inoise8_raw() [2/3]

int8_t inoise8_raw ( uint16_t x, uint16_t 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 624 of file noise.cpp.

{
    // Find the unit cube containing the point
    uint8_t X = x>>8;
    uint8_t Y = y>>8;
 
    // Hash cube corner coordinates
    uint8_t A = P(X)+Y;
    uint8_t AA = P(A);
    uint8_t AB = P(A+1);
    uint8_t B = P(X+1)+Y;
    uint8_t BA = P(B);
    uint8_t BB = P(B+1);
 
    // Get the relative position of the point in the cube
    uint8_t u = x;
    uint8_t v = y;
 
    // Get a signed version of the above for the grad function
    int8_t xx = ((uint8_t)(x)>>1) & 0x7F;
    int8_t yy = ((uint8_t)(y)>>1) & 0x7F;
    uint8_t N = 0x80;
 
    u = EASE8(u); v = EASE8(v);
 
    int8_t X1 = lerp7by8(grad8(P(AA), xx, yy), grad8(P(BA), xx - N, yy), u);
    int8_t X2 = lerp7by8(grad8(P(AB), xx, yy-N), grad8(P(BB), xx - N, yy - N), u);
 
    int8_t ans = lerp7by8(X1,X2,v);
 
    return ans;
    // return scale8((70+(ans)),234)<<1;
}

References grad8(), lerp7by8(), P, x, and y.

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