Scenic as a game dev tool

This is awesome - well done!!

This looks great! I’m re-writing the engine and html/js front-end for a game of mine and can’t wait to try doing the interface with Scenic.

Please keep us posted @amnu3387!

I’m loving reading about all these Scenic projects

@AstonJ @amnu3387

The code is online

I wonder if SchedEx would be a good fit for the scheduling for your game. It is what powers beats (a drum engine):

The talk also contains some interesting discussion on the impact of the current state of millisecond-level timers in Erlang.

SchedEx run the scheduled function with

Process.send_after(self(), :run, delay)

Still only milliseconds

To get strict 60FPS you need to run update every 16.666666[…] ms or 16,666.666[…] microseconds

Usually, in procedural languages, this is solved in the game loop in two ways

while(true)
  elapsed_time = last_time - current_time()       
  update(elapsed_time)

This way the update knows how much time has passed since the last update and can advance the game state proportionally to the amount of time passed

The other way is

while(true)
  elapsed_time = last_time - current_time()       
  while(elapsed_time < frame_duration)
    elapsed_time = last_time - current_time()       
  last_time = current_time()   

  update()

This way the game wait exactly (well, more or less) frame_duration ms (at 60FPS 16.66ms) before updating the world again

Elixir is not good in tight loops, it doesn’t even have while loops, but it’s good at sending async messages as fast as possible, so we need to use a different approach (but the logic is very similar)

If you look at the code there’s a Timer module that implements a timer with resolution in the microseconds range. It’s not used in the game, but I’ve started working on it.

I’ll be back soon with a short post that explains the internals of it.

To answer you question: music is played in BPM which is beats per minute
Having a timer that can send messages in milliseconds is more than enough, 120 BPM, which is very fast for music, sends only 2 messages per second or a message every 500ms

Thanks! I will check it once I have some time (now you made me want to write a dragon force clone… in elixir)

I’ve just completed another little challenge

This time I’ve implemented the color cycling effect natively in Elixir and Scenic

All the code, including decoding and re-encoding the PNGs and their palettes is pure Elixir

I will release it soon on Gitlab

For those who don’t know what color cycling is

Color cycling , also known as palette shifting , is a technique used in computer graphics in which colors are changed in order to give the impression of animation. This technique was mainly used in early computer games, as storing one image and changing its palette required less memory and processor power than storing the animation as several frames

I was heavily inspired by this demo

https://twitter.com/wstucco/status/1051168787347705856

Awesome stuff Massimo

Code is online for those interested