nightshade 0.13.1

A cross-platform data-oriented game engine.
Documentation
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use crate::ecs::mesh::components::{
    Vertex, create_cone_mesh, create_cube_mesh, create_cylinder_mesh, create_plane_mesh,
    create_sphere_mesh, create_subdivided_plane_mesh, create_torus_mesh,
};
use crate::ecs::prefab::resources::mesh_cache_iter;

use super::super::types::{
    BUFFER_GROWTH_FACTOR, BUFFER_SHRINK_THRESHOLD, DrawIndexedIndirect, MAX_INSTANCES, ModelMatrix,
    compute_normal_matrix,
};
use super::super::world_state::BatchRange;
use super::MeshPass;

impl MeshPass {
    pub(in super::super) fn can_do_rebatch_only(&self) -> bool {
        let Some(fd) = self.frame_dirty.as_ref() else {
            return false;
        };

        if !fd.frame_initialized
            || fd.full_rebuild_needed
            || fd.instanced_meshes_changed
            || !fd.entities_added.is_empty()
            || !fd.entities_removed.is_empty()
            || !fd.material_dirty.is_empty()
        {
            return false;
        }

        if !fd.batches_invalidated {
            return false;
        }

        let world_state = match self.world_states.get(&self.current_world_id) {
            Some(state) => state,
            None => return false,
        };

        !world_state.cached_entities.is_empty() && world_state.gpu_buffers.is_some()
    }

    pub(in super::super) fn rebatch_cached_entities(
        &mut self,
        world: &crate::ecs::world::World,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    ) {
        let dirty_transforms = self
            .frame_dirty
            .as_mut()
            .map(|fd| std::mem::take(&mut fd.transform_dirty))
            .unwrap_or_default();

        let world_state = self.world_states.get_mut(&self.current_world_id).unwrap();
        let gpu = world_state.gpu_buffers.as_ref().unwrap();

        for entity in &dirty_transforms {
            if let Some(&slot) = world_state.gpu_registry.entity_to_slot.get(entity)
                && let Some(transform) = world.core.get_global_transform(*entity)
            {
                let model_matrix = ModelMatrix {
                    model: transform.0.into(),
                    normal_matrix: compute_normal_matrix(&transform.0),
                };
                if (slot as usize) < world_state.cached_transforms.len() {
                    world_state.cached_transforms[slot as usize] = model_matrix;
                }
                let offset = (slot as u64) * std::mem::size_of::<ModelMatrix>() as u64;
                queue.write_buffer(
                    &gpu.transform_buffer,
                    offset,
                    bytemuck::cast_slice(&[model_matrix]),
                );
            }
        }

        let regular_count = world_state.regular_object_count as usize;

        let overlay_opaque_instances = std::mem::take(&mut world_state.overlay_opaque_instances);
        let overlay_opaque_double_sided_instances =
            std::mem::take(&mut world_state.overlay_opaque_double_sided_instances);
        let overlay_transparent_instances =
            std::mem::take(&mut world_state.overlay_transparent_instances);

        world_state.opaque_instances.clear();
        world_state.opaque_double_sided_instances.clear();
        world_state.transparent_instances.clear();

        let transparent_mat_ids = &world_state.cached_transparent_material_ids;
        let double_sided_mat_ids = &world_state.cached_double_sided_material_ids;

        for index in 0..regular_count.min(world_state.cached_objects.len()) {
            if world_state
                .gpu_registry
                .slot_to_entity
                .get(index)
                .copied()
                .flatten()
                .is_none()
            {
                continue;
            }

            let obj = &world_state.cached_objects[index];
            let is_transparent = transparent_mat_ids.contains(&obj.material_id);
            let is_double_sided = double_sided_mat_ids.contains(&obj.material_id);

            let object_index = index as u32;
            let mesh_id = obj.mesh_id;
            let material_id = obj.material_id;

            let batch_list = if is_transparent {
                &mut world_state.transparent_instances
            } else if is_double_sided {
                &mut world_state.opaque_double_sided_instances
            } else {
                &mut world_state.opaque_instances
            };

            if let Some(last) = batch_list.last_mut() {
                if last.0 == mesh_id && last.1 == material_id && last.3 == object_index {
                    last.3 = object_index + 1;
                } else {
                    batch_list.push((mesh_id, material_id, object_index, object_index + 1));
                }
            } else {
                batch_list.push((mesh_id, material_id, object_index, object_index + 1));
            }
        }

        if !self.mesh_lod_mesh_ids.is_empty() {
            for batch_list in [
                &mut world_state.opaque_instances,
                &mut world_state.opaque_double_sided_instances,
                &mut world_state.transparent_instances,
            ] {
                let original = std::mem::take(batch_list);
                for (mesh_id, material_id, start, end) in original {
                    if let Some(lod_ids) = self.mesh_lod_mesh_ids.get(&mesh_id) {
                        for &lod_mesh_id in lod_ids {
                            batch_list.push((lod_mesh_id, material_id, start, end));
                        }
                    } else {
                        batch_list.push((mesh_id, material_id, start, end));
                    }
                }
            }
        }

        world_state.overlay_opaque_instances = overlay_opaque_instances;
        world_state.overlay_opaque_double_sided_instances = overlay_opaque_double_sided_instances;
        world_state.overlay_transparent_instances = overlay_transparent_instances;

        let lod_sub_mesh_ids: std::collections::HashSet<u32> = self
            .mesh_lod_mesh_ids
            .values()
            .flat_map(|ids| ids.iter().skip(1).copied())
            .collect();

        let all_regular_batches: Vec<BatchRange> = world_state
            .opaque_instances
            .iter()
            .chain(world_state.opaque_double_sided_instances.iter())
            .chain(world_state.transparent_instances.iter())
            .cloned()
            .collect();

        for (batch_index, &(mesh_id, _, start, end)) in all_regular_batches.iter().enumerate() {
            if lod_sub_mesh_ids.contains(&mesh_id) {
                continue;
            }
            let batch_id = batch_index as u32;
            for slot in start..end {
                if (slot as usize) < world_state.cached_objects.len() {
                    world_state.cached_objects[slot as usize].batch_id = batch_id;
                }
            }
        }

        let overlay_batch_start = all_regular_batches.len() as u32;
        let all_overlay_batches: Vec<BatchRange> = world_state
            .overlay_opaque_instances
            .iter()
            .chain(world_state.overlay_opaque_double_sided_instances.iter())
            .chain(world_state.overlay_transparent_instances.iter())
            .cloned()
            .collect();

        for (batch_index, &(mesh_id, _, start, end)) in all_overlay_batches.iter().enumerate() {
            if lod_sub_mesh_ids.contains(&mesh_id) {
                continue;
            }
            let batch_id = overlay_batch_start + batch_index as u32;
            for slot in start..end {
                if (slot as usize) < world_state.cached_objects.len() {
                    world_state.cached_objects[slot as usize].batch_id = batch_id;
                }
            }
        }

        let instanced_batch_start = overlay_batch_start + all_overlay_batches.len() as u32;
        let all_instanced_batches: Vec<BatchRange> = world_state
            .instanced_opaque_batches
            .iter()
            .chain(world_state.instanced_opaque_double_sided_batches.iter())
            .chain(world_state.instanced_transparent_batches.iter())
            .cloned()
            .collect();

        for (batch_index, &(mesh_id, _, start, end)) in all_instanced_batches.iter().enumerate() {
            if lod_sub_mesh_ids.contains(&mesh_id) {
                continue;
            }
            let batch_id = instanced_batch_start + batch_index as u32;
            for slot in start..end {
                if (slot as usize) < world_state.cached_objects.len() {
                    world_state.cached_objects[slot as usize].batch_id = batch_id;
                }
            }
        }

        {
            let gpu = world_state.gpu_buffers.as_ref().unwrap();
            queue.write_buffer(
                &gpu.object_buffer,
                0,
                bytemuck::cast_slice(&world_state.cached_objects),
            );
        }

        let all_instances: Vec<_> = world_state
            .opaque_instances
            .iter()
            .chain(world_state.opaque_double_sided_instances.iter())
            .chain(world_state.transparent_instances.iter())
            .chain(world_state.overlay_opaque_instances.iter())
            .chain(world_state.overlay_opaque_double_sided_instances.iter())
            .chain(world_state.overlay_transparent_instances.iter())
            .chain(world_state.instanced_opaque_batches.iter())
            .chain(world_state.instanced_opaque_double_sided_batches.iter())
            .chain(world_state.instanced_transparent_batches.iter())
            .cloned()
            .collect();

        let total_batch_count = all_instances.len();
        let total_visible_slots: usize = all_instances
            .iter()
            .map(|&(_, _, start, end)| (end - start) as usize)
            .sum();

        if total_batch_count
            > world_state
                .gpu_buffers
                .as_ref()
                .unwrap()
                .indirect_buffer_size
        {
            let new_size = std::cmp::min(
                (total_batch_count as f32 * BUFFER_GROWTH_FACTOR).ceil() as usize,
                MAX_INSTANCES,
            );
            let gpu_mut = world_state.gpu_buffers.as_mut().unwrap();
            gpu_mut.indirect_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Indirect Draw Buffer (Resized)"),
                size: (std::mem::size_of::<DrawIndexedIndirect>() * new_size) as u64,
                usage: wgpu::BufferUsages::INDIRECT
                    | wgpu::BufferUsages::STORAGE
                    | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            });
            gpu_mut.indirect_buffer_size = new_size;
            gpu_mut.phase1_indirect_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Phase 1 Indirect Buffer (Resized)"),
                size: (std::mem::size_of::<DrawIndexedIndirect>() * new_size) as u64,
                usage: wgpu::BufferUsages::INDIRECT
                    | wgpu::BufferUsages::STORAGE
                    | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            });
            gpu_mut.indirect_reset_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Indirect Reset Buffer (Resized)"),
                size: (std::mem::size_of::<DrawIndexedIndirect>() * new_size) as u64,
                usage: wgpu::BufferUsages::COPY_SRC | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            });
            gpu_mut.phase1_indirect_reset_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Phase 1 Indirect Reset Buffer (Resized)"),
                size: (std::mem::size_of::<DrawIndexedIndirect>() * new_size) as u64,
                usage: wgpu::BufferUsages::COPY_SRC | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            });
            gpu_mut.culling_bind_group = None;
            gpu_mut.phase1_culling_bind_group = None;
        }

        let gpu = world_state.gpu_buffers.as_ref().unwrap();
        let mut indirect_commands = Vec::with_capacity(total_batch_count);
        let mut indirect_reset_commands = Vec::with_capacity(total_batch_count);
        let mut visible_indices = Vec::with_capacity(total_visible_slots);

        for &(mesh_id, _material_id, start, end) in all_instances.iter() {
            let mesh_data = &self.mesh_data[mesh_id as usize];
            let instance_count = end - start;
            let first_instance = visible_indices.len() as u32;
            let is_lod_sub = lod_sub_mesh_ids.contains(&mesh_id);

            indirect_commands.push(DrawIndexedIndirect {
                index_count: mesh_data.index_count,
                instance_count: if is_lod_sub { 0 } else { instance_count },
                first_index: mesh_data.index_offset,
                base_vertex: mesh_data.vertex_offset as i32,
                first_instance,
            });

            indirect_reset_commands.push(DrawIndexedIndirect {
                index_count: mesh_data.index_count,
                instance_count: 0,
                first_index: mesh_data.index_offset,
                base_vertex: mesh_data.vertex_offset as i32,
                first_instance,
            });

            for object_index in start..end {
                visible_indices.push(object_index);
            }
        }

        queue.write_buffer(
            &gpu.indirect_buffer,
            0,
            bytemuck::cast_slice(&indirect_commands),
        );
        queue.write_buffer(
            &gpu.visible_indices_buffer,
            0,
            bytemuck::cast_slice(&visible_indices),
        );
        queue.write_buffer(
            &gpu.phase1_visible_indices_buffer,
            0,
            bytemuck::cast_slice(&visible_indices),
        );
        queue.write_buffer(
            &gpu.indirect_reset_buffer,
            0,
            bytemuck::cast_slice(&indirect_reset_commands),
        );
        queue.write_buffer(
            &gpu.phase1_indirect_reset_buffer,
            0,
            bytemuck::cast_slice(&indirect_reset_commands),
        );
        world_state.indirect_reset_count = total_batch_count;
    }

    pub(in super::super) fn push_batch_with_lod(
        &self,
        instances: &mut Vec<(u32, u32, u32, u32)>,
        mesh_id: u32,
        material_id: u32,
        start: u32,
        end: u32,
    ) {
        if let Some(lod_ids) = self.mesh_lod_mesh_ids.get(&mesh_id) {
            for &lod_mesh_id in lod_ids {
                instances.push((lod_mesh_id, material_id, start, end));
            }
        } else {
            instances.push((mesh_id, material_id, start, end));
        }
    }

    pub(in super::super) fn draw_batches<'a>(
        pass: &mut wgpu::RenderPass<'a>,
        instances: &[(u32, u32, u32, u32)],
        batch_offset: usize,
        material_bind_groups: &'a std::collections::HashMap<u32, wgpu::BindGroup>,
        indirect_buffer: &'a wgpu::Buffer,
    ) {
        let mut current_material: Option<u32> = None;
        let mut batch_start_index: usize = 0;

        for (batch_index, &(_mesh_id, material_id, _start, _end)) in instances.iter().enumerate() {
            if current_material != Some(material_id) {
                if let Some(prev_material) = current_material {
                    let count = batch_index - batch_start_index;
                    if count > 0
                        && let Some(bind_group) = material_bind_groups.get(&prev_material)
                    {
                        pass.set_bind_group(2, bind_group, &[]);
                        let indirect_offset = ((batch_offset + batch_start_index)
                            * std::mem::size_of::<DrawIndexedIndirect>())
                            as u64;
                        pass.multi_draw_indexed_indirect(
                            indirect_buffer,
                            indirect_offset,
                            count as u32,
                        );
                    }
                }
                current_material = Some(material_id);
                batch_start_index = batch_index;
            }
        }

        if let Some(material_id) = current_material {
            let count = instances.len() - batch_start_index;
            if count > 0
                && let Some(bind_group) = material_bind_groups.get(&material_id)
            {
                pass.set_bind_group(2, bind_group, &[]);
                let indirect_offset = ((batch_offset + batch_start_index)
                    * std::mem::size_of::<DrawIndexedIndirect>())
                    as u64;
                pass.multi_draw_indexed_indirect(indirect_buffer, indirect_offset, count as u32);
            }
        }
    }

    pub(in super::super) fn compute_vertex_utilization(&self) -> f32 {
        let actual_vertex_count: u64 = self.mesh_data.iter().map(|m| m.vertex_count as u64).sum();
        let actual_vertex_bytes = actual_vertex_count * std::mem::size_of::<Vertex>() as u64;
        if self.vertex_buffer_size > 0 {
            actual_vertex_bytes as f32 / self.vertex_buffer_size as f32
        } else {
            1.0
        }
    }

    pub(in super::super) fn compute_index_utilization(&self) -> f32 {
        let actual_index_count: u64 = self.mesh_data.iter().map(|m| m.index_count as u64).sum();
        let actual_index_bytes = actual_index_count * std::mem::size_of::<u32>() as u64;
        if self.index_buffer_size > 0 {
            actual_index_bytes as f32 / self.index_buffer_size as f32
        } else {
            1.0
        }
    }

    pub(in super::super) fn check_and_compact_buffers(
        &mut self,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
        mesh_cache: &crate::ecs::prefab::resources::MeshCache,
    ) {
        let actual_vertex_count: u64 = self.mesh_data.iter().map(|m| m.vertex_count as u64).sum();
        let actual_index_count: u64 = self.mesh_data.iter().map(|m| m.index_count as u64).sum();

        let actual_vertex_bytes = actual_vertex_count * std::mem::size_of::<Vertex>() as u64;
        let actual_index_bytes = actual_index_count * std::mem::size_of::<u32>() as u64;

        let vertex_utilization = if self.vertex_buffer_size > 0 {
            actual_vertex_bytes as f32 / self.vertex_buffer_size as f32
        } else {
            1.0
        };

        let index_utilization = if self.index_buffer_size > 0 {
            actual_index_bytes as f32 / self.index_buffer_size as f32
        } else {
            1.0
        };

        let should_compact = vertex_utilization < BUFFER_SHRINK_THRESHOLD
            || index_utilization < BUFFER_SHRINK_THRESHOLD;

        if should_compact && actual_vertex_bytes > 0 && actual_index_bytes > 0 {
            self.meshes.clear();
            self.mesh_data.clear();
            self.current_vertex_offset = 0;
            self.current_index_offset = 0;
            self.current_morph_displacement_offset = 0;

            self.add_mesh(device, queue, "Cube", create_cube_mesh());
            self.add_mesh(device, queue, "Sphere", create_sphere_mesh(1.0, 16));
            self.add_mesh(device, queue, "Sphere_LOD1", create_sphere_mesh(1.0, 8));
            self.add_mesh(device, queue, "Sphere_LOD2", create_sphere_mesh(1.0, 4));
            self.add_mesh(device, queue, "Plane", create_plane_mesh(2.0));
            self.add_mesh(
                device,
                queue,
                "SubdividedPlane",
                create_subdivided_plane_mesh(2.0, 20),
            );
            self.add_mesh(
                device,
                queue,
                "Cylinder",
                create_cylinder_mesh(0.5, 1.0, 16),
            );
            self.add_mesh(device, queue, "Cone", create_cone_mesh(0.5, 1.0, 16));
            self.add_mesh(device, queue, "Torus", create_torus_mesh(1.0, 0.3, 16, 16));

            for (name, mesh) in mesh_cache_iter(mesh_cache) {
                if !self.meshes.contains_key(name) {
                    self.add_mesh(device, queue, name, mesh.clone());
                }
            }

            let new_vertex_size = (actual_vertex_bytes as f32 * BUFFER_GROWTH_FACTOR).ceil() as u64;
            let new_index_size = (actual_index_bytes as f32 * BUFFER_GROWTH_FACTOR).ceil() as u64;

            if new_vertex_size < self.vertex_buffer_size {
                let new_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                    label: Some("Mesh Vertex Buffer (Compacted)"),
                    size: new_vertex_size,
                    usage: wgpu::BufferUsages::VERTEX
                        | wgpu::BufferUsages::COPY_DST
                        | wgpu::BufferUsages::COPY_SRC,
                    mapped_at_creation: false,
                });

                let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
                    label: Some("Mesh Vertex Buffer Compaction"),
                });

                encoder.copy_buffer_to_buffer(
                    &self.vertex_buffer,
                    0,
                    &new_buffer,
                    0,
                    actual_vertex_bytes,
                );

                queue.submit(std::iter::once(encoder.finish()));
                self.vertex_buffer = new_buffer;
                self.vertex_buffer_size = new_vertex_size;
            }

            if new_index_size < self.index_buffer_size {
                let new_buffer = device.create_buffer(&wgpu::BufferDescriptor {
                    label: Some("Mesh Index Buffer (Compacted)"),
                    size: new_index_size,
                    usage: wgpu::BufferUsages::INDEX
                        | wgpu::BufferUsages::COPY_DST
                        | wgpu::BufferUsages::COPY_SRC,
                    mapped_at_creation: false,
                });

                let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
                    label: Some("Mesh Index Buffer Compaction"),
                });

                encoder.copy_buffer_to_buffer(
                    &self.index_buffer,
                    0,
                    &new_buffer,
                    0,
                    actual_index_bytes,
                );

                queue.submit(std::iter::once(encoder.finish()));
                self.index_buffer = new_buffer;
                self.index_buffer_size = new_index_size;
            }
        }
    }
}