shader_type canvas_item;

// Parameters
uniform sampler2D water_texture;      // Your 3x3 water texture
uniform vec4 water_color : source_color = vec4(0.0, 0.0, 1.0, 1.0);
uniform float speed : hint_range(0.0, 10.0) = 1.0;
uniform float strength : hint_range(0.0, 0.2) = 0.05;
uniform float tile_repeat : hint_range(1.0, 10.0) = 3.0;
uniform vec2 pan_speed = vec2(0.2, 0.1); // how fast the water texture moves

void fragment() {
    vec2 uv = UV;

    // Sample the base tile texture
    vec4 base_tex = texture(TEXTURE, uv);

    // Compute mask for water pixels only
    float is_water = step(0.8, 1.0 - distance(base_tex.rgb, water_color.rgb));

    // Tile the water texture
    vec2 water_uv = uv * tile_repeat;
	water_uv = fract(water_uv);

    // Apply panning / movement
    water_uv += pan_speed * TIME;

    // Add wave distortion on top of the moving texture
    water_uv.y += sin(water_uv.x * 2.0 + TIME * speed) * strength * is_water;
    water_uv.x += cos(water_uv.y * 2.0 + TIME * speed * 0.5) * strength * is_water;

    // Sample the animated water texture
    vec4 water_sample = texture(water_texture, water_uv);

    // Combine: water animates, other pixels stay the same
    COLOR = mix(base_tex, water_sample, is_water);
}