shader_type canvas_item;

uniform float time_scale : hint_range(0.1, 5.0) = 1.0;
uniform float fog_intensity : hint_range(0.0, 1.0) = 0.8;

// 噪声函数
float noise(vec2 uv) {
    return fract(sin(dot(uv, vec2(12.9898, 78.233))) * 43758.5453);
}

float fbm(vec2 uv) {
    float value = 0.0;
    float amplitude = 0.5;
    float frequency = 1.0;

    for(int i = 0; i < 4; i++) {
        value += amplitude * noise(uv * frequency);
        amplitude *= 0.5;
        frequency *= 2.0;
    }
    return value;
}

void fragment() {
    vec2 uv = UV;
    float time = TIME * time_scale;
	float sin_time_x = sin(time * 2.1) * 0.15 + 2.0;
	float sin_time_y = sin(time * 3.5) * 0.15 + 2.0;

    // 基础轮廓
    vec2 center = vec2(0.5, 0.5); // 重心稍微偏上
    float body_shape = 1.0 - length((uv - center) * vec2(sin_time_x, sin_time_y));
	float base_shape = smoothstep(0.0, 0.8, body_shape);

    // 飘动的雾气效果
    float fog_noise = fbm(uv * 5.0 + vec2(time * 0.3, time * 0.2));
    fog_noise = mix(fog_noise, fbm(uv * 9.0 - vec2(time * 0.4, 0.0)), 0.5);

    // 组合形状和噪声
    float final_alpha = base_shape * fog_noise * fog_intensity;

    //// 添加边缘发光效果
    //float edge_glow = 0.6 - smoothstep(0.0, 0.4, abs(base_shape - 0.3));
    //final_alpha += edge_glow * 0.02;

    // 最终颜色
    COLOR.rgb = vec3(0.0);
	COLOR.a = final_alpha * 2.5;
}