fix snow

core/daynight/tree_leaves.gdshader

@@ -6,10 +6,11 @@ global uniform vec2  global_wind_direction;
 global uniform float global_wind_scale;
 global uniform float global_wind_strength;
 global uniform float global_wind_fade;
-global uniform float global_snow_start_time;
-global uniform float global_snow_accumulation_speed;
-global uniform float global_snow_melt_time;
-global uniform float global_snow_melt_speed;
+global uniform float global_snow_start_time = -1.0;
+global uniform float global_snow_accumulation_speed = 0.005;
+global uniform float global_snow_melt_time = -1.0;
+global uniform float global_snow_melt_speed = 0.1;
+global uniform float global_snow_amount = 0.0;
 global uniform vec4  global_snow_color;
 global uniform float global_rain_intensity;
 
@@ -30,6 +31,7 @@ uniform float light_steps : hint_range(1.0, 10.0) = 4.0;
 uniform float random_mix : hint_range(0.0, 1.0) = 0.3;
 uniform float cast_shadow_strength : hint_range(0.0, 1.0) = 0.6;
 uniform float wetness_darkening : hint_range(0.0, 0.5) = 0.25;
+uniform float snow_visibility : hint_range(0.0, 1.0) = 1.0;
 
 varying vec3 v_final_color;
 varying float v_shade_factor;
@@ -40,6 +42,21 @@ float hash(vec3 p) {
     return fract((p.x + p.y) * p.z);
 }
 
+float get_snow_progress() {
+    float snow_progress = clamp(global_snow_amount, 0.0, 1.0);
+
+    if (global_snow_start_time >= 0.0) {
+        float timed_progress = clamp((TIME - global_snow_start_time) * global_snow_accumulation_speed, 0.0, 1.0);
+        snow_progress = max(snow_progress, timed_progress);
+    }
+    if (global_snow_melt_time >= 0.0) {
+        float melt = clamp((TIME - global_snow_melt_time) * global_snow_melt_speed, 0.0, 1.0);
+        snow_progress = min(snow_progress, 1.0 - melt);
+    }
+
+    return snow_progress;
+}
+
 void vertex() {
     vec3 instance_pos = MODEL_MATRIX[3].xyz;
 
@@ -88,17 +105,10 @@ void fragment() {
     vec4 tex = texture(alpha_texture, shifted_uv);
 
     // Snow accumulation
-    float snow_amount = 0.0;
-    if (global_snow_start_time >= 0.0) {
-        snow_amount = clamp((TIME - global_snow_start_time) * global_snow_accumulation_speed, 0.0, 1.0);
-    }
-    if (global_snow_melt_time >= 0.0) {
-        float melt = clamp((TIME - global_snow_melt_time) * global_snow_melt_speed, 0.0, 1.0);
-        snow_amount *= (1.0 - melt);
-    }
+    float snow_amount = pow(get_snow_progress(), 0.55);
 
     float top_mask = 1.0 - shifted_uv.y;
-    float snow_mask = smoothstep(1.0 - snow_amount, 1.2 - snow_amount, top_mask);
+    float snow_mask = smoothstep(1.0 - snow_amount * 1.35, 1.08 - snow_amount * 1.35, top_mask) * snow_visibility;
     snow_mask *= step(0.01, snow_amount);
 
     vec3 dark_snow = global_snow_color.rgb * (1.0 - shadow_intensity);