mirror of
https://github.com/IfcOpenShell/IfcOpenShell.git
synced 2026-10-02 21:12:07 +00:00
Dion Moult
6ca38f8bf6
Use IfcMapConversion.Scale as the source of truth for converting map coordinates to metres, instead of deriving that scale from IfcProjectedCRS.MapUnit. Bump the sidecar version because cached georef matrices and unit scales may differ under the new interpretation. Generated with the assistance of an AI coding tool.
124 lines
6.2 KiB
C++
124 lines
6.2 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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// NOTE: Sidecar format v3 is being rewritten to v4 (instanced geometry layout).
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// During the instancing rewrite (Commit A) the cache is a no-op: reads always
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// miss and writes always succeed without producing a file. Commit B will
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// re-introduce the on-disk format with MeshInfo + InstanceGpu sections.
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#ifndef SIDECARCACHE_H
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#define SIDECARCACHE_H
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#include "InstancedGeometry.h"
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#include <cstdint>
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#include <optional>
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#include <string>
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#include <vector>
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#include <memory>
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static constexpr uint32_t SIDECAR_MAGIC = 0x49465657; // "IFVW"
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// v5 = MeshInfo extended with lod1_ebo_byte_offset + lod1_index_count (56 B).
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// sd.indices may contain an appended LOD1 index slice for each mesh
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// where meshoptimizer decimation produced useful output.
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// v6 = VBO vertices quantized to 16 B/vertex (pos u16x3 + normal oct i16x2 +
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// color u8x4). Dequant basis is per-mesh MeshInfo.local_aabb_min/max.
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// v7 = VBO vertices shrunk to 12 B/vertex (normal oct i8x2 replaces i16x2,
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// eliminating 2-byte pad + saving 2 bytes on normal).
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// v8 = source_file_size field dropped from header. Sidecar is keyed purely
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// on path stem (foo.ifc and foo.ifcdb/ both map to foo.ifcview) so the
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// same cache serves either source format. Staleness is user-managed
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// (delete the sidecar to force a rebuild).
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// v9 = unused `reserved` field dropped from header (16 B -> 12 B).
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// v10 = InstanceCpu gains placement_transformation[16] alongside transform[16]
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// — record grew from 104 B to 168 B. placement_transformation is the
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// raw streamer output; transform is the composed FederatedFalseOrigin ·
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// ModelTransformation · CoordinateOperation · placement_transformation
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// result. Sidecar serialises both; on load the transform is recomputed
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// from placement_transformation + the ViewportWindow's current stage
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// matrices, so v10 sidecars are reusable across .ifcfeds.
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// v11 = SidecarData gains a per-model CoordinateOperation cache:
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// coordinate_operation_meters[16] (column-major), unit scales, and a
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// has_coordinate_operation flag. Lets sidecar-loaded models apply
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// georef without re-parsing the IFC source. Edits to the IFC's
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// IfcMapConversion do NOT invalidate the sidecar — delete the
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// .ifcview manually if you change the source's georef parameters.
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// v12 = InstanceCpu::placement_transformation is double[16], and
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// InstanceChunk carries the streamer placement as double[16]. This keeps
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// large IFC placements exact until CoordinateOperation / FederatedFalseOrigin
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// composition has reduced them to viewport-local float-sized values.
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// v13 = Map unit scale in cached ModelGeoref is derived from
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// IfcMapConversion.Scale, not IfcProjectedCRS.MapUnit.
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static constexpr uint32_t SIDECAR_VERSION = 13;
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static constexpr uint32_t SIDECAR_ENDIAN = 0x01020304;
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// Fixed-size element record. Strings are stored as (offset, length) pairs
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// into a separate string table.
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struct PackedElementInfo {
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uint32_t object_id;
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uint32_t model_id;
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int32_t ifc_id;
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int32_t parent_id;
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uint32_t guid_offset;
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uint32_t guid_length;
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uint32_t name_offset;
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uint32_t name_length;
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uint32_t type_offset;
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uint32_t type_length;
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};
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// Everything needed to display an already-tessellated model without
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// re-running the iterator. v6 schema: instanced + quantized geometry.
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struct SidecarData {
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// Per-model GPU geometry (local coords). Raw VBO bytes at the
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// INSTANCED_VERTEX_STRIDE_BYTES layout (12 B/vertex as of v7).
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std::vector<uint8_t> vertices;
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std::vector<uint32_t> indices;
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// Mesh dictionary and per-instance data.
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std::vector<MeshInfo> meshes; // indexed by local_mesh_id
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std::vector<InstanceCpu> instances; // sorted by mesh_id
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// CoordinateOperation cache (v11+). Mirrors ModelGeoref so a sidecar
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// load can apply georef without re-parsing the IFC source.
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// has_coordinate_operation == 0 means the model has no
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// IfcMapConversion; the matrix is then the identity placeholder.
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double coordinate_operation_meters[16] = {
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1, 0, 0, 0,
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0, 1, 0, 0,
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0, 0, 1, 0,
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0, 0, 0, 1 };
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double project_length_to_meters = 1.0;
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double map_unit_to_meters = 1.0;
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uint32_t has_coordinate_operation = 0;
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// Element tree metadata.
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std::vector<PackedElementInfo> elements;
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std::string string_table;
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};
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// Sidecar is keyed on the path stem: foo.ifc and foo.ifcdb/ both resolve to
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// foo.ifcview alongside the source. No staleness check — callers delete the
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// file to invalidate.
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bool writeSidecar(const std::string& ifc_path, const SidecarData& data);
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std::optional<SidecarData> readSidecar(const std::string& ifc_path);
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#endif // SIDECARCACHE_H
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