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ofxLiveShader

github.com/Littlebigdondon/ofxLiveShader · @Littlebigdondon
OF 0.10 Shaders Graphics

OpenFrameworks addon for hot-reloading GLSL shader files on the fly

6 1 Last commit 7y ago Created 7y ago

README

ofxLiveShader



An openFrameworks addon for hot-reloading shader files on the fly. Utilizes Facebook’s Watchman service to monitor filesystem changes. Tested on macOS, but as long as you can build the <a href="#install-dependencies">dependencies</a>, it should work on your platform.

PREREQUISITE NOTES:





Using this Addon



_Note: This currently assumes you’re using Xcode. If you got this built & running on another platform, and want to document it, reach out and I’ll update this guide._

Install Dependencies



``brew install folly watchman
	


Project Setup 



  • Simply include this as an addon when using the Project Generator, or, if adding manually, be sure to include each source file in Project -> [select target] -> Build Phases -> Compile Sources
  • Add libfolly.dylib, libevent.dylib, libglog.dylib, and libssl.dylib to Project -> [select target] -> General -> Linked Frameworks and Libraries.
_NOTE: After clicking “+” to add a framework, I had to manually select “Add Other”, and navigate to /usr/local/opt (using cmd+shift+G should help out) to get to these libraries._

  • Add /usr/local/include to Project -> [select target] -> Build Settings -> Header Search Paths

_NOTE: This next step may not be necessary based on your project/dependency settings/how far into the future you’re doing this, but as of right now, Xcode defaults to c++11 so you absolutely must change it to build against c++14 at minimum (the _-std=c++1z_ flag below will build against c++17, for example)._


  • Add a few C++ compiler flags to your target under Project -> [select target] -> Build Settings -> Other C++ Flags :
-I/usr/local/opt/openssl/include -std=c++1z 



Usage 



  • First, in ofApp.h, we need to add #include "ShaderFileWatcher.h" to the list of includes, and create a public ShaderFileWatcher pointer member in the ofApp class
c++ class ofApp : public ofBaseApp { public: ... ... ShaderFileWatcher* fileWatcher; // And obviously you'll be updating a shader: ofShader shader; } 


  • Next, we must instantiate the folly library in our main. The init function requires argc and argv, so we’ll need to expose these parameters in main.cpp by changing
c++ int main() {…} ` to `c++ int main(int argc, char** argv) {…} 
    and immediately passing these to folly::init(). I'm going to only pass the first argument because of this.
c++ int main(int argc, char** argv) { argc = 1; folly::init(&argc, &argv); ... } 


  • Awesome! With all of that out of the way, now we can instantiate a fileWatcher which will tell the watchman server to watch a directory of our choosing, and will automatically listen for changes to certain (or any) shader files within that directory. So navigate to ofApp.cpp, and in setup(), initialize the ShaderFileWatcher pointer
c++ void ofApp::setup() { fileWatcher = new ShaderFileWatcher( // 1. Folder containing shader files (default = project/bin/data) "/absolute/path/to/folder/of/shaders", // 2. Name of vertex shader to monitor for changes (default = ".vert") "shader.vert", // 3. Name of fragment shader to monitor for changes (default = ".frag") "shader.frag", // 4. Path to your Watchman executable (default = "/usr/local/bin") "/usr/local/bin" ); ... ... } 


  • Lastly, all we have to do is call checkForUpdate(), which will return true if we need to reload our shaders
c++ void ofApp::update() { if (fileWatcher->checkForUpdate()) { shader.load("shader.vert", "shader.frag"); } ... ... } ``



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