Add read support for Google's Draco (.drc) format.

src/libslic3r/Format/DRC.cpp

@@ -0,0 +1,126 @@
+#include <string>
+#include <utility>
+#include <cstring>
+
+#include <draco/compression/decode.h>
+#include <draco/io/mesh_io.h>
+#include <draco/mesh/mesh.h>
+using namespace draco;
+
+#include "libslic3r/Model.hpp"
+#include "libslic3r/TriangleMesh.hpp"
+#include "DRC.hpp"
+
+#ifdef _WIN32
+#define DIR_SEPARATOR '\\'
+#else
+#define DIR_SEPARATOR '/'
+#endif
+
+namespace Slic3r {
+
+bool load_drc(const char *path, TriangleMesh *meshptr)
+{
+    struct stat st;
+    if (stat(path, &st)) {
+        return false;
+    }
+
+    FILE *fp = fopen(path, "rb");
+    if (fp == nullptr) {
+        return false;
+    }
+
+    char *data = new char[st.st_size];
+    if (fread(data, 1, st.st_size, fp) != st.st_size) {
+        fclose(fp);
+        delete[] data;
+        return false;
+    }
+    fclose(fp);
+    
+    DecoderBuffer buffer;
+    buffer.Init(data, st.st_size);
+
+    auto geotype = Decoder::GetEncodedGeometryType(&buffer);
+    if ((!geotype.ok()) || geotype.value() != TRIANGULAR_MESH) {
+        delete[] data;
+        return false;
+    }
+    
+    Decoder decoder;
+    Mesh dracoMesh;
+    Status status = decoder.DecodeBufferToGeometry(&buffer, &dracoMesh);
+    delete[] data;
+    if (!status.ok()) {
+        return false;
+    }
+    
+    indexed_triangle_set its;
+    
+    const PointAttribute *const positions = dracoMesh.GetNamedAttribute(GeometryAttribute::POSITION);    
+    size_t num_vertices = positions->size();
+    its.vertices.reserve(num_vertices);
+    for (AttributeValueIndex i(0); i < num_vertices; ++ i) {
+        float pos[3];
+        positions->ConvertValue<float>(i, 3, pos);
+        its.vertices.emplace_back(pos[0], pos[1], pos[2]);
+    }
+    
+    size_t num_faces = dracoMesh.num_faces();
+    its.indices.reserve(num_faces);
+    for (FaceIndex i(0); i < num_faces; ++ i) {
+        Mesh::Face face = dracoMesh.face(i);
+        
+        its.indices.emplace_back(
+            positions->mapped_index(face[0]).value(),
+            positions->mapped_index(face[1]).value(),
+            positions->mapped_index(face[2]).value()
+        );
+    }
+
+    *meshptr = TriangleMesh(std::move(its));
+    if (meshptr->volume() < 0)
+        meshptr->flip_triangles();
+    return true;
+}
+
+bool load_drc(const char *path, Model *model, const char *object_name_in)
+{
+    TriangleMesh mesh;
+    
+    bool ret = load_drc(path, &mesh);
+    
+    if (ret) {
+        std::string  object_name;
+        if (object_name_in == nullptr) {
+            const char *last_slash = strrchr(path, DIR_SEPARATOR);
+            object_name.assign((last_slash == nullptr) ? path : last_slash + 1);
+        } else
+           object_name.assign(object_name_in);
+    
+        model->add_object(object_name.c_str(), path, std::move(mesh));
+    }
+    
+    return ret;
+}
+
+bool store_drc(const char *path, TriangleMesh *mesh, bool binary)
+{
+    // TODO
+    return false;
+}
+
+bool store_drc(const char *path, ModelObject *model_object, bool binary)
+{
+    TriangleMesh mesh = model_object->mesh();
+    return store_drc(path, &mesh, binary);
+}
+
+bool store_drc(const char *path, Model *model, bool binary)
+{
+    TriangleMesh mesh = model->mesh();
+    return store_drc(path, &mesh, binary);
+}
+
+}; // namespace Slic3r