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High Performance Ray Tracing Kernels

Supported Platforms

Embree supports Windows (32 bit and 64 bit), Linux (64 bit) and Mac OS X (64 bit). The code compiles with the Intel Compiler, GCC, CLANG and the Microsoft Compiler. Embree is tested with Intel Compiler 15.0.0, CLANG 3.4.2, GCC 4.8.2, and Visual Studio 12 2013. Using the Intel Compiler improves performance by approximately 10%.

Performance also varies across different operating systems. Embree is optimized for Intel CPUs supporting SSE, AVX, and AVX2 instructions, and requires at least a CPU with support for SSE2.

The Xeon Phi™ version of Embree only works under Linux in 64 bit mode. For compilation of the the Xeon Phi™ code the Intel Compiler is required. The host side code compiles with GCC, CLANG, and the Intel Compiler.

Downloading Embree

We provide binaries for Embree for Linux (64 bit), Mac OS X (64 bit), and Windows (64 bit and 32bit):

If you need to recompile Embree for your platform, please download the sources and follow the compilation instructions below:

Alternatively you can also use git to get the latest Embree 2.4:

$ git clone embree
$ cd embree
$ git checkout v2.4

You can also check out Embree with subversion:

$ svn checkout embree
$ cd embree

If you encounter bugs please report them to the GitHub Issue Tracker for Embree.

Once you downloaded or checked out Embree you will see the following folder structure:

Embree root folder
User API to the ray tracing kernels
Embree ray tracing kernels implementation
Embree kernels for Intel® Xeon® CPUs
Embree kernels for Intel® Xeon Phi™ Accelerators
Embree tutorials

Compiling Embree

Linux and Mac OS X

Embree is tested with Intel Compiler 15.0.0, CLANG 3.4.2, and GCC 4.8.2.

Embree also requires the Intel® SPMD Program Compiler (ISPC) to compile. We have tested ISPC version 1.8.0, but more recent versions of ISPC should also work. You can download and install the ISPC binaries from After installation, either put the path to the ispc executable permanently into your PATH:

export PATH=path-to-ispc:$PATH

Or provide the path to the ispc executable to CMake via the ISPC_EXECUTABLE variable.

You additionally have to install CMake 2.8.12 or higher and the developer version of GLUT. Under Mac OS X, these dependencies can be installed using MacPorts:

sudo port install cmake freeglut

Under Linux you can install these dependencies using yum or apt-get. Depending on your Linux distribution, some of these packages might already be installed or might have slightly different names.

Type the following to install the dependencies using yum:

sudo yum install cmake.x86_64
sudo yum install freeglut.x86_64 freeglut-devel.x86_64
sudo yum install libXmu.x86_64 libXi.x86_64
sudo yum install libXmu-devel.x86_64 libXi-devel.x86_64

Type the following to install the dependencies using apt-get:

sudo apt-get install cmake-curses-gui
sudo apt-get install freeglut3-dev
sudo apt-get install libxmu-dev libxi-dev

Finally you can compile Embree using CMake. Create a build directory and execute "ccmake .." inside this directory.

mkdir build
cd build
ccmake ..

This will open a configuration dialog where you can perform various configurations as described below. After having configured Embree, press c (for configure) and g (for generate) to generate a Makefile and leave the configuration. The code can be compiled by executing make.


The executables will be generated inside the build folder. We recommend to finally install the Embree library and header files on your system:

sudo make install

If you cannot install Embree on your system (e.g. when you don't have administrator rights) you need to add embree_root_directory/build to your LD_LIBRARY_PATH (and SINK_LD_LIBRARY_PATH in case you want to use Embree on Xeon Phi™).

The default configuration in the configuration dialog should be appropriate for most usages. The following table described all parameters that can be configured:

CMake build options for Embree.
Option Description Default
BUILD_EMBREE_SHARED_LIB Build Embree as a shared library. ON
BUILD_TUTORIALS Builds the C++ version of the Embree tutorials. ON
BUILD_TUTORIALS_ISPC Builds the ISPC version of the Embree tutorials. ON
CMAKE_BUILD_TYPE Can be used to switch between Debug mode (Debug) and Release mode (Release). Release
COMPILER Select either GCC, ICC, or CLANG as compiler. GCC
RTCORE_BACKFACE_CULLING Enables backface culling, i.e. only surfaces facing a ray can be hit. OFF
RTCORE_BUFFER_STRIDE Enables the buffer stride feature. ON
RTCORE_INTERSECTION_FILTER Enables the intersection filter feature. ON
RTCORE_RAY_MASK Enables the ray masking feature. OFF
RTCORE_SPINLOCKS Enables faster spinlocks for some builders. OFF
RTCORE_RETURN_SUBDIV_NORMAL Instead of the triangle normal the ray returns a smooth normal based on evaluating the subdivision surface patch. OFF
XEON_ISA Select highest supported ISA on Xeon™ CPUs (SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX-I, or AVX2). AVX2
XEON_PHI_ISA Enables generation of Xeon Phi™ version of kernels and tutorials (when BUILD_TUTORIALS is ON). OFF

Xeon Phi™

Embree supports the Xeon Phi™ coprocessor under Linux. To compile Embree for Xeon Phi you need to enable the XEON_PHI_ISA option in CMake and have the Intel Compiler and the Intel Manycore Platform Software Stack (MPSS) installed.

Enabling the buffer stride feature reduces performance for building spatial hierarchies on Xeon Phi.


Embree requires Visual Studio 12 2013 and the Intel SPMD Program Compiler (ISPC) to compile. We have tested ISPC version 1.8.0, but more recent versions of ISPC should also work. You can download and install the ISPC binaries from After installation, put the path to ispc.exe permanently into your PATH environment variable or you need to correctly set the ISPC_EXECUTABLE variable during CMake configuration.

You additionally have to install CMake (version 2.8.12 or higher). Note that you need a native Windows CMake installation, because CMake under Cygwin cannot generate solution files for Visual Studio.

Using the IDE

Run cmake-gui, browse to the Embree sources, set the build directory and click Configure. Now you can select the Generator, e.g. "Visual Studio 12 2013" for a 32 bit build or "Visual Studio 12 2013 Win64" for a 64 bit build. Most configuration parameters described for the Linux build can be set under Windows as well. Finally, click "Generate" to create the Visual Studio solution files.

For compilation of Embree under Windows use the generated Visual Studio solution file embree.sln. The solution is by default setup to use the Microsoft Compiler. You can switch to the Intel Compiler by right clicking onto the solution in the Solution Explorer and then selecting the Intel Compiler. We recommend using 64 bit mode and the Intel Compiler for best performance.

To build Embree with support for the AVX2 instruction set you need at least Visual Studio 2013 Update 4. When switching to the Intel Compiler to build with AVX2 you currently need to manually remove the switch /arch:AVX2 from the embree_avx2 project, which can be found under Properties ⇒ C/C++ ⇒ All Options ⇒ Additional Options.

To build all projects of the solution it is recommend to build the CMake utility project ALL_BUILD, which depends on all projects. Using "Build Solution" would also build all other CMake utility projects (such as INSTALL), which is usually not wanted.

We recommend enabling syntax highlighting for the .ispc source and .isph header files. To do so open Visual Studio 2008, go to Tools ⇒ Options ⇒ Text Editor ⇒ File Extension and add the isph and ispc extension for the "Microsoft Visual C++" editor.

Using the Command Line

Embree can also be configured and built without the IDE using the Visual Studio command prompt:

cd path\to\embree
mkdir build
cd build
cmake -G "Visual Studio 12 2013 Win64" ..
cmake --build . --config Release

You can also build only some projects with the --target switch. Additional parameters after "--" will be passed to msbuild. For example, to build the Embree library in parallel use

cmake --build . --config Release --target embree -- /m