change noise4f to a function that does not crash

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@7371 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/fractalnoise.c b/fractalnoise.c
index 40beb8af3cc2315451627ead0816164fecda78be..1bb1c55abf8eebb087a6573626583e8357ff561b 100644 (file)
--- a/fractalnoise.c
+++ b/fractalnoise.c
@@ -154,12 +154,13 @@ float noise4f(float x, float y, float z, float w)
                        noisetable[i] = (rand() / (double)RAND_MAX) * 2 - 1;
                // r is a remapping table to make each dimension of the index have different indexing behavior
                for (i = 0;i < NOISE_SIZE;i++)
-                       r[i] = (int)(rand() * (double)NOISE_MASK / (double)RAND_MAX);
+                       r[i] = (int)(rand() * (double)NOISE_SIZE / ((double)RAND_MAX + 1)) & NOISE_MASK;
+                       // that & is only needed if RAND_MAX is > the range of double, which isn't the case on most platforms
        }
-       frac[1][0] = x - floor(x);index[0][0] = (int)floor(x);
-       frac[1][1] = y - floor(y);index[1][0] = (int)floor(y);
-       frac[1][2] = z - floor(z);index[2][0] = (int)floor(z);
-       frac[1][3] = w - floor(w);index[3][0] = (int)floor(w);
+       frac[1][0] = x - floor(x);index[0][0] = ((int)floor(x)) & NOISE_MASK;
+       frac[1][1] = y - floor(y);index[1][0] = ((int)floor(y)) & NOISE_MASK;
+       frac[1][2] = z - floor(z);index[2][0] = ((int)floor(z)) & NOISE_MASK;
+       frac[1][3] = w - floor(w);index[3][0] = ((int)floor(w)) & NOISE_MASK;
        for (i = 0;i < 4;i++)
                frac[i][0] = 1 - frac[i][1];
        for (i = 0;i < 4;i++)