Camera and model controls

Camera control

auto viewer = guik::LightViewer::instance();

// Use a camera control that moves along with the XY-plane
viewer->use_orbit_camera_control();

// Use a camera control that moves along with the XZ-plane
viewer->use_orbit_camera_control_xz();

// Use a top-down camera control facing to the XY-plane
viewer->use_topdown_camera_control();

// Use an arcball-like camera control that can make an arbitrary pose
viewer->use_arcball_camera_control();

// Use an FPS-like camera control with keyboard (WASD) control
viewer->use_fps_camera_control();

A useful method to let the camera keep focusing on a moving object is lookat() that moves the camera such that the specified position comes to the center of the camera view.

Eigen::Vector3f center_pos = ...;
viewer->lookat(center_pos);

lookat example (0:13 ~)

Keyboard control

Key	Description
Ctrl + Arrow	Move camera
Ctrl + Page UP / Down	Zoom in/out
Ctrl + Home / End	Increase / decrease moving speed (permanently)
Shift	Increase moving speed (while holding)

FPS-camera control

Key	Description
W / A / S / D	Forward / Left / Backward / Right
R / F	Up / Down
E / Q	Heading (Yaw rotation)

Mouse	Description
Hold left button	Yaw / Pitch rotation
Hold right button	Up / Down
Hold scroll button	Forward / Backward / Left/ Right
Scroll	Change FOV

Implementing custom camera control

In case you want to directly control the camera properties, use StaticCameraControl and StaticProjectionControl. This combination enables, for example, AR-like visualization through direct manipulation of camera pose and projection.

Eigen::Isometry3f T_world_camera = ...;   // Camera pose (X = right, Y = down, Z = forward)
auto static_camera = std::make_shared<guik::StaticCameraControl>(T_world_camera);
viewer->set_camera_control(static_camera);

Eigen::Vector2i canvas_size = viewer->canvas_size();
Eigen::Matrix3f camera_matrix = ...;  // OpenCV camera intrinsic matrix [[fx, 0, cx], [0, fy, cy], [0, 0, 1]]
auto static_projection = std::make_shared<guik::StaticProjectionControl>(canvas_size, camera_matrix);
viewer->set_projection_control(static_projection);

Model matrix control (ImGuizmo)

#include <guik/model_control.hpp>

Eigen::Matrix4f init_model_matrix = Eigen::Matrix4f::Identity();
guik::ModelControl model_control("model_control", init_model_matrix);

viewer->register_ui_callback("model_control_ui", [&]{
  model_control.draw_gizmo_ui();
  model_control.draw_gizmo();

  Eigen::Matrix4f model_matrix = model_control.model_matrix();
  viewer->update_drawable("cube", glk::Primitives::cube(), guik::Rainbow(model_matrix));
});

Note: ImGuizmo cannot be shown twice or more in one rendering frame.

Guizmo can be drawn on subviewers.

auto sub = viewer->sub_viewer("sub");

auto model_control = std::make_shared<guik::ModelControl>("model_control");
sub->register_ui_callback("model_control", [=] {
  const ImVec2 canvas_rect_min = ImGui::GetItemRectMin();
  const ImVec2 canvas_rect_max = ImGui::GetItemRectMax();
  const int win_x = canvas_rect_min.x;
  const int win_y = canvas_rect_min.y;
  const int win_w = canvas_rect_max.x - canvas_rect_min.x;
  const int win_h = canvas_rect_max.y - canvas_rect_min.y;

  const Eigen::Matrix4f view_matrix = sub->get_camera_control()->view_matrix();
  const Eigen::Matrix4f projection_matrix = sub->get_projection_control()->projection_matrix();

  model_control->draw_gizmo(win_x, win_y, win_w, win_h, view_matrix, projection_matrix, true);

  sub->update_coord("coord", guik::VertexColor(model_control->model_matrix()));
});