2D的烫金字shader。

shader_type canvas_item;

uniform float time_speed : hint_range(0.0, 10.0) = 2.0;
uniform vec4 flame_color1 : source_color = vec4(1.0, 0.4, 0.0, 1.0);
uniform vec4 flame_color2 : source_color = vec4(1.0, 1.0, 0.2, 1.0);
uniform float noise_scale : hint_range(0.1, 10.0) = 3.0;
uniform float distortion_strength : hint_range(0.0, 1.0) = 0.3;
uniform float flame_height : hint_range(0.5, 2.0) = 1.0;

float rand(vec2 n) {
    return fract(sin(dot(n, vec2(12.9898, 78.233))) * 43758.5453);
}

float noise(vec2 p){
    vec2 ip = floor(p);
    vec2 u = fract(p);
    u = u*u*(3.0-2.0*u);
    float res = mix(
        mix(rand(ip), rand(ip+vec2(1.0,0.0)), u.x),
        mix(rand(ip+vec2(0.0,1.0)), rand(ip+vec2(1.0,1.0)), u.x),
        u.y);
    return res;
}

void fragment() {
    // 时间循环
    float t = mod(TIME * time_speed, 100.0);

    vec2 uv = UV;
    uv.y += t;

    // 噪声扰动
    float n = noise(uv * noise_scale);
    float distort = n * distortion_strength;

    // 火焰颜色渐变
    vec4 fire = mix(flame_color1, flame_color2, fract(uv.y * flame_height + distort));

    // 顶部渐隐
    float fade = smoothstep(1.0, 0.2, fract(uv.y + distort));

    // 获取文字纹理的原始颜色
    vec4 text_color = texture(TEXTURE, UV);

    // 将火焰效果应用于文字颜色
    vec3 final_color = text_color.rgb * fire.rgb * fade;

    // 保留文字的 Alpha
    float alpha = text_color.a;

    COLOR = vec4(final_color, alpha);
}