// SPDX-FileCopyrightText: 2026 fuddlesworth
// SPDX-License-Identifier: LGPL-2.1-or-later
//
// Crosshatch transition — ported from liixini/shaders niri shader
// (https://github.com/liixini/shaders/tree/main/crosshatch). Crosshatch
// reveal — random diagonal threshold with radial falloff from center.
//
// Niri's crosshatch ships symmetric close.glsl/open.glsl. PlasmaZones'
// runtime flips iTime on reverse legs (1→0 on close, 0→1 on open),
// so we use the niri OPEN body verbatim with `niri_clamped_progress`
// translated to `clamp(iTime, 0.0, 1.0)` and the runtime flip
// auto-mirrors the visual on close — no iIsReversed branch needed.
//
// niri's `niri_geo_to_tex` is the identity mat3 in PlasmaZones (geometry
// == texture coords here), so the matrix multiply is dropped and
// `texture(uTexture0, uv)` samples directly. `texture2D` (GLSL ES) is
// rewritten to `texture` (GLSL 4.50 core) inline.

#version 450

#include <animation_uniforms.glsl>

// metadata.json declaration order → customParams[0] sub-slots
#define radialFalloff customParams[0].x
#define edgeFade      customParams[0].y

layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 fragColor;

float crosshatch_rand(vec2 co) {
    return fract(sin(dot(co.xy, vec2(12.9898, 78.233))) * 43758.5453);
}

void main() {
    // ── niri OPEN body (handles both legs via runtime iTime flip) ──
    float p = clamp(iTime, 0.0, 1.0);
    vec2 uv = vTexCoord;
    vec4 win = surfaceColor(uv);

    vec2 center = vec2(0.5);
    float dist = distance(center, uv) / radialFalloff;
    float r = p - min(crosshatch_rand(vec2(uv.y, 0.0)), crosshatch_rand(vec2(0.0, uv.x)));
    float reveal = mix(0.0, mix(step(dist, r), 1.0, smoothstep(1.0 - edgeFade, 1.0, p)), smoothstep(0.0, edgeFade, p));

    fragColor = win * reveal;
}
