inoise8_raw() [2/3]

fl::i8 inoise8_raw ( fl::u16 x, fl::u16 y )

extern

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

Coordinates are 8.8 fixed point values, 16-bit integers with integral coordinates in the high 8-bits and fractional in the low 8-bits.

Returns

unscaled noise value as a signed integer, roughly -70 to 70

Parameters

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

Definition at line 621 of file noise.cpp.hpp.

             {
    // Find the unit cube containing the point
    fl::u8 X = x>>8;
    fl::u8 Y = y>>8;
 
    // 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::u8 u = x;
    fl::u8 v = y;
 
    // Get a signed version of the above for the grad function
    fl::i8 xx = ((fl::u8)(x)>>1) & 0x7F;
    fl::i8 yy = ((fl::u8)(y)>>1) & 0x7F;
    fl::u8 N = 0x80;
 
    u = EASE8(u); v = EASE8(v);
 
    fl::i8 X1 = lerp7by8(grad8(NOISE_P(AA), xx, yy), grad8(NOISE_P(BA), xx - N, yy), u);
    fl::i8 X2 = lerp7by8(grad8(NOISE_P(AB), xx, yy-N), grad8(NOISE_P(BB), xx - N, yy - N), u);
 
    fl::i8 ans = lerp7by8(X1,X2,v);
 
    return ans;
    // return scale8((70+(ans)),234)<<1;
}

References FL_NO_EXCEPT, grad8(), lerp7by8(), NOISE_P, x, and y.

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