lyra-game/src/render/render_job.rs

@@ -1,14 +1,16 @@
 use lyra_ecs::Entity;
 
+use super::transform_buffer_storage::TransformIndex;
+
 pub struct RenderJob {
     pub entity: Entity,
     pub shader_id: u64,
     pub mesh_uuid: uuid::Uuid,
-    pub transform_id: u32,
+    pub transform_id: TransformIndex,
 }
 
 impl RenderJob {
-    pub fn new(entity: Entity, shader_id: u64, mesh_buffer_id: uuid::Uuid, transform_id: u32) -> Self {
+    pub fn new(entity: Entity, shader_id: u64, mesh_buffer_id: uuid::Uuid, transform_id: TransformIndex) -> Self {
         Self {
             entity,
             shader_id,

lyra-game/src/render/renderer.rs

@@ -29,7 +29,7 @@ use super::light_cull_compute::LightCullCompute;
 use super::material::Material;
 use super::render_buffer::BufferWrapper;
 use super::texture::RenderTexture;
-use super::transform_buffer_storage::TransformBuffers;
+use super::transform_buffer_storage::{TransformBuffers, TransformGroup};
 use super::vertex::Vertex;
 use super::{render_pipeline::FullRenderPipeline, render_buffer::BufferStorage, render_job::RenderJob};
 
@@ -452,8 +452,10 @@ impl Renderer for BasicRenderer {
                         self.check_mesh_buffers(entity, &mesh_han);
                     }
                     
-                    let transform_id = self.transform_buffers.push_transform(&self.queue, &self.render_limits, interop_pos.calculate_mat4(), glam::Mat3::from_quat(interop_pos.rotation));
-                    
+                    let group = TransformGroup::EntityRes(entity, mesh_han.uuid());
+                    let transform_id = self.transform_buffers.update_or_push(&self.queue, &self.render_limits,
+                        group, || ( interop_pos.calculate_mat4(), glam::Mat3::from_quat(interop_pos.rotation) ));
+
                     let material = mesh.material.as_ref().unwrap()
                         .data_ref().unwrap();
                     let shader = material.shader_uuid.unwrap_or(0);
@@ -482,7 +484,10 @@ impl Renderer for BasicRenderer {
                                     self.check_mesh_buffers(entity, &mesh_han);
                                 }
 
-                                let transform_id = self.transform_buffers.push_transform(&self.queue, &self.render_limits, mesh_interpo.calculate_mat4(), glam::Mat3::from_quat(mesh_interpo.rotation));
+                                let scene_mesh_group = TransformGroup::Res(scene_han.uuid(), mesh_han.uuid());
+                                let group = TransformGroup::OwnedGroup(entity, scene_mesh_group.into());
+                                let transform_id = self.transform_buffers.update_or_push(&self.queue, &self.render_limits,
+                                    group, || ( mesh_interpo.calculate_mat4(), glam::Mat3::from_quat(mesh_interpo.rotation) ));
                                 
                                 let material = mesh.material.as_ref().unwrap()
                                     .data_ref().unwrap();
@@ -581,11 +586,8 @@ impl Renderer for BasicRenderer {
                     }
 
                     // Get the bindgroup for job's transform and bind to it using an offset.
-                    /* let transform_indices = *self.transform_buffers.transform_indices(job.entity).unwrap();
-                    let bindgroup = self.transform_buffers.bind_group(transform_indices).unwrap(); */
-
                     let bindgroup = self.transform_buffers.bind_group(job.transform_id);
-                    let offset = self.transform_buffers.buffer_offset(job.transform_id);//TransformBuffers::index_offset(&self.render_limits, transform_indices) as u32;
+                    let offset = self.transform_buffers.buffer_offset(job.transform_id);
                     render_pass.set_bind_group(1, bindgroup, &[ offset, offset, ]);
 
                     render_pass.set_bind_group(2, &self.camera_buffer.bindgroup(), &[]);

lyra-game/src/render/transform_buffer_storage.rs

@@ -1,37 +1,167 @@
-use std::num::NonZeroU64;
+use std::{collections::{HashMap, VecDeque}, hash::{BuildHasher, DefaultHasher, Hash, Hasher, RandomState}, num::NonZeroU64};
 
+use lyra_ecs::Entity;
+use uuid::Uuid;
 use wgpu::Limits;
 
 use std::mem;
 
+/// A group id created from a [`TransformGroup`].
+/// 
+/// This is mainly created so that [`TransformGroup::OwnedGroup`] can use another group inside of it.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct TransformGroupId(u64);
+
+impl From<TransformGroup> for TransformGroupId {
+    fn from(value: TransformGroup) -> Self {
+        let mut hasher = DefaultHasher::new();
+        value.hash(&mut hasher);
+        let hash = hasher.finish();
+        
+        TransformGroupId(hash)
+    }
+}
+
+/// Used as a key into the [`TransformBuffers`].
+/// 
+/// This enum is used as a key to identify a transform for a RenderJob. The renderer uses this
+/// to differentiate a transform between two entities that share a resource handle to the same
+/// scene:
+/// ```nobuild
+/// // The group of the mesh in the scene.
+/// let scene_mesh_group = TransformGroup::Res(scene_handle.uuid(), mesh_handle.uuid());
+/// // The group of the owned entity that has mesh in a scene.
+/// let finished_group = TransformGroup::OwnedGroup(entity, scene_mesh_group.into());
+/// ```
+/// 
+/// A simpler example of the use of a transform group is when processing lone mesh handles
+/// owned by entities:
+/// ```nobuild
+/// let group = TransformGroup::EntityRes(entity, mesh_handle.uuid());
+/// ```
+/// 
+/// These were made to fix [#6](https://git.seanomik.net/SeanOMik/lyra-engine/issues/6).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum TransformGroup {
+    /// Just an entity.
+    Entity(Entity),
+    /// An entity that owns another group.
+    OwnedGroup(Entity, TransformGroupId),
+    /// A resource uuid grouped with an owning Entity.
+    EntityRes(Entity, Uuid),
+    /// A resource uuid grouped with another resource uuid.
+    Res(Uuid, Uuid),
+}
+
+/// The index of a specific Transform inside of the buffers.
 #[derive(Default, Copy, Clone, PartialEq, Eq, Debug)]
-pub(crate) struct TransformBufferIndices {
-    pub buffer_index: usize,
-    pub transform_index: usize,
+pub struct TransformIndex {
+    /// The index of the entry in the buffer chain.
+    entry_index: usize,
+    /// The index of the transform in the entry.
+    transform_index: usize,
 }
 
 /// A struct representing a single transform buffer. There can be multiple of these
-pub(crate) struct TransformBufferEntry {
+struct BufferEntry {
     pub len: usize,
     pub bindgroup: wgpu::BindGroup,
     pub transform_buffer: wgpu::Buffer,
     pub normal_buffer: wgpu::Buffer,
 }
 
+/// A HashMap that caches values for reuse.
+/// 
+/// The map detects dead values by tracking which entries were not updated since the last time
+/// [`CachedValMap::update`] was ran. When dead values are collected, they can be reused on an
+/// [`insert`](CachedValMap::insert) into the map.
+struct CachedValMap<K, V, S = RandomState> {
+    latest: HashMap<K, V, S>,
+    old: HashMap<K, V, S>,
+    dead: VecDeque<V>,
+}
+
+impl<K, V, S: Default> Default for CachedValMap<K, V, S> {
+    fn default() -> Self {
+        Self {
+            latest: Default::default(),
+            old: Default::default(),
+            dead: Default::default()
+        }
+    }
+}
+
+#[allow(dead_code)]
+impl<K: Hash + Eq + PartialEq + Clone, V: Clone, S: BuildHasher> CachedValMap<K, V, S> {
+    /// Insert a key, possibly reusing a value in the map.
+    /// 
+    /// Returns the reused value, if one was reused. If its `None`, then the value was retrieved
+    /// from running `val_fn`.
+    pub fn insert<F>(&mut self, key: K, mut val_fn: F) -> Option<V>
+    where
+        F: FnMut() -> V
+    {
+        if self.latest.contains_key(&key) {
+            self.latest.insert(key, val_fn());
+            None
+        } else {
+            let val = self.dead.pop_front()
+                .unwrap_or_else(val_fn);
+            self.latest.insert(key, val.clone());
+            Some(val)
+        }
+    }
+
+    /// Returns a reference to the value corresponding to the key.
+    pub fn get(&mut self, key: K) -> Option<&V> {
+        if let Some(v) = self.old.remove(&key) {
+            self.latest.insert(key.clone(), v);
+        }
+
+        self.latest.get(&key)
+    }
+
+    /// Keep a key alive without updating its value.
+    pub fn keep_alive(&mut self, key: K) {
+        if let Some(v) = self.old.remove(&key) {
+            self.latest.insert(key, v);
+        }
+    }
+
+    /// Returns `true` if the map contains a value for the specified key.
+    pub fn contains(&self, key: K) -> bool {
+        self.old.contains_key(&key) || self.latest.contains_key(&key)
+    }
+
+    /// Collects the now dead values for reuse.
+    /// 
+    /// This detects dead values by tracking which entries were not updated since the last time
+    /// update was ran.
+    pub fn update(&mut self) {
+        // drain the dead values into the dead queue
+        self.dead.extend(self.old.drain().map(|(_, v)| v));
+
+        // now drain the latest entries into the old entries
+        self.old.extend(self.latest.drain());
+    }
+}
+
 /// A helper struct for managing the Transform buffers for meshes.
 /// 
-/// This struct manages a "chain" of uniform buffers that store Transform for meshes. When
-/// first created it only has a single "chain-link" with a buffer that is the maximum length
+/// This struct manages a "chain" of uniform buffers that store Transform for [`TransformGroup`]s.
+/// When first created it only has a single "chain-link" with a buffer that is the maximum length
 /// the GPU supports. When the first buffer fills up, a new one should be created which will also
 /// be the maximum length the GPU supports. When the new buffer fills up, a new one will be
 /// created once again, and so on.
 /// 
-/// `Uuid`'s are used to represent entries (usually Meshes) in the buffer. The Uuid's can be used
-/// to insert, update, and retrieve the transforms.
-pub(crate) struct TransformBuffers {
+/// [`TransformGroup`]s are used to represent entries in the buffer. They are used to insert,
+/// update, and retrieve the transforms.
+pub struct TransformBuffers {
     pub bindgroup_layout: wgpu::BindGroupLayout,
-    pub entries: Vec<TransformBufferEntry>,
+    groups: CachedValMap<TransformGroupId, TransformIndex>,
+    entries: Vec<BufferEntry>,
     limits: wgpu::Limits,
+    max_transform_count: usize,
 }
 
 impl TransformBuffers {
@@ -66,7 +196,9 @@ impl TransformBuffers {
 
         let mut s = Self {
             bindgroup_layout,
-            entries: vec![],
+            groups: Default::default(),
+            entries: Default::default(),
+            max_transform_count: (limits.max_uniform_buffer_binding_size / 2) as usize / (mem::size_of::<glam::Mat4>()),
             limits,
         };
 
@@ -76,26 +208,70 @@ impl TransformBuffers {
         s
     }
 
-    pub fn push_transform(&mut self, queue: &wgpu::Queue, limits: &Limits, transform: glam::Mat4, normal_matrix: glam::Mat3) -> u32 {
-        let entry = self.entries.iter_mut().next().unwrap(); // TODO: use other buffers than just the first
+    /// Update an existing transform in the buffers.
+    /// 
+    /// # Panics
+    /// Panics if the `entity_group` is not already inside of the buffers.
+    pub fn update_transform(&mut self, queue: &wgpu::Queue, limits: &Limits, entity_group: TransformGroup, transform: glam::Mat4, normal_matrix: glam::Mat3) -> TransformIndex {
+        let index = *self.groups.get(entity_group.into())
+            .expect("Use 'push_transform' for new entities");
+        let entry = self.entries.get_mut(index.entry_index).unwrap();
 
         let normal_matrix = glam::Mat4::from_mat3(normal_matrix);
 
         // write the transform and normal to the end of the transform
-        //let offset = (mem::size_of::<glam::Mat4>() * entry.len) as u64;
-        let offset = Self::get_buffer_offset(limits, entry.len as u32) as _;
+        let offset = Self::get_buffer_offset(limits, index) as _;
         queue.write_buffer(&entry.transform_buffer, offset, bytemuck::bytes_of(&transform));
         queue.write_buffer(&entry.normal_buffer, offset, bytemuck::bytes_of(&normal_matrix));
 
-        let index = entry.len;
-        entry.len += 1;
-        index as _
+        index
+    }
+
+    /// Push a new transform into the buffers.
+    pub fn push_transform(&mut self, queue: &wgpu::Queue, limits: &Limits, entity_group: TransformGroup, transform: glam::Mat4, normal_matrix: glam::Mat3) -> TransformIndex {
+        self.groups.insert(entity_group.into(), || {
+            // this closure is only called when there are no values that can be reused,
+            // so we get a brand new index at the end of the last entry in the chain.
+            let last = self.entries.last_mut().unwrap();
+            
+            // ensure the gpu buffer is not overflown
+            debug_assert!(last.len < self.max_transform_count,
+                "Transform buffer is filled and 'next_indices' was not incremented! \
+                    Was a new buffer created?");
+            
+            let tidx = last.len;
+            last.len += 1;
+
+            TransformIndex {
+                entry_index: self.entries.len() - 1,
+                transform_index: tidx
+            }
+        });
+
+        self.update_transform(queue, limits, entity_group, transform, normal_matrix)
     }
 
     /// Collect the dead transforms and prepare self to check next time.
     pub fn tick(&mut self) {
-        for entry in self.entries.iter_mut() {
-            entry.len = 0;
+        self.groups.update();
+    }
+
+    /// Returns a boolean indicating if the buffer contains this group.
+    pub fn contains(&self, group: TransformGroup) -> bool {
+        self.groups.contains(group.into())
+    }
+
+    /// Update an existing transform group or if its not existing yet, pushes it to the buffer.
+    /// 
+    /// Returns: the index that the transform is at in the buffers.
+    pub fn update_or_push<F>(&mut self, queue: &wgpu::Queue, limits: &Limits, group: TransformGroup, transform_fn: F) -> TransformIndex
+        where F: Fn() -> (glam::Mat4, glam::Mat3)
+    {   
+        let (transform, normal_matrix) = transform_fn();
+        if self.contains(group) {
+            self.update_transform(queue, limits, group, transform, normal_matrix)
+        } else {
+            self.push_transform(queue, limits, group, transform, normal_matrix)
         }
     }
 
@@ -105,7 +281,7 @@ impl TransformBuffers {
     /// "chain-link" is created.
     pub fn expand_buffers(&mut self, device: &wgpu::Device) {
         let limits = device.limits();
-        let max_buffer_sizes = (limits.max_uniform_buffer_binding_size as u64) / 2;
+        let max_buffer_sizes = self.max_transform_count as u64 * limits.min_uniform_buffer_offset_alignment as u64;
 
         let transform_buffer = device.create_buffer(
             &wgpu::BufferDescriptor {
@@ -157,7 +333,7 @@ impl TransformBuffers {
             label: Some("BG_Transforms"),
         });
 
-        let entry = TransformBufferEntry {
+        let entry = BufferEntry {
             bindgroup: transform_bind_group,
             transform_buffer,
             normal_buffer: normal_mat_buffer,
@@ -166,24 +342,28 @@ impl TransformBuffers {
         self.entries.push(entry);
     }
 
-    pub fn bind_group(&self, transform_id: u32) -> &wgpu::BindGroup {
-        let _ = transform_id;
-
-        let entry = self.entries.iter().next().unwrap(); // TODO: use other buffers than just the first
+    /// Returns the bind group for the transform index.
+    pub fn bind_group(&self, transform_id: TransformIndex) -> &wgpu::BindGroup {
+        let entry = self.entries.get(transform_id.entry_index).unwrap();
         &entry.bindgroup
     }
 
     /// Get the buffer offset for a transform using wgpu limits.
     /// 
     /// If its possible to borrow immutably, use [`TransformBuffers::buffer_offset`].
-    fn get_buffer_offset(limits: &wgpu::Limits, transform_id: u32) -> u32 {
-        //let entry = self.entries.iter().next().unwrap(); // TODO: use other buffers than just the first
-
-        transform_id * limits.min_uniform_buffer_offset_alignment as u32//mem::size_of::<glam::Mat4>() as u32
+    fn get_buffer_offset(limits: &wgpu::Limits, transform_index: TransformIndex) -> u32 {
+        transform_index.transform_index as u32 * limits.min_uniform_buffer_offset_alignment as u32
     }
 
-    pub fn buffer_offset(&self, transform_id: u32) -> u32 {
-        Self::get_buffer_offset(&self.limits, transform_id)
+    /// Returns the offset of the transform inside the bind group buffer.
+    /// 
+    /// ```nobuild
+    /// let bindgroup = transform_buffers.bind_group(job.transform_id);
+    /// let offset = transform_buffers.buffer_offset(job.transform_id);
+    /// render_pass.set_bind_group(1, bindgroup, &[ offset, offset, ]);
+    /// ```
+    pub fn buffer_offset(&self, transform_index: TransformIndex) -> u32 {
+        Self::get_buffer_offset(&self.limits, transform_index)
     }
 }