#version 450 core
#include "common.glsl"

layout(location = 0) in vec3 aPos;
layout(location = 1) in vec3 aNormal;
layout(location = 2) in vec2 aUV;
layout(location = 3) in vec4 aColor;      // rgb = tint/AO, a = wind weight
layout(location = 4) in vec4 iPosYaw;     // pivot xyz, yaw
layout(location = 5) in vec4 iScaleTint;  // scale xyz, tint

uniform float uWindScale;

out VS {
    vec3 worldPos;
    vec3 normal;
    vec2 uv;
    vec3 color;
    float height;  // above the model's base (ground contact AO)
} o;

void main() {
    float c = cos(iPosYaw.w), s = sin(iPosYaw.w);
    vec3 lp = aPos * iScaleTint.xyz;
    vec3 p = vec3(c * lp.x + s * lp.z, lp.y, -s * lp.x + c * lp.z) + iPosYaw.xyz;
    vec3 ln = aNormal / iScaleTint.xyz;
    vec3 n = normalize(vec3(c * ln.x + s * ln.z, ln.y, -s * ln.x + c * ln.z));

    float w = aColor.a * uWindScale;
    if (w > 0.0) {
        vec3 pivot = iPosYaw.xyz;
        float ph = dot(pivot.xz, vec2(0.37, 0.61));
        vec2 wdir = normalize(uWind.xy + 1e-5);
        float gust = vnoise(pivot.xz * 0.12 - wdir * uTime * uWind.w * 0.6);
        // Whole-crown sway grows with height; leaves add a fast, small flutter.
        float sway = (sin(uTime * 1.1 + ph) * 0.5 + sin(uTime * 1.9 + ph * 1.3) * 0.25 + gust * 1.2) * uWind.z;
        float h = max(lp.y, 0.0);
        p.xz += wdir * sway * w * h * 0.35;
        // Leaf flutter scales with wind strength, so storms visibly thrash the canopy.
        p += n * sin(uTime * (3.0 + uWind.w * 2.0) + dot(aPos, vec3(7.1, 11.3, 5.7)) + ph) * 0.4 * uWind.z * w;
        // Low foliage (bushes) parts around the player like the grass does.
        vec3 toP = p - uInteractor.xyz;
        float d = length(toP.xz);
        float push = clamp(1.0 - d / (uInteractor.w * 1.3), 0.0, 1.0) * step(abs(toP.y), 1.2);
        p.xz += (d > 1e-3 ? toP.xz / d : vec2(0.0)) * push * 0.3 * w;
    }

    o.worldPos = p;
    o.normal = n;
    o.uv = aUV;
    o.color = aColor.rgb * iScaleTint.w;
    o.height = lp.y;
    gl_Position = uViewProj * vec4(p, 1.0);
    gl_ClipDistance[0] = dot(vec4(p, 1.0), uClipPlane);
}