Visualization

GLFW window management and the real-time render/tick loop. More...

Classes
struct	mj_kdl::Viewer

Functions
bool	mj_kdl::init_window (Viewer *v, Robot *r, const char *title="MuJoCo", int width=1280, int height=720)
bool	mj_kdl::init_window_sim (Viewer *v, Robot *r, const char *title="MuJoCo")
bool	mj_kdl::init_window_sim (Viewer *v, mjModel *m, mjData *d, const char *title="MuJoCo")
void	mj_kdl::clear_trace (Viewer *v)
void	mj_kdl::add_trace_segment (Viewer *v, const KDL::Vector &a, const KDL::Vector &b, const float rgba[4]=nullptr)
void	mj_kdl::cleanup (Viewer *v)
bool	mj_kdl::step (Viewer *v, mjModel *m, mjData *d)
bool	mj_kdl::is_running (const Viewer *v)
bool	mj_kdl::render (Viewer *v, const Robot *r)
bool	mj_kdl::render (Viewer *v, mjModel *m, mjData *d)
bool	mj_kdl::use_camera (Viewer *v, const mjModel *model, const char *name)

Detailed Description

GLFW window management and the real-time render/tick loop.

Use init_window_sim() + step() for the full simulate UI with physics panels. Use init_window() + render() for a lightweight manual render loop.

The simulate UI owns a user scene merged into every frame; draw your own overlay geometry (e.g. a live end-effector trajectory trace) into it with clear_trace() and add_trace_segment(). Both are no-ops in headless mode.

Function Documentation

add_trace_segment()

void mj_kdl::add_trace_segment	(	Viewer *	v,
		const KDL::Vector &	a,
		const KDL::Vector &	b,
		const float	rgba[4] = nullptr )

Append a single line segment to the viewer's user scene. Thread-safe. The render thread merges the user scene into each frame automatically. Silently drops the segment once the user-scene geom buffer is full. No-op when v is not backed by an init_window_sim() window (e.g. headless).

Parameters

[in,out]	v	Viewer initialised by init_window_sim().
[in]	a	Segment start point (world frame) [m].
[in]	b	Segment end point (world frame) [m].
[in]	rgba	Optional [r, g, b, a] colour; nullptr -> warm orange.

Referenced by admittance_ft::run_gui().

cleanup()

void mj_kdl::cleanup

(

Viewer *

v

)

Release the GLFW window and MuJoCo visualization contexts owned by v.

Parameters

[in,out]

v

Viewer to tear down; all pointers set to null afterwards.

clear_trace()

void mj_kdl::clear_trace

(

Viewer *

v

)

Reset the viewer's user-scene geom count to 0. Call once per frame before appending trace segments with add_trace_segment(). No-op when v is not backed by an init_window_sim() window (e.g. headless).

Parameters

[in,out]

v

Viewer initialised by init_window_sim().

init_window()

bool mj_kdl::init_window	(	Viewer *	v,
		Robot *	r,
		const char *	title = "MuJoCo",
		int	width = 1280,
		int	height = 720 )

Open a GLFW window and initialise MuJoCo visualization contexts. Must be called after init_robot() or init_from_mjcf().

Parameters

[out]	v	Viewer to initialise; must be zero-initialised before call.
[in]	r	Robot whose model drives the rendering context.
[in]	title	Window title string.
[in]	width	Window width in pixels.
[in]	height	Window height in pixels.

Returns

true on success, false if GLFW or MuJoCo context creation fails.

init_window_sim() [1/2]

bool mj_kdl::init_window_sim	(	Viewer *	v,
		mjModel *	m,
		mjData *	d,
		const char *	title = "MuJoCo" )

Open the simulate UI for a robot-less model/data pair (e.g. a Scene or Env with no Robot). Physics, camera and pause are handled by the UI directly.

Returns

true on success.

init_window_sim() [2/2]

bool mj_kdl::init_window_sim	(	Viewer *	v,
		Robot *	r,
		const char *	title = "MuJoCo" )

Open the full MuJoCo simulate UI (panels, physics controls, joint viewer) in a background render thread, then return so the caller can drive the physics loop with tick().

Use this instead of init_window() when you want the simulate UI panels alongside a user-owned loop. tick() automatically acquires the render mutex, steps physics, and handles pause / perturbation / speed controls.

Note: the render thread owns the GLFW window; on Linux (X11 / Wayland) this works correctly. Not supported on macOS.

Parameters

[out]	v	Viewer to initialise; freed by cleanup(Viewer *).
[in]	r	Robot to simulate. r is registered globally; pass the same Robot to every subsequent step() call so that keyboard and mouse perturbation callbacks operate on the correct model. Only one (Viewer, Robot) pair may be active at a time.
[in]	title	Label shown in the window title bar (default "MuJoCo").

Returns

true on success.

Referenced by main(), main(), and admittance_ft::run_gui().

is_running()

bool mj_kdl::is_running

(

const Viewer *

v

)

Returns true if the viewer window is open and not scheduled for closing.

Parameters

[in]

v

Viewer created by init_window().

Referenced by admittance_ft::run_gui().

render() [1/2]

bool mj_kdl::render	(	Viewer *	v,
		const Robot *	r )

Render the current simulation frame to the viewer window.

Parameters

[in,out]	v	Viewer created by init_window().
[in]	r	Robot whose model and data are rendered.

Returns

true if the window is still open after rendering.

render() [2/2]

bool mj_kdl::render	(	Viewer *	v,
		mjModel *	m,
		mjData *	d )

Render the current simulation frame to the viewer window. Model/data overload – use when no single Robot owns the scene (e.g. multi-robot).

Parameters

[in,out]	v	Viewer created by init_window().
[in]	m	MuJoCo model.
[in]	d	MuJoCo data.

Returns

true if the window is still open after rendering.

step()

bool mj_kdl::step	(	Viewer *	v,
		mjModel *	m,
		mjData *	d )

Model/data overload of step() for multi-robot or no-robot GUI loops. Equivalent to the former tick(Viewer*, mjModel*, mjData*).

Parameters

[in,out]	v	Viewer initialised by init_window() or init_window_sim().
[in]	m	Shared MuJoCo model.
[in]	d	Shared MuJoCo data.

Returns

true while the window is open; false once the user closes it.

use_camera()

bool mj_kdl::use_camera	(	Viewer *	v,
		const mjModel *	model,
		const char *	name )

Switch the viewer to a named fixed camera defined in the model. Works for both init_window() and init_window_sim() paths. Pass nullptr or an empty string to return to the free camera.

Returns

true if the camera name was found; false if not found (viewer unchanged).