> ## Documentation Index > Fetch the complete documentation index at: https://docs.summerengine.com/llms.txt > Use this file to discover all available pages before exploring further. # Splash loop: a living painting (Hero Art skill) > splash-loop.md from the Hero Art skill in the Summer Engine skill library. Hero splash art, seamless splash loops and rigged animated heroes, gated. > [!NOTE] > > Part of the [`hero-art` skill](https://docs.summerengine.com/skills/hero-art). The skill links here when your agent needs the detail. **Goal:** the hero's splash, alive: hair and cloth sway, magic glows and drifts, the camera never moves, and after 15 s it returns to the exact painting, so the loop has no visible seam. On the select screen it must cost nothing until it is seen: the still shows at once and the video takes over without a jump. Start from an approved still (`splash-art.md`). This step never changes the design; it only adds motion. ## 1. Generate: the splash is the first AND the last frame `assets.generate_video` with `model: "seedance-2"`, `imageUrl` and `endImageUrl` both the splash, `duration: 15` (the longest; longer loops repeat less), `resolution: "720p"`, `aspectRatio` matching the splash. Wait with `jobs.wait`. `summer ops describe assets.generate_video` shows the exact input; `dryRun: true` shows the credit cost first. Run every hero in parallel; each clip takes a few minutes. A splash that is only on disk needs a URL first: `assets.upload_begin`, POST the file, `assets.upload_complete`, then `assets.get`. If the server you reach has no `endImageUrl` field, generate with the start frame only and the same prompt, then make the loop a ping-pong in step 3. Sway-only motion (step 2) reads naturally played forward then backward. ## 2. Prompt: hover and sway, never cycle This is the rule that decides whether the loop works. Anything that has to complete a cycle (a clock hand turning, a vortex spinning, clouds travelling across the sky, a cape blowing one way) cannot finish in 15 s, so it slides back at the loop point and the seam shows. Everything moves back and forth around where it started: > A living painting. The exact same image throughout: same character, same pose, same framing, same background. Static > locked-off camera: no camera movement, no zoom, no pan. \ holds the exact pose and only breathes slowly; \ cloth> sway gently back and forth. \ pulse, flicker and drift, then return. Objects hover > and sway in place. No spinning, no rotation, no travel. No new objects, no new characters, no pose change, no text. > The final frame returns exactly to the starting image for a seamless loop. Name the hero's actual moving parts (twin tails, a fur collar, a glowing staff head). Generic prompts give generic motion. ## 3. Check the seam before anyone sees it Numbers first, then eyes: ```bash theme={null} n=$(ffprobe -v error -select_streams v:0 -count_frames -show_entries stream=nb_read_frames -of csv=p=0 master.mp4) ffmpeg -v error -i master.mp4 -vf "select=eq(n\,0)+eq(n\,1)+eq(n\,$((n-2)))" -fps_mode passthrough f_%d.png compare -metric RMSE f_1.png f_2.png null: # a normal step between two frames compare -metric RMSE f_3.png f_1.png null: # the wrap: second-to-last frame -> first frame ``` The wrap should sit inside the range of normal steps (check a few pairs: busy moments step more). A wrap several times the usual step is a visible pop: regenerate with a stricter prompt, or use the ping-pong below. Then watch the last 2 s into the first 2 s yourself: no jump, no slide, nothing spinning, no face or hand change. The video model frames slightly tighter than the painting (about 7 % on 16:9): compare frame 1 with the splash and note the zoom; the still poster must be shown at the same zoom or the hand-off jumps. No end frame (step 1 fallback): build the ping-pong master, which has a clean seam by construction: ```bash theme={null} ffmpeg -i clip.mp4 -filter_complex "[0:v]split[a][b];[b]reverse,trim=start_frame=1,setpts=PTS-STARTPTS[r];[a][r]concat=n=2:v=1[v]" -map "[v]" -an -c:v libx264 -crf 14 master.mp4 ``` Show the person the master, looped, with one line of what to look for ("loop point at 0:15: no jump, nothing spins"). ## 4. Encode for the engine Summer Engine plays Ogg Theora (`.ogv`), not MP4. Drop the last frame (it repeats the first and stutters the loop) and make two copies, a desktop one and a small one for phones: ```bash theme={null} ffmpeg -i master.mp4 -frames:v $((n-1)) -an -c:v libtheora -q:v 7 -g 240 hero_loop.ogv ffmpeg -i master.mp4 -frames:v $((n-1)) -an -vf scale=640:-2 -c:v libtheora -q:v 6 -g 240 hero_loop_mobile.ogv ``` Expect about 3-4 MB (desktop) and under 1 MB (mobile) for 15 s. Many ffmpeg builds ship without `libtheora` (`ffmpeg -encoders | grep theora` prints nothing). Then pipe the frames into libtheora's reference encoder (`encoder_example`, built from the libtheora source if the person agrees): ```bash theme={null} ffmpeg -v error -i master.mp4 -frames:v $((n-1)) -vf "format=yuv420p" -f yuv4mpegpipe -strict -1 - \ | encoder_example -v 6 -k 240 -o hero_loop.ogv - ``` Ship each export preset only its own copy. ## 5. Play it in the game The rules, each learned from lag or a visible jump: * **The still is the poster.** Show the splash at once (zoomed to the video's framing). The video fades in over it only after its first frame has decoded, so nobody sees a black frame or a jump. * **Load async and late.** Start loading the loop about 0.7 s after a pick (`ResourceLoader.load_threaded_request`), so browsing quickly through heroes never opens a decoder. * **Only the hero on screen plays.** A new pick fades the old loop out and frees its stream (`stop()`, `stream = null`). A hidden screen or a paused app stops at once and shows the poster again; showing again resumes. * **Phones play the mobile copy.** Nothing preloads, ever. A `VideoStreamPlayer` with `loop = true`, `expand = true`, no audio, sized to cover the screen like the poster (keep aspect, cover) does the playing. Write it as one small script on the select screen (`summer_run_script` or a `.gd` file), then verify headless: it starts after the delay, decodes frames, loops past 15 s, frees the stream when hidden, and the frame rate holds while decoding. Finish with `summer_play`, a quick browse through every hero, and `summer_get_debugger_errors`. ## Done means Every hero with an approved splash has a loop whose seam passed the numbers and your eyes, desktop and mobile `.ogv` files in the project, a player that loads late and frees early, and the person has watched at least one loop on the real select screen. Record the prompt and the encode settings in `.summer/art-bible.md`. *** Source: [`library/skills/hero-art/references/splash-loop.md`](https://github.com/SummerEngine/summer/blob/main/library/skills/hero-art/references/splash-loop.md), rendered from `summer-engine@4.9.2` on npm. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.