The renderer lays every slide background over white (as PowerPoint does),
so a PNG export was always opaque. A new transparentBackground option leaves
the slide background out (both the white underlay and the background fill),
so only what is on the slide is drawn over transparency. Shapes filled with
the background (useBgFill) still show it.
- render: RenderOpts::transparent_background
- engine: file.export {transparentBackground} (PNG only; other formats
refuse it and write nothing), file.render {transparentBackground}
- UI: Transparent background checkbox in the Export dialog (PNG) and in
File > Export > Change File Type > PNG; the web download honours it
- CLI: render --transparent
Every transition and Effect Option was built in PowerPoint (COM), exported as
video and compared frame by frame with DeckCraft at the same progress
(mean abs diff over 150 variants 35.7 -> 15.0, 0-255).
- anim: transition_frame(kind, option, t, aspect) with measured curves
(smoothstep fades, ease-in-out moves, Cover/Uncover/Pan curves), directions
and option meanings, soft edges as per-corner opacity, 3-D effects as
perspective-projected cards, Dynamic Content moving slide contents over
cross-fading backgrounds (Source::OldBack/NewBack/OldContent/NewContent);
layer_mesh subdivides perspective quads so textures stay straight.
- New options: Page Curl Single, Glitter Hexagons, Shred In/Out, Zoom and
Rotate; PowerPoint-style Effect Options labels.
- render: composite_transition (CPU twin of the show), render_slide_part,
render_transition; deckcraft-cli render-transition FILE --slide N --t T.
- show: per-vertex opacity meshes, slide parts rendered once per transition.
- pptx: PowerPoint's elements and defaults (p:strips diagonal wipes, p14:warp
and p:newsflash for Zoom, p:zoom for Shape In/Out, glitter pattern, shred
rectangle/dir, prstTrans invX per preset, pageCurlSingle, defaults for
randomBar/doors/window/pan/zoom); PowerPoint reopens DeckCraft's files with
the same effects.
- Tests: measured curves, probes of which slide shows where at t, option
coverage, per-frame triangle budget, PowerPoint XML and defaults round trip.
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Gert Pellin