On 02/17/2014 08:21 AM, Juha-Pekka Heikkila wrote: > % operator could return negative value which would cause > indexing before perm table. > > Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikk...@gmail.com> > --- > src/mesa/program/prog_noise.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/src/mesa/program/prog_noise.c b/src/mesa/program/prog_noise.c > index c258c5e..12bb4d9 100644 > --- a/src/mesa/program/prog_noise.c > +++ b/src/mesa/program/prog_noise.c > @@ -282,8 +282,8 @@ _mesa_noise2(GLfloat x, GLfloat y) > y2 = y0 - 1.0f + 2.0f * G2; > > /* Wrap the integer indices at 256, to avoid indexing perm[] out of > bounds */ > - ii = i % 256; > - jj = j % 256; > + ii = abs(i % 256); > + jj = abs(j % 256);
It seems like ii = i & 0x0ff; is a better way to do this. Perhaps add a comment about 'int % int' possibly returning NULL so that someone doesn't come a long and change it back. :) At that point, ii, jj, i1, and j1 should probably be unsigned. I think only i and j need to be int. > /* Calculate the contribution from the three corners */ > t0 = 0.5f - x0 * x0 - y0 * y0; > @@ -423,9 +423,9 @@ _mesa_noise3(GLfloat x, GLfloat y, GLfloat z) > z3 = z0 - 1.0f + 3.0f * G3; > > /* Wrap the integer indices at 256 to avoid indexing perm[] out of bounds > */ > - ii = i % 256; > - jj = j % 256; > - kk = k % 256; > + ii = abs(i % 256); > + jj = abs(j % 256); > + kk = abs(k % 256); > > /* Calculate the contribution from the four corners */ > t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0; > @@ -573,10 +573,10 @@ _mesa_noise4(GLfloat x, GLfloat y, GLfloat z, GLfloat w) > w4 = w0 - 1.0f + 4.0f * G4; > > /* Wrap the integer indices at 256, to avoid indexing perm[] out of > bounds */ > - ii = i % 256; > - jj = j % 256; > - kk = k % 256; > - ll = l % 256; > + ii = abs(i % 256); > + jj = abs(j % 256); > + kk = abs(k % 256); > + ll = abs(l % 256); > > /* Calculate the contribution from the five corners */ > t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0 - w0 * w0; > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
