diff options
Diffstat (limited to 'src/noise.cpp')
| -rw-r--r-- | src/noise.cpp | 57 |
1 files changed, 33 insertions, 24 deletions
diff --git a/src/noise.cpp b/src/noise.cpp index 2ddc3926f..b918c9936 100644 --- a/src/noise.cpp +++ b/src/noise.cpp @@ -93,22 +93,31 @@ u32 PcgRandom::range(u32 bound) // If the bound is 0, we cover the whole RNG's range if (bound == 0) return next(); + /* - If the bound is not a multiple of the RNG's range, it may cause bias, - e.g. a RNG has a range from 0 to 3 and we take want a number 0 to 2. - Using rand() % 3, the number 0 would be twice as likely to appear. - With a very large RNG range, the effect becomes less prevalent but - still present. This can be solved by modifying the range of the RNG - to become a multiple of bound by dropping values above the a threshold. - In our example, threshold == 4 - 3 = 1 % 3 == 1, so reject 0, thus - making the range 3 with no bias. - - This loop looks dangerous, but will always terminate due to the - RNG's property of uniformity. + This is an optimization of the expression: + 0x100000000ull % bound + since 64-bit modulo operations typically much slower than 32. */ u32 threshold = -bound % bound; u32 r; + /* + If the bound is not a multiple of the RNG's range, it may cause bias, + e.g. a RNG has a range from 0 to 3 and we take want a number 0 to 2. + Using rand() % 3, the number 0 would be twice as likely to appear. + With a very large RNG range, the effect becomes less prevalent but + still present. + + This can be solved by modifying the range of the RNG to become a + multiple of bound by dropping values above the a threshold. + + In our example, threshold == 4 % 3 == 1, so reject values < 1 + (that is, 0), thus making the range == 3 with no bias. + + This loop may look dangerous, but will always terminate due to the + RNG's property of uniformity. + */ while ((r = next()) < threshold) ; @@ -156,7 +165,7 @@ s32 PcgRandom::randNormalDist(s32 min, s32 max, int num_trials) /////////////////////////////////////////////////////////////////////////////// -float noise2d(int x, int y, int seed) +float noise2d(int x, int y, s32 seed) { unsigned int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y + NOISE_MAGIC_SEED * seed) & 0x7fffffff; @@ -166,7 +175,7 @@ float noise2d(int x, int y, int seed) } -float noise3d(int x, int y, int z, int seed) +float noise3d(int x, int y, int z, s32 seed) { unsigned int n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y + NOISE_MAGIC_Z * z + NOISE_MAGIC_SEED * seed) & 0x7fffffff; @@ -235,7 +244,7 @@ float triLinearInterpolationNoEase( return linearInterpolation(u, v, z); } -float noise2d_gradient(float x, float y, int seed, bool eased) +float noise2d_gradient(float x, float y, s32 seed, bool eased) { // Calculate the integer coordinates int x0 = myfloor(x); @@ -256,7 +265,7 @@ float noise2d_gradient(float x, float y, int seed, bool eased) } -float noise3d_gradient(float x, float y, float z, int seed, bool eased) +float noise3d_gradient(float x, float y, float z, s32 seed, bool eased) { // Calculate the integer coordinates int x0 = myfloor(x); @@ -290,7 +299,7 @@ float noise3d_gradient(float x, float y, float z, int seed, bool eased) } -float noise2d_perlin(float x, float y, int seed, +float noise2d_perlin(float x, float y, s32 seed, int octaves, float persistence, bool eased) { float a = 0; @@ -306,7 +315,7 @@ float noise2d_perlin(float x, float y, int seed, } -float noise2d_perlin_abs(float x, float y, int seed, +float noise2d_perlin_abs(float x, float y, s32 seed, int octaves, float persistence, bool eased) { float a = 0; @@ -321,7 +330,7 @@ float noise2d_perlin_abs(float x, float y, int seed, } -float noise3d_perlin(float x, float y, float z, int seed, +float noise3d_perlin(float x, float y, float z, s32 seed, int octaves, float persistence, bool eased) { float a = 0; @@ -336,7 +345,7 @@ float noise3d_perlin(float x, float y, float z, int seed, } -float noise3d_perlin_abs(float x, float y, float z, int seed, +float noise3d_perlin_abs(float x, float y, float z, s32 seed, int octaves, float persistence, bool eased) { float a = 0; @@ -363,7 +372,7 @@ float contour(float v) ///////////////////////// [ New noise ] //////////////////////////// -float NoisePerlin2D(NoiseParams *np, float x, float y, int seed) +float NoisePerlin2D(NoiseParams *np, float x, float y, s32 seed) { float a = 0; float f = 1.0; @@ -389,7 +398,7 @@ float NoisePerlin2D(NoiseParams *np, float x, float y, int seed) } -float NoisePerlin3D(NoiseParams *np, float x, float y, float z, int seed) +float NoisePerlin3D(NoiseParams *np, float x, float y, float z, s32 seed) { float a = 0; float f = 1.0; @@ -416,7 +425,7 @@ float NoisePerlin3D(NoiseParams *np, float x, float y, float z, int seed) } -Noise::Noise(NoiseParams *np_, int seed, u32 sx, u32 sy, u32 sz) +Noise::Noise(NoiseParams *np_, s32 seed, u32 sx, u32 sy, u32 sz) { memcpy(&np, np_, sizeof(np)); this->seed = seed; @@ -543,7 +552,7 @@ void Noise::resizeNoiseBuf(bool is3d) void Noise::gradientMap2D( float x, float y, float step_x, float step_y, - int seed) + s32 seed) { float v00, v01, v10, v11, u, v, orig_u; u32 index, i, j, noisex, noisey; @@ -607,7 +616,7 @@ void Noise::gradientMap2D( void Noise::gradientMap3D( float x, float y, float z, float step_x, float step_y, float step_z, - int seed) + s32 seed) { float v000, v010, v100, v110; float v001, v011, v101, v111; |