diff options
Diffstat (limited to 'src/tgp.cpp')
-rw-r--r-- | src/tgp.cpp | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/src/tgp.cpp b/src/tgp.cpp index ba223938f..99ef12bb9 100644 --- a/src/tgp.cpp +++ b/src/tgp.cpp @@ -510,6 +510,141 @@ static void HeightMapSineTransform(height_t h_min, height_t h_max) } } +/* 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. + * + * At this point in map generation, all height data has been normalized to 0 + * to 239. + */ +struct control_point_t { + height_t x; + height_t y; +}; + +struct control_point_list_t { + size_t length; + const control_point_t *list; +}; + +static const control_point_t _curve_map_1[] = { + { 0, 0 }, { 48, 24 }, { 192, 32 }, { 240, 96 } +}; + +static const control_point_t _curve_map_2[] = { + { 0, 0 }, { 16, 24 }, { 128, 32 }, { 192, 64 }, { 240, 144 } +}; + +static const control_point_t _curve_map_3[] = { + { 0, 0 }, { 16, 24 }, { 128, 64 }, { 192, 144 }, { 240, 192 } +}; + +static const control_point_t _curve_map_4[] = { + { 0, 0 }, { 16, 24 }, { 96, 72 }, { 160, 192 }, { 220, 239 }, { 240, 239 } +}; + +static 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 }, +}; + +static void HeightMapCurves(uint level) +{ + height_t ht[lengthof(_curve_maps)]; + + /* Set up a grid to choose curve maps based on location */ + uint sx = Clamp(1 << level, 2, 32); + uint sy = Clamp(1 << level, 2, 32); + byte *c = (byte *)alloca(sx * sy); + + for (uint i = 0; i < sx * sy; i++) { + c[i] = Random() % lengthof(_curve_maps); + } + + /* Apply curves */ + for (uint 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 + 0.5f; + uint x1 = 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 (uint 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 + 0.5f; + uint y1 = 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); + + /* 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; + + 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); + break; + } + } + } + + /* Apply interpolation of curve map results. */ + *h = (ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr; + } + } +} + /** Adjusts heights in height map to contain required amount of water tiles */ static void HeightMapAdjustWaterLevel(amplitude_t water_percent, height_t h_max_new) { @@ -728,6 +863,11 @@ static void HeightMapNormalize() HeightMapSmoothSlopes(roughness); HeightMapSineTransform(12, h_max_new); + + if (_settings_game.game_creation.variety > 0) { + HeightMapCurves(_settings_game.game_creation.variety); + } + HeightMapSmoothSlopes(16); } |