add recharge

shaders/simple.frag

@@ -30,6 +30,8 @@ uniform vec3 roadBorderColor;
 
 uniform float time;
 uniform int riverMask;
+uniform float waterLevelKm = 0.08235294;
+uniform float coastBeachWidthKm = 0.022;
 
 smooth in vec3 vNormal;
 smooth in vec3 vWorldPos;
@@ -232,8 +234,12 @@ void main() {
     // Snowline in kilometers: 2.5 (2500m) in temperate zone, dropping to 0.0 (sea level) at poles!
     float snowLine = mix(2.5, 0.0, poleFactor);
 
-    // 3. Water vs Land detection (z_pos = height in kilometers, 0.0 = sea level)
-    float oceanWaterFac = 1.0 - smoothstep(0.005, 0.025, z_pos);
+    // 3. Water vs Land detection (z_pos = height in kilometers; water is height < water_height_threshold)
+    // One heightmap step is 3.5 / 255.0 = 0.0137255 km, so height = threshold - 1 is at waterLevelKm - 0.0137255.
+    // All water hexes (height <= threshold - 1) remain 100% water and transition smoothly across the shoreline.
+    float waterEdgeLow  = max(0.0, waterLevelKm - 0.0135);
+    float waterEdgeHigh = max(waterEdgeLow + 0.002, waterLevelKm - 0.0015);
+    float oceanWaterFac = 1.0 - smoothstep(waterEdgeLow, waterEdgeHigh, z_pos);
 
     // River water detection
     float riverDist = getRiverDistance(fragVert.xy, riverMask);
@@ -321,10 +327,13 @@ void main() {
         biomeGround = farmColor;
     }
 
-    // Shoreline beach: where gentle slopes meet water (sea level up to ~110m, or along rivers)
+    // Shoreline beach: where gentle slopes meet water right along the waterline (or along rivers)
     // Steep slopes (norm.z < 0.55) remain rocky cliffs; gentle slopes (norm.z > 0.80) get a sandy beach
     float gentleSlope = smoothstep(0.55, 0.85, norm.z);
-    float coastBeach = (1.0 - smoothstep(0.015, 0.110, z_pos)) * smoothstep(0.003, 0.015, z_pos) * gentleSlope;
+    float beachStart = max(0.0, waterLevelKm - 0.015);
+    float beachPeak  = waterEdgeHigh;
+    float beachEnd   = waterLevelKm + max(0.005, coastBeachWidthKm);
+    float coastBeach = (1.0 - smoothstep(beachPeak, beachEnd, z_pos)) * smoothstep(beachStart, beachPeak, z_pos) * gentleSlope;
     float riverBeach = riverBankFac;
     float beachFac = max(coastBeach, riverBeach);