Add fast normalize for SkLightingImageFilter.

Add fast normalize for SkLightingImageFilter.

The normalize routine in SkPoint3 is very robust. However, for simple
lighting cases we prefer speed over robustness. This fixes a perf
regression in smoothness.tough_filters_cases.

BUG=chromium:510562
Committed: https://skia.googlesource.com/skia/+/dfa0ecf169db87f7afddd93bc1c500de481a62c7

[jvanverth1, 2015-07-16 19:13:21]

jvanverth@google.com changed reviewers:
+ reed@google.com, senorblanco@google.com

[Stephen White, 2015-07-16 19:14:44]

senorblanco@chromium.org changed reviewers:
+ senorblanco@chromium.org

[Stephen White, 2015-07-16 19:14:45]

LGTM, but will leave for Mike.

[reed1, 2015-07-16 19:44:50]

lgtm w/ nits

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
File src/effects/SkLightingImageFilter.cpp (right):

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
src/effects/SkLightingImageFilter.cpp:63: inline void fast_normalize(SkPoint3*
vector) {
static inline ...

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
src/effects/SkLightingImageFilter.cpp:64: SkScalar magSq = vector->dot(*vector)
+ SK_ScalarNearlyZero;
// add a tiny bit so we don't have to worry about divide-by-zero

[jvanverth1, 2015-07-16 19:47:55]

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
File src/effects/SkLightingImageFilter.cpp (right):

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
src/effects/SkLightingImageFilter.cpp:63: inline void fast_normalize(SkPoint3*
vector) {
On 2015/07/16 19:44:50, reed1 wrote:
> static inline ...

Done.

https://codereview.chromium.org/1240023002/diff/1/src/effects/SkLightingImage...
src/effects/SkLightingImageFilter.cpp:64: SkScalar magSq = vector->dot(*vector)
+ SK_ScalarNearlyZero;
On 2015/07/16 19:44:50, reed1 wrote:
> // add a tiny bit so we don't have to worry about divide-by-zero

Done.

[jvanverth1, 2015-07-16 19:47:59]

The CQ bit was checked by jvanverth@google.com

[jvanverth1, 2015-07-16 19:47:59]

The patchset sent to the CQ was uploaded after l-g-t-m from
senorblanco@chromium.org, reed@google.com
Link to the patchset: https://codereview.chromium.org/1240023002/#ps20001
(title: "Address nits")

[commit-bot: I haz the power, 2015-07-16 19:48:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1240023002/20001

[commit-bot: I haz the power, 2015-07-16 19:56:49]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/dfa0ecf169db87f7afddd93bc1c500de481a62c7

[reed2, 2015-07-16 23:02:20]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1244523002/ by reed@chromium.org.

The reason for reverting is: Speculative revert -- DEPS roll block on
linux_blink_rel

https://storage.googleapis.com/chromium-layout-test-archives/linux_blink_rel/....