Use truncation, not rounding, when converting perlin noise seed (required by SVG spec).

Use truncation, not rounding, when converting perlin noise seed (required by SVG spec).

BUG=
R=reed@google.com

Committed: https://code.google.com/p/skia/source/detail?r=12995

[Stephen White, 2014-01-09 16:29:13]

sugoi@: PTAL. Thanks!

[sugoi, 2014-01-09 16:30:44]

On 2014/01/09 16:29:13, Stephen White wrote:
> sugoi@: PTAL. Thanks!

lgtm

[reed1, 2014-01-09 16:33:47]

since this is non-obvious (obviously), lets add a comment above the call to
floor/trunc that we are following svg's spec

[reed1, 2014-01-09 16:34:18]

hmm, is the spec for trunc or floor?

[Stephen White, 2014-01-09 16:50:56]

On 2014/01/09 16:34:18, reed1 wrote:
> hmm, is the spec for trunc or floor?

From http://www.w3.org/TR/SVG/filters.html:

"When the seed number is handed over to the algorithm above it must first be
truncated, i.e. rounded to the closest integer value towards zero."

[Stephen White, 2014-01-09 17:28:45]

On 2014/01/09 16:33:47, reed1 wrote:
> since this is non-obvious (obviously), lets add a comment above the call to
> floor/trunc that we are following svg's spec

Done.

[reed1, 2014-01-09 17:40:28]

lgtm

[Stephen White, 2014-01-09 17:41:47]

Committed patchset #2 manually as r12995 (presubmit successful).