Graphics Reference
In-Depth Information
Example 14-15
Generating Gradient Vectors
(continued)
0xF4, 0xC3, 0xE3, 0x0D, 0x23, 0x4D, 0xC4, 0xB9,
0x1A, 0xC8, 0xE2, 0x77, 0x1F, 0x7B, 0xA8, 0x7D,
0xF9, 0x44, 0xB7, 0xE6, 0xB1, 0x87, 0xA0, 0xB4,
0x0C, 0x01, 0xF3, 0x94, 0x66, 0xA6, 0x26, 0xEE,
0xFB, 0x25, 0xF0, 0x7E, 0x40, 0x4A, 0xA1, 0x28,
0xB8, 0x95, 0xAB, 0xB2, 0x65, 0x42, 0x1D, 0x3B,
0x92, 0x3D, 0xFE, 0x6B, 0x2A, 0x56, 0x9A, 0x04,
0xEC, 0xE8, 0x78, 0x15, 0xE9, 0xD1, 0x2D, 0x62,
0xC1, 0x72, 0x4E, 0x13, 0xCE, 0x0E, 0x76, 0x7F,
0x30, 0x4F, 0x93, 0x55, 0x1E, 0xCF, 0xDB, 0x36,
0x58, 0xEA, 0xBE, 0x7A, 0x5F, 0x43, 0x8F, 0x6D,
0x89, 0xD6, 0x91, 0x5D, 0x5C, 0x64, 0xF5, 0x00,
0xD8, 0xBA, 0x3C, 0x53, 0x69, 0x61, 0xCC, 0x34,
};
#define NOISE_TABLE_MASK 255
// lattice gradients 3D noise
static float gradientTable[256*3];
#define FLOOR(x) ((int)(x) − ((x) < 0 && (x) != (int)(x)))
#define smoothstep(t) (t * t * (3.0f − 2.0f * t))
#define lerp(t, a, b) (a + t * (b − a))
void initNoiseTable()
{
int i;
float a;
float x, y, z, r, theta;
float gradients[256*3];
unsigned int *p, *psrc;
srandom(0);
// build gradient table for 3D noise
for (i=0; i<256; i++)
{
/*
* calculate 1 − 2 * random number
*/
a = (random() % 32768) / 32768.0f;
z = (1.0f − 2.0f * a);
r = sqrtf(1.0f − z * z); // r is radius of circle
a = (random() % 32768) / 32768.0f;
theta = (2.0f * (float)M_PI * a);
x = (r * cosf(a));
y = (r * sinf(a));
(continues)
