Perfect Vector: Advanced VFX Motion Vector Generator

A flipbook played at a low frame rate either stutters (hard cuts) or ghosts (a cross-fade doubles every moving edge). Perfect Vector bakes a motion-vector texture for your flipbook in the Unity Editor, and its shaders move the pixels along those vectors. A 6×6 fireball made for 8 fps flows smoothly at 60 fps and in slow motion.

You don't need Houdini, After Effects or a command-line tool. Pick the atlas, preview the blend, save the textures and put the generated material on a Particle System.

Key advantages

• Pixels move between frames instead of cross-fading, so moving edges don't double.
• Built for VFX: fire, smoke, explosions and glowing effects, with straight alpha or on a black plate, and HDR EXR input.
• One motion texture per flipbook: the blend reads three textures per pixel.
• You bake, preview and compare entirely in the Unity Editor.
• Ready for Particle Systems (Built-in, URP, HDRP) and VFX Graph (URP, HDRP).

Bake in the editor

• Motion Vector Generator window: a flipbook atlas (up to 64×64 cells) or a start and an end frame.
• Live preview: play and scrub the blend, then compare it with the source frames, a plain cross-fade or the motion vectors themselves.
• The defaults work on most flipbooks. Max quality is for final art; High and Fast are for quick iteration.
• Coverage from the texture's alpha, or from the background: black for additive effects, white, any flat color, or a baked transparency checkerboard. Auto picks one for you.
• Sequence Edge Smoothing calms the first and last frames, where a tiny spark grows into a fireball or a shape collapses.
• Loop Last Frame To First for seamless loops.
• A progress window counts the solved frame pairs, and Cancel stops the bake without writing files.

The solver

• Each frame pair is solved forward and backward, and both are fused into one motion field.
• Coarse-to-fine search over an image pyramid catches large motion first, then refines it at full resolution. The search range adapts to each frame pair, up to 128 px.
• Structural (census) and photometric matching tolerate the brightness changes of emissive effects.
• PatchMatch spatial propagation and a dense sub-pixel refinement keep the motion inside each shape consistent.
• Cleanup removes speckles and fills holes without dragging the background along.
• Native, multithreaded code that gives the same result for any thread count.

Output

• 16-bit EXR (recommended) or 8-bit PNG with sub-pixel precision.
• Optionally, a motion-vector map in Unity VFX Graph's own format for its 'FlipbookMotionBlend' UV mode.
• When the bake finishes, a ready-to-use particle material is one click away.

Runtime

• Particle System shaders 'Perfect Vector/Particles/Unlit' and 'Lit' for Built-in, URP and HDRP. HDRP Lit goes through a generated Shader Graph that keeps HDRP's own lighting, fog and exposure.
• Shader Graph nodes for your own graphs:
• Flipbook
• Flipbook Lit (normal and mask maps warped with the color)
• Flipbook Six-way
• Sprite UV
• Create-menu templates:
• Particle Unlit Shader Graph for every pipeline
• Unlit, Lit and Six-way particle Shader Graphs for VFX Graph
• Each material switches between Perfect Vector, Linear Blend and Hard Flipbook.
• Follows your quality settings: soft particles, fog, reduced texture quality, and URP Forward+, Deferred+, light cookies and probe blending.
• Validate Runtime Integration checks shader names, material properties, keywords, compiler messages and the color space.

Samples and documentation

• Three HDR flipbooks from Bark Button (circle, fireball and seamless fire loop; 6×6 frames of 512 px), with their baked motion vectors.
• One Particle System scene per pipeline: Linear Blend, the Perfect Vector shader and its Shader Graph side by side, each ready as a prefab.
• VFX Graph scenes for URP and HDRP. The unlit row plays the fireball as a hard flipbook, with linear blend, with VFX Graph's motion-vector blend and with Perfect Vector; a six-way lit row follows.
• An artist guide and a quick start guide (PDF).

Ideal for

• Smooth playback of low-frame-rate flipbooks and sprite-sheet effects.
• Fewer frames per atlas, and less texture memory, for the same smoothness.
• Slow-motion explosions, fire and smoke.
• Hand-drawn or rendered VFX on 60 and 120 fps displays.
• VFX Graph projects that need baked vectors for `FlipbookMotionBlend`.
• Custom flipbook shaders built from the Shader Graph nodes.