tgp.cpp

Go to the documentation of this file.
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 
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 
00183   inline height_t &height(uint x, uint y)
00184   {
00185     return h[x + y * dim_x];
00186   }
00187 };
00188 
00190 static HeightMap _height_map = {NULL, 0, 0, 0, 0};
00191 
00193 #define I2H(i) ((i) << height_decimal_bits)
00194 
00195 #define H2I(i) ((i) >> height_decimal_bits)
00196 
00198 #define I2A(i) ((i) << amplitude_decimal_bits)
00199 
00200 #define A2I(i) ((i) >> amplitude_decimal_bits)
00201 
00203 #define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
00204 
00205 
00207 #define FOR_ALL_TILES_IN_HEIGHT(h) for (h = _height_map.h; h < &_height_map.h[_height_map.total_size]; h++)
00208 
00210 static const int TGP_FREQUENCY_MAX = 6;
00211 
00214 static const amplitude_t _amplitudes_by_smoothness_and_frequency[4][TGP_FREQUENCY_MAX + 1] = {
00215   /* lowest frequncy....  ...highest (every corner) */
00216   /* Very smooth */
00217   {16000,  5600,  1968,   688,   240,    16,    16},
00218   /* Smooth */
00219   {16000, 16000,  6448,  3200,  1024,   128,    16},
00220   /* Rough */
00221   {16000, 19200, 12800,  8000,  3200,   256,    64},
00222   /* Very Rough */
00223   {24000, 16000, 19200, 16000,  8000,   512,   320},
00224 };
00225 
00227 static const amplitude_t _water_percent[4] = {20, 80, 250, 400};
00228 
00230 static const int8 _max_height[4] = {
00231   6,       
00232   9,       
00233   12,      
00234   15       
00235 };
00236 
00242 static inline bool IsValidXY(uint x, uint y)
00243 {
00244   return ((int)x) >= 0 && x < _height_map.size_x && ((int)y) >= 0 && y < _height_map.size_y;
00245 }
00246 
00247 
00252 static inline bool AllocHeightMap()
00253 {
00254   height_t *h;
00255 
00256   _height_map.size_x = MapSizeX();
00257   _height_map.size_y = MapSizeY();
00258 
00259   /* Allocate memory block for height map row pointers */
00260   _height_map.total_size = (_height_map.size_x + 1) * (_height_map.size_y + 1);
00261   _height_map.dim_x = _height_map.size_x + 1;
00262   _height_map.h = CallocT<height_t>(_height_map.total_size);
00263 
00264   /* Iterate through height map initialize values */
00265   FOR_ALL_TILES_IN_HEIGHT(h) *h = _invalid_height;
00266 
00267   return true;
00268 }
00269 
00271 static inline void FreeHeightMap()
00272 {
00273   if (_height_map.h == NULL) return;
00274   free(_height_map.h);
00275   _height_map.h = NULL;
00276 }
00277 
00283 static inline height_t RandomHeight(amplitude_t rMax)
00284 {
00285   amplitude_t ra = (Random() << 16) | (Random() & 0x0000FFFF);
00286   height_t rh;
00287   /* Spread height into range -rMax..+rMax */
00288   rh = A2H(ra % (2 * rMax + 1) - rMax);
00289   return rh;
00290 }
00291 
00310 static bool ApplyNoise(uint log_frequency, amplitude_t amplitude)
00311 {
00312   uint size_min = min(_height_map.size_x, _height_map.size_y);
00313   uint step = size_min >> log_frequency;
00314   uint x, y;
00315 
00316   /* Trying to apply noise to uninitialized height map */
00317   assert(_height_map.h != NULL);
00318 
00319   /* Are we finished? */
00320   if (step == 0) return false;
00321 
00322   if (log_frequency == 0) {
00323     /* This is first round, we need to establish base heights with step = size_min */
00324     for (y = 0; y <= _height_map.size_y; y += step) {
00325       for (x = 0; x <= _height_map.size_x; x += step) {
00326         height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
00327         _height_map.height(x, y) = height;
00328       }
00329     }
00330     return true;
00331   }
00332 
00333   /* It is regular iteration round.
00334    * Interpolate height values at odd x, even y tiles */
00335   for (y = 0; y <= _height_map.size_y; y += 2 * step) {
00336     for (x = 0; x < _height_map.size_x; x += 2 * step) {
00337       height_t h00 = _height_map.height(x + 0 * step, y);
00338       height_t h02 = _height_map.height(x + 2 * step, y);
00339       height_t h01 = (h00 + h02) / 2;
00340       _height_map.height(x + 1 * step, y) = h01;
00341     }
00342   }
00343 
00344   /* Interpolate height values at odd y tiles */
00345   for (y = 0; y < _height_map.size_y; y += 2 * step) {
00346     for (x = 0; x <= _height_map.size_x; x += step) {
00347       height_t h00 = _height_map.height(x, y + 0 * step);
00348       height_t h20 = _height_map.height(x, y + 2 * step);
00349       height_t h10 = (h00 + h20) / 2;
00350       _height_map.height(x, y + 1 * step) = h10;
00351     }
00352   }
00353 
00354   /* Add noise for next higher frequency (smaller steps) */
00355   for (y = 0; y <= _height_map.size_y; y += step) {
00356     for (x = 0; x <= _height_map.size_x; x += step) {
00357       _height_map.height(x, y) += RandomHeight(amplitude);
00358     }
00359   }
00360 
00361   return (step > 1);
00362 }
00363 
00365 static void HeightMapGenerate()
00366 {
00367   uint size_min = min(_height_map.size_x, _height_map.size_y);
00368   uint iteration_round = 0;
00369   amplitude_t amplitude;
00370   bool continue_iteration;
00371   int log_size_min, log_frequency_min;
00372   int log_frequency;
00373 
00374   /* Find first power of two that fits, so that later log_frequency == TGP_FREQUENCY_MAX in the last iteration */
00375   for (log_size_min = TGP_FREQUENCY_MAX; (1U << log_size_min) < size_min; log_size_min++) { }
00376   log_frequency_min = log_size_min - TGP_FREQUENCY_MAX;
00377 
00378   /* Zero must be part of the iteration, else initialization will fail. */
00379   assert(log_frequency_min >= 0);
00380 
00381   /* Keep increasing the frequency until we reach the step size equal to one tile */
00382   do {
00383     log_frequency = iteration_round - log_frequency_min;
00384     if (log_frequency >= 0) {
00385       /* Apply noise for the next frequency */
00386       assert(log_frequency <= TGP_FREQUENCY_MAX);
00387       amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][log_frequency];
00388     } else {
00389       /* Amplitude for the low frequencies on big maps is 0, i.e. initialise with zero height */
00390       amplitude = 0;
00391     }
00392     continue_iteration = ApplyNoise(iteration_round, amplitude);
00393     iteration_round++;
00394   } while (continue_iteration);
00395   assert(log_frequency == TGP_FREQUENCY_MAX);
00396 }
00397 
00399 static void HeightMapGetMinMaxAvg(height_t *min_ptr, height_t *max_ptr, height_t *avg_ptr)
00400 {
00401   height_t h_min, h_max, h_avg, *h;
00402   int64 h_accu = 0;
00403   h_min = h_max = _height_map.height(0, 0);
00404 
00405   /* Get h_min, h_max and accumulate heights into h_accu */
00406   FOR_ALL_TILES_IN_HEIGHT(h) {
00407     if (*h < h_min) h_min = *h;
00408     if (*h > h_max) h_max = *h;
00409     h_accu += *h;
00410   }
00411 
00412   /* Get average height */
00413   h_avg = (height_t)(h_accu / (_height_map.size_x * _height_map.size_y));
00414 
00415   /* Return required results */
00416   if (min_ptr != NULL) *min_ptr = h_min;
00417   if (max_ptr != NULL) *max_ptr = h_max;
00418   if (avg_ptr != NULL) *avg_ptr = h_avg;
00419 }
00420 
00422 static int *HeightMapMakeHistogram(height_t h_min, height_t h_max, int *hist_buf)
00423 {
00424   int *hist = hist_buf - h_min;
00425   height_t *h;
00426 
00427   /* Count the heights and fill the histogram */
00428   FOR_ALL_TILES_IN_HEIGHT(h) {
00429     assert(*h >= h_min);
00430     assert(*h <= h_max);
00431     hist[*h]++;
00432   }
00433   return hist;
00434 }
00435 
00437 static void HeightMapSineTransform(height_t h_min, height_t h_max)
00438 {
00439   height_t *h;
00440 
00441   FOR_ALL_TILES_IN_HEIGHT(h) {
00442     double fheight;
00443 
00444     if (*h < h_min) continue;
00445 
00446     /* Transform height into 0..1 space */
00447     fheight = (double)(*h - h_min) / (double)(h_max - h_min);
00448     /* Apply sine transform depending on landscape type */
00449     switch (_settings_game.game_creation.landscape) {
00450       case LT_TOYLAND:
00451       case LT_TEMPERATE:
00452         /* Move and scale 0..1 into -1..+1 */
00453         fheight = 2 * fheight - 1;
00454         /* Sine transform */
00455         fheight = sin(fheight * M_PI_2);
00456         /* Transform it back from -1..1 into 0..1 space */
00457         fheight = 0.5 * (fheight + 1);
00458         break;
00459 
00460       case LT_ARCTIC:
00461         {
00462           /* Arctic terrain needs special height distribution.
00463            * Redistribute heights to have more tiles at highest (75%..100%) range */
00464           double sine_upper_limit = 0.75;
00465           double linear_compression = 2;
00466           if (fheight >= sine_upper_limit) {
00467             /* Over the limit we do linear compression up */
00468             fheight = 1.0 - (1.0 - fheight) / linear_compression;
00469           } else {
00470             double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
00471             /* Get 0..sine_upper_limit into -1..1 */
00472             fheight = 2.0 * fheight / sine_upper_limit - 1.0;
00473             /* Sine wave transform */
00474             fheight = sin(fheight * M_PI_2);
00475             /* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
00476             fheight = 0.5 * (fheight + 1.0) * m;
00477           }
00478         }
00479         break;
00480 
00481       case LT_TROPIC:
00482         {
00483           /* Desert terrain needs special height distribution.
00484            * Half of tiles should be at lowest (0..25%) heights */
00485           double sine_lower_limit = 0.5;
00486           double linear_compression = 2;
00487           if (fheight <= sine_lower_limit) {
00488             /* Under the limit we do linear compression down */
00489             fheight = fheight / linear_compression;
00490           } else {
00491             double m = sine_lower_limit / linear_compression;
00492             /* Get sine_lower_limit..1 into -1..1 */
00493             fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
00494             /* Sine wave transform */
00495             fheight = sin(fheight * M_PI_2);
00496             /* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
00497             fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
00498           }
00499         }
00500         break;
00501 
00502       default:
00503         NOT_REACHED();
00504         break;
00505     }
00506     /* Transform it back into h_min..h_max space */
00507     *h = (height_t)(fheight * (h_max - h_min) + h_min);
00508     if (*h < 0) *h = I2H(0);
00509     if (*h >= h_max) *h = h_max - 1;
00510   }
00511 }
00512 
00513 /* Additional map variety is provided by applying different curve maps
00514  * to different parts of the map. A randomized low resolution grid contains
00515  * which curve map to use on each part of the make. This filtered non-linearly
00516  * to smooth out transitions between curves, so each tile could have between
00517  * 100% of one map applied or 25% of four maps.
00518  *
00519  * The curve maps define different land styles, i.e. lakes, low-lands, hills
00520  * and mountain ranges, although these are dependent on the landscape style
00521  * chosen as well.
00522  *
00523  * The level parameter dictates the resolution of the grid. A low resolution
00524  * grid will result in larger continuous areas of a land style, a higher
00525  * resolution grid splits the style into smaller areas.
00526  *
00527  * At this point in map generation, all height data has been normalized to 0
00528  * to 239.
00529  */
00530 struct control_point_t {
00531   height_t x;
00532   height_t y;
00533 };
00534 
00535 struct control_point_list_t {
00536   size_t length;
00537   const control_point_t *list;
00538 };
00539 
00540 static const control_point_t _curve_map_1[] = {
00541   { 0, 0 }, { 48, 24 }, { 192, 32 }, { 240, 96 }
00542 };
00543 
00544 static const control_point_t _curve_map_2[] = {
00545   { 0, 0 }, { 16, 24 }, { 128, 32 }, { 192, 64 }, { 240, 144 }
00546 };
00547 
00548 static const control_point_t _curve_map_3[] = {
00549   { 0, 0 }, { 16, 24 }, { 128, 64 }, { 192, 144 }, { 240, 192 }
00550 };
00551 
00552 static const control_point_t _curve_map_4[] = {
00553   { 0, 0 }, { 16, 24 }, { 96, 72 }, { 160, 192 }, { 220, 239 }, { 240, 239 }
00554 };
00555 
00556 static const control_point_list_t _curve_maps[] = {
00557   { lengthof(_curve_map_1), _curve_map_1 },
00558   { lengthof(_curve_map_2), _curve_map_2 },
00559   { lengthof(_curve_map_3), _curve_map_3 },
00560   { lengthof(_curve_map_4), _curve_map_4 },
00561 };
00562 
00563 static void HeightMapCurves(uint level)
00564 {
00565   height_t ht[lengthof(_curve_maps)];
00566 
00567   /* Set up a grid to choose curve maps based on location */
00568   uint sx = Clamp(1 << level, 2, 32);
00569   uint sy = Clamp(1 << level, 2, 32);
00570   byte *c = (byte *)alloca(sx * sy);
00571 
00572   for (uint i = 0; i < sx * sy; i++) {
00573     c[i] = Random() % lengthof(_curve_maps);
00574   }
00575 
00576   /* Apply curves */
00577   for (uint x = 0; x < _height_map.size_x; x++) {
00578 
00579     /* Get our X grid positions and bi-linear ratio */
00580     float fx = (float)(sx * x) / _height_map.size_x + 0.5f;
00581     uint x1 = (uint)fx;
00582     uint x2 = x1;
00583     float xr = 2.0f * (fx - x1) - 1.0f;
00584     xr = sin(xr * M_PI_2);
00585     xr = sin(xr * M_PI_2);
00586     xr = 0.5f * (xr + 1.0f);
00587     float xri = 1.0f - xr;
00588 
00589     if (x1 > 0) {
00590       x1--;
00591       if (x2 >= sx) x2--;
00592     }
00593 
00594     for (uint y = 0; y < _height_map.size_y; y++) {
00595 
00596       /* Get our Y grid position and bi-linear ratio */
00597       float fy = (float)(sy * y) / _height_map.size_y + 0.5f;
00598       uint y1 = (uint)fy;
00599       uint y2 = y1;
00600       float yr = 2.0f * (fy - y1) - 1.0f;
00601       yr = sin(yr * M_PI_2);
00602       yr = sin(yr * M_PI_2);
00603       yr = 0.5f * (yr + 1.0f);
00604       float yri = 1.0f - yr;
00605 
00606       if (y1 > 0) {
00607         y1--;
00608         if (y2 >= sy) y2--;
00609       }
00610 
00611       uint corner_a = c[x1 + sx * y1];
00612       uint corner_b = c[x1 + sx * y2];
00613       uint corner_c = c[x2 + sx * y1];
00614       uint corner_d = c[x2 + sx * y2];
00615 
00616       /* Bitmask of which curve maps are chosen, so that we do not bother
00617        * calculating a curve which won't be used. */
00618       uint corner_bits = 0;
00619       corner_bits |= 1 << corner_a;
00620       corner_bits |= 1 << corner_b;
00621       corner_bits |= 1 << corner_c;
00622       corner_bits |= 1 << corner_d;
00623 
00624       height_t *h = &_height_map.height(x, y);
00625 
00626       /* Apply all curve maps that are used on this tile. */
00627       for (uint t = 0; t < lengthof(_curve_maps); t++) {
00628         if (!HasBit(corner_bits, t)) continue;
00629 
00630         const control_point_t *cm = _curve_maps[t].list;
00631         for (uint i = 0; i < _curve_maps[t].length - 1; i++) {
00632           const control_point_t &p1 = cm[i];
00633           const control_point_t &p2 = cm[i + 1];
00634 
00635           if (*h >= p1.x && *h < p2.x) {
00636             ht[t] = p1.y + (*h - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
00637             break;
00638           }
00639         }
00640       }
00641 
00642       /* Apply interpolation of curve map results. */
00643       *h = (height_t)((ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr);
00644     }
00645   }
00646 }
00647 
00649 static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new)
00650 {
00651   height_t h_min, h_max, h_avg, h_water_level;
00652   int water_tiles, desired_water_tiles;
00653   height_t *h;
00654   int *hist;
00655 
00656   HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
00657 
00658   /* Allocate histogram buffer and clear its cells */
00659   int *hist_buf = CallocT<int>(h_max - h_min + 1);
00660   /* Fill histogram */
00661   hist = HeightMapMakeHistogram(h_min, h_max, hist_buf);
00662 
00663   /* How many water tiles do we want? */
00664   desired_water_tiles = (int)(((int64)water_percent) * (int64)(_height_map.size_x * _height_map.size_y)) >> amplitude_decimal_bits;
00665 
00666   /* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
00667   for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
00668     water_tiles += hist[h_water_level];
00669     if (water_tiles >= desired_water_tiles) break;
00670   }
00671 
00672   /* We now have the proper water level value.
00673    * Transform the height map into new (normalized) height map:
00674    *   values from range: h_min..h_water_level will become negative so it will be clamped to 0
00675    *   values from range: h_water_level..h_max are transformed into 0..h_max_new
00676    *   where h_max_new is 4, 8, 12 or 16 depending on terrain type (very flat, flat, hilly, mountains)
00677    */
00678   FOR_ALL_TILES_IN_HEIGHT(h) {
00679     /* Transform height from range h_water_level..h_max into 0..h_max_new range */
00680     *h = (height_t)(((int)h_max_new) * (*h - h_water_level) / (h_max - h_water_level)) + I2H(1);
00681     /* Make sure all values are in the proper range (0..h_max_new) */
00682     if (*h < 0) *h = I2H(0);
00683     if (*h >= h_max_new) *h = h_max_new - 1;
00684   }
00685 
00686   free(hist_buf);
00687 }
00688 
00689 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
00690 
00711 static void HeightMapCoastLines(uint8 water_borders)
00712 {
00713   int smallest_size = min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
00714   const int margin = 4;
00715   uint y, x;
00716   double max_x;
00717   double max_y;
00718 
00719   /* Lower to sea level */
00720   for (y = 0; y <= _height_map.size_y; y++) {
00721     if (HasBit(water_borders, BORDER_NE)) {
00722       /* Top right */
00723       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);
00724       max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
00725       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
00726       for (x = 0; x < max_x; x++) {
00727         _height_map.height(x, y) = 0;
00728       }
00729     }
00730 
00731     if (HasBit(water_borders, BORDER_SW)) {
00732       /* Bottom left */
00733       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);
00734       max_x = max((smallest_size * smallest_size / 16) + max_x, (smallest_size * smallest_size / 16) + margin - max_x);
00735       if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
00736       for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
00737         _height_map.height(x, y) = 0;
00738       }
00739     }
00740   }
00741 
00742   /* Lower to sea level */
00743   for (x = 0; x <= _height_map.size_x; x++) {
00744     if (HasBit(water_borders, BORDER_NW)) {
00745       /* Top left */
00746       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);
00747       max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
00748       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
00749       for (y = 0; y < max_y; y++) {
00750         _height_map.height(x, y) = 0;
00751       }
00752     }
00753 
00754     if (HasBit(water_borders, BORDER_SE)) {
00755       /* Bottom right */
00756       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);
00757       max_y = max((smallest_size * smallest_size / 16) + max_y, (smallest_size * smallest_size / 16) + margin - max_y);
00758       if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
00759       for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
00760         _height_map.height(x, y) = 0;
00761       }
00762     }
00763   }
00764 }
00765 
00767 static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
00768 {
00769   const int max_coast_dist_from_edge = 35;
00770   const int max_coast_Smooth_depth = 35;
00771 
00772   int x, y;
00773   int ed; // coast distance from edge
00774   int depth;
00775 
00776   height_t h_prev = 16;
00777   height_t h;
00778 
00779   assert(IsValidXY(org_x, org_y));
00780 
00781   /* Search for the coast (first non-water tile) */
00782   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++) {
00783     /* Coast found? */
00784     if (_height_map.height(x, y) > 15) break;
00785 
00786     /* Coast found in the neighborhood? */
00787     if (IsValidXY(x + dir_y, y + dir_x) && _height_map.height(x + dir_y, y + dir_x) > 0) break;
00788 
00789     /* Coast found in the neighborhood on the other side */
00790     if (IsValidXY(x - dir_y, y - dir_x) && _height_map.height(x - dir_y, y - dir_x) > 0) break;
00791   }
00792 
00793   /* Coast found or max_coast_dist_from_edge has been reached.
00794    * Soften the coast slope */
00795   for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
00796     h = _height_map.height(x, y);
00797     h = min(h, h_prev + (4 + depth)); // coast softening formula
00798     _height_map.height(x, y) = h;
00799     h_prev = h;
00800   }
00801 }
00802 
00804 static void HeightMapSmoothCoasts(uint8 water_borders)
00805 {
00806   uint x, y;
00807   /* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
00808   for (x = 0; x < _height_map.size_x; x++) {
00809     if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
00810     if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
00811   }
00812   /* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
00813   for (y = 0; y < _height_map.size_y; y++) {
00814     if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
00815     if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
00816   }
00817 }
00818 
00826 static void HeightMapSmoothSlopes(height_t dh_max)
00827 {
00828   int x, y;
00829   for (y = 0; y <= (int)_height_map.size_y; y++) {
00830     for (x = 0; x <= (int)_height_map.size_x; x++) {
00831       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;
00832       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
00833     }
00834   }
00835   for (y = _height_map.size_y; y >= 0; y--) {
00836     for (x = _height_map.size_x; x >= 0; x--) {
00837       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;
00838       if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
00839     }
00840   }
00841 }
00842 
00848 static void HeightMapNormalize()
00849 {
00850   const amplitude_t water_percent = _water_percent[_settings_game.difficulty.quantity_sea_lakes];
00851   const height_t h_max_new = I2H(_max_height[_settings_game.difficulty.terrain_type]);
00852   const height_t roughness = 7 + 3 * _settings_game.game_creation.tgen_smoothness;
00853 
00854   HeightMapAdjustWaterLevel(water_percent, h_max_new);
00855 
00856   byte water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
00857   if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
00858 
00859   HeightMapCoastLines(water_borders);
00860   HeightMapSmoothSlopes(roughness);
00861 
00862   HeightMapSmoothCoasts(water_borders);
00863   HeightMapSmoothSlopes(roughness);
00864 
00865   HeightMapSineTransform(12, h_max_new);
00866 
00867   if (_settings_game.game_creation.variety > 0) {
00868     HeightMapCurves(_settings_game.game_creation.variety);
00869   }
00870 
00871   HeightMapSmoothSlopes(16);
00872 }
00873 
00881 static double int_noise(const long x, const long y, const int prime)
00882 {
00883   long n = x + y * prime + _settings_game.game_creation.generation_seed;
00884 
00885   n = (n << 13) ^ n;
00886 
00887   /* Pseudo-random number generator, using several large primes */
00888   return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
00889 }
00890 
00891 
00898 static double smoothed_noise(const int x, const int y, const int prime)
00899 {
00900 #if 0
00901   /* A hilly world (four corner smooth) */
00902   const double sides = int_noise(x - 1, y) + int_noise(x + 1, y) + int_noise(x, y - 1) + int_noise(x, y + 1);
00903   const double center  =  int_noise(x, y);
00904   return (sides + sides + center * 4) / 8.0;
00905 #endif
00906 
00907   /* This gives very hilly world */
00908   return int_noise(x, y, prime);
00909 }
00910 
00911 
00915 static inline double linear_interpolate(const double a, const double b, const double x)
00916 {
00917   return a + x * (b - a);
00918 }
00919 
00920 
00925 static double interpolated_noise(const double x, const double y, const int prime)
00926 {
00927   const int integer_X = (int)x;
00928   const int integer_Y = (int)y;
00929 
00930   const double fractional_X = x - (double)integer_X;
00931   const double fractional_Y = y - (double)integer_Y;
00932 
00933   const double v1 = smoothed_noise(integer_X,     integer_Y,     prime);
00934   const double v2 = smoothed_noise(integer_X + 1, integer_Y,     prime);
00935   const double v3 = smoothed_noise(integer_X,     integer_Y + 1, prime);
00936   const double v4 = smoothed_noise(integer_X + 1, integer_Y + 1, prime);
00937 
00938   const double i1 = linear_interpolate(v1, v2, fractional_X);
00939   const double i2 = linear_interpolate(v3, v4, fractional_X);
00940 
00941   return linear_interpolate(i1, i2, fractional_Y);
00942 }
00943 
00944 
00951 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
00952 {
00953   double total = 0.0;
00954   int i;
00955 
00956   for (i = 0; i < 6; i++) {
00957     const double frequency = (double)(1 << i);
00958     const double amplitude = pow(p, (double)i);
00959 
00960     total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
00961   }
00962 
00963   return total;
00964 }
00965 
00966 
00968 static void TgenSetTileHeight(TileIndex tile, int height)
00969 {
00970   SetTileHeight(tile, height);
00971 
00972   /* Only clear the tiles within the map area. */
00973   if (TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY() &&
00974       (!_settings_game.construction.freeform_edges || (TileX(tile) != 0 && TileY(tile) != 0))) {
00975     MakeClear(tile, CLEAR_GRASS, 3);
00976   }
00977 }
00978 
00986 void GenerateTerrainPerlin()
00987 {
00988   uint x, y;
00989 
00990   if (!AllocHeightMap()) return;
00991   GenerateWorldSetAbortCallback(FreeHeightMap);
00992 
00993   HeightMapGenerate();
00994 
00995   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
00996 
00997   HeightMapNormalize();
00998 
00999   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
01000 
01001   /* First make sure the tiles at the north border are void tiles if needed. */
01002   if (_settings_game.construction.freeform_edges) {
01003     for (y = 0; y < _height_map.size_y - 1; y++) MakeVoid(_height_map.size_x * y);
01004     for (x = 0; x < _height_map.size_x;     x++) MakeVoid(x);
01005   }
01006 
01007   /* Transfer height map into OTTD map */
01008   for (y = 0; y < _height_map.size_y; y++) {
01009     for (x = 0; x < _height_map.size_x; x++) {
01010       int height = H2I(_height_map.height(x, y));
01011       if (height < 0) height = 0;
01012       if (height > 15) height = 15;
01013       TgenSetTileHeight(TileXY(x, y), height);
01014     }
01015   }
01016 
01017   IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
01018 
01019   FreeHeightMap();
01020   GenerateWorldSetAbortCallback(NULL);
01021 }

Generated on Sat Dec 26 20:06:06 2009 for OpenTTD by  doxygen 1.5.6