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https://github.com/IfcOpenShell/IfcOpenShell.git
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Dion Moult
1f8f6bffc4
Preparatory refactor for spatial instance bucketing (#55). Cull previously routed through per-mesh tables (mesh_chunk_idx, mesh_chunk_local_base_vertex, _ebo_first_u32, _lod1_first_u32) to find the chunk and chunk-local offsets for each instance. That assumes a mesh lives in EXACTLY ONE chunk — the assumption holds under the current mesh-keyed planner but breaks under spatial bucketing, where the same mesh can be duplicated across multiple buckets if its instances are scattered. Adds four per-instance arrays (instance_chunk_idx, instance_base_vertex, instance_ebo_first_u32, instance_lod1_first_u32) populated at planning time. The current mesh-keyed planner derives them by translation: instance_chunk_idx[i] = mesh_chunk_idx[instances[i].mesh_id] The spatial-bucket planner (next commit) will populate them directly, allowing the same mesh_id to map to different chunks for different instances. cullModelCpuCompute now reads the per-instance arrays: - frustum_visible_count uses chunks[instance_chunk_idx[i]] - VisibleDrawGpu uses instance_base_vertex / instance_ebo_first_u32 / instance_lod1_first_u32 - LOD-select branch and use_lod1 logic unchanged. Per-mesh tables stay (used by makeChunkRequest, debug logs, the planner itself). Memory cost: 16 bytes × N instances ≈ 16 MB on a 1M-instance scene. Pixel-identical on basic.ifc in both non-streaming and streaming modes. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
290 lines
16 KiB
C++
290 lines
16 KiB
C++
/********************************************************************************
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* *
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* This file is part of IfcOpenShell. *
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* *
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* IfcOpenShell is free software: you can redistribute it and/or modify *
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* it under the terms of the Lesser GNU General Public License as published by *
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* the Free Software Foundation, either version 3.0 of the License, or *
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* (at your option) any later version. *
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* *
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* IfcOpenShell is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* Lesser GNU General Public License for more details. *
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* *
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* You should have received a copy of the Lesser GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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* *
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********************************************************************************/
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#ifndef WGPUMODELGPUDATA_H
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#define WGPUMODELGPUDATA_H
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#include <webgpu/webgpu.h>
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#include <cstddef>
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#include <cstdint>
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#include <limits>
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#include <string>
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#include <vector>
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#include "InstancedGeometry.h"
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#include "WgpuBufferPool.h"
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// Per-model wgpu state. Mirrors the GL backend's ModelGpuData but with
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// wgpu handles. Stage 2 only allocates and uploads the four core buffers;
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// bind groups, pipelines, BVH and cull scratch land in later stages.
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//
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// All vertex/index/mesh/instance bytes are uploaded once at load time via
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// wgpuQueueWriteBuffer. The vertex storage buffer is read by the vertex
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// shader (vertex pulling), not used as a classic vertex buffer — there is
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// no input-assembler vertex layout to match.
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// Web (WebGPU) mandates `maxStorageBufferBindingSize` ≥ 128 MB; some browsers
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// grant more, but we plan for the floor. Applied identically on desktop —
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// the cost is a few extra draws per frame (1 per chunk; typical models =
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// 1–3 chunks), which is invisible compared to per-frame GPU work.
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//
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// At INSTANCED_VERTEX_STRIDE_BYTES = 12 B/vertex this caps a chunk at
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// ~1.4 M vertices. 16 MB is the sweet spot once background-thread I/O
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// (WgpuStreamingThread) is in place: scatter-gather per-mesh seeks
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// happen on the worker, not the render thread, so smaller chunks
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// (and thus more per-frame loads as orbit shifts) no longer stall
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// rendering. The win is much finer pool-allocation granularity —
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// a 3 GB pool fits ~190 chunks vs ~21 at 128 MB — so visible
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// geometry is far less likely to get "trapped" behind invisible
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// chunkmates. Pre-async this size gave 7 fps (the sync loads blocked
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// the render thread); now it's bounded by cull cost not stream cost.
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//
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// Sidecar v14 (on-disk spatial reorder) would let us go smaller still
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// (~4 MB) with single-fread chunk loads, but the difference between
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// 16 MB and 4 MB is much smaller than the difference between 128 MB
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// and 16 MB.
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static constexpr uint64_t WGPU_CHUNK_VERTEX_BYTES_LIMIT = 16ull * 1024 * 1024;
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struct WgpuModelGpuData {
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// std430 layout: 16 bytes per entry, naturally aligned. base_vertex is
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// CHUNK-LOCAL — the bound vertex_storage on that chunk's bind group
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// gives the right slice when the shader indexes vertices[].
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struct alignas(16) VisibleDrawGpu {
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uint32_t mesh_id; // -> meshes[] for quantisation basis
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uint32_t instance_idx; // -> instances[] for transform + ids
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uint32_t ebo_first_u32; // start of this entry's slice in indices[] (global)
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uint32_t base_vertex; // chunk-local start of this mesh's slice in vertex_storage
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};
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static_assert(sizeof(VisibleDrawGpu) == 16, "VisibleDrawGpu must be 16 bytes");
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// Per-chunk state. Each chunk references a vertex range and an
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// index range inside WgpuViewportWindow::pool_, plus a small set of
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// per-frame buffers (visible_draws, prefix_sums, uniform) and a bind
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// group that binds the pool ranges alongside the model-shared
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// mesh/instance storage. Rendering issues one drawcall per non-empty
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// chunk.
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//
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// Streaming (task #16): a chunk may be marked is_resident=false; its
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// pool ranges (pool_*_size == 0) and bind_group are then unclaimed
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// until the streaming loader brings it in. Other per-chunk buffers
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// (visible_draws etc.) stay allocated regardless because cull still
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// needs them. Non-streaming path always sets is_resident=true and
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// populates pool ranges at applyCachedModel time.
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struct Chunk {
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// Pool-allocated vertex + index bytes. Both slices land in the
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// shared WgpuViewportWindow::pool_; the slice tells us which
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// sub-buffer they live in (the pool may span multiple sub-buffers
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// when scenes exceed wgpu's single-buffer cap). When non-resident,
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// both .size are 0.
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WgpuBufferPool::Slice vertex_slice;
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WgpuBufferPool::Slice index_slice;
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WGPUBuffer visible_draws_buffer = nullptr;
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WGPUBuffer prefix_sums_buffer = nullptr;
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WGPUBuffer per_chunk_uniform = nullptr;
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WGPUBindGroup bind_group = nullptr;
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uint32_t vertex_count = 0; // chunk capacity (vertices)
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size_t visible_draws_capacity = 0;
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size_t prefix_sums_capacity = 0;
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// Per-frame, populated by cullModelCpuCompute and consumed by render().
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// total_visible_* are post-frustum + contribution + HiZ — used to size
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// the actual draw call. frustum_visible_count is bumped immediately
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// after the frustum check (before contribution / HiZ), and is what
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// driveStreamingLoads keys on for residency decisions. Streaming
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// must NOT use the HiZ-post counters: HiZ visibility flips
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// frame-to-frame as occluders shift, which would otherwise thrash
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// the loader (evict-then-reload every frame even with the camera
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// stationary, killing FPS and producing visible flicker).
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uint32_t total_visible_vertices = 0;
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uint32_t total_visible_draws = 0;
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uint32_t frustum_visible_count = 0;
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std::vector<VisibleDrawGpu> visible_draws_scratch;
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std::vector<uint32_t> prefix_sums_scratch;
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// Residency. Streaming sets is_resident=false at applyCachedModel
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// and flips true once the chunk's vertex bytes are uploaded.
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// Render and pick skip chunks where !is_resident.
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bool is_resident = true;
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// Set true while a worker-thread read is in flight for this
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// chunk. Prevents driveStreamingLoads from re-enqueueing it
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// every frame until its result is drained. Cleared when the
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// result is applied (or dropped on failure / stale model).
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// Eviction is not gated on this (eviction only acts on resident
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// chunks; a loading chunk has no slice to free yet).
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bool is_loading = false;
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// Aggregate vertex / index sizes across all meshes in this chunk
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// (sum of mesh.vertex_count * stride / mesh.index_count for each
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// mesh in mesh_ids). Used to size the pool allocation and to
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// compute the cull's per-chunk free-room check. Per-mesh layout
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// is recovered by walking mesh_ids and the model's MeshInfo[].
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uint64_t vertex_byte_size = 0;
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uint64_t index_count = 0;
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// Of `index_count`, how many are LOD1 indices. LOD0 indices occupy
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// chunk-local u32 offsets [0, index_count - lod1_index_count); LOD1
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// indices occupy [index_count - lod1_index_count, index_count). 0
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// when no mesh in this chunk had a baked LOD1 slice.
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uint32_t lod1_index_count = 0;
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// World-space AABB covering every instance whose mesh lives in
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// this chunk. With spatial chunk planning this AABB is tight
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// (chunks group meshes by world centroid, not mesh-id), so the
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// distance-based evictor can meaningfully tell chunks apart.
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// Used by cull to reject whole chunks against the frustum before
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// iterating instances — and by the streaming loader to
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// prioritise which non-resident chunks to fetch first.
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float aabb_min[3] = { std::numeric_limits<float>::infinity(),
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std::numeric_limits<float>::infinity(),
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std::numeric_limits<float>::infinity() };
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float aabb_max[3] = { -std::numeric_limits<float>::infinity(),
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-std::numeric_limits<float>::infinity(),
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-std::numeric_limits<float>::infinity() };
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// Mesh IDs assigned to this chunk, in chunk-local layout order.
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// Spatial chunk planning sorts meshes by world centroid first,
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// so this list is not in mesh-id order in general — each mesh's
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// bytes live at scattered offsets in the sidecar file. The
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// loader walks this list to scatter-gather the chunk's vertex
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// + index bytes; mesh_chunk_local_base_vertex /
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// mesh_chunk_local_ebo_first_u32 are computed in this same
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// order at planning time so the cull's VisibleDrawGpu entries
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// point at the correct chunk-local offsets.
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std::vector<uint32_t> mesh_ids;
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// Instance indices belonging to this chunk (i.e. whose mesh lives
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// in this chunk). Built at chunk-planning time. Lets cull iterate
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// chunks as the outer loop, frustum-test the chunk AABB once,
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// and skip every instance inside in one shot when the chunk is
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// off-screen — far cheaper than the per-instance frustum check
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// on flat-scan culls of 1M+ instance scenes.
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std::vector<uint32_t> instance_ids;
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// LRU marker for streaming eviction. Updated to the window's
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// streaming_frame_idx_ every frame the chunk is rendered (i.e.
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// total_visible_draws > 0). The evictor picks the smallest value
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// among non-visible resident chunks when it needs to free VRAM.
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uint64_t last_visible_frame_idx = 0;
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// EMA-smoothed visibility score, in [0, 1]. Bumped each frame
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// toward 1 when total_visible_draws > 0 (the chunk's instances
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// passed frustum + contribution + HiZ), toward 0 otherwise.
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// Time constant ~30 frames. Used by the streaming evictor to
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// de-prioritise chunks that are technically in the frustum but
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// consistently HiZ-occluded — e.g. interior pipes behind a
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// building's exterior walls. The smoothing prevents thrash from
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// momentary HiZ flicker (a wall briefly visible behind a panning
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// window doesn't displace the window from the pool).
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float visibility_history = 0.0f;
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// streaming_frame_idx_ when this chunk was last loaded. The
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// evictor grants newly-loaded chunks ~30 frames of grace at
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// full priority (max history factor = 1.0) so they have time
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// for visibility_history to develop. Without this, a just-
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// loaded chunk's effective priority drops to contribution ×
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// 0.05 next frame, and the chunk it displaced — back as a
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// candidate at full priority — re-displaces it: infinite
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// cycle between equal-priority chunks. The cycle prevents any
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// lower-priority candidate (e.g. a structural-brace chunk
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// ranked position 20 in the missing list) from ever getting
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// attempted.
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uint64_t loaded_frame_idx = 0;
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// How many times this chunk has been (re-)loaded over the
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// session. Bumped each successful applyStreamedChunk. A chunk
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// with load_count >> 1 has been cycling — used by the stream
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// debug log (WGPU_STREAM_DEBUG=1) to surface thrash.
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uint32_t load_count = 0;
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};
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std::vector<Chunk> chunks;
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// Streaming source. Non-empty path means this model was loaded via the
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// streaming path: chunks may be non-resident and need byte-range reads
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// from this file. Empty path = legacy non-streaming load.
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std::string streaming_file_path;
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uint64_t streaming_vertex_section_offset = 0;
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uint64_t streaming_index_section_offset = 0;
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// For each mesh in meshes[], the chunk it lives in plus the chunk-local
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// offsets into that chunk's vertex_storage and index_buffer. Populated
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// at applyCachedModel time; consumed by cullModelCpuCompute when it
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// populates VisibleDrawGpu entries.
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std::vector<uint32_t> mesh_chunk_idx;
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std::vector<uint32_t> mesh_chunk_local_base_vertex;
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std::vector<uint32_t> mesh_chunk_local_ebo_first_u32;
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// Where in the chunk's index slice this mesh's LOD1 indices start
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// (in u32 units). Only meaningful when m.meshes[mi].lod1_index_count > 0;
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// entries for meshes without LOD1 are 0 and unused.
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std::vector<uint32_t> mesh_chunk_local_lod1_first_u32;
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// Per-INSTANCE chunk lookup tables. Mirror the per-mesh arrays above,
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// but resolved at planning time so cull can read them directly without
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// routing through mesh_id. The split exists because the spatial-
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// bucketing planner (#55) can place the same mesh in multiple chunks
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// (mesh data duplicated when its instances live in different buckets)
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// — under that scheme `mesh_chunk_idx[mesh_id]` is ambiguous, but
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// `instance_chunk_idx[instance_id]` is always exactly one chunk.
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// The mesh-keyed planner populates these by translation
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// (instance_chunk_idx[i] = mesh_chunk_idx[instances[i].mesh_id]);
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// the spatial-bucket planner populates them directly.
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std::vector<uint32_t> instance_chunk_idx;
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std::vector<uint32_t> instance_base_vertex;
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std::vector<uint32_t> instance_ebo_first_u32;
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std::vector<uint32_t> instance_lod1_first_u32;
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// Model-shared buffers. Mesh + instance storage are small (<10 MB on
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// any real scene we've seen); the chunked index buffer lives in Chunk
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// alongside vertex_storage so streaming can defer both together.
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WGPUBuffer mesh_storage = nullptr; // MeshGpu[]: aabb_min/max
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WGPUBuffer instance_storage = nullptr; // InstanceGpu[]: transform + ids
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// Cumulative VRAM accounting (bytes), populated at applyCachedModel
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// time. Sum of vertex_storage across chunks + index_buffer + mesh_storage
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// + instance_storage + per-chunk visible_draws + prefix_sums + uniforms.
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// Used by the per-frame stats log to attribute total VRAM.
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uint64_t vram_bytes_vbo = 0; // vertex storage total
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uint64_t vram_bytes_ebo = 0; // index buffer
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uint64_t vram_bytes_ssbo = 0; // mesh + instance + per-chunk small buffers
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// Size mirrors for stats / range checks. vertex_bytes is the sum across
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// all chunks; index_count / mesh_count / instance_count are unchanged.
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size_t vertex_bytes = 0;
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uint32_t index_count = 0;
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uint32_t mesh_count = 0;
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uint32_t instance_count = 0;
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// CPU side, kept for cull / picking / federation recompose.
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std::vector<MeshInfo> meshes;
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std::vector<InstanceCpu> instances;
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// Spatial chunk-cull replaced the per-model BVH walk — chunks are
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// already a one-level spatial partition of the instances, so a
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// single frustum test per chunk gives the same wholesale-reject
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// win without the BVH's per-node traversal overhead. The BVH field
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// is gone; cull iterates m.chunks instead.
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bool hidden = false;
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};
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// Release every wgpu handle in `m` (including per-chunk and per-model pool
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// ranges via `pool.free()`) and clear its size mirrors. Safe to call
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// repeatedly; idempotent on already-released entries.
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void releaseWgpuModelGpuData(WgpuModelGpuData& m, WgpuBufferPool& pool);
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#endif // WGPUMODELGPUDATA_H
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