tgp.cpp

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00001 /* $Id: tgp.cpp 11834 2008-01-13 14:37:30Z rubidium $ */
00002 
00005 #include "stdafx.h"
00006 #include <math.h>
00007 #include "openttd.h"
00008 #include "clear_map.h"
00009 #include "clear_map.h"
00010 #include "variables.h"
00011 #include "void_map.h"
00012 #include "tgp.h"
00013 #include "console.h"
00014 #include "genworld.h"
00015 #include "core/alloc_func.hpp"
00016 #include "core/random_func.hpp"
00017 #include "settings_type.h"
00018 
00019 #include "table/strings.h"
00020 
00021 /*
00022  *
00023  * Quickie guide to Perlin Noise
00024  * Perlin noise is a predictable pseudo random number sequence. By generating
00025  * it in 2 dimensions, it becomes a useful random map, that for a given seed
00026  * and starting X & Y is entirely predictable. On the face of it, that may not
00027  * be useful. However, it means that if you want to replay a map in a different
00028  * terrain, or just vary the sea level, you just re-run the generator with the
00029  * same seed. The seed is an int32, and is randomised on each run of New Game.
00030  * The Scenario Generator does not randomise the value, so that you can
00031  * experiment with one terrain until you are happy, or click "Random" for a new
00032  * random seed.
00033  *
00034  * Perlin Noise is a series of "octaves" of random noise added together. By
00035  * reducing the amplitude of the noise with each octave, the first octave of
00036  * noise defines the main terrain sweep, the next the ripples on that, and the
00037  * next the ripples on that. I use 6 octaves, with the amplitude controlled by
00038  * a power ratio, usually known as a persistence or p value. This I vary by the
00039  * smoothness selection, as can be seen in the table below. The closer to 1,
00040  * the more of that octave is added. Each octave is however raised to the power
00041  * of its position in the list, so the last entry in the "smooth" row, 0.35, is
00042  * raised to the power of 6, so can only add 0.001838...  of the amplitude to
00043  * the running total.
00044  *
00045  * In other words; the first p value sets the general shape of the terrain, the
00046  * second sets the major variations to that, ... until finally the smallest
00047  * bumps are added.
00048  *
00049  * Usefully, this routine is totally scaleable; so when 32bpp comes along, the
00050  * terrain can be as bumpy as you like! It is also infinitely expandable; a
00051  * single random seed terrain continues in X & Y as far as you care to
00052  * calculate. In theory, we could use just one seed value, but randomly select
00053  * where in the Perlin XY space we use for the terrain. Personally I prefer
00054  * using a simple (0, 0) to (X, Y), with a varying seed.
00055  *
00056  *
00057  * Other things i have had to do: mountainous wasnt mountainous enough, and
00058  * since we only have 0..15 heights available, I add a second generated map
00059  * (with a modified seed), onto the original. This generally raises the
00060  * terrain, which then needs scaling back down. Overall effect is a general
00061  * uplift.
00062  *
00063  * However, the values on the top of mountains are then almost guaranteed to go
00064  * too high, so large flat plateaus appeared at height 15. To counter this, I
00065  * scale all heights above 12 to proportion up to 15. It still makes the
00066  * mountains have flatish tops, rather than craggy peaks, but at least they
00067  * arent smooth as glass.
00068  *
00069  *
00070  * For a full discussion of Perlin Noise, please visit:
00071  * http://freespace.virgin.net/hugo.elias/models/m_perlin.htm
00072  *
00073  *
00074  * Evolution II
00075  *
00076  * The algorithm as described in the above link suggests to compute each tile height
00077  * as composition of several noise waves. Some of them are computed directly by
00078  * noise(x, y) function, some are calculated using linear approximation. Our
00079  * first implementation of perlin_noise_2D() used 4 noise(x, y) calls plus
00080  * 3 linear interpolations. It was called 6 times for each tile. This was a bit
00081  * CPU expensive.
00082  *
00083  * The following implementation uses optimized algorithm that should produce
00084  * the same quality result with much less computations, but more memory accesses.
00085  * The overal speedup should be 300% to 800% depending on CPU and memory speed.
00086  *
00087  * I will try to explain it on the example below:
00088  *
00089  * Have a map of 4 x 4 tiles, our simplifiead noise generator produces only two
00090  * values -1 and +1, use 3 octaves with wave lenght 1, 2 and 4, with amplitudes
00091  * 3, 2, 1. Original algorithm produces:
00092  *
00093  * 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
00094  * 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
00095  * 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
00096  * 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
00097  *
00098  * 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
00099  * 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
00100  * 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
00101  * 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
00102  *
00103  *
00104  * Optimization 1:
00105  *
00106  * 1) we need to allocate a bit more tiles: (size_x + 1) * (size_y + 1) = (5 * 5):
00107  *
00108  * 2) setup corner values using amplitude 3
00109  * {    -3.0        X          X          X          3.0   }
00110  * {     X          X          X          X          X     }
00111  * {     X          X          X          X          X     }
00112  * {     X          X          X          X          X     }
00113  * {     3.0        X          X          X         -3.0   }
00114  *
00115  * 3a) interpolate values in the middle
00116  * {    -3.0        X          0.0        X          3.0   }
00117  * {     X          X          X          X          X     }
00118  * {     0.0        X          0.0        X          0.0   }
00119  * {     X          X          X          X          X     }
00120  * {     3.0        X          0.0        X         -3.0   }
00121  *
00122  * 3b) add patches with amplitude 2 to them
00123  * {    -5.0        X          2.0        X          1.0   }
00124  * {     X          X          X          X          X     }
00125  * {     2.0        X         -2.0        X          2.0   }
00126  * {     X          X          X          X          X     }
00127  * {     1.0        X          2.0        X         -5.0   }
00128  *
00129  * 4a) interpolate values in the middle
00130  * {    -5.0       -1.5        2.0        1.5        1.0   }
00131  * {    -1.5       -0.75       0.0        0.75       1.5   }
00132  * {     2.0        0.0       -2.0        0.0        2.0   }
00133  * {     1.5        0.75       0.0       -0.75      -1.5   }
00134  * {     1.0        1.5        2.0       -1.5       -5.0   }
00135  *
00136  * 4b) add patches with amplitude 1 to them
00137  * {    -6.0       -0.5        1.0        2.5        0.0   }
00138  * {    -0.5       -1.75       1.0       -0.25       2.5   }
00139  * {     1.0        1.0       -3.0        1.0        1.0   }
00140  * {     2.5       -0.25       1.0       -1.75      -0.5   }
00141  * {     0.0        2.5        1.0       -0.5       -6.0   }
00142  *
00143  *
00144  *
00145  * Optimization 2:
00146  *
00147  * As you can see above, each noise function was called just once. Therefore
00148  * we don't need to use noise function that calculates the noise from x, y and
00149  * some prime. The same quality result we can obtain using standard Random()
00150  * function instead.
00151  *
00152  */
00153 
00154 #ifndef M_PI_2
00155 #define M_PI_2 1.57079632679489661923
00156 #define M_PI   3.14159265358979323846
00157 #endif /* M_PI_2 */
00158 
00160 typedef int16 height_t;
00161 static const int height_decimal_bits = 4;
00162 static const height_t _invalid_height = -32768;
00163 
00165 typedef int amplitude_t;
00166 static const int amplitude_decimal_bits = 10;
00167 
00169 struct HeightMap
00170 {
00171   height_t *h;         //< array of heights
00172   uint     dim_x;      //< height map size_x MapSizeX() + 1
00173   uint     total_size; //< height map total size
00174   uint     size_x;     //< MapSizeX()
00175   uint     size_y;     //< MapSizeY()
00176 };
00177 
00179 static HeightMap _height_map = {NULL, 0, 0, 0, 0};
00180 
00182 #define HeightMapXY(x, y) _height_map.h[(x) + (y) * _height_map.dim_x]
00183 
00185 #define I2H(i) ((i) << height_decimal_bits)
00186 
00187 #define H2I(i) ((i) >> height_decimal_bits)
00188 
00190 #define I2A(i) ((i) << amplitude_decimal_bits)
00191 
00192 #define A2I(i) ((i) >> amplitude_decimal_bits)
00193 
00195 #define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
00196 
00197 
00199 #define FOR_ALL_TILES_IN_HEIGHT(h) for (h = _height_map.h; h < &_height_map.h[_height_map.total_size]; h++)
00200 
00203 static const amplitude_t _amplitudes_by_smoothness_and_frequency[4][12] = {
00204   /* Very smooth */
00205   {1000,  350,  123,   43,   15,    1,     1,    0,    0,    0,    0,    0},
00206   /* Smooth */
00207   {1000, 1000,  403,  200,   64,    8,     1,    0,    0,    0,    0,    0},
00208   /* Rough */
00209   {1000, 1200,  800,  500,  200,   16,     4,    0,    0,    0,    0,    0},
00210   /* Very Rough */
00211   {1500, 1000, 1200, 1000,  500,   32,    20,    0,    0,    0,    0,    0},
00212 };
00213 
00215 static const amplitude_t _water_percent[4] = {20, 80, 250, 400};
00216 
00218 static const int8 _max_height[4] = {
00219   6,       
00220   9,       
00221   12,      
00222   15       
00223 };
00224 
00230 static inline bool IsValidXY(uint x, uint y)
00231 {
00232   return ((int)x) >= 0 && x < _height_map.size_x && ((int)y) >= 0 && y < _height_map.size_y;
00233 }
00234 
00235 
00237 static inline bool AllocHeightMap()
00238 {
00239   height_t *h;
00240 
00241   _height_map.size_x = MapSizeX();
00242   _height_map.size_y = MapSizeY();
00243 
00244   /* Allocate memory block for height map row pointers */
00245   _height_map.total_size = (_height_map.size_x + 1) * (_height_map.size_y + 1);
00246   _height_map.dim_x = _height_map.size_x + 1;
00247   _height_map.h = CallocT<height_t>(_height_map.total_size);
00248   if (_height_map.h == NULL) return false;
00249 
00250   /* Iterate through height map initialize values */
00251   FOR_ALL_TILES_IN_HEIGHT(h) *h = _invalid_height;
00252 
00253   return true;
00254 }
00255 
00257 static inline void FreeHeightMap()
00258 {
00259   if (_height_map.h == NULL) return;
00260   free(_height_map.h);
00261   _height_map.h = NULL;
00262 }
00263 
00265 static inline height_t RandomHeight(amplitude_t rMax)
00266 {
00267   amplitude_t ra = (Random() << 16) | (Random() & 0x0000FFFF);
00268   height_t rh;
00269   /* Scale the amplitude for better resolution */
00270   rMax *= 16;
00271   /* Spread height into range -rMax..+rMax */
00272   rh = A2H(ra % (2 * rMax + 1) - rMax);
00273   return rh;
00274 }
00275 
00277 static bool ApplyNoise(uint log_frequency, amplitude_t amplitude)
00278 {
00279   uint size_min = min(_height_map.size_x, _height_map.size_y);
00280   uint step = size_min >> log_frequency;
00281   uint x, y;
00282 
00283   assert(_height_map.h != NULL);
00284 
00285   /* Are we finished? */
00286   if (step == 0) return false;
00287 
00288   if (log_frequency == 0) {
00289     /* This is first round, we need to establish base heights with step = size_min */
00290     for (y = 0; y <= _height_map.size_y; y += step) {
00291       for (x = 0; x <= _height_map.size_x; x += step) {
00292         height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
00293         HeightMapXY(x, y) = height;
00294       }
00295     }
00296     return true;
00297   }
00298 
00299   /* It is regular iteration round.
00300    * Interpolate height values at odd x, even y tiles */
00301   for (y = 0; y <= _height_map.size_y; y += 2 * step) {
00302     for (x = 0; x < _height_map.size_x; x += 2 * step) {
00303       height_t h00 = HeightMapXY(x + 0 * step, y);
00304       height_t h02 = HeightMapXY(x + 2 * step, y);
00305       height_t h01 = (h00 + h02) / 2;
00306       HeightMapXY(x + 1 * step, y) = h01;
00307     }
00308   }
00309 
00310   /* Interpolate height values at odd y tiles */
00311   for (y = 0; y < _height_map.size_y; y += 2 * step) {
00312     for (x = 0; x <= _height_map.size_x; x += step) {
00313       height_t h00 = HeightMapXY(x, y + 0 * step);
00314       height_t h20 = HeightMapXY(x, y + 2 * step);
00315       height_t h10 = (h00 + h20) / 2;
00316       HeightMapXY(x, y + 1 * step) = h10;
00317     }
00318   }
00319 
00320   for (y = 0; y <= _height_map.size_y; y += step) {
00321     for (x = 0; x <= _height_map.size_x; x += step) {
00322       HeightMapXY(x, y) += RandomHeight(amplitude);
00323     }
00324   }
00325   return (step > 1);
00326 }
00327 
00329 static void HeightMapGenerate()
00330 {
00331   uint size_min = min(_height_map.size_x, _height_map.size_y);
00332   uint iteration_round = 0;
00333   amplitude_t amplitude;
00334   bool continue_iteration;
00335   uint log_size_min, log_frequency_min;
00336   int log_frequency;
00337 
00338   /* Find first power of two that fits */
00339   for (log_size_min = 6; (1U << log_size_min) < size_min; log_size_min++) { }
00340   log_frequency_min = log_size_min - 6;
00341 
00342   do {
00343     log_frequency = iteration_round - log_frequency_min;
00344     if (log_frequency >= 0) {
00345       amplitude = _amplitudes_by_smoothness_and_frequency[_patches.tgen_smoothness][log_frequency];
00346     } else {
00347       amplitude = 0;
00348     }
00349     continue_iteration = ApplyNoise(iteration_round, amplitude);
00350     iteration_round++;
00351   } while(continue_iteration);
00352 }
00353 
00355 static void HeightMapGetMinMaxAvg(height_t *min_ptr, height_t *max_ptr, height_t *avg_ptr)
00356 {
00357   height_t h_min, h_max, h_avg, *h;
00358   int64 h_accu = 0;
00359   h_min = h_max = HeightMapXY(0, 0);
00360 
00361   /* Get h_min, h_max and accumulate heights into h_accu */
00362   FOR_ALL_TILES_IN_HEIGHT(h) {
00363     if (*h < h_min) h_min = *h;
00364     if (*h > h_max) h_max = *h;
00365     h_accu += *h;
00366   }
00367 
00368   /* Get average height */
00369   h_avg = (height_t)(h_accu / (_height_map.size_x * _height_map.size_y));
00370 
00371   /* Return required results */
00372   if (min_ptr != NULL) *min_ptr = h_min;
00373   if (max_ptr != NULL) *max_ptr = h_max;
00374   if (avg_ptr != NULL) *avg_ptr = h_avg;
00375 }
00376 
00378 static int *HeightMapMakeHistogram(height_t h_min, height_t h_max, int *hist_buf)
00379 {
00380   int *hist = hist_buf - h_min;
00381   height_t *h;
00382 
00383   /* Fill histogram */
00384   FOR_ALL_TILES_IN_HEIGHT(h) {
00385     assert(*h >= h_min);
00386     assert(*h <= h_max);
00387     hist[*h]++;
00388   }
00389   return hist;
00390 }
00391 
00393 static void HeightMapSineTransform(height_t h_min, height_t h_max)
00394 {
00395   height_t *h;
00396 
00397   FOR_ALL_TILES_IN_HEIGHT(h) {
00398     double fheight;
00399 
00400     if (*h < h_min) continue;
00401 
00402     /* Transform height into 0..1 space */
00403     fheight = (double)(*h - h_min) / (double)(h_max - h_min);
00404     /* Apply sine transform depending on landscape type */
00405     switch(_opt.landscape) {
00406       case LT_TOYLAND:
00407       case LT_TEMPERATE:
00408         /* Move and scale 0..1 into -1..+1 */
00409         fheight = 2 * fheight - 1;
00410         /* Sine transform */
00411         fheight = sin(fheight * M_PI_2);
00412         /* Transform it back from -1..1 into 0..1 space */
00413         fheight = 0.5 * (fheight + 1);
00414         break;
00415 
00416       case LT_ARCTIC:
00417         {
00418           /* Arctic terrain needs special height distribution.
00419            * Redistribute heights to have more tiles at highest (75%..100%) range */
00420           double sine_upper_limit = 0.75;
00421           double linear_compression = 2;
00422           if (fheight >= sine_upper_limit) {
00423             /* Over the limit we do linear compression up */
00424             fheight = 1.0 - (1.0 - fheight) / linear_compression;
00425           } else {
00426             double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
00427             /* Get 0..sine_upper_limit into -1..1 */
00428             fheight = 2.0 * fheight / sine_upper_limit - 1.0;
00429             /* Sine wave transform */
00430             fheight = sin(fheight * M_PI_2);
00431             /* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
00432             fheight = 0.5 * (fheight + 1.0) * m;
00433           }
00434         }
00435         break;
00436 
00437       case LT_TROPIC:
00438         {
00439           /* Desert terrain needs special height distribution.
00440            * Half of tiles should be at lowest (0..25%) heights */
00441           double sine_lower_limit = 0.5;
00442           double linear_compression = 2;
00443           if (fheight <= sine_lower_limit) {
00444             /* Under the limit we do linear compression down */
00445             fheight = fheight / linear_compression;
00446           } else {
00447             double m = sine_lower_limit / linear_compression;
00448             /* Get sine_lower_limit..1 into -1..1 */
00449             fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
00450             /* Sine wave transform */
00451             fheight = sin(fheight * M_PI_2);
00452             /* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
00453             fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
00454           }
00455         }
00456         break;
00457 
00458       default:
00459         NOT_REACHED();
00460         break;
00461     }
00462     /* Transform it back into h_min..h_max space */
00463     *h = (height_t)(fheight * (h_max - h_min) + h_min);
00464     if (*h < 0) *h = I2H(0);
00465     if (*h >= h_max) *h = h_max - 1;
00466   }
00467 }
00468 
00470 static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new)
00471 {
00472   height_t h_min, h_max, h_avg, h_water_level;
00473   int water_tiles, desired_water_tiles;
00474   height_t *h;
00475   int *hist;
00476 
00477   HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
00478 
00479   /* Allocate histogram buffer and clear its cells */
00480   int *hist_buf = CallocT<int>(h_max - h_min + 1);
00481   /* Fill histogram */
00482   hist = HeightMapMakeHistogram(h_min, h_max, hist_buf);
00483 
00484   /* How many water tiles do we want? */
00485   desired_water_tiles = (int)(((int64)water_percent) * (int64)(_height_map.size_x * _height_map.size_y)) >> amplitude_decimal_bits;
00486 
00487   /* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
00488   for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
00489     water_tiles += hist[h_water_level];
00490     if (water_tiles >= desired_water_tiles) break;
00491   }
00492 
00493   /* We now have the proper water level value.
00494    * Transform the height map into new (normalized) height map:
00495    *   values from range: h_min..h_water_level will become negative so it will be clamped to 0
00496    *   values from range: h_water_level..h_max are transformed into 0..h_max_new
00497    * , where h_max_new is 4, 8, 12 or 16 depending on terrain type (very flat, flat, hilly, mountains)
00498    */
00499   FOR_ALL_TILES_IN_HEIGHT(h) {
00500     /* Transform height from range h_water_level..h_max into 0..h_max_new range */
00501     *h = (height_t)(((int)h_max_new) * (*h - h_water_level) / (h_max - h_water_level)) + I2H(1);
00502     /* Make sure all values are in the proper range (0..h_max_new) */
00503     if (*h < 0) *h = I2H(0);
00504     if (*h >= h_max_new) *h = h_max_new - 1;
00505   }
00506 
00507   free(hist_buf);
00508 }
00509 
00510 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
00511 
00532 static void HeightMapCoastLines()
00533 {
00534   int smallest_size = min(_patches.map_x, _patches.map_y);
00535   const int margin = 4;
00536   uint y, x;
00537   double max_x;
00538   double max_y;
00539 
00540   /* Lower to sea level */
00541   for (y = 0; y <= _height_map.size_y; y++) {
00542     /* Top right */
00543     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);
00544     max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
00545     if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
00546     for (x = 0; x < max_x; x++) {
00547       HeightMapXY(x, y) = 0;
00548     }
00549 
00550     /* Bottom left */
00551     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);
00552     max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
00553     if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
00554     for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
00555       HeightMapXY(x, y) = 0;
00556     }
00557   }
00558 
00559   /* Lower to sea level */
00560   for (x = 0; x <= _height_map.size_x; x++) {
00561     /* Top left */
00562     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);
00563     max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
00564     if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
00565     for (y = 0; y < max_y; y++) {
00566       HeightMapXY(x, y) = 0;
00567     }
00568 
00569 
00570     /* Bottom right */
00571     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);
00572     max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
00573     if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
00574     for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
00575       HeightMapXY(x, y) = 0;
00576     }
00577   }
00578 }
00579 
00581 static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
00582 {
00583   const int max_coast_dist_from_edge = 35;
00584   const int max_coast_Smooth_depth = 35;
00585 
00586   int x, y;
00587   int ed; // coast distance from edge
00588   int depth;
00589 
00590   height_t h_prev = 16;
00591   height_t h;
00592 
00593   assert(IsValidXY(org_x, org_y));
00594 
00595   /* Search for the coast (first non-water tile) */
00596   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++) {
00597     /* Coast found? */
00598     if (HeightMapXY(x, y) > 15) break;
00599 
00600     /* Coast found in the neighborhood? */
00601     if (IsValidXY(x + dir_y, y + dir_x) && HeightMapXY(x + dir_y, y + dir_x) > 0) break;
00602 
00603     /* Coast found in the neighborhood on the other side */
00604     if (IsValidXY(x - dir_y, y - dir_x) && HeightMapXY(x - dir_y, y - dir_x) > 0) break;
00605   }
00606 
00607   /* Coast found or max_coast_dist_from_edge has been reached.
00608    * Soften the coast slope */
00609   for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
00610     h = HeightMapXY(x, y);
00611     h = min(h, h_prev + (4 + depth)); // coast softening formula
00612     HeightMapXY(x, y) = h;
00613     h_prev = h;
00614   }
00615 }
00616 
00618 static void HeightMapSmoothCoasts()
00619 {
00620   uint x, y;
00621   /* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
00622   for (x = 0; x < _height_map.size_x; x++) {
00623     HeightMapSmoothCoastInDirection(x, 0, 0, 1);
00624     HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
00625   }
00626   /* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
00627   for (y = 0; y < _height_map.size_y; y++) {
00628     HeightMapSmoothCoastInDirection(0, y, 1, 0);
00629     HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
00630   }
00631 }
00632 
00640 static void HeightMapSmoothSlopes(height_t dh_max)
00641 {
00642   int x, y;
00643   for (y = 1; y <= (int)_height_map.size_y; y++) {
00644     for (x = 1; x <= (int)_height_map.size_x; x++) {
00645       height_t h_max = min(HeightMapXY(x - 1, y), HeightMapXY(x, y - 1)) + dh_max;
00646       if (HeightMapXY(x, y) > h_max) HeightMapXY(x, y) = h_max;
00647     }
00648   }
00649   for (y = _height_map.size_y - 1; y >= 0; y--) {
00650     for (x = _height_map.size_x - 1; x >= 0; x--) {
00651       height_t h_max = min(HeightMapXY(x + 1, y), HeightMapXY(x, y + 1)) + dh_max;
00652       if (HeightMapXY(x, y) > h_max) HeightMapXY(x, y) = h_max;
00653     }
00654   }
00655 }
00656 
00662 static void HeightMapNormalize()
00663 {
00664   const amplitude_t water_percent = _water_percent[_opt.diff.quantity_sea_lakes];
00665   const height_t h_max_new = I2H(_max_height[_opt.diff.terrain_type]);
00666   const height_t roughness = 7 + 3 * _patches.tgen_smoothness;
00667 
00668   HeightMapAdjustWaterLevel(water_percent, h_max_new);
00669 
00670   HeightMapCoastLines();
00671   HeightMapSmoothSlopes(roughness);
00672 
00673   HeightMapSmoothCoasts();
00674   HeightMapSmoothSlopes(roughness);
00675 
00676   HeightMapSineTransform(12, h_max_new);
00677   HeightMapSmoothSlopes(16);
00678 }
00679 
00680 static inline int perlin_landXY(uint x, uint y)
00681 {
00682   return HeightMapXY(x, y);
00683 }
00684 
00685 
00686 /* The following decimals are the octave power modifiers for the Perlin noise */
00687 static const double _perlin_p_values[][7] = {    // perlin frequency per power
00688   { 0.35, 0.35, 0.35, 0.35, 0.35, 0.25, 0.539 }, 
00689   { 0.45, 0.55, 0.45, 0.45, 0.35, 0.25, 0.89  }, 
00690   { 0.85, 0.80, 0.70, 0.45, 0.45, 0.35, 1.825 }, 
00691   { 0.95, 0.85, 0.80, 0.55, 0.55, 0.45, 2.245 }  //< Very Rough 2.25
00692 };
00693 
00701 static double int_noise(const long x, const long y, const int prime)
00702 {
00703   long n = x + y * prime + _patches.generation_seed;
00704 
00705   n = (n << 13) ^ n;
00706 
00707   /* Pseudo-random number generator, using several large primes */
00708   return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
00709 }
00710 
00711 
00718 static double smoothed_noise(const int x, const int y, const int prime)
00719 {
00720 #if 0
00721   /* A hilly world (four corner smooth) */
00722   const double sides = int_noise(x - 1, y) + int_noise(x + 1, y) + int_noise(x, y - 1) + int_noise(x, y + 1);
00723   const double center  =  int_noise(x, y);
00724   return (sides + sides + center * 4) / 8.0;
00725 #endif
00726 
00727   /* This gives very hilly world */
00728   return int_noise(x, y, prime);
00729 }
00730 
00731 
00735 static inline double linear_interpolate(const double a, const double b, const double x)
00736 {
00737   return a + x * (b - a);
00738 }
00739 
00740 
00745 static double interpolated_noise(const double x, const double y, const int prime)
00746 {
00747   const int integer_X = (int)x;
00748   const int integer_Y = (int)y;
00749 
00750   const double fractional_X = x - (double)integer_X;
00751   const double fractional_Y = y - (double)integer_Y;
00752 
00753   const double v1 = smoothed_noise(integer_X,     integer_Y,     prime);
00754   const double v2 = smoothed_noise(integer_X + 1, integer_Y,     prime);
00755   const double v3 = smoothed_noise(integer_X,     integer_Y + 1, prime);
00756   const double v4 = smoothed_noise(integer_X + 1, integer_Y + 1, prime);
00757 
00758   const double i1 = linear_interpolate(v1, v2, fractional_X);
00759   const double i2 = linear_interpolate(v3, v4, fractional_X);
00760 
00761   return linear_interpolate(i1, i2, fractional_Y);
00762 }
00763 
00764 
00771 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
00772 {
00773   double total = 0.0;
00774   int i;
00775 
00776   for (i = 0; i < 6; i++) {
00777     const double frequency = (double)(1 << i);
00778     const double amplitude = pow(p, (double)i);
00779 
00780     total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
00781   }
00782 
00783   return total;
00784 }
00785 
00786 
00788 static void TgenSetTileHeight(TileIndex tile, int height)
00789 {
00790   SetTileHeight(tile, height);
00791   MakeClear(tile, CLEAR_GRASS, 3);
00792 }
00793 
00801 void GenerateTerrainPerlin()
00802 {
00803   uint x, y;
00804 
00805   if (!AllocHeightMap()) return;
00806   GenerateWorldSetAbortCallback(FreeHeightMap);
00807 
00808   HeightMapGenerate();
00809 
00810   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
00811 
00812   HeightMapNormalize();
00813 
00814   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
00815 
00816   /* Transfer height map into OTTD map */
00817   for (y = 2; y < _height_map.size_y - 2; y++) {
00818     for (x = 2; x < _height_map.size_x - 2; x++) {
00819       int height = H2I(HeightMapXY(x, y));
00820       if (height < 0) height = 0;
00821       if (height > 15) height = 15;
00822       TgenSetTileHeight(TileXY(x, y), height);
00823     }
00824   }
00825 
00826   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
00827 
00828   /* Recreate void tiles at the border in case they have been affected by generation */
00829   for (y = 0; y < _height_map.size_y - 1; y++) MakeVoid(_height_map.size_x * y + _height_map.size_x - 1);
00830   for (x = 0; x < _height_map.size_x;     x++) MakeVoid(_height_map.size_x * y + x);
00831 
00832   FreeHeightMap();
00833   GenerateWorldSetAbortCallback(NULL);
00834 }

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