shader_type canvas_item;

uniform sampler2D trail_tex;

uniform float sensor_distance = 2.0;
uniform float sensor_angle = 15.0;
uniform float rotation_angle = 23.0;
uniform float move_distance = 2.67;
uniform float decay_factor = 0.75;

void fragment() {
    vec2 uv = UV;
    // Read current trail value
    vec4 trail = texture(trail_tex, uv);
    // Apply decay
    trail *= decay_factor;
    
    COLOR = trail;
}