// 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 threshhold.
- In our example, threshhold == 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 threshhold = -bound % bound;
+ u32 threshold = -bound % bound;
u32 r;
- while ((r = next()) < threshhold)
+ /*
+ 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)
;
return r % bound;
///////////////////////////////////////////////////////////////////////////////
-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;
}
-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;
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);
}
-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);
}
-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;
}
-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;
}
-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;
}
-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;
///////////////////////// [ 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;
}
-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;
}
-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;
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;
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;