Get image

A tool for rendering a fragment shader to a PNG file.

This version of get image currently uses EGL and OpenGL ES 3. Thus, libEGL.so and libGLESv2.so (yes, v2) will be loaded at runtime on Linux (and similarly for other OS's). You can use the swiftshader version of these libraries to perform software rendering, or the ANGLE version of these libraries to perform rendering using ANGLE (using Direct3D on Windows and OpenGL on Linux).

Run get_image on the provided simple.frag shader to test that it works. E.g.

./get_image --persist simple.frag

Note:

You should also have a file with the same name as the shader but with a .json extension. This file should only contain an "{}"

Usage

./get_image <PATH_TO_FRAGMENT_SHADER>

Useful flags:

• --persist - causes the shader to be rendered until the window is closed
• --output <OUTPUT_FILE> - a png file will be produced at the given location with the contents of the rendered shader (default is output.png)
• --vertex <PATH_TO_VERTEX_SHADER> - provide a custom vertex shader file rather than using the default (provided in get_image.cpp).

Building

Building the project uses CMake.

First you must ensure you have the dependencies. There are scripts in buildscripts intended to run on the CI that can also be used to build locally. You can run these as follows:

On Windows:

bash buildscripts\1-install-deps-appveyor.sh

On Linux or OSX:

bash buildscripts/1-install-deps-travis.sh

Alternatively on Ubuntu you can:

sudo apt-get install libgles2-mesa-dev

(This will probably fail with an error at the last step, but all that matters is that the deps are created)

Once you have the deps downloaded, you can build with CMake as follows:

mkdir build
cmake ..
cmake --build .

Note that if you are building on Windows you must have Visual Studio installed and you must specify the build generator explicitly:

cmake -G "Visual Studio 15 2017 Win64"  -T v140 ..

The reason for this is that if you do not specify Win64 it will default to 32-bit (which is incompatible with the libraries in deps). The "-T v140" flag specifies that it should build with a VS2015 C++ compiler (which is the same one the libraries are built with).

If this complains about being unable to install a compiler and you do have Visual Studio installed, then you will need to install Visual C++ support for VS2015. You can obtain the build tools from https://www.visualstudio.com/ by signing up for the Microsoft Developer Essentials (it's free). Note that you don't have to install the entirety of VS2015 (which is much larger).

It may work correctly if you simply omit the "-T v140" flag, but we think that might be a bad idea but are not entirely sure.

Note that you will see an awful lot of warnings. This is fine. As long as the build exits successfully, try running the generated executable (in either Debug or Release in your build directory) on sample.frag in the root of this project. If you get a pretty image called output.png then it has worked.