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70bc55cfd6e14f710427012b03aa211a0d85ca0f
openttd/src/tgp.cpp
Patric Stout 70bc55cfd6 Feature: setting to indicate desert coverage for tropic climate 
This is an indication value; the game tries to get as close as it
can, but due to the complex tropic rules, that is unlikely to be
exact.

In the end, it picks a height-level to base the desert/tropic
line on. This is strictly seen not needed, as we can convert any
tile to either. But it is the simplest way to get started with
this without redoing all related functions.
2021-03-26 12:22:32 +01:00

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/*
* This file is part of OpenTTD.
* 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.
* 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.
* 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/>.
*/
/** @file tgp.cpp OTTD Perlin Noise Landscape Generator, aka TerraGenesis Perlin */
#include "stdafx.h"
#include <math.h>
#include "clear_map.h"
#include "void_map.h"
#include "genworld.h"
#include "core/random_func.hpp"
#include "landscape_type.h"
#include "safeguards.h"
/*
*
* Quickie guide to Perlin Noise
* Perlin noise is a predictable pseudo random number sequence. By generating
* it in 2 dimensions, it becomes a useful random map that, for a given seed
* and starting X & Y, is entirely predictable. On the face of it, that may not
* be useful. However, it means that if you want to replay a map in a different
* terrain, or just vary the sea level, you just re-run the generator with the
* same seed. The seed is an int32, and is randomised on each run of New Game.
* The Scenario Generator does not randomise the value, so that you can
* experiment with one terrain until you are happy, or click "Random" for a new
* random seed.
*
* Perlin Noise is a series of "octaves" of random noise added together. By
* reducing the amplitude of the noise with each octave, the first octave of
* noise defines the main terrain sweep, the next the ripples on that, and the
* next the ripples on that. I use 6 octaves, with the amplitude controlled by
* a power ratio, usually known as a persistence or p value. This I vary by the
* smoothness selection, as can be seen in the table below. The closer to 1,
* the more of that octave is added. Each octave is however raised to the power
* of its position in the list, so the last entry in the "smooth" row, 0.35, is
* raised to the power of 6, so can only add 0.001838... of the amplitude to
* the running total.
*
* In other words; the first p value sets the general shape of the terrain, the
* second sets the major variations to that, ... until finally the smallest
* bumps are added.
*
* Usefully, this routine is totally scalable; so when 32bpp comes along, the
* terrain can be as bumpy as you like! It is also infinitely expandable; a
* single random seed terrain continues in X & Y as far as you care to
* calculate. In theory, we could use just one seed value, but randomly select
* where in the Perlin XY space we use for the terrain. Personally I prefer
* using a simple (0, 0) to (X, Y), with a varying seed.
*
*
* Other things i have had to do: mountainous wasn't mountainous enough, and
* since we only have 0..15 heights available, I add a second generated map
* (with a modified seed), onto the original. This generally raises the
* terrain, which then needs scaling back down. Overall effect is a general
* uplift.
*
* However, the values on the top of mountains are then almost guaranteed to go
* too high, so large flat plateaus appeared at height 15. To counter this, I
* scale all heights above 12 to proportion up to 15. It still makes the
* mountains have flattish tops, rather than craggy peaks, but at least they
* aren't smooth as glass.
*
*
* For a full discussion of Perlin Noise, please visit:
* http://freespace.virgin.net/hugo.elias/models/m_perlin.htm
*
*
* Evolution II
*
* The algorithm as described in the above link suggests to compute each tile height
* as composition of several noise waves. Some of them are computed directly by
* noise(x, y) function, some are calculated using linear approximation. Our
* first implementation of perlin_noise_2D() used 4 noise(x, y) calls plus
* 3 linear interpolations. It was called 6 times for each tile. This was a bit
* CPU expensive.
*
* The following implementation uses optimized algorithm that should produce
* the same quality result with much less computations, but more memory accesses.
* The overall speedup should be 300% to 800% depending on CPU and memory speed.
*
* I will try to explain it on the example below:
*
* Have a map of 4 x 4 tiles, our simplified noise generator produces only two
* values -1 and +1, use 3 octaves with wave length 1, 2 and 4, with amplitudes
* 3, 2, 1. Original algorithm produces:
*
* 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
* 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
* 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
* 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
*
* 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
* 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
* 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
* 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
*
*
* Optimization 1:
*
* 1) we need to allocate a bit more tiles: (size_x + 1) * (size_y + 1) = (5 * 5):
*
* 2) setup corner values using amplitude 3
* { -3.0 X X X 3.0 }
* { X X X X X }
* { X X X X X }
* { X X X X X }
* { 3.0 X X X -3.0 }
*
* 3a) interpolate values in the middle
* { -3.0 X 0.0 X 3.0 }
* { X X X X X }
* { 0.0 X 0.0 X 0.0 }
* { X X X X X }
* { 3.0 X 0.0 X -3.0 }
*
* 3b) add patches with amplitude 2 to them
* { -5.0 X 2.0 X 1.0 }
* { X X X X X }
* { 2.0 X -2.0 X 2.0 }
* { X X X X X }
* { 1.0 X 2.0 X -5.0 }
*
* 4a) interpolate values in the middle
* { -5.0 -1.5 2.0 1.5 1.0 }
* { -1.5 -0.75 0.0 0.75 1.5 }
* { 2.0 0.0 -2.0 0.0 2.0 }
* { 1.5 0.75 0.0 -0.75 -1.5 }
* { 1.0 1.5 2.0 -1.5 -5.0 }
*
* 4b) add patches with amplitude 1 to them
* { -6.0 -0.5 1.0 2.5 0.0 }
* { -0.5 -1.75 1.0 -0.25 2.5 }
* { 1.0 1.0 -3.0 1.0 1.0 }
* { 2.5 -0.25 1.0 -1.75 -0.5 }
* { 0.0 2.5 1.0 -0.5 -6.0 }
*
*
*
* Optimization 2:
*
* As you can see above, each noise function was called just once. Therefore
* we don't need to use noise function that calculates the noise from x, y and
* some prime. The same quality result we can obtain using standard Random()
* function instead.
*
*/
/** Fixed point type for heights */
typedef int16 height_t;
static const int height_decimal_bits = 4;
/** Fixed point array for amplitudes (and percent values) */
typedef int amplitude_t;
static const int amplitude_decimal_bits = 10;
/** Height map - allocated array of heights (MapSizeX() + 1) x (MapSizeY() + 1) */
struct HeightMap
{
height_t *h; //< array of heights
/* Even though the sizes are always positive, there are many cases where
* X and Y need to be signed integers due to subtractions. */
int dim_x; //< height map size_x MapSizeX() + 1
int total_size; //< height map total size
int size_x; //< MapSizeX()
int size_y; //< MapSizeY()
/**
* Height map accessor
* @param x X position
* @param y Y position
* @return height as fixed point number
*/
inline height_t &height(uint x, uint y)
{
return h[x + y * dim_x];
}
};
/** Global height map instance */
static HeightMap _height_map = {nullptr, 0, 0, 0, 0};
/** Conversion: int to height_t */
#define I2H(i) ((i) << height_decimal_bits)
/** Conversion: height_t to int */
#define H2I(i) ((i) >> height_decimal_bits)
/** Conversion: int to amplitude_t */
#define I2A(i) ((i) << amplitude_decimal_bits)
/** Conversion: amplitude_t to int */
#define A2I(i) ((i) >> amplitude_decimal_bits)
/** Conversion: amplitude_t to height_t */
#define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
/** Walk through all items of _height_map.h */
#define FOR_ALL_TILES_IN_HEIGHT(h) for (h = _height_map.h; h < &_height_map.h[_height_map.total_size]; h++)
/** Maximum number of TGP noise frequencies. */
static const int MAX_TGP_FREQUENCIES = 10;
/** Desired water percentage (100% == 1024) - indexed by _settings_game.difficulty.quantity_sea_lakes */
static const amplitude_t _water_percent[4] = {70, 170, 270, 420};
/**
* Gets the maximum allowed height while generating a map based on
* mapsize, terraintype, and the maximum height level.
* @return The maximum height for the map generation.
* @note Values should never be lower than 3 since the minimum snowline height is 2.
*/
static height_t TGPGetMaxHeight()
{
/**
* Desired maximum height - indexed by:
* - _settings_game.difficulty.terrain_type
* - min(MapLogX(), MapLogY()) - MIN_MAP_SIZE_BITS
*
* It is indexed by map size as well as terrain type since the map size limits the height of
* a usable mountain. For example, on a 64x64 map a 24 high single peak mountain (as if you
* raised land 24 times in the center of the map) will leave only a ring of about 10 tiles
* around the mountain to build on. On a 4096x4096 map, it won't cover any major part of the map.
*/
static const int max_height[5][MAX_MAP_SIZE_BITS - MIN_MAP_SIZE_BITS + 1] = {
/* 64 128 256 512 1024 2048 4096 */
{ 3, 3, 3, 3, 4, 5, 7 }, ///< Very flat
{ 5, 7, 8, 9, 14, 19, 31 }, ///< Flat
{ 8, 9, 10, 15, 23, 37, 61 }, ///< Hilly
{ 10, 11, 17, 19, 49, 63, 73 }, ///< Mountainous
{ 12, 19, 25, 31, 67, 75, 87 }, ///< Alpinist
};
int map_size_bucket = std::min(MapLogX(), MapLogY()) - MIN_MAP_SIZE_BITS;
int max_height_from_table = max_height[_settings_game.difficulty.terrain_type][map_size_bucket];
return I2H(std::min<uint>(max_height_from_table, _settings_game.construction.max_heightlevel));
}
/**
* Get the amplitude associated with the currently selected
* smoothness and maximum height level.
* @param frequency The frequency to get the amplitudes for
* @return The amplitudes to apply to the map.
*/
static amplitude_t GetAmplitude(int frequency)
{
/* Base noise amplitudes (multiplied by 1024) and indexed by "smoothness setting" and log2(frequency). */
static const amplitude_t amplitudes[][7] = {
/* lowest frequency ...... highest (every corner) */
{16000, 5600, 1968, 688, 240, 16, 16}, ///< Very smooth
{24000, 12800, 6400, 2700, 1024, 128, 16}, ///< Smooth
{32000, 19200, 12800, 8000, 3200, 256, 64}, ///< Rough
{48000, 24000, 19200, 16000, 8000, 512, 320}, ///< Very rough
};
/*
* Extrapolation factors for ranges before the table.
* The extrapolation is needed to account for the higher map heights. They need larger
* areas with a particular gradient so that we are able to create maps without too
* many steep slopes up to the wanted height level. It's definitely not perfect since
* it will bring larger rectangles with similar slopes which makes the rectangular
* behaviour of TGP more noticeable. However, these height differentiations cannot
* happen over much smaller areas; we basically double the "range" to give a similar
* slope for every doubling of map height.
*/
static const double extrapolation_factors[] = { 3.3, 2.8, 2.3, 1.8 };
int smoothness = _settings_game.game_creation.tgen_smoothness;
/* Get the table index, and return that value if possible. */
int index = frequency - MAX_TGP_FREQUENCIES + lengthof(amplitudes[smoothness]);
amplitude_t amplitude = amplitudes[smoothness][std::max(0, index)];
if (index >= 0) return amplitude;
/* We need to extrapolate the amplitude. */
double extrapolation_factor = extrapolation_factors[smoothness];
int height_range = I2H(16);
do {
amplitude = (amplitude_t)(extrapolation_factor * (double)amplitude);
height_range <<= 1;
index++;
} while (index < 0);
return Clamp((TGPGetMaxHeight() - height_range) / height_range, 0, 1) * amplitude;
}
/**
* Check if a X/Y set are within the map.
* @param x coordinate x
* @param y coordinate y
* @return true if within the map
*/
static inline bool IsValidXY(int x, int y)
{
return x >= 0 && x < _height_map.size_x && y >= 0 && y < _height_map.size_y;
}
/**
* Allocate array of (MapSizeX()+1)*(MapSizeY()+1) heights and init the _height_map structure members
* @return true on success
*/
static inline bool AllocHeightMap()
{
height_t *h;
_height_map.size_x = MapSizeX();
_height_map.size_y = MapSizeY();
/* Allocate memory block for height map row pointers */
_height_map.total_size = (_height_map.size_x + 1) * (_height_map.size_y + 1);
_height_map.dim_x = _height_map.size_x + 1;
_height_map.h = CallocT<height_t>(_height_map.total_size);
/* Iterate through height map and initialise values. */
FOR_ALL_TILES_IN_HEIGHT(h) *h = 0;
return true;
}
/** Free height map */
static inline void FreeHeightMap()
{
free(_height_map.h);
_height_map.h = nullptr;
}
/**
* Generates new random height in given amplitude (generated numbers will range from - amplitude to + amplitude)
* @param rMax Limit of result
* @return generated height
*/
static inline height_t RandomHeight(amplitude_t rMax)
{
/* Spread height into range -rMax..+rMax */
return A2H(RandomRange(2 * rMax + 1) - rMax);
}
/**
* Base Perlin noise generator - fills height map with raw Perlin noise.
*
* This runs several iterations with increasing precision; the last iteration looks at areas
* of 1 by 1 tiles, the second to last at 2 by 2 tiles and the initial 2**MAX_TGP_FREQUENCIES
* by 2**MAX_TGP_FREQUENCIES tiles.
*/
static void HeightMapGenerate()
{
/* Trying to apply noise to uninitialized height map */
assert(_height_map.h != nullptr);
int start = std::max(MAX_TGP_FREQUENCIES - (int)std::min(MapLogX(), MapLogY()), 0);
bool first = true;
for (int frequency = start; frequency < MAX_TGP_FREQUENCIES; frequency++) {
const amplitude_t amplitude = GetAmplitude(frequency);
/* Ignore zero amplitudes; it means our map isn't height enough for this
* amplitude, so ignore it and continue with the next set of amplitude. */
if (amplitude == 0) continue;
const int step = 1 << (MAX_TGP_FREQUENCIES - frequency - 1);
if (first) {
/* This is first round, we need to establish base heights with step = size_min */
for (int y = 0; y <= _height_map.size_y; y += step) {
for (int x = 0; x <= _height_map.size_x; x += step) {
height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
_height_map.height(x, y) = height;
}
}
first = false;
continue;
}
/* It is regular iteration round.
* Interpolate height values at odd x, even y tiles */
for (int y = 0; y <= _height_map.size_y; y += 2 * step) {
for (int x = 0; x <= _height_map.size_x - 2 * step; x += 2 * step) {
height_t h00 = _height_map.height(x + 0 * step, y);
height_t h02 = _height_map.height(x + 2 * step, y);
height_t h01 = (h00 + h02) / 2;
_height_map.height(x + 1 * step, y) = h01;
}
}
/* Interpolate height values at odd y tiles */
for (int y = 0; y <= _height_map.size_y - 2 * step; y += 2 * step) {
for (int x = 0; x <= _height_map.size_x; x += step) {
height_t h00 = _height_map.height(x, y + 0 * step);
height_t h20 = _height_map.height(x, y + 2 * step);
height_t h10 = (h00 + h20) / 2;
_height_map.height(x, y + 1 * step) = h10;
}
}
/* Add noise for next higher frequency (smaller steps) */
for (int y = 0; y <= _height_map.size_y; y += step) {
for (int x = 0; x <= _height_map.size_x; x += step) {
_height_map.height(x, y) += RandomHeight(amplitude);
}
}
}
}
/** Returns min, max and average height from height map */
static void HeightMapGetMinMaxAvg(height_t *min_ptr, height_t *max_ptr, height_t *avg_ptr)
{
height_t h_min, h_max, h_avg, *h;
int64 h_accu = 0;
h_min = h_max = _height_map.height(0, 0);
/* Get h_min, h_max and accumulate heights into h_accu */
FOR_ALL_TILES_IN_HEIGHT(h) {
if (*h < h_min) h_min = *h;
if (*h > h_max) h_max = *h;
h_accu += *h;
}
/* Get average height */
h_avg = (height_t)(h_accu / (_height_map.size_x * _height_map.size_y));
/* Return required results */
if (min_ptr != nullptr) *min_ptr = h_min;
if (max_ptr != nullptr) *max_ptr = h_max;
if (avg_ptr != nullptr) *avg_ptr = h_avg;
}
/** Dill histogram and return pointer to its base point - to the count of zero heights */
static int *HeightMapMakeHistogram(height_t h_min, height_t h_max, int *hist_buf)
{
int *hist = hist_buf - h_min;
height_t *h;
/* Count the heights and fill the histogram */
FOR_ALL_TILES_IN_HEIGHT(h) {
assert(*h >= h_min);
assert(*h <= h_max);
hist[*h]++;
}
return hist;
}
/** Applies sine wave redistribution onto height map */
static void HeightMapSineTransform(height_t h_min, height_t h_max)
{
height_t *h;
FOR_ALL_TILES_IN_HEIGHT(h) {
double fheight;
if (*h < h_min) continue;
/* Transform height into 0..1 space */
fheight = (double)(*h - h_min) / (double)(h_max - h_min);
/* Apply sine transform depending on landscape type */
switch (_settings_game.game_creation.landscape) {
case LT_TOYLAND:
case LT_TEMPERATE:
/* Move and scale 0..1 into -1..+1 */
fheight = 2 * fheight - 1;
/* Sine transform */
fheight = sin(fheight * M_PI_2);
/* Transform it back from -1..1 into 0..1 space */
fheight = 0.5 * (fheight + 1);
break;
case LT_ARCTIC:
{
/* Arctic terrain needs special height distribution.
* Redistribute heights to have more tiles at highest (75%..100%) range */
double sine_upper_limit = 0.75;
double linear_compression = 2;
if (fheight >= sine_upper_limit) {
/* Over the limit we do linear compression up */
fheight = 1.0 - (1.0 - fheight) / linear_compression;
} else {
double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
/* Get 0..sine_upper_limit into -1..1 */
fheight = 2.0 * fheight / sine_upper_limit - 1.0;
/* Sine wave transform */
fheight = sin(fheight * M_PI_2);
/* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
fheight = 0.5 * (fheight + 1.0) * m;
}
}
break;
case LT_TROPIC:
{
/* Desert terrain needs special height distribution.
* Half of tiles should be at lowest (0..25%) heights */
double sine_lower_limit = 0.5;
double linear_compression = 2;
if (fheight <= sine_lower_limit) {
/* Under the limit we do linear compression down */
fheight = fheight / linear_compression;
} else {
double m = sine_lower_limit / linear_compression;
/* Get sine_lower_limit..1 into -1..1 */
fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
/* Sine wave transform */
fheight = sin(fheight * M_PI_2);
/* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
}
}
break;
default:
NOT_REACHED();
break;
}
/* Transform it back into h_min..h_max space */
*h = (height_t)(fheight * (h_max - h_min) + h_min);
if (*h < 0) *h = I2H(0);
if (*h >= h_max) *h = h_max - 1;
}
}
/**
* Additional map variety is provided by applying different curve maps
* to different parts of the map. A randomized low resolution grid contains
* which curve map to use on each part of the make. This filtered non-linearly
* to smooth out transitions between curves, so each tile could have between
* 100% of one map applied or 25% of four maps.
*
* The curve maps define different land styles, i.e. lakes, low-lands, hills
* and mountain ranges, although these are dependent on the landscape style
* chosen as well.
*
* The level parameter dictates the resolution of the grid. A low resolution
* grid will result in larger continuous areas of a land style, a higher
* resolution grid splits the style into smaller areas.
* @param level Rough indication of the size of the grid sections to style. Small level means large grid sections.
*/
static void HeightMapCurves(uint level)
{
height_t mh = TGPGetMaxHeight() - I2H(1); // height levels above sea level only
/** Basically scale height X to height Y. Everything in between is interpolated. */
struct control_point_t {
height_t x; ///< The height to scale from.
height_t y; ///< The height to scale to.
};
/* Scaled curve maps; value is in height_ts. */
#define F(fraction) ((height_t)(fraction * mh))
const control_point_t curve_map_1[] = { { F(0.0), F(0.0) }, { F(0.8), F(0.13) }, { F(1.0), F(0.4) } };
const control_point_t curve_map_2[] = { { F(0.0), F(0.0) }, { F(0.53), F(0.13) }, { F(0.8), F(0.27) }, { F(1.0), F(0.6) } };
const control_point_t curve_map_3[] = { { F(0.0), F(0.0) }, { F(0.53), F(0.27) }, { F(0.8), F(0.57) }, { F(1.0), F(0.8) } };
const control_point_t curve_map_4[] = { { F(0.0), F(0.0) }, { F(0.4), F(0.3) }, { F(0.7), F(0.8) }, { F(0.92), F(0.99) }, { F(1.0), F(0.99) } };
#undef F
/** Helper structure to index the different curve maps. */
struct control_point_list_t {
size_t length; ///< The length of the curve map.
const control_point_t *list; ///< The actual curve map.
};
const control_point_list_t curve_maps[] = {
{ lengthof(curve_map_1), curve_map_1 },
{ lengthof(curve_map_2), curve_map_2 },
{ lengthof(curve_map_3), curve_map_3 },
{ lengthof(curve_map_4), curve_map_4 },
};
height_t ht[lengthof(curve_maps)];
MemSetT(ht, 0, lengthof(ht));
/* Set up a grid to choose curve maps based on location; attempt to get a somewhat square grid */
float factor = sqrt((float)_height_map.size_x / (float)_height_map.size_y);
uint sx = Clamp((int)(((1 << level) * factor) + 0.5), 1, 128);
uint sy = Clamp((int)(((1 << level) / factor) + 0.5), 1, 128);
byte *c = AllocaM(byte, sx * sy);
for (uint i = 0; i < sx * sy; i++) {
c[i] = Random() % lengthof(curve_maps);
}
/* Apply curves */
for (int x = 0; x < _height_map.size_x; x++) {
/* Get our X grid positions and bi-linear ratio */
float fx = (float)(sx * x) / _height_map.size_x + 1.0f;
uint x1 = (uint)fx;
uint x2 = x1;
float xr = 2.0f * (fx - x1) - 1.0f;
xr = sin(xr * M_PI_2);
xr = sin(xr * M_PI_2);
xr = 0.5f * (xr + 1.0f);
float xri = 1.0f - xr;
if (x1 > 0) {
x1--;
if (x2 >= sx) x2--;
}
for (int y = 0; y < _height_map.size_y; y++) {
/* Get our Y grid position and bi-linear ratio */
float fy = (float)(sy * y) / _height_map.size_y + 1.0f;
uint y1 = (uint)fy;
uint y2 = y1;
float yr = 2.0f * (fy - y1) - 1.0f;
yr = sin(yr * M_PI_2);
yr = sin(yr * M_PI_2);
yr = 0.5f * (yr + 1.0f);
float yri = 1.0f - yr;
if (y1 > 0) {
y1--;
if (y2 >= sy) y2--;
}
uint corner_a = c[x1 + sx * y1];
uint corner_b = c[x1 + sx * y2];
uint corner_c = c[x2 + sx * y1];
uint corner_d = c[x2 + sx * y2];
/* Bitmask of which curve maps are chosen, so that we do not bother
* calculating a curve which won't be used. */
uint corner_bits = 0;
corner_bits |= 1 << corner_a;
corner_bits |= 1 << corner_b;
corner_bits |= 1 << corner_c;
corner_bits |= 1 << corner_d;
height_t *h = &_height_map.height(x, y);
/* Do not touch sea level */
if (*h < I2H(1)) continue;
/* Only scale above sea level */
*h -= I2H(1);
/* Apply all curve maps that are used on this tile. */
for (uint t = 0; t < lengthof(curve_maps); t++) {
if (!HasBit(corner_bits, t)) continue;
bool found = false;
const control_point_t *cm = curve_maps[t].list;
for (uint i = 0; i < curve_maps[t].length - 1; i++) {
const control_point_t &p1 = cm[i];
const control_point_t &p2 = cm[i + 1];
if (*h >= p1.x && *h < p2.x) {
ht[t] = p1.y + (*h - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
found = true;
break;
}
}
assert(found);
}
/* Apply interpolation of curve map results. */
*h = (height_t)((ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr);
/* Readd sea level */
*h += I2H(1);
}
}
}
/** Adjusts heights in height map to contain required amount of water tiles */
static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new)
{
height_t h_min, h_max, h_avg, h_water_level;
int64 water_tiles, desired_water_tiles;
height_t *h;
int *hist;
HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
/* Allocate histogram buffer and clear its cells */
int *hist_buf = CallocT<int>(h_max - h_min + 1);
/* Fill histogram */
hist = HeightMapMakeHistogram(h_min, h_max, hist_buf);
/* How many water tiles do we want? */
desired_water_tiles = A2I(((int64)water_percent) * (int64)(_height_map.size_x * _height_map.size_y));
/* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
water_tiles += hist[h_water_level];
if (water_tiles >= desired_water_tiles) break;
}
/* We now have the proper water level value.
* Transform the height map into new (normalized) height map:
* values from range: h_min..h_water_level will become negative so it will be clamped to 0
* values from range: h_water_level..h_max are transformed into 0..h_max_new
* where h_max_new is depending on terrain type and map size.
*/
FOR_ALL_TILES_IN_HEIGHT(h) {
/* Transform height from range h_water_level..h_max into 0..h_max_new range */
*h = (height_t)(((int)h_max_new) * (*h - h_water_level) / (h_max - h_water_level)) + I2H(1);
/* Make sure all values are in the proper range (0..h_max_new) */
if (*h < 0) *h = I2H(0);
if (*h >= h_max_new) *h = h_max_new - 1;
}
free(hist_buf);
}
static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
/**
* This routine sculpts in from the edge a random amount, again a Perlin
* sequence, to avoid the rigid flat-edge slopes that were present before. The
* Perlin noise map doesn't know where we are going to slice across, and so we
* often cut straight through high terrain. The smoothing routine makes it
* legal, gradually increasing up from the edge to the original terrain height.
* By cutting parts of this away, it gives a far more irregular edge to the
* map-edge. Sometimes it works beautifully with the existing sea & lakes, and
* creates a very realistic coastline. Other times the variation is less, and
* the map-edge shows its cliff-like roots.
*
* This routine may be extended to randomly sculpt the height of the terrain
* near the edge. This will have the coast edge at low level (1-3), rising in
* smoothed steps inland to about 15 tiles in. This should make it look as
* though the map has been built for the map size, rather than a slice through
* a larger map.
*
* Please note that all the small numbers; 53, 101, 167, etc. are small primes
* to help give the perlin noise a bit more of a random feel.
*/
static void HeightMapCoastLines(uint8 water_borders)
{
int smallest_size = std::min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
const int margin = 4;
int y, x;
double max_x;
double max_y;
/* Lower to sea level */
for (y = 0; y <= _height_map.size_y; y++) {
if (HasBit(water_borders, BORDER_NE)) {
/* Top right */
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);
max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
for (x = 0; x < max_x; x++) {
_height_map.height(x, y) = 0;
}
}
if (HasBit(water_borders, BORDER_SW)) {
/* Bottom left */
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);
max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
_height_map.height(x, y) = 0;
}
}
}
/* Lower to sea level */
for (x = 0; x <= _height_map.size_x; x++) {
if (HasBit(water_borders, BORDER_NW)) {
/* Top left */
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);
max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
for (y = 0; y < max_y; y++) {
_height_map.height(x, y) = 0;
}
}
if (HasBit(water_borders, BORDER_SE)) {
/* Bottom right */
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);
max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
_height_map.height(x, y) = 0;
}
}
}
}
/** Start at given point, move in given direction, find and Smooth coast in that direction */
static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
{
const int max_coast_dist_from_edge = 35;
const int max_coast_Smooth_depth = 35;
int x, y;
int ed; // coast distance from edge
int depth;
height_t h_prev = I2H(1);
height_t h;
assert(IsValidXY(org_x, org_y));
/* Search for the coast (first non-water tile) */
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++) {
/* Coast found? */
if (_height_map.height(x, y) >= I2H(1)) break;
/* Coast found in the neighborhood? */
if (IsValidXY(x + dir_y, y + dir_x) && _height_map.height(x + dir_y, y + dir_x) > 0) break;
/* Coast found in the neighborhood on the other side */
if (IsValidXY(x - dir_y, y - dir_x) && _height_map.height(x - dir_y, y - dir_x) > 0) break;
}
/* Coast found or max_coast_dist_from_edge has been reached.
* Soften the coast slope */
for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
h = _height_map.height(x, y);
h = std::min<uint>(h, h_prev + (4 + depth)); // coast softening formula
_height_map.height(x, y) = h;
h_prev = h;
}
}
/** Smooth coasts by modulating height of tiles close to map edges with cosine of distance from edge */
static void HeightMapSmoothCoasts(uint8 water_borders)
{
int x, y;
/* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
for (x = 0; x < _height_map.size_x; x++) {
if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
}
/* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
for (y = 0; y < _height_map.size_y; y++) {
if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
}
}
/**
* This routine provides the essential cleanup necessary before OTTD can
* display the terrain. When generated, the terrain heights can jump more than
* one level between tiles. This routine smooths out those differences so that
* the most it can change is one level. When OTTD can support cliffs, this
* routine may not be necessary.
*/
static void HeightMapSmoothSlopes(height_t dh_max)
{
for (int y = 0; y <= (int)_height_map.size_y; y++) {
for (int x = 0; x <= (int)_height_map.size_x; x++) {
height_t h_max = std::min(_height_map.height(x > 0 ? x - 1 : x, y), _height_map.height(x, y > 0 ? y - 1 : y)) + dh_max;
if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
}
}
for (int y = _height_map.size_y; y >= 0; y--) {
for (int x = _height_map.size_x; x >= 0; x--) {
height_t h_max = std::min(_height_map.height(x < _height_map.size_x ? x + 1 : x, y), _height_map.height(x, y < _height_map.size_y ? y + 1 : y)) + dh_max;
if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
}
}
}
/**
* Height map terraform post processing:
* - water level adjusting
* - coast Smoothing
* - slope Smoothing
* - height histogram redistribution by sine wave transform
*/
static void HeightMapNormalize()
{
int sea_level_setting = _settings_game.difficulty.quantity_sea_lakes;
const amplitude_t water_percent = sea_level_setting != (int)CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY ? _water_percent[sea_level_setting] : _settings_game.game_creation.custom_sea_level * 1024 / 100;
const height_t h_max_new = TGPGetMaxHeight();
const height_t roughness = 7 + 3 * _settings_game.game_creation.tgen_smoothness;
HeightMapAdjustWaterLevel(water_percent, h_max_new);
byte water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
HeightMapCoastLines(water_borders);
HeightMapSmoothSlopes(roughness);
HeightMapSmoothCoasts(water_borders);
HeightMapSmoothSlopes(roughness);
HeightMapSineTransform(I2H(1), h_max_new);
if (_settings_game.game_creation.variety > 0) {
HeightMapCurves(_settings_game.game_creation.variety);
}
HeightMapSmoothSlopes(I2H(1));
}
/**
* The Perlin Noise calculation using large primes
* The initial number is adjusted by two values; the generation_seed, and the
* passed parameter; prime.
* prime is used to allow the perlin noise generator to create useful random
* numbers from slightly different series.
*/
static double int_noise(const long x, const long y, const int prime)
{
long n = x + y * prime + _settings_game.game_creation.generation_seed;
n = (n << 13) ^ n;
/* Pseudo-random number generator, using several large primes */
return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
}
/**
* This routine determines the interpolated value between a and b
*/
static inline double linear_interpolate(const double a, const double b, const double x)
{
return a + x * (b - a);
}
/**
* This routine returns the smoothed interpolated noise for an x and y, using
* the values from the surrounding positions.
*/
static double interpolated_noise(const double x, const double y, const int prime)
{
const int integer_X = (int)x;
const int integer_Y = (int)y;
const double fractional_X = x - (double)integer_X;
const double fractional_Y = y - (double)integer_Y;
const double v1 = int_noise(integer_X, integer_Y, prime);
const double v2 = int_noise(integer_X + 1, integer_Y, prime);
const double v3 = int_noise(integer_X, integer_Y + 1, prime);
const double v4 = int_noise(integer_X + 1, integer_Y + 1, prime);
const double i1 = linear_interpolate(v1, v2, fractional_X);
const double i2 = linear_interpolate(v3, v4, fractional_X);
return linear_interpolate(i1, i2, fractional_Y);
}
/**
* This is a similar function to the main perlin noise calculation, but uses
* the value p passed as a parameter rather than selected from the predefined
* sequences. as you can guess by its title, i use this to create the indented
* coastline, which is just another perlin sequence.
*/
static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
{
double total = 0.0;
for (int i = 0; i < 6; i++) {
const double frequency = (double)(1 << i);
const double amplitude = pow(p, (double)i);
total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
}
return total;
}
/** A small helper function to initialize the terrain */
static void TgenSetTileHeight(TileIndex tile, int height)
{
SetTileHeight(tile, height);
/* Only clear the tiles within the map area. */
if (IsInnerTile(tile)) {
MakeClear(tile, CLEAR_GRASS, 3);
}
}
/**
* The main new land generator using Perlin noise. Desert landscape is handled
* different to all others to give a desert valley between two high mountains.
* Clearly if a low height terrain (flat/very flat) is chosen, then the tropic
* areas won't be high enough, and there will be very little tropic on the map.
* Thus Tropic works best on Hilly or Mountainous.
*/
void GenerateTerrainPerlin()
{
if (!AllocHeightMap()) return;
GenerateWorldSetAbortCallback(FreeHeightMap);
HeightMapGenerate();
IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
HeightMapNormalize();
IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
/* First make sure the tiles at the north border are void tiles if needed. */
if (_settings_game.construction.freeform_edges) {
for (uint x = 0; x < MapSizeX(); x++) MakeVoid(TileXY(x, 0));
for (uint y = 0; y < MapSizeY(); y++) MakeVoid(TileXY(0, y));
}
int max_height = H2I(TGPGetMaxHeight());
/* Transfer height map into OTTD map */
for (int y = 0; y < _height_map.size_y; y++) {
for (int x = 0; x < _height_map.size_x; x++) {
TgenSetTileHeight(TileXY(x, y), Clamp(H2I(_height_map.height(x, y)), 0, max_height));
}
}
IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
FreeHeightMap();
GenerateWorldSetAbortCallback(nullptr);
}
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