# wf_particle
Waterfall particle card: mist, foam and droplet looks selected by `mode`, with sun forward-scatter
and a view-dependent rainbow, premultiplied output and a soft depth fade. One shader draws the whole
spray family:
- Mode 0, mist: big soft camera-facing cards (`zero_billboard`). A four-octave `fx_noise` fBm,
offset per particle and drifting with time, billows a round puff. It is lit by the ambient light
and by the sun through a Henyey-Greenstein phase (g 0.62), so the mist glows when the sun is
behind it. The rainbow lives in these cards: a band 42 degrees from the anti-solar point, about
1.7 degrees half-width, red outside and violet inside, scaled by `rainbow`.
- Mode 1, foam: bright bubbly clumps on camera-facing cards. Worley cells drift through a ragged
disc, lit by ambient and sun light.
- Mode 2, droplet: a teardrop on a card turned onto its motion (`zero_billboard_streak`), with a fat
head leading along +Y and a tail thinning to a hair, plus a sun glint on the head when the sun is
behind it.
- Mode 3, flat foam: the foam look on a card lying on the water, its right along world X and its up
along world Z (`zero_card_clip`).
Every card dissolves into whatever is drawn behind it over `depth_fade` (`zero_scene_depth_fade`),
so cards blend softly where they meet rock or water. The output is premultiplied: the colour, scaled
by `energy`, carries its own coverage, and the rainbow and glint add on top.
Three graphs beside it in `waterfall/` draw with it, all premultiplied with culling off and depth
writes off, and in the Procgen Effects Showcase world the `fx_falls` scene places them: `wf_mist` (mode 0, `opacity` from its `density` input, default
0.7, `energy` 1.7, `depth_fade` 2.2, `rainbow` from its `rainbow` input, default 1.0), `wf_foam`
(mode 1, `depth_fade` 0.9, `rainbow` 0) and `wf_spray` (mode 2, `depth_fade` 0.6, `rainbow` 0). Each
writes `data0` from a colour ramp over life and `data1` as (particle id, life, 0).
The shader includes `@builtin::shaderModules.billboard`, `fx_noise` and `zero::scene_depth`.
## Properties
| Property | Type | Default | Meaning |
|---|---|---|---|
| `mode` | float | 0 | Look selector, range 0 to 3: mist, foam, droplet, flat foam. |
| `opacity` | float | 1 | Multiplies the coverage (range 0 to 4). |
| `energy` | float | 1 | Multiplies the lit colour (range 0 to 8). |
| `depth_fade` | float | 1.2 | Distance over which a card fades into the surface behind it (range 0 to 10). |
| `rainbow` | float | 0.6 | Strength of the rainbow in mist cards (range 0 to 4). |
| `vertexBoundsDilation` | float | 11 | How far the vertex hook moves a vertex past the mesh, in world units: the culling bounds grow by it so a moved vertex stays inside them. |
## Lanes
| Lane | Carries |
|---|---|
| `data0.rgb` | Colour, multiplied by the lighting. |
| `data0.a` | Opacity over life. |
| `data1.x` | Particle id; its low 16 bits seed the per-card noise offsets. |
| `data1.y` | Life, 0 to 1. |
| `data1.z` | Spin phase, as the shader header names it; the graphs write 0. |
# effectShowcase
The procedural effects of the Procgen Effects Showcase world. Each one is a `.procGraph` that plays
through a `Generator`, and every shader, material and module a graph draws with sits beside it in
this package, so the package carries everything its graphs need. Each graph's README says what it
makes, how to place it and what each of its inputs changes.
## Contents
| Folder | Graphs | What they make |
|---|---|---|
| `combat/` | `impact`, `muzzleFlash`, `tracer` | A round striking a hard surface, the bloom at a barrel as a weapon fires, and the glowing streak of a round in flight. They draw with `fxFlash`, `fxSmoke` and `fxSpark` in `combat/shaders/`. |
| `blast/` | `wall_blast` | A charge blowing a breach through a stone block wall, on a 9.6 s loop. |
| `storm/` | `storm`, `tower` | A thunderstorm around a lone tower: wind-driven rain, lightning striking on the schedule `schedule.module` keeps, and sparks and smoke where strikes land. `tower` is the stone keep it stands around. |
| `rift/` | `arcane_rift` | A rift tearing open in the ground, its motes and rubble moved by the compute shaders in `rift/compute/`. |
| `dragon/` | `dragon_breath` | A dragon's fire breath sweeping a courtyard: a flame jet, rolling smoke and drifting embers. |
| `launch/` | `launch` | A heavy-lift rocket liftoff on one looping timeline, with the heat-haze material `rk_haze_mat`. |
| `waterfall/` | `wf_env`, `wf_water`, `wf_spray`, `wf_foam`, `wf_mist` | A waterfall built in parts: the cliff, basin and boulders, the falling and still water, the droplets, the foam where the falls land, and the mist with its rainbow. Its water materials are in `waterfall/materials/`. |
| `shaders/` | | `fx_noise`, the noise functions the waterfall and wall blast shaders include. |
## Playing one
A graph plays on a `Generator` component bound to it:
```lua
-- `graph` is the graph's reference: the AssetRef `asset.resolve` or a search returns for it.
local e = entity.spawn("impact", { position = { 0, 1, 0 } })
e.component.add("Generator", { graph = graph, playOn = "load" })
```
Set a graph's inputs with the Generator's `params`, e.g. `params = { size = 3 }`.