Reference

Per-mode notes

• Bone stores a (numBones × (frames + 1)) RGBA32F texture pair (position + axis-angle rotation). Row 0 = ref pose, rows 1+ = animated. Bone weights live in UV3/UV4 of the static mesh; bone indices in UV1/UV2 (half-pixel centred). Linear blend skinning runs entirely on the GPU.

• Vertex stores one row per vertex per frame (with multi-row per frame for high-vertex-count meshes — RowsPerFrame > 1). Per-vertex offset (delta from rest) + per-vertex normal. Heavier than Bone but captures any deformation.

• Alembic auto-detects topology stability across the playback. Constant topology → delta encoding (smaller, smoother). Dynamic topology → absolute-position encoding via _USE_ABSOLUTE_POSITIONS keyword + _VAT_LocalBoundsMin/Max.

• Sprite captures up to 1024 unique particles using Particle.randomSeed as a stable ID. Quad-grid mesh, camera-facing billboard shader (unity_CameraToWorld._m00_m10_m20 columns).

• VFX Graph Sprite uses EQVATVFXGraphCaptureSource as an explicit capture bridge. Production graphs must emit output events with stable particle id, position, color, size, and alive attributes; the procedural fixture mode exists only for validation scenes and tests. See Documentation/VFXGraphOutputEventContract.md for the exact graph contract.

Texture import settings (validation)

VAT data textures must have:

• Filter Mode = Point (no bilinear bleeding between vertices/frames/pieces)
• sRGB = OFF (linear)
• Mip Maps = OFF
• NPOT Scaling = None
• Compression = Uncompressed
• Wrap Mode = Clamp

For Houdini VAT 3 imports, use the Import Wizard’s Auto-Detect VAT 3 button on the export folder. It reads the .mat companion when present, pulls bounds/FPS/frame metadata, and wires EQVAT URP shaders rather than SideFX shadergraphs. For a guided first import, open Demo/URP/EQVATLab_HoudiniImport_Demo.unity, assign your export folder, and press Import + Place.

The Import Wizard’s Validate button checks all of the above; Auto-Fix Textures rewrites the importer settings + reimports. The EQVAT bakers write textures with these settings already applied — you only need Validate / Auto-Fix when bringing in textures baked from a different tool (e.g. Houdini SideFX VAT export).

Material parameters

Property	Type	Notes
_VAT_Speed	Float	Playback speed multiplier. 1.0 = native, 0.5 = half-speed
_VAT_FrameRate	Float	Source FPS, set by the baker
_VAT_HoudiniFPS	Float	Source FPS for Houdini VAT 3 import shaders
_VAT_TotalFrames	Float	Number of animation frames
_VAT_DisplayFrame	Float	If ≥ 0, freeze on this frame (useful for debugging)
_VAT_PositionBound	Float	Magnitude cap for delta-mode encoding
_VAT_LocalBoundsMin/Max	Vector	Used by Alembic absolute mode + Houdini import shaders
_BaseMap, _BumpMap, _BaseColor, _BumpScale, _Smoothness, _Metallic	Standard URP Lit-style surface inputs

Motion vectors

All EQVAT URP master shaders ship a hand-authored MotionVectors pass that recomputes the VAT WPO at _Time.y - unity_DeltaTime.x and outputs the screen-space delta against the current frame. This is required for TAA / DLSS / TSR; without it, VAT meshes ghost or smear under temporal anti-aliasing.

One documented exception: the Fluid shader’s MotionVectors pass renders the deformed surface for correct coverage but writes zero motion for the deformation itself — a fluid cache’s topology changes between frames, so per-vertex motion cannot be reconstructed and a wrong vector smears worse than none. Camera motion is still correct; fast fluid surfaces may show mild TAA softening.

GPU instancing and per-instance tint (Bone / Vertex)

The Bone and Vertex master shaders declare their per-instance playback state (_VAT_DisplayFrame, _VAT_PrevDisplayFrame, _VAT_Speed, _VAT_FrameRate, _VAT_TotalFrames) plus _VAT_InstanceTint in a GPU instancing buffer, and the bakers enable instancing on the materials they generate. That means the per-instance values a playback controller writes through a MaterialPropertyBlock are gathered into instanced draws instead of forcing a separate draw call per character — which is what makes large crowds cheap.

The crowd demo at an Instance Count of 2,000: every soldier from one bake and one shared material.

The crowd demo's phase debug view: each hue is where that soldier is in its walk.

Set _VAT_InstanceTint through a MaterialPropertyBlock to vary colour per character without cloning materials. Writing _BaseColor per renderer instead works visually but is a material-level property, so it costs the instancing.

Trade-off worth knowing: instanced properties cannot live in the UnityPerMaterial buffer, so these two shaders are not SRP Batcher compatible. For crowds this is a large net win; the other master shaders (Alembic, Sprite, VFX Graph, Houdini) are untouched.

Runtime playback

Add EQ VAT Playback Controller to a generated prefab instance when you need deterministic per-instance playback. The controller writes _VAT_DisplayFrame, _VAT_Speed, _VAT_FrameRate, _VAT_HoudiniFPS, and _VAT_TotalFrames through MaterialPropertyBlock, so many instances can run different phases without cloning materials. It supports loop, one-shot, manual frame, clip frame ranges, random start frame, start delay, and completion events.

EQVATSocketTracker can reference the controller directly so sockets sample the same frame that the renderer displays.

Bake budgets

The Baker tab includes a Quality Profile selector and optional max texture width override. Profiles drive the estimate line before baking and the allocation clamp inside each native baker:

Profile	Max width	Max height	Texture memory budget
Preview	2048	4096	256 MB
Production	4096	8192	1024 MB
Cinematic	8192	8192	2048 MB
Mobile	2048	4096	128 MB

Each bake report records source element count, texture count, estimated texture bytes, bake duration, and managed memory delta.

Managing generated output

The Manager tab: it finds every baked set in the project, shows the selected set's mode, frames, texture layout and memory, and flags a bake whose source changed after it was made.

With a bake’s _VATMeta.asset (or any of its generated assets) selected in the Project view:

• Tools → EQLabs → EQ VAT Lab → Generation → Regenerate Selected Output re-runs the bake that produced it, using the recorded source and settings.
• Tools → EQLabs → EQ VAT Lab → Generation → Clean Selected Output moves the bake’s generated assets to the system trash (recoverable from the OS recycle bin) after a confirmation listing exactly what will go.