Which technique do you use to compress scene json file?

sooyong_Kim · March 11, 2024, 8:29am

When we download a scene from playcanvas studio, the scene json file is quite compressed with unreadable format if I select “optimize scene format” enabled.

Sometimes I want to go through a post process with scene file. Then I have to disable the option.

But I still need a compressed version when it goes to production.

So, I just wonder if I can do the same action by myself.
compress-json - npm (npmjs.com)

this opensource project seems doing the similar task,but somehow the output looks little different.

Can anyone tried this without studio export?

mvaligursky · March 11, 2024, 9:04am

It replaces long IDs by short ids, and does some compression (don’t remember the details) to transform storage, and possibly few others, but it was a pretty simple compression.

The decompression code is here: https://github.com/playcanvas/engine/tree/main/src/scene/compress

It’s called on an array of entity data in the scene:

github.com

playcanvas/engine/blob/82502f50849b3d50d67e121c939ff83797faccd7/src/framework/parsers/scene.js#L21


      
              this._isTemplate = isTemplate;
          }
          
          parse(data) {
              const entities = {};
              let parent = null;
          
              const compressed = data.compressedFormat;
              if (compressed && !data.entDecompressed) {
                  data.entDecompressed = true;
                  data.entities = new Decompress(data.entities, compressed).run();
              }
          
              // instantiate entities
              for (const id in data.entities) {
                  const curData = data.entities[id];
                  const curEnt = this._createEntity(curData, compressed);
                  entities[id] = curEnt;
                  if (curData.parent === null) {
                      parent = curEnt;
                  }

So you’d have a to write a custom compressor here, as that is not part of the engine.