pptx-animation

Problem: PowerPoint's parser accepts many XML shapes that its playback engine silently drops at slideshow time. <p:anim attrName="fill.opacity"> parses fine, round-trips cleanly, and animates nothing. Generating PPT animations from ECMA-376 alone (or by plausibly guessing at element shapes) produces broken output that looks correct but does not play.

Solution: Route every effect through this skill's oracle-backed scripts. They wrap an empirically verified template library and a catalog of falsified shapes to avoid. You describe the effect in semantic terms (shape id, filter, duration, behaviors); the scripts emit <p:par> XML ready to splice into a timing tree.

Core rules — follow these or you will produce broken XML

1. Never hand-write <p:anim>, <p:animClr>, <p:animEffect>, <p:animScale>, <p:animRot>, <p:animMotion>, or <p:set> trees. Use the scripts in scripts/ instead. Even if you think you know the right shape, the verification metadata, bldP build modes, and token plumbing have non-obvious constraints.

2. These attrName values silently drop at playback — do not use them:

   • fill.opacity → use emit_compound.py with a transparency behavior
   • stroke.opacity → no native path, EMF rasterization fallback
   • stroke.weight → no native path, EMF rasterization fallback
   • line.weight → no native path, EMF rasterization fallback
   • style.fontSize in isolation → requires full preset 28 compound
   • <p:anim> on style.opacity with tavLst → use transparency behavior See references/dead_paths.md for the full catalog with replacements.

3. The valid <p:attrName> vocabulary has exactly 17 entries. This has been confirmed exhaustive by scanning all authored PowerPoint reference files. See references/attrname_vocabulary.md. If the attribute you want to animate isn't in the list, it is not natively animatable — fall back to EMF rasterization.

4. Prefer compound emission for stacked effects. PowerPoint fires all behavior children of one <p:cTn> simultaneously on a single click. The compound API (emit_compound.py) emits this shape directly with arbitrary lists of behavior fragments. Nested <p:par> siblings work too but are structurally redundant.

When to invoke this skill

• Authoring PowerPoint animation timing XML programmatically
• Converting SVG/SMIL animations to PPTX
• Debugging why a PowerPoint animation does not play
• Composing multi-effect stacks (fade + rotate + color change + ...)
• Validating hand-written or third-party timing XML

Authoring flow — pick the right script

Every script prints its output (usually a <p:par> XML fragment) to stdout. Redirect into a file or pipe into your timing-tree assembler.

Quick examples

Entrance — wipe down

python scripts/emit_entrance.py \
  --shape 2 --filter "wipe(down)" --duration 1500

Compound emphasis — 4 effects on one click

python scripts/emit_compound.py \
  --shape 2 --duration 3000 --par-id 5 \
  --behaviors '[
    {"name": "transparency", "tokens": {"SET_BEHAVIOR_ID": 10, "EFFECT_BEHAVIOR_ID": 11, "TARGET_OPACITY": "0.5"}},
    {"name": "fill_color", "tokens": {"STYLE_CLR_BEHAVIOR_ID": 20, "FILL_CLR_BEHAVIOR_ID": 21, "FILL_TYPE_BEHAVIOR_ID": 22, "FILL_ON_BEHAVIOR_ID": 23, "TO_COLOR": "C81010"}},
    {"name": "rotate", "tokens": {"BEHAVIOR_ID": 30, "ROTATION_BY": "21600000"}},
    {"name": "motion", "tokens": {"BEHAVIOR_ID": 40, "PATH_DATA": "M 0 0 L 0.2 0.1 E"}}
  ]'

Validate untrusted XML

cat some_timing.xml | python scripts/validate.py

Non-empty output = dead paths found. Each issue names the offending element, the verdict (silently-dropped / requires-compound / …), and the replacement slot. Empty output = oracle-clean.

Look up a filter or attrName

python scripts/query_vocabulary.py filter wipe
python scripts/query_vocabulary.py attrname style.visibility
python scripts/query_vocabulary.py dead fill.opacity

Progressive disclosure

Start with SKILL.md (this file). If you need more detail:

• references/oracle_overview.md — the two-layer oracle architecture
• references/filter_vocabulary.md — 29 filter values, auto-generated
• references/attrname_vocabulary.md — the 17 valid attrNames
• references/dead_paths.md — every empirically falsified shape
• references/compound_api.md — the 10 behavior fragments in detail
• references/examples.md — complete recipes for common patterns
• oracle/ — the raw SSOT XML files consumed by the scripts

When the scripts don't cover your case

1. Check references/attrname_vocabulary.md to see if your target attribute is natively animatable.
2. Check references/dead_paths.md to see if your approach is a known failure with a documented replacement.
3. If the effect is expressible as a compound (multiple disjoint behavior channels on one shape), use emit_compound.py — it accepts any combination of the 10 behavior fragments.
4. If no oracle path exists, the effect probably can't be natively animated in current PowerPoint. Fall back to EMF rasterization or a discrete <p:set> step approximation.

Self-test

After installing or updating this skill, run:

python scripts/emit_entrance.py --shape 2 --filter fade --duration 1000

You should see a well-formed <p:par> on stdout. If you see an import error, the svg2ooxml package is not on the Python path — the scripts import svg2ooxml.drawingml.animation.oracle directly, so you need either the svg2ooxml repository or pip install svg2ooxml.