Wisp

Wisp is the master card shader. Anything you’d render on a quad that has to face the camera and not look like a quad — smoke, dust, fire, splashes, distant foliage, magic — goes through it.

A billboard is an illusion, and every problem with it is a moment where the illusion breaks. Wisp is mostly a collection of solutions to those moments.

Animation

• Flipbooks. Point it at an atlas, set the grid, set the frame rate. Frames are always blended into each other, so a short animation doesn’t strobe — you can ship a 16-frame smoke puff and have it read as smooth.
• Seamless loops. Fade the card in at the start of its cycle and out at the end, and a looping effect stops announcing where the loop is.
• No marching in step. Turn on world-position randomisation and every instance starts at a different point in the animation, with no per-instance setup and no scripting.
• Manual control. Scrub the animation by hand from a script when you want the timing to follow gameplay instead of the clock.
• Scrolling textures for effects that don’t need a flipbook at all.

Flow

Flow maps distort the card over time, in two modes:

• Distortion — the texture churns and warps continuously. Good for smoke, fog and fire, and it never pops as it cycles.
• Optical flow — a low-frame-count flipbook is interpolated along real motion, so it moves like a high-frame-rate one without the memory cost of the extra frames.

Wind

A wind field drifts and warps the card independently of everything else, with its own speed, scale and intensity. Cards in a group sway together instead of each doing its own thing, so a stand of foliage moves like one plant rather than fifty.

Hiding the illusion

The part that matters:

• Soft intersections — smoke meets the floor instead of slicing into it.
• Fade on approach — the card dissolves as the camera walks into it, rather than filling the screen.
• Fade at distance — cards can be culled far away without a visible pop.
• Fade at extreme angles — a billboard gives itself away when you see it edge-on, so past a threshold it fades out.
• Facing behaviour past a threshold — instead of pivoting forever to face you, the card can compensate in a way that stays convincing from above.
• Soft edges — a rounded mask so the quad’s corners never show.

Each of these has its own transition control, so you tune where it starts and how sharply it happens.

Lighting

Cards take a normal map for real surface detail, and a roundness control that makes a flat quad shade like a volume — a puff of smoke lights from the side like a sphere, not like a poster. Combined with proper alpha handling, cards light and self-shadow plausibly from any direction.