land.perlin

LandPerlin

land_perlin_create

Parameters: LandRandom * seed, int w, int h

Returns: LandPerlin*

Create a Perlin noise of the given resolution.

The noise at any integer coordinate is always 0. Other coordinates
return a random value in the range -1..1.

If w and h are 1, each noise sample will have the identical vector
at each corner.

For point 0.5/0.5 this means:

a = 0.5 * u + 0.5 * v
b = -0.5 * u + 0.5 * v
c = 0.5 * u + -0.5 * v
d = -0.5 * u + -0.5 * v
a + b + c + d = 0
result = 0

Also any other point:

a = x * u + y * v
b = -X * u + y * v
c = x * u + -Y * v
d = -X * u + -Y * v
e = X * a + x * b = xX * u + yX * v + -xX * u + xy * v
f = X * c + x * d = xX * u + -XY * v + -xX * u + -xY * v
result = Y * e + y * f =
         xXY * u + yXY * v + -xXY * u + xyY * v + xXy * u + -XYy * v + -xXy * u + -xYy * v
         u * (xXY - xXY + xXy - xXy) + v * (yXY + xyY - XYy - xYy)
         u * 0 + v * 0
         0

Note that this is not necessarily true for non-linear interpolation.

land_perlin_set_lerp_callback

Parameters: LandPerlin * self, float(* lerp)(float a, float b, float p)

land_perlin_set_lerp

Parameters: LandPerlin * self, LandPerlinLerp lerp

land_perlin_destroy

Parameters: LandPerlin * self

land_perlin_at

Parameters: LandPerlin * self, float x, float y

Returns: float

Get a noise value from a Perlin noise. If x/y are not from inside the resolution of the noise they will wrap around.

land_perlin_displace

Parameters: LandPerlin * self, float x, float y, float * xd, float * yd

Instead of getting the result of the Perlin noise at x/y, directly get the random displacement vector xd/yd.

Generated: Thu 27 Feb 2020 10:49:37 PM EST