uniform mat4  g_WorldViewProjectionMatrix;
uniform mat4  g_WorldMatrix;
uniform float g_Time;

uniform float m_WindSpeed;
uniform float m_WindStrength;
uniform vec2  m_WindDir;

in vec3 inPosition;
in vec2 inTexCoord;   // echte UV-Koordinaten der Samen-Textur

out vec2 varUV;

void main() {
    vec4 pos = vec4(inPosition, 1.0);

    vec2 worldXZ = (g_WorldMatrix * pos).xz;
    float t = g_Time * m_WindSpeed;

    vec2 windN = (dot(m_WindDir, m_WindDir) > 0.001) ? normalize(m_WindDir) : vec2(0.0, 1.0);
    float wavePhase = dot(worldXZ, windN);
    float randPhase = fract(sin(dot(worldXZ, vec2(127.1, 311.7))) * 43758.5453) * 6.2832;

    float sway = sin(t * 2.1 + wavePhase * 0.10 + randPhase) * 0.6
               + sin(t * 1.4 + wavePhase * 0.06 + randPhase * 0.73) * 0.4;

    // Samen sitzen immer an der Spitze → voller Windfaktor (wf = 1.0)
    float bend = sway * m_WindStrength;
    pos.x += windN.x * bend;
    pos.z += windN.y * bend;

    varUV = inTexCoord;
    gl_Position = g_WorldViewProjectionMatrix * pos;
}