add random start for train o start from a stop

core/daynight/weather_overlay.gdshader

@@ -9,6 +9,7 @@ global uniform float global_snow_melt_speed        = 0.1;
 global uniform float global_snow_threshold         = 0.5;
 global uniform vec4  global_snow_color             = vec4(0.92, 0.96, 1.0, 1.0);
 global uniform float global_snow_max_accumulation  = 0.72;
+global uniform float global_snow_cap_enabled       = 1.0;
 global uniform float global_snow_cap_height        = 0.06;
 global uniform float global_snow_cap_flatness_start = 0.72;
 global uniform float global_snow_cap_flatness_end  = 0.96;
@@ -92,6 +93,7 @@ void vertex() {
     float snow_amount = get_snow_amount();
     vec3 world_pos = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
     vec3 world_normal = normalize((MODEL_MATRIX * vec4(NORMAL, 0.0)).xyz);
+    float snow_cap_enabled = step(0.5, global_snow_cap_enabled);
 
     float flat_surface = smoothstep(
         max(global_snow_threshold, global_snow_cap_flatness_start),
@@ -103,7 +105,7 @@ void vertex() {
     float cap_variation = mix(1.0 - global_snow_cap_noise_strength, 1.0 + global_snow_cap_noise_strength, cap_noise);
 
     v_snow_amount = snow_amount;
-    v_snow_cap_mask = flat_surface * accumulation_growth * cap_variation;
+    v_snow_cap_mask = flat_surface * accumulation_growth * cap_variation * snow_cap_enabled;
 
     VERTEX += NORMAL * (global_snow_cap_height * snow_amount * v_snow_cap_mask);
 }