hmm understood. But, can you explain some things about the technologies used in both realtime engine and corona which makes them really difference and you dont want it?
sorry i know this is a dumb question, but i'd like to understand this better
It would be best if Ondra (or someone else from the dev team) answered on this, but here is my 2 cents. There is no amazing info here, just some obvious ideas:
There are various types of "render engines", and if we are considering "real-time" vs "offline" render engines, I would divide them into:
-Full real time (game) engines:
Most of the work is done on the GPU because GPUs are designed for exactly this kind of work. We are dealing with relatively low-poly geometry (for faster load times and good FPS), and complex shaders rendered by the GPU (bump, reflections, other effects). Such render engines are used in games and also for some archviz works (like UE, Unity). The "rendering" speed is at least 20+fps to have smooth motion. The idea is to have good realism-performance-bias ratio.
The output is a 3d scene, where you can manipulate objects, move camera, etc.
-Offline render engines:
Can use CPU or GPU (or both). The idea is to have as photorealistic output as possible. We can have whatever complex geometry and materials that fit in the RAM. An example of this is regular rendering in Corona. The expected "fps" is very low - like 1 frame per hour or so, depending on scene complexity. It is so slow because the engine is calculating physical phenomena such as light bouncing around very carefully, and for each pixel.
The output is a 2D image, which is generated based on the 3d scene. You can no longer manipulate objects, or move camera. You can only edit the image in 2D.
-Semi-real time engines
Rendering is done on the GPU or CPU, and basically it is the same as "offline" rendering, but the image is rendered as quickly as possible, based on some optimizations. An example of this is interactive rendering in Corona. The expected fps is not as high as in real time engines, but should be as high as possible, and definitely not as low as in offline rendering.
The output is a 2D image like in the case of an offline renderer.
Note:
-If you render an extremely complex scene in high enough resolution in a real-time engine, it may take 1 hour or more to render!
-Likewise, if you render an extremely simple scene in an offline renderer, you may get 20+ fps!
Now we cannot say that we "do not want" real-time rendering in Corona. But it is just a very different thing. It is like comparing a petrol engine and a waterfall turbine, and asking why we don't want waterfall turbines in a car. ;)