# tgp.cpp

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    00001 /* $Id$ */
    00002
    00003 /*
    00004  * This file is part of OpenTTD.
    00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
    00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
    00008  */
    00009
    00012 #include "stdafx.h"
    00013 #include <math.h>
    00014 #include "clear_map.h"
    00015 #include "void_map.h"
    00016 #include "genworld.h"
    00017 #include "core/alloc_func.hpp"
    00018 #include "core/random_func.hpp"
    00019 #include "landscape_type.h"
    00020 #include "tgp.h"
    00021 #include "debug.h"
    00022
    00023 /*
    00024  *
    00025  * Quickie guide to Perlin Noise
    00026  * Perlin noise is a predictable pseudo random number sequence. By generating
    00027  * it in 2 dimensions, it becomes a useful random map that, for a given seed
    00028  * and starting X & Y, is entirely predictable. On the face of it, that may not
    00029  * be useful. However, it means that if you want to replay a map in a different
    00030  * terrain, or just vary the sea level, you just re-run the generator with the
    00031  * same seed. The seed is an int32, and is randomised on each run of New Game.
    00032  * The Scenario Generator does not randomise the value, so that you can
    00033  * experiment with one terrain until you are happy, or click "Random" for a new
    00034  * random seed.
    00035  *
    00036  * Perlin Noise is a series of "octaves" of random noise added together. By
    00037  * reducing the amplitude of the noise with each octave, the first octave of
    00038  * noise defines the main terrain sweep, the next the ripples on that, and the
    00039  * next the ripples on that. I use 6 octaves, with the amplitude controlled by
    00040  * a power ratio, usually known as a persistence or p value. This I vary by the
    00041  * smoothness selection, as can be seen in the table below. The closer to 1,
    00042  * the more of that octave is added. Each octave is however raised to the power
    00043  * of its position in the list, so the last entry in the "smooth" row, 0.35, is
    00044  * raised to the power of 6, so can only add 0.001838...  of the amplitude to
    00045  * the running total.
    00046  *
    00047  * In other words; the first p value sets the general shape of the terrain, the
    00048  * second sets the major variations to that, ... until finally the smallest
    00049  * bumps are added.
    00050  *
    00051  * Usefully, this routine is totally scaleable; so when 32bpp comes along, the
    00052  * terrain can be as bumpy as you like! It is also infinitely expandable; a
    00053  * single random seed terrain continues in X & Y as far as you care to
    00054  * calculate. In theory, we could use just one seed value, but randomly select
    00055  * where in the Perlin XY space we use for the terrain. Personally I prefer
    00056  * using a simple (0, 0) to (X, Y), with a varying seed.
    00057  *
    00058  *
    00059  * Other things i have had to do: mountainous wasnt mountainous enough, and
    00060  * since we only have 0..15 heights available, I add a second generated map
    00061  * (with a modified seed), onto the original. This generally raises the
    00062  * terrain, which then needs scaling back down. Overall effect is a general
    00063  * uplift.
    00064  *
    00065  * However, the values on the top of mountains are then almost guaranteed to go
    00066  * too high, so large flat plateaus appeared at height 15. To counter this, I
    00067  * scale all heights above 12 to proportion up to 15. It still makes the
    00068  * mountains have flatish tops, rather than craggy peaks, but at least they
    00069  * arent smooth as glass.
    00070  *
    00071  *
    00072  * For a full discussion of Perlin Noise, please visit:
    00073  * http://freespace.virgin.net/hugo.elias/models/m_perlin.htm
    00074  *
    00075  *
    00076  * Evolution II
    00077  *
    00078  * The algorithm as described in the above link suggests to compute each tile height
    00079  * as composition of several noise waves. Some of them are computed directly by
    00080  * noise(x, y) function, some are calculated using linear approximation. Our
    00081  * first implementation of perlin_noise_2D() used 4 noise(x, y) calls plus
    00082  * 3 linear interpolations. It was called 6 times for each tile. This was a bit
    00083  * CPU expensive.
    00084  *
    00085  * The following implementation uses optimized algorithm that should produce
    00086  * the same quality result with much less computations, but more memory accesses.
    00087  * The overal speedup should be 300% to 800% depending on CPU and memory speed.
    00088  *
    00089  * I will try to explain it on the example below:
    00090  *
    00091  * Have a map of 4 x 4 tiles, our simplifiead noise generator produces only two
    00092  * values -1 and +1, use 3 octaves with wave lenght 1, 2 and 4, with amplitudes
    00093  * 3, 2, 1. Original algorithm produces:
    00094  *
    00095  * h00 = lerp(lerp(-3, 3, 0/4), lerp(3, -3, 0/4), 0/4) + lerp(lerp(-2,  2, 0/2), lerp( 2, -2, 0/2), 0/2) + -1 = lerp(-3.0,  3.0, 0/4) + lerp(-2,  2, 0/2) + -1 = -3.0  + -2 + -1 = -6.0
    00096  * h01 = lerp(lerp(-3, 3, 1/4), lerp(3, -3, 1/4), 0/4) + lerp(lerp(-2,  2, 1/2), lerp( 2, -2, 1/2), 0/2) +  1 = lerp(-1.5,  1.5, 0/4) + lerp( 0,  0, 0/2) +  1 = -1.5  +  0 +  1 = -0.5
    00097  * h02 = lerp(lerp(-3, 3, 2/4), lerp(3, -3, 2/4), 0/4) + lerp(lerp( 2, -2, 0/2), lerp(-2,  2, 0/2), 0/2) + -1 = lerp(   0,    0, 0/4) + lerp( 2, -2, 0/2) + -1 =    0  +  2 + -1 =  1.0
    00098  * h03 = lerp(lerp(-3, 3, 3/4), lerp(3, -3, 3/4), 0/4) + lerp(lerp( 2, -2, 1/2), lerp(-2,  2, 1/2), 0/2) +  1 = lerp( 1.5, -1.5, 0/4) + lerp( 0,  0, 0/2) +  1 =  1.5  +  0 +  1 =  2.5
    00099  *
    00100  * h10 = lerp(lerp(-3, 3, 0/4), lerp(3, -3, 0/4), 1/4) + lerp(lerp(-2,  2, 0/2), lerp( 2, -2, 0/2), 1/2) +  1 = lerp(-3.0,  3.0, 1/4) + lerp(-2,  2, 1/2) +  1 = -1.5  +  0 +  1 = -0.5
    00101  * h11 = lerp(lerp(-3, 3, 1/4), lerp(3, -3, 1/4), 1/4) + lerp(lerp(-2,  2, 1/2), lerp( 2, -2, 1/2), 1/2) + -1 = lerp(-1.5,  1.5, 1/4) + lerp( 0,  0, 1/2) + -1 = -0.75 +  0 + -1 = -1.75
    00102  * h12 = lerp(lerp(-3, 3, 2/4), lerp(3, -3, 2/4), 1/4) + lerp(lerp( 2, -2, 0/2), lerp(-2,  2, 0/2), 1/2) +  1 = lerp(   0,    0, 1/4) + lerp( 2, -2, 1/2) +  1 =    0  +  0 +  1 =  1.0
    00103  * h13 = lerp(lerp(-3, 3, 3/4), lerp(3, -3, 3/4), 1/4) + lerp(lerp( 2, -2, 1/2), lerp(-2,  2, 1/2), 1/2) + -1 = lerp( 1.5, -1.5, 1/4) + lerp( 0,  0, 1/2) + -1 =  0.75 +  0 + -1 = -0.25
    00104  *
    00105  *
    00106  * Optimization 1:
    00107  *
    00108  * 1) we need to allocate a bit more tiles: (size_x + 1) * (size_y + 1) = (5 * 5):
    00109  *
    00110  * 2) setup corner values using amplitude 3
    00111  * {    -3.0        X          X          X          3.0   }
    00112  * {     X          X          X          X          X     }
    00113  * {     X          X          X          X          X     }
    00114  * {     X          X          X          X          X     }
    00115  * {     3.0        X          X          X         -3.0   }
    00116  *
    00117  * 3a) interpolate values in the middle
    00118  * {    -3.0        X          0.0        X          3.0   }
    00119  * {     X          X          X          X          X     }
    00120  * {     0.0        X          0.0        X          0.0   }
    00121  * {     X          X          X          X          X     }
    00122  * {     3.0        X          0.0        X         -3.0   }
    00123  *
    00124  * 3b) add patches with amplitude 2 to them
    00125  * {    -5.0        X          2.0        X          1.0   }
    00126  * {     X          X          X          X          X     }
    00127  * {     2.0        X         -2.0        X          2.0   }
    00128  * {     X          X          X          X          X     }
    00129  * {     1.0        X          2.0        X         -5.0   }
    00130  *
    00131  * 4a) interpolate values in the middle
    00132  * {    -5.0       -1.5        2.0        1.5        1.0   }
    00133  * {    -1.5       -0.75       0.0        0.75       1.5   }
    00134  * {     2.0        0.0       -2.0        0.0        2.0   }
    00135  * {     1.5        0.75       0.0       -0.75      -1.5   }
    00136  * {     1.0        1.5        2.0       -1.5       -5.0   }
    00137  *
    00138  * 4b) add patches with amplitude 1 to them
    00139  * {    -6.0       -0.5        1.0        2.5        0.0   }
    00140  * {    -0.5       -1.75       1.0       -0.25       2.5   }
    00141  * {     1.0        1.0       -3.0        1.0        1.0   }
    00142  * {     2.5       -0.25       1.0       -1.75      -0.5   }
    00143  * {     0.0        2.5        1.0       -0.5       -6.0   }
    00144  *
    00145  *
    00146  *
    00147  * Optimization 2:
    00148  *
    00149  * As you can see above, each noise function was called just once. Therefore
    00150  * we don't need to use noise function that calculates the noise from x, y and
    00151  * some prime. The same quality result we can obtain using standard Random()
    00152  * function instead.
    00153  *
    00154  */
    00155
    00157 typedef int16 height_t;
    00158 static const int height_decimal_bits = 4;
    00159 static const height_t _invalid_height = -32768;
    00160
    00162 typedef int amplitude_t;
    00163 static const int amplitude_decimal_bits = 10;
    00164
    00166 struct HeightMap
    00167 {
    00168   height_t *h;         //< array of heights
    00169   uint     dim_x;      //< height map size_x MapSizeX() + 1
    00170   uint     total_size; //< height map total size
    00171   uint     size_x;     //< MapSizeX()
    00172   uint     size_y;     //< MapSizeY()
    00173
    00180   inline height_t &height(uint x, uint y)
    00181   {
    00182     return h[x + y * dim_x];
    00183   }
    00184 };
    00185
    00187 static HeightMap _height_map = {NULL, 0, 0, 0, 0};
    00188
    00190 #define I2H(i) ((i) << height_decimal_bits)
    00191
    00192 #define H2I(i) ((i) >> height_decimal_bits)
    00193
    00195 #define I2A(i) ((i) << amplitude_decimal_bits)
    00196
    00197 #define A2I(i) ((i) >> amplitude_decimal_bits)
    00198
    00200 #define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
    00201
    00202
    00204 #define FOR_ALL_TILES_IN_HEIGHT(h) for (h = _height_map.h; h < &_height_map.h[_height_map.total_size]; h++)
    00205
    00213 static const amplitude_t _amplitudes_by_smoothness_and_frequency[7][TGP_FREQUENCY_MAX + 1] = {
    00214   /* lowest frequency....  ...highest (every corner) */
    00215   /* Very smooth */
    00216   { 2143, 27832, 51429, 51657, 41657, 51429, 1597, 233, 37, 16},   // backup good one except mountainous 2048 * 2048
    00217   /* Smooth */
    00218   { 6448, 911, 27832, 31131, 16511, 1427, 1597, 233, 29, 8},       // test reduce peaks
    00219   /* Rough */
    00220   {17657, 29832, 36832, 51429, 16511, 51429, 233, 1597, 1301, 16}, // backup good one except mountainous 2048 * 2048
    00221   /* Very Rough */
    00222   {17657, 6448, 36832, 51429, 16511, 17657, 233, 1597, 1301, 16},  // backup good one except mountainous 2048 * 2048
    00223   /* Cereally rough -bonus- */
    00224   { 17657, 31832, 39832, 29832, 16511, 43429, 233, 2597, 37, 16},  // test reduce peaks
    00225   /* CommutorZ -bonus- */
    00226   {25000, 10000, 8000, 24000, 12000, 2500, 250, 100, 80, 25},      // backup good one. all mapsizes. No islands.
    00227   /* Go with the flow -bonus- */
    00228   {13511, 22739, 51429, 253, 421, 21131, 137, 7, 37, 261}          // backup good one. all mapsizes. No islands.
    00229 };
    00230
    00238 static const int _smoothing_parameters[7][3] = {
    00239   {3, 3, 8},
    00240   {4, 3, 8},
    00241   {2, 7, 8},
    00242   {2, 4, 8},
    00243   {2, 5, 8},
    00244   {2, 6, 8},
    00245   {2, 5, 4}
    00246 };
    00247
    00249 static const amplitude_t _water_percent[4] = {70, 170, 270, 420};
    00250
    00269 static const int _max_height[7][9] = {
    00270   {32, 48, 72, 170, 340, 680, 1360, 2720, 5440},
    00271   {21, 40, 50,  64, 128, 380,  760, 1520, 3040},
    00272   {16, 27, 38,  51, 102, 204,  408,  916, 1832},
    00273   {12, 21, 30,  39,  60, 120,  240,  480,  960},
    00274   {10, 13, 17,  20,  33,  66,  132,  264,  528},
    00275   {9,  10, 11,  12,  13,  24,   48,   96,  192},
    00276   {5,   6,  7,   7,   7,  12,   24,   48,   96}
    00277 };
    00278
    00285 static inline bool IsValidXY(uint x, uint y)
    00286 {
    00287   return ((int)x) >= 0 && x < _height_map.size_x && ((int)y) >= 0 && y < _height_map.size_y;
    00288 }
    00289
    00294 static inline bool AllocHeightMap()
    00295 {
    00296   height_t *h;
    00297
    00298   _height_map.size_x = MapSizeX();
    00299   _height_map.size_y = MapSizeY();
    00300
    00301   /* Allocate memory block for height map row pointers */
    00302   _height_map.total_size = (_height_map.size_x + 1) * (_height_map.size_y + 1);
    00303   _height_map.dim_x = _height_map.size_x + 1;
    00304   _height_map.h = CallocT<height_t>(_height_map.total_size);
    00305
    00306   /* Iterate through height map initialize values */
    00307   FOR_ALL_TILES_IN_HEIGHT(h) *h = _invalid_height;
    00308
    00309   return true;
    00310 }
    00311
    00313 static inline void FreeHeightMap()
    00314 {
    00315   if (_height_map.h == NULL) return;
    00316   free(_height_map.h);
    00317   _height_map.h = NULL;
    00318 }
    00319
    00325 static inline height_t RandomHeight(amplitude_t rMax)
    00326 {
    00327   amplitude_t ra = (Random() << 16) | (Random() & 0x0000FFFF);
    00328   height_t rh;
    00329   /* Spread height into range -rMax..+rMax */
    00330   rh = A2H(ra % (2 * rMax + 1) - rMax);
    00331   return rh;
    00332 }
    00333
    00352 static bool ApplyNoise(uint log_frequency, amplitude_t amplitude)
    00353 {
    00354   uint size_min = min(_height_map.size_x, _height_map.size_y);
    00355   int step = size_min >> log_frequency;
    00356   int x, y;
    00357
    00358   height_t* temp_height_map;
    00359   temp_height_map = CallocT<height_t>(_height_map.total_size);
    00360
    00361   /* Trying to apply noise to uninitialized height map */
    00362   assert(_height_map.h != NULL);
    00363
    00364   /* Are we finished? */
    00365   if (step == 0) return false;
    00366
    00367   if (log_frequency == 0) {
    00368     /* This is first round, we need to establish base heights with step = size_min */
    00369     for (y = 0; y <= (int)_height_map.size_y; y += step) {
    00370       for (x = 0; x <= (int)_height_map.size_x; x += step) {
    00371         height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
    00372         _height_map.height(x, y) = height;
    00373       }
    00374     }
    00375     return true;
    00376   }
    00377
    00378   /* It is regular iteration round.
    00379    * Interpolate height values at odd x, even y tiles */
    00380   for (y = 0; y <= (int)_height_map.size_y; y += 2 * step) {
    00381     for (x = 0; x < (int)_height_map.size_x; x += 2 * step) {
    00382       height_t h00 = _height_map.height(x + 0 * step, y);
    00383       height_t h02 = _height_map.height(x + 2 * step, y);
    00384       height_t h01 = (h00 + h02) / 2;
    00385       _height_map.height(x + 1 * step, y) = h01;
    00386     }
    00387   }
    00388
    00389   /* Interpolate height values at odd y tiles */
    00390   for (y = 0; y < (int)_height_map.size_y; y += 2 * step) {
    00391     for (x = 0; x <= (int)_height_map.size_x; x += step) {
    00392       height_t h00 = _height_map.height(x, y + 0 * step);
    00393       height_t h20 = _height_map.height(x, y + 2 * step);
    00394       height_t h10 = (h00 + h20) / 2;
    00395       _height_map.height(x, y + 1 * step) = h10;
    00396     }
    00397   }
    00398
    00399   /* Add noise for next higher frequency (smaller steps) */
    00400   for (y = 0; y <= (int)_height_map.size_y; y += step) {
    00401     for (x = 0; x <= (int)_height_map.size_x; x += step) {
    00402       _height_map.height(x, y) += RandomHeight(amplitude);
    00403     }
    00404   }
    00405
    00406   return (step > 1);
    00407 }
    00408
    00418 void Smooth(uint log_frequency, int radius, int weakness, int min_step)
    00419 {
    00420   uint size_min = min(_height_map.size_x, _height_map.size_y);
    00421   int step = size_min >> log_frequency;
    00422
    00423   if(step < min_step) {
    00424     return;
    00425   } else {
    00426     if(step < min_step * 2) {
    00427       weakness += 4;
    00428     }
    00429   }
    00430
    00431   height_t* temp_height_map;
    00432   temp_height_map = CallocT<height_t>(_height_map.total_size);
    00433
    00434   for (uint y = 0; y <= _height_map.size_y; y += step) {
    00435     for (uint x = 0; x <= _height_map.size_x; x += step) {
    00436       temp_height_map[x + y * _height_map.size_x] = _height_map.height(x, y);
    00437     }
    00438   }
    00439
    00440   for (uint y = 0; y <= _height_map.size_y; y += step) {
    00441     for (uint x = 0; x <= _height_map.size_x; x += step) {
    00442       height_t current = temp_height_map[x + y * _height_map.size_x];
    00443       int sum = current * 100 * weakness;
    00444       int weights = 100 * weakness; // the inmost tile has the highest weight
    00445
    00446       for(int i = -radius; i <= radius; i++){
    00447         for(int j = -radius; j <= radius; j++){
    00448           if((i != 0 || j != 0) && x + i * step <= _height_map.size_x
    00449               && x + i * step > 0 && y + j * step <= _height_map.size_y
    00450               && y + j * step > 0) {
    00451             int square = (int) sqrt((double)(i * i + j * j));
    00452             sum += temp_height_map[x + i * step + (y + j * step) * _height_map.size_x] * 100 / square;
    00453             weights += 100 / square;
    00454           }
    00455         }
    00456       }
    00457
    00458       _height_map.height(x, y) = sum / weights;
    00459     }
    00460   }
    00461 }
    00462
    00464 static void HeightMapGenerate()
    00465 {
    00466   uint size_min = min(_height_map.size_x, _height_map.size_y);
    00467   uint iteration_round = 0;
    00468   amplitude_t amplitude;
    00469   bool continue_iteration;
    00470   int log_size_min, log_frequency_min;
    00471   int log_frequency;
    00472
    00473   /* Find first power of two that fits, so that later log_frequency == TGP_FREQUENCY_MAX in the last iteration */
    00474   for (log_size_min = TGP_FREQUENCY_MAX; (1U << log_size_min) < size_min; log_size_min++) { }
    00475   log_frequency_min = log_size_min - TGP_FREQUENCY_MAX;
    00476
    00477   /* Zero must be part of the iteration, else initialization will fail. */
    00478   assert(log_frequency_min >= 0);
    00479
    00480   /* Keep increasing the frequency until we reach the step size equal to one tile */
    00481   do {
    00482     log_frequency = iteration_round - log_frequency_min;
    00483
    00484     if (log_frequency >= 0) {
    00485       /* Apply noise for the next frequency */
    00486       assert(log_frequency <= TGP_FREQUENCY_MAX);
    00487       amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][log_frequency];
    00488     } else {
    00489       /* Amplitude for the low frequencies on big maps is 0, i.e. initialise with zero height */
    00490       amplitude = 0;
    00491     }
    00492
    00493     continue_iteration = ApplyNoise(iteration_round, amplitude);
    00494
    00495     if(amplitude > 0) {
    00496       /* Apply some extra parameters to prevent inverted pyramids. */
    00497       Smooth(iteration_round, _smoothing_parameters[_settings_game.game_creation.tgen_smoothness][0],
    00498           _smoothing_parameters[_settings_game.game_creation.tgen_smoothness][1],
    00499           _smoothing_parameters[_settings_game.game_creation.tgen_smoothness][2]);
    00500     }
    00501
    00502     iteration_round++;
    00503
    00504   } while (continue_iteration);
    00505
    00506   assert(log_frequency <= TGP_FREQUENCY_MAX);
    00507
    00508   if (log_frequency != TGP_FREQUENCY_MAX) {
    00509     DEBUG(map, 0, "Frequency wrong: log_frequency = %i, TGP_FREQUENCY_MAX = %i",
    00510         log_frequency, TGP_FREQUENCY_MAX);
    00511   }
    00512 }
    00513
    00515 static void HeightMapGetMinMaxAvg(height_t *min_ptr, height_t *max_ptr, height_t *avg_ptr)
    00516 {
    00517   height_t h_min, h_max, h_avg, *h;
    00518   int64 h_accu = 0;
    00519   h_min = h_max = _height_map.height(0, 0);
    00520
    00521   /* Get h_min, h_max and accumulate heights into h_accu */
    00522   FOR_ALL_TILES_IN_HEIGHT(h) {
    00523     if (*h < h_min) h_min = *h;
    00524     if (*h > h_max) h_max = *h;
    00525     h_accu += *h;
    00526   }
    00527
    00528   /* Get average height */
    00529   h_avg = (height_t)(h_accu / (_height_map.size_x * _height_map.size_y));
    00530
    00531   /* Return required results */
    00532   if (min_ptr != NULL) *min_ptr = h_min;
    00533   if (max_ptr != NULL) *max_ptr = h_max;
    00534   if (avg_ptr != NULL) *avg_ptr = h_avg;
    00535 }
    00536
    00538 static int *HeightMapMakeHistogram(height_t h_min, height_t h_max, int *hist_buf)
    00539 {
    00540   int *hist = hist_buf - h_min;
    00541   height_t *h;
    00542
    00543   /* Count the heights and fill the histogram */
    00544   FOR_ALL_TILES_IN_HEIGHT(h) {
    00545     assert(*h >= h_min);
    00546     assert(*h <= h_max);
    00547     hist[*h]++;
    00548   }
    00549   return hist;
    00550 }
    00551
    00553 static void HeightMapSineTransform(height_t h_min, height_t h_max)
    00554 {
    00555   if ((_settings_game.game_creation.tgen_smoothness == SMOOTHNESS_VERY_ROUGH)
    00556       || (_settings_game.game_creation.tgen_smoothness == SMOOTHNESS_CEREALLY_ROUGH)) {
    00557     /* Make the map really rough for very rough and cereally rough settings, skip this function. */
    00558     return;
    00559   }
    00560
    00561   height_t *h;
    00562
    00563   FOR_ALL_TILES_IN_HEIGHT(h) {
    00564     double fheight;
    00565
    00566     if (*h < h_min) continue;
    00567
    00568     /* Transform height into 0..1 space */
    00569     fheight = (double)(*h - h_min) / (double)(h_max - h_min);
    00570     /* Apply sine transform depending on landscape type */
    00571     switch (_settings_game.game_creation.landscape) {
    00572       case LT_TOYLAND:
    00573       case LT_TEMPERATE:
    00574         {
    00575           /* Move and scale 0..1 into -1..+1 */
    00576           fheight = 2 * fheight - 1;
    00577           /* Sine transform */
    00578           fheight = sin(fheight * M_PI_2);
    00579           /* Transform it back from -1..1 into 0..1 space */
    00580           fheight = 0.5 * (fheight + 1);
    00581         }
    00582         break;
    00583
    00584       case LT_ARCTIC:
    00585         {
    00586           /* Arctic terrain needs special height distribution.
    00587            * Redistribute heights to have more tiles at highest (75%..100%) range */
    00588           double sine_upper_limit = 0.75;
    00589           double linear_compression = 2;
    00590           if (fheight >= sine_upper_limit) {
    00591             /* Over the limit we do linear compression up */
    00592             fheight = 1.0 - (1.0 - fheight) / linear_compression;
    00593           } else {
    00594             double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
    00595             /* Get 0..sine_upper_limit into -1..1 */
    00596             fheight = 2.0 * fheight / sine_upper_limit - 1.0;
    00597             /* Sine wave transform */
    00598             fheight = sin(fheight * M_PI_2);
    00599             /* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
    00600             fheight = 0.5 * (fheight + 1.0) * m;
    00601           }
    00602         }
    00603         break;
    00604
    00605       case LT_TROPIC:
    00606         {
    00607           /* Desert terrain needs special height distribution.
    00608            * Half of tiles should be at lowest (0..25%) heights */
    00609           double sine_lower_limit = 0.5;
    00610           double linear_compression = 2;
    00611           if (fheight <= sine_lower_limit) {
    00612             /* Under the limit we do linear compression down */
    00613             fheight = fheight / linear_compression;
    00614           } else {
    00615             double m = sine_lower_limit / linear_compression;
    00616             /* Get sine_lower_limit..1 into -1..1 */
    00617             fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
    00618             /* Sine wave transform */
    00619             fheight = sin(fheight * M_PI_2);
    00620             /* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
    00621             fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
    00622           }
    00623         }
    00624         break;
    00625
    00626       default:
    00627         NOT_REACHED();
    00628         break;
    00629     }
    00630     /* Transform it back into h_min..h_max space */
    00631     *h = (height_t)(fheight * (h_max - h_min) + h_min);
    00632     if (*h < 0) *h = I2H(0);
    00633     if (*h >= h_max) *h = h_max - 1;
    00634   }
    00635 }
    00636
    00637 /* Additional map variety is provided by applying different curve maps
    00638  * to different parts of the map. A randomized low resolution grid contains
    00639  * which curve map to use on each part of the make. This filtered non-linearly
    00640  * to smooth out transitions between curves, so each tile could have between
    00641  * 100% of one map applied or 25% of four maps.
    00642  *
    00643  * The curve maps define different land styles, i.e. lakes, low-lands, hills
    00644  * and mountain ranges, although these are dependent on the landscape style
    00645  * chosen as well.
    00646  *
    00647  * The level parameter dictates the resolution of the grid. A low resolution
    00648  * grid will result in larger continuous areas of a land style, a higher
    00649  * resolution grid splits the style into smaller areas.
    00650  *
    00651  * At this point in map generation, all height data has been normalized to 0
    00652  * to 239.
    00653  */
    00654 struct control_point_t {
    00655   height_t x;
    00656   height_t y;
    00657 };
    00658
    00659 struct control_point_list_t {
    00660   size_t length;
    00661   const control_point_t *list;
    00662 };
    00663
    00664 static const control_point_t _curve_map_1[] = {
    00665   { 0, 0 }, { 48, 24 }, { 192, 32 }, { 240, 96 }
    00666 };
    00667
    00668 static const control_point_t _curve_map_2[] = {
    00669   { 0, 0 }, { 16, 24 }, { 128, 32 }, { 192, 64 }, { 240, 144 }
    00670 };
    00671
    00672 static const control_point_t _curve_map_3[] = {
    00673   { 0, 0 }, { 16, 24 }, { 128, 64 }, { 192, 144 }, { 240, 192 }
    00674 };
    00675
    00676 static const control_point_t _curve_map_4[] = {
    00677   { 0, 0 }, { 16, 24 }, { 96, 72 }, { 160, 192 }, { 220, 239 }, { 240, 239 }
    00678 };
    00679
    00680 static const control_point_list_t _curve_maps[] = {
    00681   { lengthof(_curve_map_1), _curve_map_1 },
    00682   { lengthof(_curve_map_2), _curve_map_2 },
    00683   { lengthof(_curve_map_3), _curve_map_3 },
    00684   { lengthof(_curve_map_4), _curve_map_4 },
    00685 };
    00686
    00687 static void HeightMapCurves(uint level)
    00688 {
    00689   height_t ht[lengthof(_curve_maps)];
    00690
    00691   /* Set up a grid to choose curve maps based on location */
    00692   uint sx = Clamp(1 << level, 2, 32);
    00693   uint sy = Clamp(1 << level, 2, 32);
    00694   byte *c = (byte *)alloca(sx * sy);
    00695
    00696   for (uint i = 0; i < sx * sy; i++) {
    00697     c[i] = Random() % lengthof(_curve_maps);
    00698   }
    00699
    00700   /* Apply curves */
    00701   for (uint x = 0; x < _height_map.size_x; x++) {
    00702
    00703     /* Get our X grid positions and bi-linear ratio */
    00704     float fx = (float)(sx * x) / _height_map.size_x + 0.5f;
    00705     uint x1 = (uint)fx;
    00706     uint x2 = x1;
    00707     float xr = 2.0f * (fx - x1) - 1.0f;
    00708     xr = sin(xr * M_PI_2);
    00709     xr = sin(xr * M_PI_2);
    00710     xr = 0.5f * (xr + 1.0f);
    00711     float xri = 1.0f - xr;
    00712
    00713     if (x1 > 0) {
    00714       x1--;
    00715       if (x2 >= sx) x2--;
    00716     }
    00717
    00718     for (uint y = 0; y < _height_map.size_y; y++) {
    00719
    00720       /* Get our Y grid position and bi-linear ratio */
    00721       float fy = (float)(sy * y) / _height_map.size_y + 0.5f;
    00722       uint y1 = (uint)fy;
    00723       uint y2 = y1;
    00724       float yr = 2.0f * (fy - y1) - 1.0f;
    00725       yr = sin(yr * M_PI_2);
    00726       yr = sin(yr * M_PI_2);
    00727       yr = 0.5f * (yr + 1.0f);
    00728       float yri = 1.0f - yr;
    00729
    00730       if (y1 > 0) {
    00731         y1--;
    00732         if (y2 >= sy) y2--;
    00733       }
    00734
    00735       uint corner_a = c[x1 + sx * y1];
    00736       uint corner_b = c[x1 + sx * y2];
    00737       uint corner_c = c[x2 + sx * y1];
    00738       uint corner_d = c[x2 + sx * y2];
    00739
    00740       /* Bitmask of which curve maps are chosen, so that we do not bother
    00741        * calculating a curve which won't be used. */
    00742       uint corner_bits = 0;
    00743       corner_bits |= 1 << corner_a;
    00744       corner_bits |= 1 << corner_b;
    00745       corner_bits |= 1 << corner_c;
    00746       corner_bits |= 1 << corner_d;
    00747
    00748       height_t *h = &_height_map.height(x, y);
    00749
    00750       /* Apply all curve maps that are used on this tile. */
    00751       for (uint t = 0; t < lengthof(_curve_maps); t++) {
    00752         if (!HasBit(corner_bits, t)) continue;
    00753
    00754         const control_point_t *cm = _curve_maps[t].list;
    00755         for (uint i = 0; i < _curve_maps[t].length - 1; i++) {
    00756           const control_point_t &p1 = cm[i];
    00757           const control_point_t &p2 = cm[i + 1];
    00758
    00759           if (*h >= p1.x && *h < p2.x) {
    00760             ht[t] = p1.y + (*h - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
    00761             break;
    00762           }
    00763         }
    00764       }
    00765
    00766       /* Apply interpolation of curve map results. */
    00767       *h = (height_t)((ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr);
    00768     }
    00769   }
    00770 }
    00771
    00772 /* TODO:
    00773  * Temp solution for applying curves with the more heightlevels patch enabled.
    00774  * 1 / 2
    00775  * Cut untill End when fixed.
    00776  */
    00777
    00784 struct MHScontrol_point_t {
    00785   height_t x;
    00786   height_t y;
    00787 };
    00788
    00789 static const MHScontrol_point_t _curve_map[] = {
    00790   { 0, 0 }, { 48, 48 }, { 96, 72 }, { 160, 128 }, { 192, 160 }, { 240, 255}, { 255, 255 }
    00791 };
    00792
    00793 static void MHSHeightMapCurves()
    00794 {
    00795   height_t h_min, h_max, h_avg, h_diff;
    00796   HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
    00797   h_diff = h_max - h_min;
    00798
    00799   /* "Normalize" the control points to the height map data */
    00800   MHScontrol_point_t *cm = MallocT<MHScontrol_point_t>(lengthof(_curve_map));
    00801   for (uint i = 0; i < lengthof(_curve_map); i++) {
    00802     cm[i].x = _curve_map[i].x * h_diff / 255 + h_min;
    00803     cm[i].y = _curve_map[i].y * h_diff / 255 + h_min;
    00804   }
    00805
    00806   /* Apply curve */
    00807   height_t *h;
    00808   FOR_ALL_TILES_IN_HEIGHT(h) {
    00809     for (uint i = 0; i < lengthof(_curve_map) - 1; i++) {
    00810       MHScontrol_point_t &p1 = cm[i];
    00811       MHScontrol_point_t &p2 = cm[i + 1];
    00812
    00813       if (*h >= p1.x && *h <= p2.x) {
    00814         *h = p1.y + (*h - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
    00815         break;
    00816       }
    00817     }
    00818   }
    00819
    00820   free(cm);
    00821 }
    00822 /*
    00823  * End temp solution for applying curves with the more heightlevels patch enabled.
    00824  * 1 / 2
    00825  */
    00826
    00828 static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new)
    00829 {
    00830   height_t h_min, h_max, h_avg, h_water_level;
    00831   int64 water_tiles, desired_water_tiles;
    00832   height_t *h;
    00833   int *hist;
    00834
    00835   HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
    00836
    00837   /* Allocate histogram buffer and clear its cells */
    00838   int *hist_buf = CallocT<int>(h_max - h_min + 1);
    00839   /* Fill histogram */
    00840   hist = HeightMapMakeHistogram(h_min, h_max, hist_buf);
    00841
    00842   /* How many water tiles do we want? */
    00843   desired_water_tiles = A2I(((int64)water_percent) * (int64)(_height_map.size_x * _height_map.size_y));
    00844
    00845   /* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
    00846   for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
    00847     water_tiles += hist[h_water_level];
    00848     if (water_tiles >= desired_water_tiles) break;
    00849   }
    00850
    00851   /* We now have the proper water level value.
    00852    * Transform the height map into new (normalized) height map:
    00853    *   values from range: h_min..h_water_level will become negative so it will be clamped to 0
    00854    *   values from range: h_water_level..h_max are transformed into 0..h_max_new,
    00855    *   where h_max_new is dependant on _settings_game.difficulty.terrain_type. (_max_height)
    00856    */
    00857   FOR_ALL_TILES_IN_HEIGHT(h) {
    00858     /* Transform height from range h_water_level..h_max into 0..h_max_new range */
    00859     *h = (height_t)(((int)h_max_new) * (*h - h_water_level) / (h_max - h_water_level)) + I2H(1);
    00860     /* Make sure all values are in the proper range (0..h_max_new) */
    00861     if (*h < 0) *h = I2H(0);
    00862     if (*h >= h_max_new) *h = h_max_new - 1;
    00863   }
    00864
    00865   free(hist_buf);
    00866 }
    00867
    00868 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
    00869
    00892 static void HeightMapCoastLines(uint8 water_borders)
    00893 {
    00894   int smallest_size = min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
    00895   const int margin = 4;
    00896   uint y, x;
    00897   double max_x;
    00898   double max_y;
    00899
    00900   /* Lower to sea level */
    00901   for (y = 0; y <= _height_map.size_y; y++) {
    00902     if (HasBit(water_borders, BORDER_NE)) {
    00903       /* Top right */
    00904       max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.9, 53) + 0.25) * 5 + (perlin_coast_noise_2D(y, y, 0.35, 179) + 1) * 12);
    00905       max_x = max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
    00906       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
    00907       for (x = 0; x < max_x; x++) {
    00908         _height_map.height(x, y) = 0;
    00909       }
    00910     }
    00911
    00912     if (HasBit(water_borders, BORDER_SW)) {
    00913       /* Bottom left */
    00914       max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.85, 101) + 0.3) * 6 + (perlin_coast_noise_2D(y, y, 0.45,  67) + 0.75) * 8);
    00915       max_x = max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
    00916       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
    00917       for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
    00918         _height_map.height(x, y) = 0;
    00919       }
    00920     }
    00921   }
    00922
    00923   /* Lower to sea level */
    00924   for (x = 0; x <= _height_map.size_x; x++) {
    00925     if (HasBit(water_borders, BORDER_NW)) {
    00926       /* Top left */
    00927       max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 2, 0.9, 167) + 0.4) * 5 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.4, 211) + 0.7) * 9);
    00928       max_y = max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
    00929       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
    00930       for (y = 0; y < max_y; y++) {
    00931         _height_map.height(x, y) = 0;
    00932       }
    00933     }
    00934
    00935     if (HasBit(water_borders, BORDER_SE)) {
    00936       /* Bottom right */
    00937       max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.85, 71) + 0.25) * 6 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.35, 193) + 0.75) * 12);
    00938       max_y = max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
    00939       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
    00940       for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
    00941         _height_map.height(x, y) = 0;
    00942       }
    00943     }
    00944   }
    00945 }
    00946
    00952 static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
    00953 {
    00954   if ((_settings_game.game_creation.tgen_smoothness == SMOOTHNESS_VERY_ROUGH)
    00955       || (_settings_game.game_creation.tgen_smoothness == SMOOTHNESS_CEREALLY_ROUGH)) {
    00956     /* Make the map really rough for very rough and cereally rough settings, skip this function. */
    00957     return;
    00958   }
    00959
    00960   const int max_coast_dist_from_edge = 35;
    00961   const int max_coast_Smooth_depth = 35;
    00962
    00963   int x, y;
    00964   int ed; // coast distance from edge
    00965   int depth;
    00966
    00967   height_t h_prev = min(_height_map.size_x + 1, _height_map.size_y + 1) / TGP_HEIGHT_FACTOR;
    00968   height_t h;
    00969
    00970   assert(IsValidXY(org_x, org_y));
    00971
    00972   /* Search for the coast (first non-water tile) */
    00973   for (x = org_x, y = org_y, ed = 0; IsValidXY(x, y) && ed < max_coast_dist_from_edge; x += dir_x, y += dir_y, ed++) {
    00974     /* Coast found? */
    00975     if (_height_map.height(x, y) > (int)(min(_height_map.size_x + 1, _height_map.size_y + 1) / TGP_HEIGHT_FACTOR - 1)) break;
    00976
    00977     /* Coast found in the neighborhood? */
    00978     if (IsValidXY(x + dir_y, y + dir_x) && _height_map.height(x + dir_y, y + dir_x) > 0) break;
    00979
    00980     /* Coast found in the neighborhood on the other side */
    00981     if (IsValidXY(x - dir_y, y - dir_x) && _height_map.height(x - dir_y, y - dir_x) > 0) break;
    00982   }
    00983
    00984   /* Coast found or max_coast_dist_from_edge has been reached.
    00985    * Soften the coast slope */
    00986   for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
    00987     h = _height_map.height(x, y);
    00988     h = min(h, h_prev + (4 + depth)); // coast softening formula
    00989     _height_map.height(x, y) = h;
    00990     h_prev = h;
    00991   }
    00992 }
    00993
    00995 static void HeightMapSmoothCoasts(uint8 water_borders)
    00996 {
    00997   uint x, y;
    00998   /* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
    00999   for (x = 0; x < _height_map.size_x; x++) {
    01000     if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
    01001     if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
    01002   }
    01003   /* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
    01004   for (y = 0; y < _height_map.size_y; y++) {
    01005     if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
    01006     if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
    01007   }
    01008 }
    01009
    01017 static void HeightMapSmoothSlopes(height_t dh_max)
    01018 {
    01019   int x, y;
    01020   for (y = 0; y <= (int)_height_map.size_y; y++) {
    01021     for (x = 0; x <= (int)_height_map.size_x; x++) {
    01022       height_t h_max = min(_height_map.height(x > 0 ? x - 1 : x, y), _height_map.height(x, y > 0 ? y - 1 : y)) + dh_max;
    01023       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
    01024     }
    01025   }
    01026   for (y = _height_map.size_y; y >= 0; y--) {
    01027     for (x = _height_map.size_x; x >= 0; x--) {
    01028       height_t h_max = min(_height_map.height((uint)x < _height_map.size_x ? x + 1 : x, y), _height_map.height(x, (uint)y < _height_map.size_y ? y + 1 : y)) + dh_max;
    01029       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
    01030     }
    01031   }
    01032 }
    01033
    01038 static int TGPGetMaxAllowedHeight()
    01039 {
    01040   /* Subtract 6 because the value for map size 64 = 2^6
    01041    * is stored at index 0 in the array.
    01042    * @See discussion at the definition of _max_height */
    01043   const int map_size_index_in_mh = min(MapLogX(), MapLogY()) - 6;
    01044   const int mh = _max_height[_settings_game.difficulty.terrain_type][map_size_index_in_mh];
    01045   const int retValue = I2H(min((min(_height_map.size_x + 1, _height_map.size_y + 1)) / mh, GetMaxTileHeight()));
    01046   return retValue;
    01047 }
    01048
    01056 static void HeightMapNormalize()
    01057 {
    01058   int sea_level_setting = _settings_game.difficulty.quantity_sea_lakes;
    01059   const amplitude_t water_percent = sea_level_setting != (int)CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY ? _water_percent[sea_level_setting] : _settings_game.game_creation.custom_sea_level * 1024 / 100;
    01060   const height_t h_max_new = TGPGetMaxAllowedHeight() + 1;
    01061   const height_t roughness = 7 + 3 * _settings_game.game_creation.tgen_smoothness;
    01062
    01063   HeightMapAdjustWaterLevel(water_percent, h_max_new);
    01064
    01065   byte water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
    01066   if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
    01067
    01068   HeightMapCoastLines(water_borders);
    01069   HeightMapSmoothSlopes(roughness);
    01070
    01071   HeightMapSmoothCoasts(water_borders);
    01072   HeightMapSmoothSlopes(roughness);
    01073
    01074   HeightMapSineTransform(12, h_max_new);
    01075
    01076 /* TODO:
    01077  * Temp solution for applying curves with the more heightlevels patch enabled.
    01078  * 2 / 2
    01079  * Revert to code below, untill End when fixed.
    01080 //  if (_settings_game.game_creation.variety > 0) {
    01081 //    HeightMapCurves(_settings_game.game_creation.variety);
    01082 //  }
    01083  */
    01084   if ((_settings_game.game_creation.variety > 0) && (!AllowMoreHeightlevels()) && (_settings_game.game_creation.landscape == 1)) {
    01085     HeightMapCurves(_settings_game.game_creation.variety);
    01086   }
    01087
    01088   if ((_settings_game.game_creation.variety > 0) && (AllowMoreHeightlevels()) && (_settings_game.game_creation.landscape == 1)) {
    01089     MHSHeightMapCurves();
    01090   }
    01091
    01092 /* TODO:
    01093  * End temp solution for applying curves with the more heightlevels patch enabled.
    01094  * 2 / 2
    01095  */
    01096
    01097   HeightMapSmoothSlopes(16);
    01098 }
    01099
    01107 static double int_noise(const long x, const long y, const int prime)
    01108 {
    01109   long n = x + y * prime + _settings_game.game_creation.generation_seed;
    01110
    01111   n = (n << 13) ^ n;
    01112
    01113   /* Pseudo-random number generator, using several large primes */
    01114   return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
    01115 }
    01116
    01117
    01121 static inline double linear_interpolate(const double a, const double b, const double x)
    01122 {
    01123   return a + x * (b - a);
    01124 }
    01125
    01126
    01131 static double interpolated_noise(const double x, const double y, const int prime)
    01132 {
    01133   const int integer_X = (int)x;
    01134   const int integer_Y = (int)y;
    01135
    01136   const double fractional_X = x - (double)integer_X;
    01137   const double fractional_Y = y - (double)integer_Y;
    01138
    01139   const double v1 = int_noise(integer_X,     integer_Y,     prime);
    01140   const double v2 = int_noise(integer_X + 1, integer_Y,     prime);
    01141   const double v3 = int_noise(integer_X,     integer_Y + 1, prime);
    01142   const double v4 = int_noise(integer_X + 1, integer_Y + 1, prime);
    01143
    01144   const double i1 = linear_interpolate(v1, v2, fractional_X);
    01145   const double i2 = linear_interpolate(v3, v4, fractional_X);
    01146
    01147   return linear_interpolate(i1, i2, fractional_Y);
    01148 }
    01149
    01150
    01157 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
    01158 {
    01159   double total = 0.0;
    01160   int i;
    01161
    01162   for (i = 0; i < 6; i++) {
    01163     const double frequency = (double)(1 << i);
    01164     const double amplitude = pow(p, (double)i);
    01165
    01166     total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
    01167   }
    01168
    01169   return total;
    01170 }
    01171
    01172
    01174 static void TgenSetTileHeight(TileIndex tile, int height)
    01175 {
    01176   SetTileHeight(tile, height);
    01177
    01178   /* Only clear the tiles within the map area. */
    01179   if (TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY() &&
    01180       (!_settings_game.construction.freeform_edges || (TileX(tile) != 0 && TileY(tile) != 0))) {
    01181     MakeClear(tile, CLEAR_GRASS, 3);
    01182   }
    01183 }
    01184
    01192 void GenerateTerrainPerlin()
    01193 {
    01194   uint x, y;
    01195
    01196   if (!AllocHeightMap()) return;
    01197   GenerateWorldSetAbortCallback(FreeHeightMap);
    01198
    01199   HeightMapGenerate();
    01200
    01201   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    01202
    01203   HeightMapNormalize();
    01204
    01205   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    01206
    01207   /* First make sure the tiles at the north border are void tiles if needed. */
    01208   if (_settings_game.construction.freeform_edges) {
    01209     for (y = 0; y < _height_map.size_y - 1; y++) MakeVoid(_height_map.size_x * y);
    01210     for (x = 0; x < _height_map.size_x;     x++) MakeVoid(x);
    01211   }
    01212
    01213   const int mh = H2I(TGPGetMaxAllowedHeight());
    01214
    01215   /* Transfer height map into OTTD map */
    01216   for (y = 0; y < _height_map.size_y; y++) {
    01217     for (x = 0; x < _height_map.size_x; x++) {
    01218       int height = H2I(_height_map.height(x, y));
    01219
    01220       if (height < 0) {
    01221         height = 0;
    01222       }
    01223
    01224       if (height > mh - 1) {
    01225         height = mh - 1;
    01226       }
    01227
    01228       if (height > (int)GetMaxTileHeight()) {
    01229         height = GetMaxTileHeight();
    01230       }
    01231
    01232       TgenSetTileHeight(TileXY(x, y), height);
    01233     }
    01234   }
    01235
    01236   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    01237
    01238   FreeHeightMap();
    01239   GenerateWorldSetAbortCallback(NULL);
    01240 }