[Ohrrpgce] Sprites, animation food for thought

[Seth Hetu]

3 times, but nevermind that. I've got a question about animations.

Is it possible to add a "delay" value, which delays the next frame in
the animation? Like:
>     <animation name="stand" deftime="1" loop="no">
>         <dir dir="down">
>             <frame>stand-down</frame>
>         </dir>
>         <dir dir="up" delay=3ms">
>             <frame>stand-up</frame>
>         </dir>
>         <dir dir="right">
>             <frame>stand-right</frame>
>         </dir>
>         <dir dir="left">
>             <frame>stand-left</frame>
>         </dir>
>     </animation>


Then the person remains standing for 3s longer than the other directions?

The reason I ask is that I like your idea of defining the animation by
"wrapping" a PNG sheet with XML. So maybe it would be possible/easy to
add more tags and options to an animation to increase its power. Then,
it's all described in the XML+PNG combo, which makes it really easy to
edit external to the OHR.

Just throwing out ideas, since your first email seemed to encourage
it. Cool system overall.
-->Seth



On Mon, Oct 11, 2010 at 2:01 AM, Mike <caron.mike at gmail.com> wrote:
> Shoot, if this email went out multiple times, I apologise.
>
> If not, please disregard this.
> --
> Mike Caron
>
> -----Original Message-----
> From: Mike Caron <caron.mike at gmail.com>
> Date: Sun, 10 Oct 2010 13:37:53
> To: <ohrrpgce at lists.motherhamster.org>
> Subject: Sprites, animation food for thought
>
> First off, a disclaimer: This is not an actual proposal for a data
> format for the OHR. This is something I've cooked up for another project
> which may or may not ever see the light of day (hopefully, it will, but
> it's immaterial to this discussion).
>
> This is how I've implemented sprites and animations in this other project:
>
> First, all pixel data is stored in sprite sheets. These are PNGs that
> contain all the sprites for a given on-screen entity. Technically, as I
> am writing it in .NET, nothing is stopping them from being BMP or JPG or
> something, but I prefer PNG for its true-colour and transparency support.
>
> Then, with each sprite sheet, there is an XML document that describes it:
>
> <spriteset xmlns="http://mike-caron.com/za" name="link1" file="link.png">
>     <frame x="33" y="1" width="16" height="22" ox="8" oy="19"
> name="stand-down" />
>
>     <frame x="3" y="31" width="16" height="22" ox="8" oy="19"
> name="walk1-down" />
>     <frame x="33" y="31" width="16" height="22" ox="8" oy="19"
> name="walk2-down" />
>
>     <!-- etc. -->
>
> Each frame has a name, a position and size on the sheet, and an origin.
> The origin is aligned up with the actual entity's origin (which, ATM is
> always their (x,y) position, but that may be customizable later on)
>
> Then, after the frame definitions, we have the animation definitions:
>

>
> This is mostly self explanitory. Every frame has either one or four
> directions defined, depending on if the sprite has meaningful directions
> (an item on the ground, for example, probably only has one direction. An
> NPC, on the other hand, will have all four).
>
> Each frame in a direction can have a time parameter, which describes how
> many ticks the frame is displayed for. deftime is just the default such
> value. Obviously, as well, if loop is yes, the animation will start from
> the beginning. If no, it will just stop on the last frame forever.
>
> Finally, every entity in the game references both a sprite sheet and an
> animation. The idea is that you could change one or the other. For
> example, if you get a better shield, the sprite sheet changes from
> "link1" to "link2". And, obviously, the animation changes based on what
> is happening in the game.
>
> A few notes on this structure:
>
>  - There is no accounting for palettes. If you wanted to use a paletted
> sprite, then by all means you are able, but don't expect to be able to
> change that palette in game. The canonical way to add palette swaps is
> to have a different sprite sheet with the same animations (and, I may
> add some way to automate this. Eg, "this sprite sheet is exactly the
> same as this other sprite sheet, so use those definitions")
>
>  - There is also no way to get any fancier animations. I.e, there's no
> way to automatically oscillate or go backwards or whatever. The way to
> achieve these effects would be to duplicate the frames in the animation.
>    - I may or may not add sprite flipping.
>
>  - The way the images are laid out on the sheet has absolutely nothing
> to do with how they are animated or displayed. If you wanted the same
> frame, but offset by 5 pixels or whatever, you just modify the origin.
> No muss, no fuss.
>
>  - Also, there are no inherent limitations on how large or small the
> sprite is. If you want to make a 2d version of Shadow of the Colossus,
> then be my guest! (just, don't expect the video card to necessarily play
> along ;)
>
> So... yeah. Make of that what you will, I'm just adding ideas to the
> pot. I am aware that this format, as is, is unsuitable for the OHR. It's
> just my two cents.
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