalBuffer` instead. //! //! If you just want to get started, you can use the `CpuAccessibleBuffer` everywhere, as it is //! the most flexible type of buffer. //! //! # Buffers usage //! //! When you create a buffer object, you have to specify its *usage*. In other words, you have to //! specify the way it is going to be used. Trying to use a buffer in a way that wasn't specified //! when you created it will result in an error. //! //! You can use buffers for the following purposes: //! //! - Can contain arbitrary data that can be transferred from/to other buffers and images. //! - Can be read and modified from a shader. //! - Can be used as a source of vertices and indices. //! - Can be used as a source of list of models for draw indirect commands. //! //! Accessing a buffer from a shader can be done in the following ways: //! //! - As a uniform buffer. Uniform buffers are read-only. //! - As a storage buffer. Storage buffers can be read and written. //! - As a uniform texel buffer. Contrary to a uniform buffer, the data is interpreted by the //! GPU and can be for example normalized. //! - As a storage texel buffer. Additionnally, some data formats can be modified with atomic //! operations. //! //! Using uniform/storage texel buffers requires creating a *buffer view*. See the `view` module //! for how to create a buffer view. //! use std::marker::PhantomData; use std::mem; use std::ops::Range; use std::sync::Arc; pub use self::cpu_access::CpuAccessibleBuffer; pub use self::device_local::DeviceLocalBuffer; pub use self::immutable::ImmutableBuffer; pub use self::sys::BufferCreationError; pub use self::sys::Usage as BufferUsage; pub use self::traits::Buffer; pub use self::traits::TypedBuffer; pub use self::view::BufferView; pub mod cpu_access; pub mod device_local; pub mod immutable; pub mod sys; pub mod traits; pub mod view; /// A subpart of a buffer. /// /// This object doesn't correspond to any Vulkan object. It exists for API convenience. /// /// # Example /// /// Creating a slice: /// /// ```no_run /// use vulkano::buffer::BufferSlice; /// # let buffer: std::sync::Arc<vulkano::buffer::DeviceLocalBuffer<[u8]>> = /// unsafe { std::mem::uninitialized() }; /// let _slice = BufferSlice::from(&buffer); /// ``` /// /// Selecting a slice of a buffer that contains `[T]`: /// /// ```no_run /// use vulkano::buffer::BufferSlice; /// # let buffer: std::sync::Arc<vulkano::buffer::DeviceLocalBuffer<[u8]>> = /// unsafe { std::mem::uninitialized() }; /// let _slice = BufferSlice::from(&buffer).slice(12 .. 14).unwrap(); /// ``` /// #[derive(Clone)] pub struct BufferSlice<'a, T: ?Sized, B: 'a> { marker: PhantomData<T>, resource: &'a Arc<B>, offset: usize, size: usize, } impl<'a, T: ?Sized, B: 'a> BufferSlice<'a, T, B> { /// Returns the buffer that this slice belongs to. pub fn buffer(&self) -> &'a Arc<B> { &self.resource } /// Returns the offset of that slice within the buffer. #[inline] pub fn offset(&self) -> usize { self.offset } /// Returns the size of that slice in bytes. #[inline] pub fn size(&self) -> usize { self.size } /// Builds a slice that contains an element from inside the buffer. /// /// This method builds an object that represents a slice of the buffer. No actual operation /// is performed. /// /// # Example /// /// TODO /// /// # Safety /// /// The object whose reference is passed to the closure is uninitialized. Therefore you /// **must not** access the content of the object. /// /// You **must** return a reference to an element from the parameter. The closure **must not** /// panic. #[inline] pub unsafe fn slice_custom<F, R: ?Sized>(self, f: F) -> BufferSlice<'a, R, B> where F: for<'r> FnOnce(&'r T) -> &'r R // TODO: bounds on R { let data: &T = mem::zeroed(); let result = f(data); let size = mem::size_of_val(result); let result = result as *const R as *const () as usize; assert!(result <= self.size()); assert!(result + size <= self.size()); BufferSlice { marker: PhantomData, resource: self.resource, offset: self.offset + result, size: size, } } } impl<'a, T, B: 'a> BufferSlice<'a, [T], B> { /// Returns the number of elements in this slice. #[inline] pub fn len(&self) -> usize { self.size() / mem::size_of::<T>() } /// Reduces the slice to just one element of the array. /// /// Returns `None` if out of range. #[inline] pub fn index(self, index: usize) -> Option<BufferSlice<'a, T, B>> { if index >= self.len() { return None; } Some(BufferSlice { marker: PhantomData, resource: self.resource, offset: self.offset + index * mem::size_of::<T>(), size: mem::size_of::<T>(), }) } /// Reduces the slice to just a range of the array. /// /// Returns `None` if out of range. #[inline] pub fn slice(self, range: Range<usize>) -> Option<BufferSlice<'a, [T], B>> { if range.end > self.len() { return None; } Some(BufferSlice { marker: PhantomData, resource: self.resource, offset: self.offset + range.start * mem::size_of::<T>(), size: (range.end - range.start) * mem::size_of::<T>(), }) } } impl<'a, T: ?Sized, B: 'a> From<&'a Arc<B>> for BufferSlice<'a, T, B> where B: TypedBuffer<Content = T>, T: 'static { #[inline] fn from(r: &'a Arc<B>) -> BufferSlice<'a, T, B> { BufferSlice { marker: PhantomData, resource: r, offset: 0, size: r.size(), } } } impl<'a, T, B: 'a> From<BufferSlice<'a, T, B>> for BufferSlice<'a, [T], B> where T: 'static { #[inline] fn from(r: BufferSlice<'a, T, B>) -> BufferSlice<'a, [T], B> { BufferSlice { marker: PhantomData, resource: r.resource, offset: r.offset, size: r.size, } } } /// Takes a `BufferSlice` that points to a struct, and returns a `BufferSlice` that points to /// a specific field of that struct. #[macro_export] macro_rules! buffer_slice_field { ($slice:expr, $field:ident) => ( // TODO: add #[allow(unsafe_code)] when that's allowed unsafe { $slice.slice_custom(|s| &s.$field) } ) } #[cfg(test)] mod tests { // TODO: restore these tests /*use std::mem; use buffer::Usage; use buffer::Buffer; use buffer::BufferView; use buffer::BufferViewCreationError; use memory::DeviceLocal; #[test] fn create() { let (device, queue) = gfx_dev_and_queue!(); let _ = Buffer::<[i8; 16], _>::new(&device, &Usage::all(), DeviceLocal, &queue).unwrap(); } #[test] fn array_len() { let (device, queue) = gfx_dev_and_queue!(); let b = Buffer::<[i16], _>::array(&device, 12, &Usage::all(), DeviceLocal, &queue).unwrap(); assert_eq!(b.len(), 12); assert_eq!(b.size(), 12 * mem::size_of::<i16>()); }*/ }