Implementation:Google deepmind Mujoco initOpenGL Pattern

Knowledge Sources	MuJoCo
Domains	Rendering, OpenGL, Headless
Last Updated	2026-02-15 06:00 GMT

Overview

Concrete pattern for initializing headless OpenGL contexts from the MuJoCo record sample.

Description

The initOpenGL function in sample/record.cc demonstrates the standard pattern for creating a headless OpenGL context. It uses compile-time defines (MJ_EGL, MJ_OSMESA) to select the backend. The EGL path creates a surfaceless context; the OSMesa path creates a software-rendered context; the GLFW fallback creates a hidden window.

Usage

Adapt this pattern for headless rendering applications. Select the backend via CMake defines at build time.

Code Reference

Source Location

• Repository: mujoco
• File: sample/record.cc
• Lines: 92-175

Signature

// Local helper function (not part of public API)
void initOpenGL(void);
// Selects backend based on compile-time defines:
//   MJ_EGL  -> EGL headless context
//   MJ_OSMESA -> OSMesa software context
//   else -> GLFW hidden window

Import

// Backend-specific headers
#ifdef MJ_EGL
  #include <EGL/egl.h>
#elif defined(MJ_OSMESA)
  #include <GL/osmesa.h>
#else
  #include <GLFW/glfw3.h>
#endif

I/O Contract

Inputs

Name	Type	Required	Description
(none)			Backend selected at compile time

Outputs

Name	Type	Description
side effect	OpenGL context	Active OpenGL context suitable for offscreen rendering

Usage Examples

// EGL headless initialization (simplified from record.cc)
#ifdef MJ_EGL
  const EGLint configAttribs[] = {
      EGL_RED_SIZE, 8, EGL_GREEN_SIZE, 8, EGL_BLUE_SIZE, 8,
      EGL_ALPHA_SIZE, 8, EGL_DEPTH_SIZE, 24, EGL_STENCIL_SIZE, 8,
      EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
      EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
      EGL_NONE
  };
  EGLDisplay eglDpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
  eglInitialize(eglDpy, NULL, NULL);
  EGLConfig eglCfg;
  EGLint numConfigs;
  eglChooseConfig(eglDpy, configAttribs, &eglCfg, 1, &numConfigs);
  eglBindAPI(EGL_OPENGL_API);
  EGLContext eglCtx = eglCreateContext(eglDpy, eglCfg, EGL_NO_CONTEXT, NULL);
  eglMakeCurrent(eglDpy, EGL_NO_SURFACE, EGL_NO_SURFACE, eglCtx);
#endif

Related Pages

Implements Principle

• Principle:Google_deepmind_Mujoco_Headless_OpenGL_Initialization

Requires Environment

• Environment:Google_deepmind_Mujoco_C_Build_Environment