Implement Q3DO export.

We plan to use flatbuffers in the future for the next generation of
the .slvs file format, so flatbuffers are built unconditionally; and
the Q3DO exporter itself is tiny.

.gitmodules

@@ -20,3 +20,9 @@
 [submodule "extlib/angle"]
 	path = extlib/angle
 	url = https://github.com/solvespace/angle
+[submodule "extlib/flatbuffers"]
+	path = extlib/flatbuffers
+	url = https://github.com/google/flatbuffers
+[submodule "extlib/q3d"]
+	path = extlib/q3d
+	url = https://github.com/q3k/q3d

CHANGELOG.md

@@ -42,6 +42,10 @@ New export/import features:
   * Wavefront OBJ: a material file is exported alongside the model, containing
     mesh color information.
   * DXF/DWG: 3D DXF files are imported as construction entities, in 3d.
+  * Q3D: [Q3D](https://github.com/q3k/q3d/) triangle meshes can now be
+    exported. This format allows to easily hack on triangle mesh data created
+    in SolveSpace, supports colour information and is more space efficient than
+    most other formats.
 
 New rendering features:
   * The "Show/hide hidden lines" button is now a tri-state button that allows

CMakeLists.txt

@@ -103,6 +103,17 @@ endif()
 message(STATUS "Using in-tree libdxfrw")
 add_subdirectory(extlib/libdxfrw)
 
+message(STATUS "Using in-tree flatbuffers")
+set(FLATBUFFERS_BUILD_FLATLIB ON CACHE BOOL "")
+set(FLATBUFFERS_BUILD_FLATC ON CACHE BOOL "")
+set(FLATBUFFERS_BUILD_FLATHASH OFF CACHE BOOL "")
+set(FLATBUFFERS_BUILD_TESTS OFF CACHE BOOL "")
+add_subdirectory(extlib/flatbuffers EXCLUDE_FROM_ALL)
+
+message(STATUS "Using in-tree q3d")
+add_subdirectory(extlib/q3d)
+set(Q3D_INCLUDE_DIR ${CMAKE_BINARY_DIR}/extlib/q3d)
+
 if(WIN32 OR APPLE)
     # On Win32 and macOS we use vendored packages, since there is little to no benefit
     # to trying to find system versions. In particular, trying to link to libraries from

extlib/flatbuffers

@@ -0,0 +1 @@
+Subproject commit a1f14005ab823adc1300754fd37c01e9842ed4bc

extlib/q3d

@@ -0,0 +1 @@
+Subproject commit fe71514837af1c627e9e1054d1aa0193a06d3488

src/CMakeLists.txt

@@ -79,7 +79,8 @@ include_directories(
     ${ZLIB_INCLUDE_DIR}
     ${PNG_PNG_INCLUDE_DIR}
     ${FREETYPE_INCLUDE_DIRS}
-    ${CAIRO_INCLUDE_DIRS})
+    ${CAIRO_INCLUDE_DIRS}
+    ${Q3D_INCLUDE_DIR})
 
 if(Backtrace_FOUND)
     include_directories(
@@ -211,12 +212,16 @@ add_library(solvespace-core STATIC
     ${solvespace_core_HEADERS}
     ${solvespace_core_SOURCES})
 
+add_dependencies(solvespace-core
+    q3d_header)
+
 target_link_libraries(solvespace-core
     dxfrw
     ${util_LIBRARIES}
     ${ZLIB_LIBRARY}
     ${PNG_LIBRARY}
-    ${FREETYPE_LIBRARY})
+    ${FREETYPE_LIBRARY}
+    flatbuffers)
 
 if(Backtrace_FOUND)
     target_link_libraries(solvespace-core

src/export.cpp

@@ -7,6 +7,7 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 #include "solvespace.h"
+#include "config.h"
 
 void SolveSpaceUI::ExportSectionTo(const Platform::Path &filename) {
     Vector gn = (SS.GW.projRight).Cross(SS.GW.projUp);
@@ -826,6 +827,8 @@ void SolveSpaceUI::ExportMeshTo(const Platform::Path &filename) {
         ExportMeshAsObjTo(f, fMtl, m);
 
         fclose(fMtl);
+    } else if(filename.HasExtension("q3do")) {
+        ExportMeshAsQ3doTo(f, m);
     } else if(filename.HasExtension("js") ||
               filename.HasExtension("html")) {
         SOutlineList *e = &(SK.GetGroup(SS.GW.activeGroup)->displayOutlines);
@@ -877,6 +880,54 @@ void SolveSpaceUI::ExportMeshAsStlTo(FILE *f, SMesh *sm) {
     }
 }
 
+//-----------------------------------------------------------------------------
+// Export the mesh as a Q3DO (https://github.com/q3k/q3d) file.
+//-----------------------------------------------------------------------------
+
+#include "object_generated.h"
+void SolveSpaceUI::ExportMeshAsQ3doTo(FILE *f, SMesh *sm) {
+    flatbuffers::FlatBufferBuilder builder(1024);
+    double s = SS.exportScale;
+
+    // Create a material for every colour used, keep note of triangles belonging to color/material.
+    std::map<RgbaColor, flatbuffers::Offset<q3d::Material>, RgbaColorCompare> materials;
+    std::map<RgbaColor, std::vector<flatbuffers::Offset<q3d::Triangle>>, RgbaColorCompare> materialTriangles;
+    for (const STriangle &t : sm->l) {
+        auto color = t.meta.color;
+        if (materials.find(color) == materials.end()) {
+            auto name = builder.CreateString(ssprintf("Color #%02x%02x%02x%02x", color.red, color.green, color.blue, color.alpha));
+            auto co = q3d::CreateColor(builder, color.red, color.green, color.blue, color.alpha);
+            auto mo = q3d::CreateMaterial(builder, name, co);
+            materials.emplace(color, mo);
+        }
+
+        Vector faceNormal = t.Normal();
+        auto a = q3d::Vector3(t.a.x/s, t.a.y/s, t.a.z/s);
+        auto b = q3d::Vector3(t.b.x/s, t.b.y/s, t.b.z/s);
+        auto c = q3d::Vector3(t.c.x/s, t.c.y/s, t.c.z/s);
+        auto fn = q3d::Vector3(faceNormal.x, faceNormal.y, faceNormal.x);
+        auto n1 = q3d::Vector3(t.normals[0].x, t.normals[0].y, t.normals[0].z);
+        auto n2 = q3d::Vector3(t.normals[1].x, t.normals[1].y, t.normals[1].z);
+        auto n3 = q3d::Vector3(t.normals[2].x, t.normals[2].y, t.normals[2].z);
+        auto tri = q3d::CreateTriangle(builder, &a, &b, &c, &fn, &n1, &n2, &n3);
+        materialTriangles[color].push_back(tri);
+    }
+
+    // Build all meshes sorted by material.
+    std::vector<flatbuffers::Offset<q3d::Mesh>> meshes;
+    for (auto &it : materials) {
+        auto &mato = it.second;
+        auto to = builder.CreateVector(materialTriangles[it.first]);
+        auto mo = q3d::CreateMesh(builder, to, mato);
+        meshes.push_back(mo);
+    }
+
+    auto mo = builder.CreateVector(meshes);
+    auto o = q3d::CreateObject(builder, mo);
+    q3d::FinishObjectBuffer(builder, o);
+    fwrite(builder.GetBufferPointer(), builder.GetSize(), 1, f);
+}
+
 //-----------------------------------------------------------------------------
 // Export the mesh as Wavefront OBJ format. This requires us to reduce all the
 // identical vertices to the same identifier, so do that first.

src/platform/gui.cpp

@@ -94,6 +94,7 @@ std::vector<FileFilter> MeshFileFilters = {
     { CN_("file-type", "Wavefront OBJ mesh"), { "obj" } },
     { CN_("file-type", "Three.js-compatible mesh, with viewer"), { "html" } },
     { CN_("file-type", "Three.js-compatible mesh, mesh only"), { "js" } },
+    { CN_("file-type", "Q3D Object file"), { "q3do" } },
 };
 
 std::vector<FileFilter> SurfaceFileFilters = {

src/solvespace.h

@@ -693,6 +693,7 @@ public:
     void ExportAsPngTo(const Platform::Path &filename);
     void ExportMeshTo(const Platform::Path &filename);
     void ExportMeshAsStlTo(FILE *f, SMesh *sm);
+    void ExportMeshAsQ3doTo(FILE *f, SMesh *sm);
     void ExportMeshAsObjTo(FILE *fObj, FILE *fMtl, SMesh *sm);
     void ExportMeshAsThreeJsTo(FILE *f, const Platform::Path &filename,
                                SMesh *sm, SOutlineList *sol);