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authorrubidium <rubidium@openttd.org>2014-09-29 18:18:21 +0000
committerrubidium <rubidium@openttd.org>2014-09-29 18:18:21 +0000
commit2b0a1f7beba2eeb2c5f8d992dcfed2273fda8096 (patch)
treec1f7bdfa667b9a4850fa4b35c4598de56aef9576 /src/tgp.cpp
parent1bec121248c9952b8c0118205b50c1ed71f54b30 (diff)
downloadopenttd-2b0a1f7beba2eeb2c5f8d992dcfed2273fda8096.tar.xz
(svn r26937) -Cleanup: simplify the logic for heightmap generation in TGP; instead of performing more and more loops the larger the map becomes to elaborately set the height to 0 many times, just run it for each frequency and be done with it
Diffstat (limited to 'src/tgp.cpp')
-rw-r--r--src/tgp.cpp125
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 */