Possibility to transfer the current_frame field between animations

[VictorKoenders]

In a game I'm making I have several animations that are needed for animating a player's character whenever they're moving in a certain direction. Whenever a player switches direction by pressing a different combination of arrow keys, a new animation gets selected.

Code

pub struct Player {
    pub running_map: DirectionMap<Animation>,
   ...
}

impl Player {
    pub fn set_walking(&mut self, diff: Vec2<f32>) {
        if let Some(direction) = Direction::from_diff(diff) {
            self.pos += diff;
            self.moving = true;
            if direction != self.direction {
                self.direction = direction;
                self.running_map[self.direction].restart();
            }
        } else {
            self.set_idle();
        }
    }
}

#[derive(Debug, Clone)]
pub struct DirectionMap<T> {
    pub up: T,
    pub up_right: T,
    pub right: T,
    pub down_right: T,
    pub down: T,
    pub down_left: T,
    pub left: T,
    pub up_left: T,
}

Because the walking animation is relatively long, it is very noticeable that the animation gets .restart() every time a player switches directions. If I get rid of .restart(), the animation becomes even more irregular.

I'd suggest one of two things:

• Expose current_frame (maybe as read-only) and allow a developer to set the current_frame.
• Expose an fn copy_frame_index(&mut self, other: &Animation) which copies both the current_frame and timer
  • This could possibly error if the frame_length or frames.len() is different?

Whenever we decide on an API, I can make a PR

[VictorKoenders]

[17cupsofcoffee]

I honestly think that Animation could use a lot of rework, it's a bit clunky 😅

I think I'd prefer the current_frame API, personally - the copy_frame_index API could be built on top of that in the game's code (which would give people more control over how they handle animations that are different lengths). Something like this:

fn current_frame(&self) -> usize { ... }
fn set_current_frame(&mut self, index: usize) { ... }

I'd lean towards having set_current_frame panic if you pass in an invalid index, because it seems like it'd be annoying to have to handle errors every time you call it. Unless you can think of any cases where you'd like to be able to recover from an invalid frame index? I'm open to being convinced 😄

Also, as an aside - that GIF looks very cool :) Are you making a Factorio-like kind of game?

[17cupsofcoffee]

Also, another side note: the source code for Animation is deliberately designed to not use any of Tetra's internal APIs - you're more than welcome to copy and paste it into your project and hack around if the built-in version can't be made to fit your needs 🙂

[VictorKoenders]

Are you making a Factorio-like kind of game?

I'm using the factorio assets for development.

the source code for Animation is deliberately designed to not use any of Tetra's internal APIs

Maybe it's an idea to make a seperate crate, e.g. tetra-extras, which includes things like Animation? rocket and mio do something similar. This would also make it more clear to people that these are meant as addons, and not part of the core library.

[17cupsofcoffee]

Maybe it's an idea to make a seperate crate, e.g. tetra-extras, which includes things like Animation? rocket and mio do something similar. This would also make it more clear to people that these are meant as addons, and not part of the core library.

Yeah, I'm considering doing something like this eventually :)