Add logging of Eigen matrix

Author: roym899

.gitignore

@@ -3,6 +3,7 @@ build/
 
 # LSP files
 compile_commands.json
+.cache
 
 # Prerequisites
 *.d

src/main.cpp

@@ -25,15 +25,46 @@ struct rerun::ComponentBatchAdapter<rerun::components::Position3D, std::vector<E
     }
 };
 
+template <>
+struct rerun::ComponentBatchAdapter<rerun::components::Position3D, Eigen::MatrixX3f> {
+    // Sanity check that this is binary compatible.
+    /* static_assert(sizeof(components::Position3D) == sizeof(Eigen::Vector3f));  ?? */
+    /* static_assert(alignof(components::Position3D) <= alignof(Eigen::Vector3f)); */
+
+    ComponentBatch<components::Position3D> operator()(const Eigen::MatrixX3f &matrix
+    ) {
+        return ComponentBatch<components::Position3D>::borrow(
+            reinterpret_cast<const components::Position3D *>(matrix.data()),
+            matrix.rows()
+        );
+    }
+
+    ComponentBatch<components::Position3D> operator()(std::vector<Eigen::MatrixX3f> &&container) {
+        throw std::runtime_error("Not implemented for temporaries");
+    }
+};
+
+std::vector<Eigen::Vector3f> generate_random_points_vector(int num_points) {
+    std::vector<Eigen::Vector3f> points(num_points);
+    for(auto& point : points) {
+        point.setRandom();
+    }
+    return points;
+}
+
 int main() {
-    auto rec = rerun::RecordingStream("rerun_external_cpp_app");
+    auto rec = rerun::RecordingStream("rerun_cpp_example_opencv_eigen");
     rec.connect("127.0.0.1:9876").throw_on_failure();
 
+    const int num_points = 1000;
+
     // Points represented by std::vector<Eigen::Vector3f>
-    std::vector<Eigen::Vector3f> points3d_eigen{{0.1f, 0.1f, 0.1f}};
-    rec.log("random", rerun::Points3D(points3d_eigen));
+    auto points3d_vector = generate_random_points_vector(1000);
+    rec.log("points_from_vector", rerun::Points3D(points3d_vector));
 
-    // Points represented by Nx3 Eigen::Mat...
+    // Points represented by Eigen::MatX3f (Nx3 matrix)
+    Eigen::MatrixX3f points3d_matrix = Eigen::MatrixX3f::Random(num_points, 3);
+    rec.log("points_from_matrix", rerun::Points3D(points3d_matrix));
 
     // Image
     std::string image_path = "rerun-logo.png";