generate2dsprite

name

generate2dsprite

description

Generate and postprocess general 2D game assets and animation sheets: pixel-art sprites, clean HD map props, creatures, characters, NPCs, spells, projectiles, impacts, props, summons, and transparent GIF exports. Use when Codex should infer the asset plan from a natural-language request, match a reference or map art style, call built-in `image_gen` for solid-magenta raw sheets, and use the local processor only for chroma-key cleanup, frame extraction, alignment, QC, and transparent exports.

Generate2dsprite

Use this skill for self-contained 2D sprite or animation assets.

When a larger game or playable prototype needs sprites, use this skill for the visible sprite assets and keep runtime/game assembly separate. Do not replace requested sprite assets with code-drawn placeholders.

Parameters

Infer these from the user request:

• asset_type: player | npc | creature | character | spell | projectile | impact | prop | summon | fx
• action: single | idle | cast | attack | shoot | jump | hurt | combat | walk | run | hover | charge | projectile | impact | explode | death
• view: topdown | side | 3/4
• sheet: auto | 2x2 | 2x3 | 2x4 | 3x3 | 3x4 | 4x4 | 5x5 | custom_grid | strip_1x3 | strip_1x4
• frames: auto or explicit count
• bundle: single_asset | unit_bundle | spell_bundle | combat_bundle | line_bundle | hero_action_bundle | engine_atlas
• effect_policy: all | largest
• anchor: center | bottom | feet
• scale_strategy: fit | preserve
• scale_profile: none | create_from_accepted_action | reuse_existing
• margin: tight | normal | safe
• art_style: pixel_art | clean_hd | pixel_inspired | retro_pixel | map_style | project-native
• reference: none | attached_image | generated_image | local_file
• layout_guide: none | geometry | character_anchor
• runtime_contract: none | godot_sprite3d
• world_height: desired in-engine subject height when a runtime contract is requested
• prompt: the user's theme or visual direction
• role: only when the asset is clearly an NPC role
• name: optional output slug

Read references/modes.md when the request is ambiguous.

Agent Rules

• Decide the asset plan yourself. Do not force the user to spell out sheet size, frame count, or bundle structure when the request already implies them.
• Do not pack unrelated actions into one raw generated sheet just to satisfy a 4x4, 5x5, or custom engine atlas. A raw generated sheet should represent one action family, one continuous sequence, one canonical directional locomotion sheet, or one prop/asset pack.
• For controllable heroes, main characters, and high-value player assets with multiple actions, generate separate per-action grid sheets first, QC each action, then deterministically assemble the engine-required atlas only after the grids pass visual review.
• For controllable heroes, main characters, and high-value player body actions, default attack/shoot/cast body sheets to body-only. Do not include large slash arcs, muzzle flashes, projectiles, impact bursts, detached dust, long trails, or wide detached FX in the body sheet. Generate those as separate fx, projectile, or impact sheets and layer them in the game.
• Only include wide attack FX in the same raw body sheet when the target runtime explicitly supports wider per-action cells plus per-action origin/anchor metadata. Otherwise, a wide FX bbox will force the body to shrink inside the fixed cell.
• When a grounded hero/player attack must keep an integrated weapon in the body sheet and there is no runtime FX layer, process it with scale_strategy=preserve and align=feet by default. This preserves raw-cell scale, translates frames to a shared feet line, and avoids bbox-fit shrinking from long swords, spears, weapon trails, capes, or wide melee poses.
• Write the art prompt yourself. Do not default to the prompt-builder script.
• Use built-in image_gen for every raw image.
• Do not create raw sprite art with Three.js, Canvas, SVG, HTML/CSS drawing, PIL shape drawing, procedural geometry, placeholder primitives, or code-rendered screenshots. Runtime code may display finished generated assets, and scripts may make layout guides or postprocess generated images, but requested sprite art must originate from built-in image_gen.
• When the user provides or implies a visual reference, use built-in image edit/reference semantics only after the reference image is visible in the conversation context. If the reference is a local file, call view_image first; do not rely on a filesystem path in the prompt as the visual reference.
• Do not force pixel art when the asset is a map prop for $generate2dmap or when the user/project requests a different style. Match the map or reference style first.
• Use the script only as a deterministic processor: magenta cleanup, frame splitting, component filtering, scaling, alignment, QC metadata, transparent sheet export, and GIF export.

Workflow

1. Infer the asset plan

Pick the smallest useful output.

Examples:

• controllable hero with four directions -> player + player_sheet
• side-view controllable hero with idle/run/shoot/jump -> player + hero_action_bundle
  • idle grid sheet, usually 2x2 for 4 frames
  • run grid sheet, usually 2x2 or 2x3 depending on needed frame count
  • shoot grid sheet with body/weapon only, usually 2x2
  • jump grid sheet, usually 2x2
  • projectile / muzzle flash as separate assets when needed
  • optional assembled engine atlas after per-action QC
• side-view controllable hero with melee attack -> player + hero_action_bundle
  • attack body grid sheet, usually 2x2 or 2x3, body-only
  • slash arc / weapon trail as a separate fx sheet when the attack needs a wide visual effect
  • impact spark as a separate impact sheet when hits need feedback
• healer overworld NPC -> npc + single_asset or unit_bundle
• large boss idle loop -> creature + idle + 3x3
• wizard throwing a magic orb -> spell_bundle
  • caster cast sheet
  • projectile loop
  • impact burst
• monster line request -> line_bundle
  • plan 1-3 forms
  • per form, make the sheets the request actually needs

2. Write the prompt manually

Use references/prompt-rules.md.

Choose art_style before writing the prompt:

• Use pixel_art or retro_pixel for classic sprites, 16-bit RPG actors, and requests that explicitly ask for pixel art.
• Use clean_hd for map props or assets intended to match clean hand-painted HD maps.
• Use pixel_inspired only when the user wants a pixel-adjacent look without retro chunkiness.
• Use map_style or project-native when an existing map, game, or reference should define the style.

If a reference is involved:

• Make the reference visible first. For local paths, use view_image; for freshly generated references, rely on the image already shown in context.
• State the reference role explicitly: preserve identity/style, create an animation sheet for the same subject, create an evolution/variant, or derive a matching prop/FX.
• Preserve the stable identity markers from the reference: silhouette, palette, face/eye features, costume marks, major accessories, and material language.
• Let only the requested action or evolution change. Do not redesign the subject unless the user asks.
• Still require exact sheet shape, solid magenta background, frame containment, and same scale across frames.

Keep the strict parts:

• solid #FF00FF background
• exact sheet shape
• same character or asset identity across frames
• same camera distance and standing-equivalent anatomical scale across body frames; natural pose bboxes may change, but the model must not zoom individual poses
• explicit containment: nothing may cross cell edges

Mixed-action atlas guardrail:

• Do not ask image_gen to generate unrelated action rows in one raw sheet, such as row 1 idle, row 2 run, row 3 shoot, row 4 jump, for a controllable hero or main character.
• Do not ask image_gen to generate raw single-row action strips such as 1x4 idle, 1x4 run, 1x4 shoot, or 1x4 jump for a controllable hero, character, creature, NPC, enemy, summon, or animated prop.
• If an engine needs a combined 4x4, 5x5, custom atlas, or row-strip delivery format, generate the action grids separately, process and QC them separately, then assemble the delivery atlas deterministically.
• Exceptions are canonical directional locomotion sheets, one continuous long action sequence, prop packs, tileset-like atlases, and low-stakes compact enemy combat sheets. These still need one coherent prompt and visual QC.
• Keep projectile, muzzle flash, impact, dust trails, and detached FX in separate sheets unless they are intentionally part of the same action silhouette and remain tightly attached.
• For controllable heroes and main characters, "tightly attached" is not enough when the effect makes the action bbox much wider or taller than idle/run. Split wide slash arcs, muzzle flashes, long weapon trails, dust clouds, and impact bursts into separate FX sheets by default.

Animated body grid guardrail:

• 1x4 and other raw single-row sheets are not valid defaults for animated bodies. This includes players, controllable heroes, creatures, NPCs, enemies, summons, animated props, and body-attached combat actions.
• Use 2x2 for 4-frame body actions. This is the default for idle, short attack, shoot body, jump, hurt, hover, and compact side-view walk/run actions.
• Use 2x3 for 6-frame body actions such as cast, attack, summon, run, charge, or transformation.
• Use 2x4, 3x3, 3x4, or 4x4 for longer body actions. Prefer a compact grid over a long row.
• For 4-direction top-down walk, 4x4 can remain a raw generation shape because it is a canonical directional locomotion sheet, not four unrelated action rows.
• If final runtime needs a row strip, assemble it after QC from the processed multi-row grid frames.
• Keep the character centered in every cell. The body centerline should stay near the cell center, feet/bottom anchor should stay on the same y-position when visible, and the subject should occupy only the central safe area with generous magenta padding.
• For attack, shoot, cast, charge, and other body actions, the body height should stay close to the accepted idle/run body height. If a fixed-cell runtime is being used, reject body-action output when the body appears more than about 10-15% smaller than idle/run, even if edge_touch_frames is empty.

Map prop pack guardrail:

• Use square 2x2, 3x3, and 4x4 raw prop packs only for compact props such as rocks, shrubs, barrels, crates, lamps, small signs, pots, debris, and small ornaments.
• Do not use square prop packs for wide or collision-critical map objects: floors, platforms, ledges, terrain chunks, bridges, wall runs, ladders, roads, rails, pipes, long spike traps, gates, doors, buildings, large trees, checkpoints, exits, or build pads.
• Use one-by-one generation for unique, large, important, tall, irregular, or collision-aligned props.
• Use 1x3 or 1x4 strips for repeatable platform/floor assets, with left cap, middle repeat, right cap, and optional slope/corner/end variant.
• Use custom wide cells for multiple similar wide objects. The grid must state explicit non-square cell dimensions and must not mix compact props with platform/terrain objects.
• If a square prop pack fails due to edge touch or bad cropping, do not solve it by relaxing QC. Reclassify the object and regenerate with a more suitable sheet shape.

If a layout guide is useful, generate one before calling built-in image_gen:

python scripts/make_layout_guide.py \
  --rows <rows> \
  --cols <cols> \
  --cell-width 384 \
  --cell-height 384 \
  --output <run-dir>/references/<rows>x<cols>-layout-guide.png

Then make the guide visible in the conversation context and tell image_gen to use it only for invisible slot count, spacing, centering, and safe padding. The output must not reproduce guide boxes, safe-area rectangles, center marks, labels, borders, or guide background.

Use layout guides deliberately:

• recommended for prop_pack_3x3, prop_pack_4x4, tileset-like atlases, fixed multi-row animation grids, and non-directional 16-frame action sequences such as casting, summoning, charging, death, or transformation
• optional for 3x3 large idle and high-value showcase loops when previous generations drift in scale or spacing
• not the default for 4x4 four-direction walk sheets, because the guide can make directional poses too conservative; use it only after an unguided run fails layout or edge safety

For grounded high-value character actions, an abstract box guide is weaker than a character anchor sheet. After accepting a neutral/idle master frame, create the anchor sheet:

python scripts/make_anchor_layout.py \
  --input <accepted-master-frame.png> \
  --rows 2 \
  --cols 3 \
  --cell-width 512 \
  --cell-height 512 \
  --subject-height-ratio 0.66 \
  --feet-ratio 0.82 \
  --output <run-dir>/references/attack-anchor-2x3.png

Make both the master frame and anchor sheet visible to built-in image_gen. State that the master locks identity/style and the anchor sheet locks slot positions, camera distance, standing-equivalent scale, body root, feet line, and padding. Ask the model to change only the action poses and never reproduce guides, borders, labels, or separators.

3. Generate the raw image

Use built-in image_gen.

Do not use Three.js, Canvas, SVG, HTML/CSS, PIL drawing, or other code-generated art as the raw sprite source. These are acceptable only for runtime display, debug overlays, deterministic layout guides, or postprocessing already-generated images.

After generation:

• find the raw PNG under $CODEX_HOME/generated_images/...
• copy or reference it from the working output folder
• keep the original generated image in place

4. Postprocess locally

Run scripts/generate2dsprite.py process on the raw image.

The processor is intentionally low-level. The agent chooses:

• rows / cols
• fit_scale
• align
• shared_scale
• component_mode
• component_padding
• scale_strategy
• edge_touch rejection strategy

Use the processor to gather QC metadata, not to make aesthetic decisions for you.

For hero action bundles, process each action grid as its own sheet before any final atlas assembly. Use component_mode=largest for body-only hero grids. Use component_mode=all only for projectile, impact, aura, slash FX, or intentionally detached FX sheets, not for fixed-cell hero body attacks that need stable body scale.

Use --scale-strategy preserve --align feet for grounded hero/player body sheets when the raw art already has acceptable scale but bbox-fit would shrink the character because of a long weapon, extended pose, cape, or integrated melee effect. Preserve mode applies one uniform raw-cell-to-output scale to every frame, including one shared safety margin, then translates each detected subject to the shared anchor. It never applies a different bbox-fit scale per frame. Use the default fit strategy for compact bodies, creatures, projectiles, impacts, and intentionally normalized FX.

For a character with multiple actions, write a scale profile only after an accepted reference action passes QC:

python scripts/generate2dsprite.py process \
  --input <accepted-run-raw.png> \
  --target player --mode run --rows 2 --cols 3 \
  --output-dir <run-dir> \
  --cell-size 128 --fit-scale 0.80 \
  --align feet --scale-strategy preserve --component-mode largest \
  --strict-qc --write-scale-profile <bundle>/character-scale-profile.json \
  --profile-name <character-name> --max-profile-scale-drift 0.08

Process later actions with --scale-profile <bundle>/character-scale-profile.json. Profile values override per-command scale, anchor, trim, and component defaults so actions cannot silently use different output magnification. Keep using the same generation grid geometry and character anchor sheet when possible; a processing profile cannot repair a model-generated anatomy-scale change.

When integrating a processed grid as a Godot Sprite3D, request a world-height contract instead of hand-tuning each action in the game:

python scripts/generate2dsprite.py process \
  --input <raw-sheet.png> \
  --target player --mode idle --rows 2 --cols 3 \
  --output-dir <action-dir> \
  --cell-size 256 --fit-scale 0.84 \
  --align feet --scale-strategy preserve --component-mode largest \
  --strict-qc --max-body-scale-cv 0.08 --max-anchor-y-std 0.05 \
  --duration 125 --godot-world-height 0.70

This writes godot-sprite3d.json beside the frames. The reference action derives recommended_pixel_size from the QC-measured mean subject height and stores it in the scale profile. Later actions processed with that profile reuse the exact pixel size, so crouching, recoil, hurt, and creature silhouette changes remain real pose changes instead of being normalized back to the reference height. The contract also converts the shared output origin to Godot's Sprite3D.offset, lists animation frames, and records timing. Reuse the same world_height and scale profile for every compatible action in one bundle.

After all actions pass QC, build one Godot animation bundle:

python scripts/generate2dsprite.py build-godot-bundle \
  --action idle=<bundle>/idle/godot-sprite3d.json \
  --action move=<bundle>/move/godot-sprite3d.json \
  --action attack=<bundle>/attack/godot-sprite3d.json \
  --action hurt=<bundle>/hurt/godot-sprite3d.json \
  --default-action idle --one-shot attack --one-shot hurt \
  --output <bundle>/godot-sprite3d-bundle.json

The bundle validates cross-action world height and pixel_size, stores relative contract paths, and declares loop versus one-shot playback. Treat a bundle drift failure as an asset-generation or wrong-profile error; do not compensate with per-action runtime scale.

5. QC the result

Check:

• did any frame touch the cell edge
• did any frame resize differently than intended
• did detached effects become noise
• does the sheet still read as one coherent animation
• for hero/player body actions, does the body height match the accepted idle/run scale within roughly 10-15%
• for fixed-cell runtimes, did a wide weapon trail or FX arc shrink the body inside the cell
• for preserve-scale runs, are feet/bottom anchors aligned without any paste_clamped frames
• for grounded high-value body sheets, does qc_summary.body_scale_cv stay at or below about 0.08 and qc_summary.anchor_y_std at or below about 0.05
• for rooted boss idles, do the feet and pelvis remain fixed while motion comes from compression, glow, shoulders, and attached secondary elements
• for ground-contact FX, is the authored ignition/baseline stable even when flame tips, embers, or effect height change
• for multi-action bundles, does qc_summary.profile_body_scale_drift stay within the scale profile limit, normally 0.08

If not, rerun with different processor settings or regenerate the raw sheet.

Strict QC distinguishes raw source-cell contact from processed output contact. Prefer regeneration when a body part is visibly clipped. If visual review confirms the raw subject is complete and only an antialiased or harmless contour touches the source-cell boundary, use --allow-source-edge-touch; it never permits output-edge contact, paste clamping, or empty frames.

For elongated creature attacks, any paste_clamped_frames or output_edge_touch_frames means the raw sheet must be regenerated with the shared-silhouette-envelope contract above. Do not use --allow-source-edge-touch until clamp and processed-output edge contact are both zero and visual review confirms the full snout, paws, weapon, wings, or tail are intact.

For grounded high-value humanoid player/hero body actions, run strict QC after generation-first scale control:

python scripts/generate2dsprite.py process \
  --input <raw-sheet.png> \
  --target player \
  --mode attack \
  --output-dir <out-dir> \
  --rows 2 \
  --cols 3 \
  --align feet \
  --scale-strategy preserve \
  --component-mode largest \
  --strict-qc \
  --max-body-scale-cv 0.08 \
  --max-anchor-y-std 0.05

These numeric gates are for grounded humanoid body actions, not jumps, knockback, projectiles, impacts, floating actors, creatures whose attack strongly changes silhouette/posture, or intentionally changing-scale FX. A failed gate is a regeneration signal; do not hide generation drift with per-frame scale normalization.

For ground-contact FX, prefer component_mode=largest when detached embers would corrupt the contact anchor. Accept a looser action-specific max_anchor_y_std only after visual review confirms a fixed baseline, zero output-edge contact, zero paste clamping, and correct in-engine placement. Do not loosen the grounded-character defaults globally.

Cross-action scale-profile drift is a generation QC signal. Preserve legitimate crouching, recoil, and compressed pose bboxes; inspect borderline hurt or knockback sheets visually instead of applying per-frame resize. For ordinary idle, run, walk, and grounded body attacks, reject unexplained profile drift.

6. Return the right bundle

For a single sheet, expect:

• raw-sheet.png
• raw-sheet-clean.png
• sheet-transparent.png
• frame PNGs
• animation.gif
• prompt-used.txt
• pipeline-meta.json
• optional godot-sprite3d.json when --godot-world-height is supplied
• godot-sprite3d-bundle.json for a multi-action Godot unit

For player_sheet, expect:

• transparent 4x4 sheet
• 16 frame PNGs
• direction strips
• 4 direction GIFs

For spell_bundle or unit_bundle, create one folder per asset in the bundle.

For hero_action_bundle, expect:

• one raw and processed sheet per action
• per-action frame PNGs and GIFs for visual QC
• separate projectile / muzzle / slash / impact assets when the hero shoots, casts, or uses wide melee effects
• optional assembled engine-atlas-transparent.png only after per-action QC passes
• one shared character-scale-profile.json for grounded body actions when cross-action scale consistency matters

Defaults

• idle
  • small or medium actor -> 2x2
  • large creature or boss -> 3x3
• cast -> prefer 2x3
• projectile -> prefer 2x2 for short animated loops; use row strips only when the engine specifically requires a strip, and assemble that strip after QC when practical
• impact / explode -> prefer 2x2
• walk
  • topdown actor -> 4x4 for four-direction walk
  • side-view asset -> 2x2
• controllable hero or main player with multiple actions -> hero_action_bundle
  • generate one action per raw multi-row grid sheet, not as a raw 1x4 strip
  • attack/shoot/cast body sheets are body-only by default; wide slash arcs, muzzle flashes, projectiles, trails, dust, and hit impacts are separate FX/projectile/impact sheets
  • if the weapon must stay integrated and there is no separate FX layer, use --scale-strategy preserve --align feet instead of bbox-fit normalization
  • default 4-frame action grid is 2x2
  • use 2x3 for 6-frame actions and 2x4, 3x3, 3x4, or 4x4 for longer actions
  • do not generate a mixed-action raw 4x4, 5x5, or custom atlas
  • assemble the final atlas only as a deterministic delivery step if the game requires it
• 4x4, 5x5, and custom grids
  • use as raw generation only for one coherent long action sequence, canonical directional locomotion, prop packs, or tileset-like atlases
  • use as delivery atlases for mixed actions only after separate action sheets pass QC
• use shared_scale by default for any multi-frame asset where frame-to-frame consistency matters
• use largest component mode for hero/player body grids; use all for separate FX/projectile/impact sheets
• use scale_strategy=preserve for grounded hero/player melee attacks with integrated weapons or wide body poses that would shrink under bbox-fit normalization; use for normal compact sheets and FX

Resources

• references/modes.md: asset, action, bundle, and sheet selection
• references/prompt-rules.md: manual prompt patterns and containment rules
• scripts/generate2dsprite.py: postprocess primitive for cleanup, extraction, alignment, QC, and GIF export
• scripts/make_anchor_layout.py: repeat an accepted character frame into a fixed scale/root generation template
• scripts/make_layout_guide.py: create abstract geometry-only guides for prop packs and suitable grids