From 533da47f2cc03a8b60a7c6c0bb5a938a7e523a03 Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Thu, 20 Aug 2026 23:20:21 -0700
Subject: particles

---
 src/shader/particle.wgsl | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 src/shader/particle.wgsl

(limited to 'src/shader/particle.wgsl')

diff --git a/src/shader/particle.wgsl b/src/shader/particle.wgsl
new file mode 100644
index 0000000..704cfbe
--- /dev/null
+++ b/src/shader/particle.wgsl
@@ -0,0 +1,46 @@
+struct Camera {
+    scale: vec2f,
+    centre: vec2f,
+};
+
+struct Particle {
+    position: vec2f,
+    data: u32,
+};
+
+@group(0) @binding(0) var<uniform> camera: Camera;
+@group(0) @binding(1) var<storage, read> palette: array<vec4f>;
+@group(0) @binding(2) var<storage, read> particles: array<Particle>;
+
+struct VertexOutput {
+    @builtin(position) clip_position: vec4<f32>,
+    @location(0) world: vec2<f32>,
+    @location(1) @interpolate(flat) instance: u32,
+};
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) i: u32,
+    @builtin(instance_index) n: u32,
+) -> VertexOutput {
+    let particle = particles[n];
+
+    // (0,0),(1,0),(0,1),(1,1)
+    let corner = vec2<f32>(f32(i & 1u), f32((i >> 1u) & 1u));
+    let world = particle.position + corner;
+
+    var out: VertexOutput;
+    out.clip_position = vec4f((world - camera.centre) * camera.scale, 0.0, 1.0);
+    out.world = world;
+    out.instance = n;
+
+    return out;
+}
+
+@fragment
+fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
+    let particle = particles[in.instance];
+    // TODO can pack more in here and shift
+    let c = palette[particle.data];
+    return c;
+}
-- 
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