ShaderView

Draws a Metal fragment shader every display frame, like SwiftUI's

<ShaderView ... />

Overview

TimelineView(.animation) around a ShaderLibrary color effect. The source defines fragment float4 name(ShaderVertex in [[stage_in]], constant ShaderInputs &inputs [[buffer(0)]]); inputs carries size (pixels), time (seconds), count and values[256]. Assign values from Lua to animate it. The view is transparent where the shader is. A program can instead be linked from sources, {path = …} files and {code = …} snippets compiled in order as one translation unit, so a shared library, plugin-contributed functions and an entry point can live in separate files. Each chunk opens with a #line directive, so compiler errors name the file and line they came from.

Meshes: with layers, the view first renders draws into that many offscreen HDR layers (RGBA16Float, cleared to transparent black, with a depth buffer), and function finishes the picture from them: layer i is texture2d<float> [[texture(i - 1)]], mipmapped every frame so coarse levels serve as wide blurs. Each draw is a table: vertex, fragment (function names), count (vertices), instances (1), layer (1), primitive (triangle, triangleStrip, line, lineStrip, point), blend (opaque, alpha premultiplied, add), depth (none, test, write), cull (none, back, front), data (floats at const device float *data [[buffer(1)]]) and params (up to 64 floats at constant float *params [[buffer(2)]]). Both stages get inputs at buffer(0). Vertices usually come from vertex_id and instance_id; fullscreenVertex covers the view with ShaderVertex. Assigning draws compiles their pipelines, and a bad list raises without replacing the running one.

Topics

Properties

Name	Type	Required	Description
source	string	optional	Path of a .metal file with the fragment function.
sources	table	optional	<ShaderSource path="…"> / <ShaderSource code="…"> chunks, in order.
function	string	required	Fragment function name; with layers, the finishing pass.
values	table	optional	Initial floats for inputs.values.
layers	number	optional	Offscreen layers the draws render into, 0…4 (0).
draws	table	optional	Mesh passes, in order (see above).
onClick	function	optional	onClick(view, x, y) in the view's top-left points.
onScroll	function	optional	onScroll(view, dx, dy) in points, the user's scrolling direction applied.

Platform notes

• AppKit.

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Source: lua/ui/shader.lua:14 (ns.ShaderView)