Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/vchelaru/flatredball2/animationnpx skills add vchelaru/FlatRedBall2 --skill animationgit clone --depth 1 https://github.com/vchelaru/FlatRedBall2Wrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/vchelaru/flatredball2/animation)<a href="https://agentmods.dev/skills/vchelaru/flatredball2/animation"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/animation.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00076 | $0.01735 |
| Opus 5 | $0.00038 | $0.00868 |
| Sonnet 5 | $0.00015 | $0.00347 |
| Haiku 4.5 | $0.00008 | $0.00173 |
Grade A, and why
animation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Sprite Animation in FlatRedBall2
Sprites animate via AnimationChain / AnimationChainList, driven automatically by Screen.Update — no per-frame call needed in game code.
Quick setup: adding animation content
- Create a folder in your
*.Commonproject'sContentdirectory (for exampleContent/Animations). - Copy your source spritesheet PNG into that folder.
- Open Animation Editor and save a new
.achxin the same folder as the PNG. - Ensure your project copies these files to output (for example
Content/Animations/**in.csproj; seereferences/platformer-template.md).
FileRelativeTextures in .achx expects relative texture paths, so keeping .achx and texture content together avoids broken lookups.
Runtime Types
AnimationFrame— texture + source rectangle (pixel coords) + flip flags +FrameLength(TimeSpan) + per-frameRelativeX/Yoffsets + optionalShapescollectionAnimationChain : List<AnimationFrame>— named sequence;TotalLength= sum ofFrameLengthsAnimationChainList : List<AnimationChain>— string indexer for lookup by name; the unit of "ownership" for per-frame shapes (see Topics)
Standalone AnimationChain.MonoGame/.Common Package
The types above live in FlatRedBall2.Animation and back Sprite.PlayAnimation. A separate
generic package (namespaces FlatRedBall.AnimationChain / FlatRedBall2.AnimationEditorCommon) —
AnimationChainList<TFrame>, AnimationPlayer<TFrame>, AchxLoader
(src/AnimationChain.MonoGame/AchxLoader.cs) — is for raw MonoGame projects with no FRB2
Screen/Sprite. Same names, different (generic) shape — don't conflate the two; see
samples/AnimationChainSample.
Sprite Playback API
| Member | Default | Notes |
|---|---|---|
AnimationChains |
null |
Assign before PlayAnimation; without a parent entity, RelativeX/Y and per-frame shapes don't behave usefully |
PlayAnimation(string name) |
— | Looks up by name; no-op if not found |
PlayAnimation(AnimationChain chain) |
— | Play a specific chain directly |
Animate |
false |
Auto-managed. Do not write to express idle state — see Gotchas |
IsLooping |
true |
false for one-shot |
AnimationSpeed |
1f |
Multiplier |
CurrentAnimation |
— | Read-only; returns the active chain |
AnimationFinished |
— | Fires when a non-looping animation ends |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 84 lines · 76 tokens per session scan A 7784a4606121
animation is a skill published in the GitHub repository vchelaru/FlatRedBall2 (14 stars, last pushed today), licensed MIT. It adds 76 tokens to every session and 1,735 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-04.
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