Index: src/tgp.cpp
===================================================================
--- src/tgp.cpp	(revision 13649)
+++ src/tgp.cpp	(working copy)
@@ -174,6 +174,7 @@
 	uint     size_x;     //< MapSizeX()
 	uint     size_y;     //< MapSizeY()
 
+	/* Height map accessor */
 	inline height_t &height(uint x, uint y) {
 		return h[x + y * dim_x];
 	}
@@ -262,7 +263,7 @@
 	_height_map.h = NULL;
 }
 
-/** RandomHeight() generator */
+/** Generates new height in given amplitude (generated numbers will range from - amplitude to + amplitude) */
 static inline height_t RandomHeight(amplitude_t rMax)
 {
 	amplitude_t ra = (Random() << 16) | (Random() & 0x0000FFFF);
@@ -279,13 +280,14 @@
 	uint step = size_min >> log_frequency;
 	uint x, y;
 
+	/* Trying to apply noise to uninitialized height map */
 	assert(_height_map.h != NULL);
 
 	/* Are we finished? */
 	if (step == 0) return false;
 
+	/* This is first round, we need to establish base heights with step = size_min */
 	if (log_frequency == 0) {
-		/* This is first round, we need to establish base heights with step = size_min */
 		for (y = 0; y <= _height_map.size_y; y += step) {
 			for (x = 0; x <= _height_map.size_x; x += step) {
 				height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
@@ -316,11 +318,14 @@
 		}
 	}
 
+	/* Add some more smaller noise */
 	for (y = 0; y <= _height_map.size_y; y += step) {
 		for (x = 0; x <= _height_map.size_x; x += step) {
 			_height_map.height(x, y) += RandomHeight(amplitude);
 		}
 	}
+
+	/* Return false if we are finished (reached the minimal step size) */
 	return (step > 1);
 }
 
@@ -338,11 +343,14 @@
 	for (log_size_min = 6; (1U << log_size_min) < size_min; log_size_min++) { }
 	log_frequency_min = log_size_min - 6;
 
+	/* Keep increasing the frequence unitil we reach the step size equal to one tile */
 	do {
 		log_frequency = iteration_round - log_frequency_min;
 		if (log_frequency >= 0) {
+			/* Additional noise with decreasing amplitude will be applied for first several rounds */
 			amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][log_frequency];
 		} else {
+			/* Once amplitude reaches zero, we will keep smoothing the terrain */
 			amplitude = 0;
 		}
 		continue_iteration = ApplyNoise(iteration_round, amplitude);
@@ -357,7 +365,7 @@
 	int64 h_accu = 0;
 	h_min = h_max = _height_map.height(0, 0);
 
-	/* Get h_min, h_max and accumulate heights into h_accu */
+	/* Calculate the sum of all heights in the height map */
 	FOR_ALL_TILES_IN_HEIGHT(h) {
 		if (*h < h_min) h_min = *h;
 		if (*h > h_max) h_max = *h;
@@ -379,7 +387,7 @@
 	int *hist = hist_buf - h_min;
 	height_t *h;
 
-	/* Fill histogram */
+	/* Count the heights and fill the histogram */
 	FOR_ALL_TILES_IN_HEIGHT(h) {
 		assert(*h >= h_min);
 		assert(*h <= h_max);
@@ -769,7 +777,7 @@
 }
 
 
-/** A small helper function */
+/** A small helper function to initialize the terrain */
 static void TgenSetTileHeight(TileIndex tile, int height)
 {
 	SetTileHeight(tile, height);