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Hi everyone,
I'm trying to understand how the following define works (render.cpp):
#define rand2d(a, b)
jitttab[(int)(hashTable[(int)(hashTable[(int)((a)&0xfff)]^(b))&0xfff])&0xff]
I got that jitttab is an array of 256 random float ranging from -0.5 to 0.5.
hashtable is an array of 8192 unsigned short, where the first 4096
numbers are the the growing 0..4095 scattered randomly, and the last
4096 are just the same:
for (i = 0; i < 4096; i++)
{
hashTable[i] = i;
}
for (i = 4095; i >= 0; i--)
{
j = POV_RAND() % 4096;
temp = hashTable[i];
hashTable[i] = hashTable[j];
hashTable[j] = temp;
}
for (i = 0; i < 4096; i++)
{
hashTable[4096 + i] = hashTable[i];
}
My question is: what are the and and xor mask for?
Thanxs
Adam
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