# tgp.cpp

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    00001 /* $Id: tgp.cpp 15568 2009-02-24 20:59:17Z smatz $ */
    00002
    00005 #include "stdafx.h"
    00006 #include <math.h>
    00007 #include "clear_map.h"
    00008 #include "void_map.h"
    00009 #include "genworld.h"
    00010 #include "core/alloc_func.hpp"
    00011 #include "core/random_func.hpp"
    00012 #include "landscape_type.h"
    00013 #include "settings_type.h"
    00014
    00015 /*
    00016  *
    00017  * Quickie guide to Perlin Noise
    00018  * Perlin noise is a predictable pseudo random number sequence. By generating
    00019  * it in 2 dimensions, it becomes a useful random map, that for a given seed
    00020  * and starting X & Y is entirely predictable. On the face of it, that may not
    00021  * be useful. However, it means that if you want to replay a map in a different
    00022  * terrain, or just vary the sea level, you just re-run the generator with the
    00023  * same seed. The seed is an int32, and is randomised on each run of New Game.
    00024  * The Scenario Generator does not randomise the value, so that you can
    00025  * experiment with one terrain until you are happy, or click "Random" for a new
    00026  * random seed.
    00027  *
    00028  * Perlin Noise is a series of "octaves" of random noise added together. By
    00029  * reducing the amplitude of the noise with each octave, the first octave of
    00030  * noise defines the main terrain sweep, the next the ripples on that, and the
    00031  * next the ripples on that. I use 6 octaves, with the amplitude controlled by
    00032  * a power ratio, usually known as a persistence or p value. This I vary by the
    00033  * smoothness selection, as can be seen in the table below. The closer to 1,
    00034  * the more of that octave is added. Each octave is however raised to the power
    00035  * of its position in the list, so the last entry in the "smooth" row, 0.35, is
    00036  * raised to the power of 6, so can only add 0.001838...  of the amplitude to
    00037  * the running total.
    00038  *
    00039  * In other words; the first p value sets the general shape of the terrain, the
    00040  * second sets the major variations to that, ... until finally the smallest
    00041  * bumps are added.
    00042  *
    00043  * Usefully, this routine is totally scaleable; so when 32bpp comes along, the
    00044  * terrain can be as bumpy as you like! It is also infinitely expandable; a
    00045  * single random seed terrain continues in X & Y as far as you care to
    00046  * calculate. In theory, we could use just one seed value, but randomly select
    00047  * where in the Perlin XY space we use for the terrain. Personally I prefer
    00048  * using a simple (0, 0) to (X, Y), with a varying seed.
    00049  *
    00050  *
    00051  * Other things i have had to do: mountainous wasnt mountainous enough, and
    00052  * since we only have 0..15 heights available, I add a second generated map
    00053  * (with a modified seed), onto the original. This generally raises the
    00054  * terrain, which then needs scaling back down. Overall effect is a general
    00055  * uplift.
    00056  *
    00057  * However, the values on the top of mountains are then almost guaranteed to go
    00058  * too high, so large flat plateaus appeared at height 15. To counter this, I
    00059  * scale all heights above 12 to proportion up to 15. It still makes the
    00060  * mountains have flatish tops, rather than craggy peaks, but at least they
    00061  * arent smooth as glass.
    00062  *
    00063  *
    00064  * For a full discussion of Perlin Noise, please visit:
    00065  * http://freespace.virgin.net/hugo.elias/models/m_perlin.htm
    00066  *
    00067  *
    00068  * Evolution II
    00069  *
    00070  * The algorithm as described in the above link suggests to compute each tile height
    00071  * as composition of several noise waves. Some of them are computed directly by
    00072  * noise(x, y) function, some are calculated using linear approximation. Our
    00073  * first implementation of perlin_noise_2D() used 4 noise(x, y) calls plus
    00074  * 3 linear interpolations. It was called 6 times for each tile. This was a bit
    00075  * CPU expensive.
    00076  *
    00077  * The following implementation uses optimized algorithm that should produce
    00078  * the same quality result with much less computations, but more memory accesses.
    00079  * The overal speedup should be 300% to 800% depending on CPU and memory speed.
    00080  *
    00081  * I will try to explain it on the example below:
    00082  *
    00083  * Have a map of 4 x 4 tiles, our simplifiead noise generator produces only two
    00084  * values -1 and +1, use 3 octaves with wave lenght 1, 2 and 4, with amplitudes
    00085  * 3, 2, 1. Original algorithm produces:
    00086  *
    00087  * 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
    00088  * 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
    00089  * 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
    00090  * 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
    00091  *
    00092  * 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
    00093  * 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
    00094  * 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
    00095  * 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
    00096  *
    00097  *
    00098  * Optimization 1:
    00099  *
    00100  * 1) we need to allocate a bit more tiles: (size_x + 1) * (size_y + 1) = (5 * 5):
    00101  *
    00102  * 2) setup corner values using amplitude 3
    00103  * {    -3.0        X          X          X          3.0   }
    00104  * {     X          X          X          X          X     }
    00105  * {     X          X          X          X          X     }
    00106  * {     X          X          X          X          X     }
    00107  * {     3.0        X          X          X         -3.0   }
    00108  *
    00109  * 3a) interpolate values in the middle
    00110  * {    -3.0        X          0.0        X          3.0   }
    00111  * {     X          X          X          X          X     }
    00112  * {     0.0        X          0.0        X          0.0   }
    00113  * {     X          X          X          X          X     }
    00114  * {     3.0        X          0.0        X         -3.0   }
    00115  *
    00116  * 3b) add patches with amplitude 2 to them
    00117  * {    -5.0        X          2.0        X          1.0   }
    00118  * {     X          X          X          X          X     }
    00119  * {     2.0        X         -2.0        X          2.0   }
    00120  * {     X          X          X          X          X     }
    00121  * {     1.0        X          2.0        X         -5.0   }
    00122  *
    00123  * 4a) interpolate values in the middle
    00124  * {    -5.0       -1.5        2.0        1.5        1.0   }
    00125  * {    -1.5       -0.75       0.0        0.75       1.5   }
    00126  * {     2.0        0.0       -2.0        0.0        2.0   }
    00127  * {     1.5        0.75       0.0       -0.75      -1.5   }
    00128  * {     1.0        1.5        2.0       -1.5       -5.0   }
    00129  *
    00130  * 4b) add patches with amplitude 1 to them
    00131  * {    -6.0       -0.5        1.0        2.5        0.0   }
    00132  * {    -0.5       -1.75       1.0       -0.25       2.5   }
    00133  * {     1.0        1.0       -3.0        1.0        1.0   }
    00134  * {     2.5       -0.25       1.0       -1.75      -0.5   }
    00135  * {     0.0        2.5        1.0       -0.5       -6.0   }
    00136  *
    00137  *
    00138  *
    00139  * Optimization 2:
    00140  *
    00141  * As you can see above, each noise function was called just once. Therefore
    00142  * we don't need to use noise function that calculates the noise from x, y and
    00143  * some prime. The same quality result we can obtain using standard Random()
    00144  * function instead.
    00145  *
    00146  */
    00147
    00148 #ifndef M_PI_2
    00149 #define M_PI_2 1.57079632679489661923
    00150 #define M_PI   3.14159265358979323846
    00151 #endif /* M_PI_2 */
    00152
    00154 typedef int16 height_t;
    00155 static const int height_decimal_bits = 4;
    00156 static const height_t _invalid_height = -32768;
    00157
    00159 typedef int amplitude_t;
    00160 static const int amplitude_decimal_bits = 10;
    00161
    00163 struct HeightMap
    00164 {
    00165   height_t *h;         //< array of heights
    00166   uint     dim_x;      //< height map size_x MapSizeX() + 1
    00167   uint     total_size; //< height map total size
    00168   uint     size_x;     //< MapSizeX()
    00169   uint     size_y;     //< MapSizeY()
    00170
    00177   inline height_t &height(uint x, uint y) {
    00178     return h[x + y * dim_x];
    00179   }
    00180 };
    00181
    00183 static HeightMap _height_map = {NULL, 0, 0, 0, 0};
    00184
    00186 #define I2H(i) ((i) << height_decimal_bits)
    00187
    00188 #define H2I(i) ((i) >> height_decimal_bits)
    00189
    00191 #define I2A(i) ((i) << amplitude_decimal_bits)
    00192
    00193 #define A2I(i) ((i) >> amplitude_decimal_bits)
    00194
    00196 #define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
    00197
    00198
    00200 #define FOR_ALL_TILES_IN_HEIGHT(h) for (h = _height_map.h; h < &_height_map.h[_height_map.total_size]; h++)
    00201
    00203 static const int TGP_FREQUENCY_MAX = 6;
    00204
    00207 static const amplitude_t _amplitudes_by_smoothness_and_frequency[4][TGP_FREQUENCY_MAX + 1] = {
    00208   /* lowest frequncy....  ...highest (every corner) */
    00209   /* Very smooth */
    00210   {16000,  5600,  1968,   688,   240,    16,    16},
    00211   /* Smooth */
    00212   {16000, 16000,  6448,  3200,  1024,   128,    16},
    00213   /* Rough */
    00214   {16000, 19200, 12800,  8000,  3200,   256,    64},
    00215   /* Very Rough */
    00216   {24000, 16000, 19200, 16000,  8000,   512,   320},
    00217 };
    00218
    00220 static const amplitude_t _water_percent[4] = {20, 80, 250, 400};
    00221
    00223 static const int8 _max_height[4] = {
    00224   6,
    00225   9,
    00226   12,
    00227   15
    00228 };
    00229
    00235 static inline bool IsValidXY(uint x, uint y)
    00236 {
    00237   return ((int)x) >= 0 && x < _height_map.size_x && ((int)y) >= 0 && y < _height_map.size_y;
    00238 }
    00239
    00240
    00245 static inline bool AllocHeightMap()
    00246 {
    00247   height_t *h;
    00248
    00249   _height_map.size_x = MapSizeX();
    00250   _height_map.size_y = MapSizeY();
    00251
    00252   /* Allocate memory block for height map row pointers */
    00253   _height_map.total_size = (_height_map.size_x + 1) * (_height_map.size_y + 1);
    00254   _height_map.dim_x = _height_map.size_x + 1;
    00255   _height_map.h = CallocT<height_t>(_height_map.total_size);
    00256
    00257   /* Iterate through height map initialize values */
    00258   FOR_ALL_TILES_IN_HEIGHT(h) *h = _invalid_height;
    00259
    00260   return true;
    00261 }
    00262
    00264 static inline void FreeHeightMap()
    00265 {
    00266   if (_height_map.h == NULL) return;
    00267   free(_height_map.h);
    00268   _height_map.h = NULL;
    00269 }
    00270
    00276 static inline height_t RandomHeight(amplitude_t rMax)
    00277 {
    00278   amplitude_t ra = (Random() << 16) | (Random() & 0x0000FFFF);
    00279   height_t rh;
    00280   /* Spread height into range -rMax..+rMax */
    00281   rh = A2H(ra % (2 * rMax + 1) - rMax);
    00282   return rh;
    00283 }
    00284
    00303 static bool ApplyNoise(uint log_frequency, amplitude_t amplitude)
    00304 {
    00305   uint size_min = min(_height_map.size_x, _height_map.size_y);
    00306   uint step = size_min >> log_frequency;
    00307   uint x, y;
    00308
    00309   /* Trying to apply noise to uninitialized height map */
    00310   assert(_height_map.h != NULL);
    00311
    00312   /* Are we finished? */
    00313   if (step == 0) return false;
    00314
    00315   if (log_frequency == 0) {
    00316     /* This is first round, we need to establish base heights with step = size_min */
    00317     for (y = 0; y <= _height_map.size_y; y += step) {
    00318       for (x = 0; x <= _height_map.size_x; x += step) {
    00319         height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
    00320         _height_map.height(x, y) = height;
    00321       }
    00322     }
    00323     return true;
    00324   }
    00325
    00326   /* It is regular iteration round.
    00327    * Interpolate height values at odd x, even y tiles */
    00328   for (y = 0; y <= _height_map.size_y; y += 2 * step) {
    00329     for (x = 0; x < _height_map.size_x; x += 2 * step) {
    00330       height_t h00 = _height_map.height(x + 0 * step, y);
    00331       height_t h02 = _height_map.height(x + 2 * step, y);
    00332       height_t h01 = (h00 + h02) / 2;
    00333       _height_map.height(x + 1 * step, y) = h01;
    00334     }
    00335   }
    00336
    00337   /* Interpolate height values at odd y tiles */
    00338   for (y = 0; y < _height_map.size_y; y += 2 * step) {
    00339     for (x = 0; x <= _height_map.size_x; x += step) {
    00340       height_t h00 = _height_map.height(x, y + 0 * step);
    00341       height_t h20 = _height_map.height(x, y + 2 * step);
    00342       height_t h10 = (h00 + h20) / 2;
    00343       _height_map.height(x, y + 1 * step) = h10;
    00344     }
    00345   }
    00346
    00347   /* Add noise for next higher frequency (smaller steps) */
    00348   for (y = 0; y <= _height_map.size_y; y += step) {
    00349     for (x = 0; x <= _height_map.size_x; x += step) {
    00350       _height_map.height(x, y) += RandomHeight(amplitude);
    00351     }
    00352   }
    00353
    00354   return (step > 1);
    00355 }
    00356
    00358 static void HeightMapGenerate()
    00359 {
    00360   uint size_min = min(_height_map.size_x, _height_map.size_y);
    00361   uint iteration_round = 0;
    00362   amplitude_t amplitude;
    00363   bool continue_iteration;
    00364   int log_size_min, log_frequency_min;
    00365   int log_frequency;
    00366
    00367   /* Find first power of two that fits, so that later log_frequency == TGP_FREQUENCY_MAX in the last iteration */
    00368   for (log_size_min = TGP_FREQUENCY_MAX; (1U << log_size_min) < size_min; log_size_min++) { }
    00369   log_frequency_min = log_size_min - TGP_FREQUENCY_MAX;
    00370
    00371   /* Zero must be part of the iteration, else initialization will fail. */
    00372   assert(log_frequency_min >= 0);
    00373
    00374   /* Keep increasing the frequency until we reach the step size equal to one tile */
    00375   do {
    00376     log_frequency = iteration_round - log_frequency_min;
    00377     if (log_frequency >= 0) {
    00378       /* Apply noise for the next frequency */
    00379       assert(log_frequency <= TGP_FREQUENCY_MAX);
    00380       amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][log_frequency];
    00381     } else {
    00382       /* Amplitude for the low frequencies on big maps is 0, i.e. initialise with zero height */
    00383       amplitude = 0;
    00384     }
    00385     continue_iteration = ApplyNoise(iteration_round, amplitude);
    00386     iteration_round++;
    00387   } while (continue_iteration);
    00388   assert(log_frequency == TGP_FREQUENCY_MAX);
    00389 }
    00390
    00392 static void HeightMapGetMinMaxAvg(height_t *min_ptr, height_t *max_ptr, height_t *avg_ptr)
    00393 {
    00394   height_t h_min, h_max, h_avg, *h;
    00395   int64 h_accu = 0;
    00396   h_min = h_max = _height_map.height(0, 0);
    00397
    00398   /* Get h_min, h_max and accumulate heights into h_accu */
    00399   FOR_ALL_TILES_IN_HEIGHT(h) {
    00400     if (*h < h_min) h_min = *h;
    00401     if (*h > h_max) h_max = *h;
    00402     h_accu += *h;
    00403   }
    00404
    00405   /* Get average height */
    00406   h_avg = (height_t)(h_accu / (_height_map.size_x * _height_map.size_y));
    00407
    00408   /* Return required results */
    00409   if (min_ptr != NULL) *min_ptr = h_min;
    00410   if (max_ptr != NULL) *max_ptr = h_max;
    00411   if (avg_ptr != NULL) *avg_ptr = h_avg;
    00412 }
    00413
    00415 static int *HeightMapMakeHistogram(height_t h_min, height_t h_max, int *hist_buf)
    00416 {
    00417   int *hist = hist_buf - h_min;
    00418   height_t *h;
    00419
    00420   /* Count the heights and fill the histogram */
    00421   FOR_ALL_TILES_IN_HEIGHT(h) {
    00422     assert(*h >= h_min);
    00423     assert(*h <= h_max);
    00424     hist[*h]++;
    00425   }
    00426   return hist;
    00427 }
    00428
    00430 static void HeightMapSineTransform(height_t h_min, height_t h_max)
    00431 {
    00432   height_t *h;
    00433
    00434   FOR_ALL_TILES_IN_HEIGHT(h) {
    00435     double fheight;
    00436
    00437     if (*h < h_min) continue;
    00438
    00439     /* Transform height into 0..1 space */
    00440     fheight = (double)(*h - h_min) / (double)(h_max - h_min);
    00441     /* Apply sine transform depending on landscape type */
    00442     switch(_settings_game.game_creation.landscape) {
    00443       case LT_TOYLAND:
    00444       case LT_TEMPERATE:
    00445         /* Move and scale 0..1 into -1..+1 */
    00446         fheight = 2 * fheight - 1;
    00447         /* Sine transform */
    00448         fheight = sin(fheight * M_PI_2);
    00449         /* Transform it back from -1..1 into 0..1 space */
    00450         fheight = 0.5 * (fheight + 1);
    00451         break;
    00452
    00453       case LT_ARCTIC:
    00454         {
    00455           /* Arctic terrain needs special height distribution.
    00456            * Redistribute heights to have more tiles at highest (75%..100%) range */
    00457           double sine_upper_limit = 0.75;
    00458           double linear_compression = 2;
    00459           if (fheight >= sine_upper_limit) {
    00460             /* Over the limit we do linear compression up */
    00461             fheight = 1.0 - (1.0 - fheight) / linear_compression;
    00462           } else {
    00463             double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
    00464             /* Get 0..sine_upper_limit into -1..1 */
    00465             fheight = 2.0 * fheight / sine_upper_limit - 1.0;
    00466             /* Sine wave transform */
    00467             fheight = sin(fheight * M_PI_2);
    00468             /* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
    00469             fheight = 0.5 * (fheight + 1.0) * m;
    00470           }
    00471         }
    00472         break;
    00473
    00474       case LT_TROPIC:
    00475         {
    00476           /* Desert terrain needs special height distribution.
    00477            * Half of tiles should be at lowest (0..25%) heights */
    00478           double sine_lower_limit = 0.5;
    00479           double linear_compression = 2;
    00480           if (fheight <= sine_lower_limit) {
    00481             /* Under the limit we do linear compression down */
    00482             fheight = fheight / linear_compression;
    00483           } else {
    00484             double m = sine_lower_limit / linear_compression;
    00485             /* Get sine_lower_limit..1 into -1..1 */
    00486             fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
    00487             /* Sine wave transform */
    00488             fheight = sin(fheight * M_PI_2);
    00489             /* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
    00490             fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
    00491           }
    00492         }
    00493         break;
    00494
    00495       default:
    00496         NOT_REACHED();
    00497         break;
    00498     }
    00499     /* Transform it back into h_min..h_max space */
    00500     *h = (height_t)(fheight * (h_max - h_min) + h_min);
    00501     if (*h < 0) *h = I2H(0);
    00502     if (*h >= h_max) *h = h_max - 1;
    00503   }
    00504 }
    00505
    00507 static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new)
    00508 {
    00509   height_t h_min, h_max, h_avg, h_water_level;
    00510   int water_tiles, desired_water_tiles;
    00511   height_t *h;
    00512   int *hist;
    00513
    00514   HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
    00515
    00516   /* Allocate histogram buffer and clear its cells */
    00517   int *hist_buf = CallocT<int>(h_max - h_min + 1);
    00518   /* Fill histogram */
    00519   hist = HeightMapMakeHistogram(h_min, h_max, hist_buf);
    00520
    00521   /* How many water tiles do we want? */
    00522   desired_water_tiles = (int)(((int64)water_percent) * (int64)(_height_map.size_x * _height_map.size_y)) >> amplitude_decimal_bits;
    00523
    00524   /* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
    00525   for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
    00526     water_tiles += hist[h_water_level];
    00527     if (water_tiles >= desired_water_tiles) break;
    00528   }
    00529
    00530   /* We now have the proper water level value.
    00531    * Transform the height map into new (normalized) height map:
    00532    *   values from range: h_min..h_water_level will become negative so it will be clamped to 0
    00533    *   values from range: h_water_level..h_max are transformed into 0..h_max_new
    00534    * , where h_max_new is 4, 8, 12 or 16 depending on terrain type (very flat, flat, hilly, mountains)
    00535    */
    00536   FOR_ALL_TILES_IN_HEIGHT(h) {
    00537     /* Transform height from range h_water_level..h_max into 0..h_max_new range */
    00538     *h = (height_t)(((int)h_max_new) * (*h - h_water_level) / (h_max - h_water_level)) + I2H(1);
    00539     /* Make sure all values are in the proper range (0..h_max_new) */
    00540     if (*h < 0) *h = I2H(0);
    00541     if (*h >= h_max_new) *h = h_max_new - 1;
    00542   }
    00543
    00544   free(hist_buf);
    00545 }
    00546
    00547 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
    00548
    00569 static void HeightMapCoastLines(uint8 water_borders)
    00570 {
    00571   int smallest_size = min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
    00572   const int margin = 4;
    00573   uint y, x;
    00574   double max_x;
    00575   double max_y;
    00576
    00577   /* Lower to sea level */
    00578   for (y = 0; y <= _height_map.size_y; y++) {
    00579     if (HasBit(water_borders, BORDER_NE)) {
    00580       /* Top right */
    00581       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);
    00582       max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
    00583       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
    00584       for (x = 0; x < max_x; x++) {
    00585         _height_map.height(x, y) = 0;
    00586       }
    00587     }
    00588
    00589     if (HasBit(water_borders, BORDER_SW)) {
    00590       /* Bottom left */
    00591       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);
    00592       max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
    00593       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
    00594       for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
    00595         _height_map.height(x, y) = 0;
    00596       }
    00597     }
    00598   }
    00599
    00600   /* Lower to sea level */
    00601   for (x = 0; x <= _height_map.size_x; x++) {
    00602     if (HasBit(water_borders, BORDER_NW)) {
    00603       /* Top left */
    00604       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);
    00605       max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
    00606       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
    00607       for (y = 0; y < max_y; y++) {
    00608         _height_map.height(x, y) = 0;
    00609       }
    00610     }
    00611
    00612     if (HasBit(water_borders, BORDER_SE)) {
    00613       /* Bottom right */
    00614       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);
    00615       max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
    00616       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
    00617       for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
    00618         _height_map.height(x, y) = 0;
    00619       }
    00620     }
    00621   }
    00622 }
    00623
    00625 static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
    00626 {
    00627   const int max_coast_dist_from_edge = 35;
    00628   const int max_coast_Smooth_depth = 35;
    00629
    00630   int x, y;
    00631   int ed; // coast distance from edge
    00632   int depth;
    00633
    00634   height_t h_prev = 16;
    00635   height_t h;
    00636
    00637   assert(IsValidXY(org_x, org_y));
    00638
    00639   /* Search for the coast (first non-water tile) */
    00640   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++) {
    00641     /* Coast found? */
    00642     if (_height_map.height(x, y) > 15) break;
    00643
    00644     /* Coast found in the neighborhood? */
    00645     if (IsValidXY(x + dir_y, y + dir_x) && _height_map.height(x + dir_y, y + dir_x) > 0) break;
    00646
    00647     /* Coast found in the neighborhood on the other side */
    00648     if (IsValidXY(x - dir_y, y - dir_x) && _height_map.height(x - dir_y, y - dir_x) > 0) break;
    00649   }
    00650
    00651   /* Coast found or max_coast_dist_from_edge has been reached.
    00652    * Soften the coast slope */
    00653   for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
    00654     h = _height_map.height(x, y);
    00655     h = min(h, h_prev + (4 + depth)); // coast softening formula
    00656     _height_map.height(x, y) = h;
    00657     h_prev = h;
    00658   }
    00659 }
    00660
    00662 static void HeightMapSmoothCoasts(uint8 water_borders)
    00663 {
    00664   uint x, y;
    00665   /* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
    00666   for (x = 0; x < _height_map.size_x; x++) {
    00667     if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
    00668     if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
    00669   }
    00670   /* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
    00671   for (y = 0; y < _height_map.size_y; y++) {
    00672     if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
    00673     if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
    00674   }
    00675 }
    00676
    00684 static void HeightMapSmoothSlopes(height_t dh_max)
    00685 {
    00686   int x, y;
    00687   for (y = 0; y <= (int)_height_map.size_y; y++) {
    00688     for (x = 0; x <= (int)_height_map.size_x; x++) {
    00689       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;
    00690       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
    00691     }
    00692   }
    00693   for (y = _height_map.size_y; y >= 0; y--) {
    00694     for (x = _height_map.size_x; x >= 0; x--) {
    00695       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;
    00696       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
    00697     }
    00698   }
    00699 }
    00700
    00706 static void HeightMapNormalize()
    00707 {
    00708   const amplitude_t water_percent = _water_percent[_settings_game.difficulty.quantity_sea_lakes];
    00709   const height_t h_max_new = I2H(_max_height[_settings_game.difficulty.terrain_type]);
    00710   const height_t roughness = 7 + 3 * _settings_game.game_creation.tgen_smoothness;
    00711
    00712   HeightMapAdjustWaterLevel(water_percent, h_max_new);
    00713
    00714   byte water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
    00715   if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
    00716
    00717   HeightMapCoastLines(water_borders);
    00718   HeightMapSmoothSlopes(roughness);
    00719
    00720   HeightMapSmoothCoasts(water_borders);
    00721   HeightMapSmoothSlopes(roughness);
    00722
    00723   HeightMapSineTransform(12, h_max_new);
    00724   HeightMapSmoothSlopes(16);
    00725 }
    00726
    00734 static double int_noise(const long x, const long y, const int prime)
    00735 {
    00736   long n = x + y * prime + _settings_game.game_creation.generation_seed;
    00737
    00738   n = (n << 13) ^ n;
    00739
    00740   /* Pseudo-random number generator, using several large primes */
    00741   return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
    00742 }
    00743
    00744
    00751 static double smoothed_noise(const int x, const int y, const int prime)
    00752 {
    00753 #if 0
    00754   /* A hilly world (four corner smooth) */
    00755   const double sides = int_noise(x - 1, y) + int_noise(x + 1, y) + int_noise(x, y - 1) + int_noise(x, y + 1);
    00756   const double center  =  int_noise(x, y);
    00757   return (sides + sides + center * 4) / 8.0;
    00758 #endif
    00759
    00760   /* This gives very hilly world */
    00761   return int_noise(x, y, prime);
    00762 }
    00763
    00764
    00768 static inline double linear_interpolate(const double a, const double b, const double x)
    00769 {
    00770   return a + x * (b - a);
    00771 }
    00772
    00773
    00778 static double interpolated_noise(const double x, const double y, const int prime)
    00779 {
    00780   const int integer_X = (int)x;
    00781   const int integer_Y = (int)y;
    00782
    00783   const double fractional_X = x - (double)integer_X;
    00784   const double fractional_Y = y - (double)integer_Y;
    00785
    00786   const double v1 = smoothed_noise(integer_X,     integer_Y,     prime);
    00787   const double v2 = smoothed_noise(integer_X + 1, integer_Y,     prime);
    00788   const double v3 = smoothed_noise(integer_X,     integer_Y + 1, prime);
    00789   const double v4 = smoothed_noise(integer_X + 1, integer_Y + 1, prime);
    00790
    00791   const double i1 = linear_interpolate(v1, v2, fractional_X);
    00792   const double i2 = linear_interpolate(v3, v4, fractional_X);
    00793
    00794   return linear_interpolate(i1, i2, fractional_Y);
    00795 }
    00796
    00797
    00804 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
    00805 {
    00806   double total = 0.0;
    00807   int i;
    00808
    00809   for (i = 0; i < 6; i++) {
    00810     const double frequency = (double)(1 << i);
    00811     const double amplitude = pow(p, (double)i);
    00812
    00813     total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
    00814   }
    00815
    00816   return total;
    00817 }
    00818
    00819
    00821 static void TgenSetTileHeight(TileIndex tile, int height)
    00822 {
    00823   SetTileHeight(tile, height);
    00824
    00825   /* Only clear the tiles within the map area. */
    00826   if (TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY() &&
    00827       (!_settings_game.construction.freeform_edges || (TileX(tile) != 0 && TileY(tile) != 0))) {
    00828     MakeClear(tile, CLEAR_GRASS, 3);
    00829   }
    00830 }
    00831
    00839 void GenerateTerrainPerlin()
    00840 {
    00841   uint x, y;
    00842
    00843   if (!AllocHeightMap()) return;
    00844   GenerateWorldSetAbortCallback(FreeHeightMap);
    00845
    00846   HeightMapGenerate();
    00847
    00848   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    00849
    00850   HeightMapNormalize();
    00851
    00852   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    00853
    00854   /* First make sure the tiles at the north border are void tiles if needed. */
    00855   if (_settings_game.construction.freeform_edges) {
    00856     for (y = 0; y < _height_map.size_y - 1; y++) MakeVoid(_height_map.size_x * y);
    00857     for (x = 0; x < _height_map.size_x;     x++) MakeVoid(x);
    00858   }
    00859
    00860   /* Transfer height map into OTTD map */
    00861   for (y = 0; y < _height_map.size_y; y++) {
    00862     for (x = 0; x < _height_map.size_x; x++) {
    00863       int height = H2I(_height_map.height(x, y));
    00864       if (height < 0) height = 0;
    00865       if (height > 15) height = 15;
    00866       TgenSetTileHeight(TileXY(x, y), height);
    00867     }
    00868   }
    00869
    00870   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
    00871
    00872   FreeHeightMap();
    00873   GenerateWorldSetAbortCallback(NULL);
    00874 }