(svn r27330) -Fix [FS#6335]: Make variety distribution not assume that sea level is at height 0.2 / 3 * TGPGetMaxHeight().

src/tgp.cpp

@@ -573,7 +573,7 @@ static void HeightMapSineTransform(height_t h_min, height_t h_max)
  */
 static void HeightMapCurves(uint level)
 {
-	height_t mh = TGPGetMaxHeight();
+	height_t mh = TGPGetMaxHeight() - I2H(1); // height levels above sea level only
 
 	/** Basically scale height X to height Y. Everything in between is interpolated. */
 	struct control_point_t {
@@ -582,10 +582,10 @@ static void HeightMapCurves(uint level)
 	};
 	/* Scaled curve maps; value is in height_ts. */
 #define F(fraction) ((height_t)(fraction * mh))
-	const control_point_t curve_map_1[] = { { F(0.0), F(0.0) }, { F(0.6 / 3), F(0.1) }, { F(2.4 / 3), F(0.4 / 3) },                                                       { F(1.0), F(0.4)  } };
-	const control_point_t curve_map_2[] = { { F(0.0), F(0.0) }, { F(0.2 / 3), F(0.1) }, { F(1.6 / 3), F(0.4 / 3) }, { F(2.4 / 3), F(0.8 / 3) },                           { F(1.0), F(0.6)  } };
-	const control_point_t curve_map_3[] = { { F(0.0), F(0.0) }, { F(0.2 / 3), F(0.1) }, { F(1.6 / 3), F(0.8 / 3) }, { F(2.4 / 3), F(1.8 / 3) },                           { F(1.0), F(0.8)  } };
-	const control_point_t curve_map_4[] = { { F(0.0), F(0.0) }, { F(0.2 / 3), F(0.1) }, { F(1.2 / 3), F(0.9 / 3) }, { F(2.0 / 3), F(2.4 / 3) } , { F(5.5 / 6), F(0.99) }, { F(1.0), F(0.99) } };
+	const control_point_t curve_map_1[] = { { F(0.0), F(0.0) }, { F(2.4 / 3), F(0.4 / 3) },                                                       { F(1.0), F(0.4)  } };
+	const control_point_t curve_map_2[] = { { F(0.0), F(0.0) }, { F(1.6 / 3), F(0.4 / 3) }, { F(2.4 / 3), F(0.8 / 3) },                           { F(1.0), F(0.6)  } };
+	const control_point_t curve_map_3[] = { { F(0.0), F(0.0) }, { F(1.6 / 3), F(0.8 / 3) }, { F(2.4 / 3), F(1.8 / 3) },                           { F(1.0), F(0.8)  } };
+	const control_point_t curve_map_4[] = { { F(0.0), F(0.0) }, { F(1.2 / 3), F(0.9 / 3) }, { F(2.0 / 3), F(2.4 / 3) } , { F(5.5 / 6), F(0.99) }, { F(1.0), F(0.99) } };
 #undef F
 
 	/** Helper structure to index the different curve maps. */
@@ -663,6 +663,12 @@ static void HeightMapCurves(uint level)
 
 			height_t *h = &_height_map.height(x, y);
 
+			/* Do not touch sea level */
+			if (*h < I2H(1)) continue;
+
+			/* Only scale above sea level */
+			*h -= I2H(1);
+
 			/* Apply all curve maps that are used on this tile. */
 			for (uint t = 0; t < lengthof(curve_maps); t++) {
 				if (!HasBit(corner_bits, t)) continue;
@@ -684,6 +690,9 @@ static void HeightMapCurves(uint level)
 
 			/* Apply interpolation of curve map results. */
 			*h = (height_t)((ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr);
+
+			/* Readd sea level */
+			*h += I2H(1);
 		}
 	}
 }