Add uninitialised buffer support to builder

Also uses this support in brickmap

src/gfx/buffer.rs

@@ -5,13 +5,17 @@ use super::Context;
 
 #[derive(Debug)]
 pub struct BulkBufferBuilder<'a> {
-    descriptors: Vec<wgpu::util::BufferInitDescriptor<'a>>,
+    order: Vec<(bool, usize)>,
+    init_descriptors: Vec<wgpu::util::BufferInitDescriptor<'a>>,
+    descriptors: Vec<wgpu::BufferDescriptor<'a>>,
     current_usage: wgpu::BufferUsages,
 }
 
 impl<'a> BulkBufferBuilder<'a> {
     pub fn new() -> Self {
         Self {
+            order: vec![],
+            init_descriptors: vec![],
             descriptors: vec![],
             current_usage: wgpu::BufferUsages::UNIFORM,
         }
@@ -22,26 +26,48 @@ impl<'a> BulkBufferBuilder<'a> {
         self
     }
 
-    pub fn with_buffer(mut self, label: &'a str, contents: &'a [u8]) -> Self {
+    pub fn with_buffer(mut self, label: &'a str, size: u64, mapped: bool) -> Self {
+        let descriptor = wgpu::BufferDescriptor {
+            label: Some(label),
+            size,
+            usage: self.current_usage,
+            mapped_at_creation: mapped,
+        };
+
+        self.order.push((false, self.descriptors.len()));
+        self.descriptors.push(descriptor);
+        self
+    }
+
+    pub fn with_init_buffer(mut self, label: &'a str, contents: &'a [u8]) -> Self {
         let descriptor = wgpu::util::BufferInitDescriptor {
             label: Some(label),
             contents,
             usage: self.current_usage,
         };
 
-        self.descriptors.push(descriptor);
+        self.order.push((true, self.init_descriptors.len()));
+        self.init_descriptors.push(descriptor);
         self
     }
 
-    pub fn with_bytemuck_buffer<A: NoUninit>(self, label: &'a str, contents: &'a [A]) -> Self {
-        self.with_buffer(label, bytemuck::cast_slice(contents))
+    pub fn with_init_buffer_bm<A: NoUninit>(self, label: &'a str, contents: &'a [A]) -> Self {
+        self.with_init_buffer(label, bytemuck::cast_slice(contents))
     }
 
     pub fn build(self, context: &Context) -> Vec<wgpu::Buffer> {
+        let device = &context.device;
         let mut buffers = vec![];
-        for descriptor in self.descriptors {
-            buffers.push(context.device.create_buffer_init(&descriptor));
+        for (init, index) in self.order {
+            let buffer = if init {
+                device.create_buffer_init(&(self.init_descriptors[index]))
+            } else {
+                device.create_buffer(&(self.descriptors[index]))
+            };
+
+            buffers.push(buffer);
         }
+
         buffers
     }
 }

src/voxel/brickmap.rs

@@ -92,12 +92,6 @@ impl BrickmapManager {
         let mut feedback_data = vec![0u32; 4 + 4 * max_requested_brickmaps as usize];
         feedback_data[0] = max_requested_brickmaps;
         let feedback_data_u8 = bytemuck::cast_slice(&feedback_data);
-        let feedback_result_buffer = device.create_buffer(&wgpu::BufferDescriptor {
-            label: Some("Feedback Read"),
-            size: feedback_data_u8.len() as u64,
-            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
-            mapped_at_creation: false,
-        });
 
         let mut brickgrid_upload_data = vec![0u32; 4 + 4 * max_uploaded_brickmaps as usize];
         brickgrid_upload_data[0] = max_uploaded_brickmaps;
@@ -108,19 +102,21 @@ impl BrickmapManager {
         let brickmap_staged = Vec::new();
 
         let mut buffers = gfx::BulkBufferBuilder::new()
-            .with_bytemuck_buffer("Brick World State", &[state_uniform])
+            .with_init_buffer_bm("Brick World State", &[state_uniform])
             .set_usage(wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_DST)
-            .with_bytemuck_buffer("Brickgrid", &brickgrid)
-            .with_bytemuck_buffer("Brickmap Cache", &brickmap_cache)
-            .with_bytemuck_buffer("Shading Table", &shading_table)
-            .with_bytemuck_buffer("Brickgrid Unpack", &brickgrid_upload_data)
-            .with_bytemuck_buffer("Brickmap Unpack", &brickmap_upload_data)
+            .with_init_buffer_bm("Brickgrid", &brickgrid)
+            .with_init_buffer_bm("Brickmap Cache", &brickmap_cache)
+            .with_init_buffer_bm("Shading Table", &shading_table)
+            .with_init_buffer_bm("Brickgrid Unpack", &brickgrid_upload_data)
+            .with_init_buffer_bm("Brickmap Unpack", &brickmap_upload_data)
             .set_usage(
                 wgpu::BufferUsages::STORAGE
                     | wgpu::BufferUsages::COPY_DST
                     | wgpu::BufferUsages::COPY_SRC,
             )
-            .with_buffer("Feedback", feedback_data_u8)
+            .with_init_buffer("Feedback", feedback_data_u8)
+            .set_usage(wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ)
+            .with_buffer("Feedback Read", feedback_data_u8.len() as u64, false)
             .build(context);
 
         Self {
@@ -129,7 +125,6 @@ impl BrickmapManager {
             brickmap_cache_map,
             brickmap_cache_idx: 0,
             shading_table_allocator,
-            feedback_result_buffer,
             unpack_max_count: max_uploaded_brickmaps as usize,
             brickgrid_staged,
             brickmap_staged,
@@ -141,6 +136,7 @@ impl BrickmapManager {
             brickgrid_unpack_buffer: buffers.remove(0),
             brickmap_unpack_buffer: buffers.remove(0),
             feedback_buffer: buffers.remove(0),
+            feedback_result_buffer: buffers.remove(0),
         }
     }