//SPDX-License-Identifier: MIT
//SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

// HDRBloom blur pass (PlainComputeShader). Box-blurs the thresholded bloom
// mip into a second rgba16float target — demonstrating an N-target float
// chain: this pass SAMPLES the texture the threshold pass wrote (storage
// write → sampled read across a submit barrier) and WRITES another
// user-owned float storage texture. Two such targets prove the mip-pyramid
// shape a real bloom needs.
//
// Layout mirrors threshold.comp.wgsl (src = bloom mip A, dst = bloom mip B).

struct Dim { w: u32, h: u32, _0: u32, _1: u32 };
@group(0) @binding(0) var<uniform> dim : Dim;
@group(1) @binding(0) var src : texture_2d<f32>;
@group(1) @binding(1) var dst : texture_storage_2d<rgba16float, write>;

const R: i32 = 6;   // box radius → 13×13 kernel; a wide, cheap glow

@compute @workgroup_size(8, 8, 1)
fn main(@builtin(global_invocation_id) gid: vec3<u32>) {
    if (gid.x >= dim.w || gid.y >= dim.h) { return; }
    let maxX = i32(dim.w) - 1;
    let maxY = i32(dim.h) - 1;
    var sum = vec3<f32>(0.0);
    var count = 0.0;
    for (var dy = -R; dy <= R; dy = dy + 1) {
        for (var dx = -R; dx <= R; dx = dx + 1) {
            let x = clamp(i32(gid.x) + dx, 0, maxX);
            let y = clamp(i32(gid.y) + dy, 0, maxY);
            sum = sum + textureLoad(src, vec2<i32>(x, y), 0).rgb;
            count = count + 1.0;
        }
    }
    textureStore(dst, vec2<i32>(i32(gid.x), i32(gid.y)), vec4<f32>(sum / count, 1.0));
}