WIP refactor rerender render-v2

frontend/render_v2/cpp/README.md

@@ -0,0 +1,49 @@
+# Renderer
+
+## How this works?
+
+First of all we need a proper environment to build Skia, this
+environment is heavily based on the [Skia docker image](https://github.com/google/skia/blob/main/docker/skia-release/Dockerfile) but with some tweaks to support building
+a C++ WebAssembly module using [Emscripten](https://emscripten.org/index.html).
+
+## Building everything
+
+From the root directory of `frontend/renderer` just run:
+
+```sh
+./build
+```
+
+This is going to build the docker image and run the container to build
+the artifacts and then copy them to the necessary directories.
+
+> :smile_cat: Be patient, the first time the docker image is built usually takes
+> a few minutes.
+
+## Building the Skia build tools Docker image
+
+To build just the Skia build tools image:
+
+```sh
+cd frontend/renderer
+docker build . -t skia-build-tools
+```
+
+## Building the renderer WebAssembly module
+
+Just run the container and it will generate all the necessary
+artifacts in the `out` directory.
+
+```sh
+cd frontend/renderer
+docker run -t -v ${PWD}:/tmp/renderer skia-build-tools
+```
+
+Once the `renderer.js` and `renderer.wasm` are created in the `out` directory
+we need to move them where Penpot can have access to them, so we need to execute
+`./scripts/copy-artifacts`.
+
+## C++ <-> JS
+
+To add some extra functionality to the exported `Module` by the Emscripten
+compiler, we use a series of javascript scripts that exist on the `js` directory.