inoise16_raw() [2/4]

fl::i16 inoise16_raw ( fl::u32 x, fl::u32 y )

extern

16-bit, fixed point implementation of Perlin's noise without scaling.

Coordinates are 16.16 fixed point values, 32 bit integers with integral coordinates in the high 16-bits and fractional in the low 16-bits.

Returns

unscaled noise value as a signed integer, roughly -18k to 18k

Parameters

x	x-axis coordinate on noise map (1D)
y	y-axis coordinate on noise map (2D)

Definition at line 495 of file noise.cpp.hpp.

             {
    // Find the unit cube containing the point
    fl::u8 X = x>>16;
    fl::u8 Y = y>>16;
 
    // Hash cube corner coordinates
    fl::u8 A = NOISE_P(X)+Y;
    fl::u8 AA = NOISE_P(A);
    fl::u8 AB = NOISE_P(A+1);
    fl::u8 B = NOISE_P(X+1)+Y;
    fl::u8 BA = NOISE_P(B);
    fl::u8 BB = NOISE_P(B+1);
 
    // Get the relative position of the point in the cube
    fl::u16 u = x & 0xFFFF;
    fl::u16 v = y & 0xFFFF;
 
    // Get a signed version of the above for the grad function
    fl::i16 xx = (u >> 1) & 0x7FFF;
    fl::i16 yy = (v >> 1) & 0x7FFF;
    fl::u16 N = 0x8000L;
 
    u = EASE16(u); v = EASE16(v);
 
    fl::i16 X1 = LERP(grad16(NOISE_P(AA), xx, yy), grad16(NOISE_P(BA), xx - N, yy), u);
    fl::i16 X2 = LERP(grad16(NOISE_P(AB), xx, yy-N), grad16(NOISE_P(BB), xx - N, yy - N), u);
 
    fl::i16 ans = LERP(X1,X2,v);
 
    return ans;
}

References FL_NO_EXCEPT, grad16(), NOISE_P, x, and y.

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