1 files changed, 106 insertions, 3 deletions
diff --git a/wgpu/src/buffer.rs b/wgpu/src/buffer.rs
index 7c092d0b..94122187 100644
--- a/wgpu/src/buffer.rs
+++ b/wgpu/src/buffer.rs
@@ -1,3 +1,106 @@
-//! Utilities for buffer operations.
-pub mod dynamic;
-pub mod r#static;
+use std::marker::PhantomData;
+use std::ops::RangeBounds;
+
+#[derive(Debug)]
+pub struct Buffer<T> {
+    label: &'static str,
+    size: u64,
+    usage: wgpu::BufferUsages,
+    pub(crate) raw: wgpu::Buffer,
+    offsets: Vec<wgpu::BufferAddress>,
+    type_: PhantomData<T>,
+}
+
+impl<T: bytemuck::Pod> Buffer<T> {
+    pub fn new(
+        device: &wgpu::Device,
+        label: &'static str,
+        amount: usize,
+        usage: wgpu::BufferUsages,
+    ) -> Self {
+        let size = next_copy_size::<T>(amount);
+
+        let raw = device.create_buffer(&wgpu::BufferDescriptor {
+            label: Some(label),
+            size,
+            usage,
+            mapped_at_creation: false,
+        });
+
+        Self {
+            label,
+            size,
+            usage,
+            raw,
+            offsets: Vec::new(),
+            type_: PhantomData,
+        }
+    }
+
+    pub fn resize(&mut self, device: &wgpu::Device, new_count: usize) -> bool {
+        let new_size = (std::mem::size_of::<T>() * new_count) as u64;
+
+        if self.size < new_size {
+            self.offsets.clear();
+
+            self.raw = device.create_buffer(&wgpu::BufferDescriptor {
+                label: Some(self.label),
+                size: new_size,
+                usage: self.usage,
+                mapped_at_creation: false,
+            });
+
+            self.size = new_size;
+
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Returns the size of the written bytes.
+    pub fn write(
+        &mut self,
+        queue: &wgpu::Queue,
+        offset: usize,
+        contents: &[T],
+    ) -> usize {
+        let bytes: &[u8] = bytemuck::cast_slice(contents);
+        queue.write_buffer(&self.raw, offset as u64, bytes);
+
+        self.offsets.push(offset as u64);
+
+        bytes.len()
+    }
+
+    pub fn slice(
+        &self,
+        bounds: impl RangeBounds<wgpu::BufferAddress>,
+    ) -> wgpu::BufferSlice<'_> {
+        self.raw.slice(bounds)
+    }
+
+    /// Returns the slice calculated from the offset stored at the given index.
+    pub fn slice_from_index(&self, index: usize) -> wgpu::BufferSlice<'_> {
+        self.raw.slice(self.offset_at(index)..)
+    }
+
+    /// Clears any temporary data (i.e. offsets) from the buffer.
+    pub fn clear(&mut self) {
+        self.offsets.clear()
+    }
+
+    /// Returns the offset at `index`, if it exists.
+    fn offset_at(&self, index: usize) -> &wgpu::BufferAddress {
+        self.offsets.get(index).expect("No offset at index.")
+    }
+}
+
+fn next_copy_size<T>(amount: usize) -> u64 {
+    let align_mask = wgpu::COPY_BUFFER_ALIGNMENT - 1;
+
+    (((std::mem::size_of::<T>() * amount).next_power_of_two() as u64
+        + align_mask)
+        & !align_mask)
+        .max(wgpu::COPY_BUFFER_ALIGNMENT)
+}