diff options
| -rw-r--r-- | src/tgp.cpp | 125 |
1 files changed, 38 insertions, 87 deletions
diff --git a/src/tgp.cpp b/src/tgp.cpp index 87b3eb9e0..225f3bb71 100644 --- a/src/tgp.cpp +++ b/src/tgp.cpp @@ -289,109 +289,60 @@ static inline height_t RandomHeight(amplitude_t rMax) } /** - * One interpolation and noise round + * Base Perlin noise generator - fills height map with raw Perlin noise. * - * The heights on the map are generated in an iterative process. - * We start off with a frequency of 1 (log_frequency == 0), and generate heights only for corners on the most coarsest mesh - * (i.e. only for x/y coordinates which are multiples of the minimum edge length). - * - * After this initial step the frequency is doubled (log_frequency incremented) each iteration to generate corners on the next finer mesh. - * The heights of the newly added corners are first set by interpolating the heights from the previous iteration. - * Finally noise with the given amplitude is applied to all corners of the new mesh. - * - * Generation terminates, when the frequency has reached the map size. I.e. the mesh is as fine as the map, and every corner height - * has been set. - * - * @param log_frequency frequency (logarithmic) to apply noise for - * @param amplitude Amplitude for the noise - * @return false if we are finished (reached the minimal step size / highest frequency) + * 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**TGP_FREQUENCY_MAX + * by 2**TGP_FREQUENCY_MAX tiles. */ -static bool ApplyNoise(uint log_frequency, amplitude_t amplitude) +static void HeightMapGenerate() { - uint size_min = min(_height_map.size_x, _height_map.size_y); - uint step = size_min >> log_frequency; - uint x, y; - /* Trying to apply noise to uninitialized height map */ assert(_height_map.h != NULL); - /* Are we finished? */ - if (step == 0) return false; + for (uint frequency = 0; frequency <= TGP_FREQUENCY_MAX; frequency++) { + const amplitude_t amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][frequency]; + const uint step = 1 << (TGP_FREQUENCY_MAX - frequency); - if (log_frequency == 0) { - /* This is first round, we need to establish base heights with step = size_min */ - for (y = 0; y <= _height_map.size_y; y += step) { - for (x = 0; x <= _height_map.size_x; x += step) { - height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0; - _height_map.height(x, y) = height; + if (frequency == 0) { + /* This is first round, we need to establish base heights with step = size_min */ + for (uint y = 0; y <= _height_map.size_y; y += step) { + for (uint x = 0; x <= _height_map.size_x; x += step) { + height_t height = (amplitude > 0) ? RandomHeight(amplitude) : 0; + _height_map.height(x, y) = height; + } } + continue; } - return true; - } - /* It is regular iteration round. - * Interpolate height values at odd x, even y tiles */ - for (y = 0; y <= _height_map.size_y; y += 2 * step) { - for (x = 0; x < _height_map.size_x; 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; + /* It is regular iteration round. + * Interpolate height values at odd x, even y tiles */ + for (uint y = 0; y <= _height_map.size_y; y += 2 * step) { + for (uint x = 0; x < _height_map.size_x; 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 (y = 0; y < _height_map.size_y; y += 2 * step) { - for (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; + /* Interpolate height values at odd y tiles */ + for (uint y = 0; y < _height_map.size_y; y += 2 * step) { + for (uint 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 (y = 0; y <= _height_map.size_y; y += step) { - for (x = 0; x <= _height_map.size_x; x += step) { - _height_map.height(x, y) += RandomHeight(amplitude); + /* Add noise for next higher frequency (smaller steps) */ + for (uint y = 0; y <= _height_map.size_y; y += step) { + for (uint x = 0; x <= _height_map.size_x; x += step) { + _height_map.height(x, y) += RandomHeight(amplitude); + } } } - - return (step > 1); -} - -/** Base Perlin noise generator - fills height map with raw Perlin noise */ -static void HeightMapGenerate() -{ - uint size_min = min(_height_map.size_x, _height_map.size_y); - uint iteration_round = 0; - amplitude_t amplitude; - bool continue_iteration; - int log_size_min, log_frequency_min; - int log_frequency; - - /* Find first power of two that fits, so that later log_frequency == TGP_FREQUENCY_MAX in the last iteration */ - for (log_size_min = TGP_FREQUENCY_MAX; (1U << log_size_min) < size_min; log_size_min++) { } - log_frequency_min = log_size_min - TGP_FREQUENCY_MAX; - - /* Zero must be part of the iteration, else initialization will fail. */ - assert(log_frequency_min >= 0); - - /* Keep increasing the frequency until we reach the step size equal to one tile */ - do { - log_frequency = iteration_round - log_frequency_min; - if (log_frequency >= 0) { - /* Apply noise for the next frequency */ - assert(log_frequency <= TGP_FREQUENCY_MAX); - amplitude = _amplitudes_by_smoothness_and_frequency[_settings_game.game_creation.tgen_smoothness][log_frequency]; - } else { - /* Amplitude for the low frequencies on big maps is 0, i.e. initialise with zero height */ - amplitude = 0; - } - continue_iteration = ApplyNoise(iteration_round, amplitude); - iteration_round++; - } while (continue_iteration); - assert(log_frequency == TGP_FREQUENCY_MAX); } /** Returns min, max and average height from height map */ |