Changeset 266353 in webkit

Timestamp:

Aug 31, 2020, 8:14:57 AM (6 years ago)

Author:

Wenson Hsieh

Message:

Optimize the implementation of TransformationMatrix::rotate(double)
​https://bugs.webkit.org/show_bug.cgi?id=215994

Reviewed by Tim Horton.

TransformationMatrix::rotate(angle) currently just calls TransformationMatrix::rotate3d(0, 0, 1, angle), which
has a fast path for the case where we're rotating about the z-axis. However, we can make this *slightly* faster
by omitting the hypotenuse computation, several floating point comparisons, and several assignments in this case
because we already know that we're just rotating about the z-axis.

This is a small (but measurable) improvement on the Multiply subtest of MotionMark, which applies a little over
3 million rotation transformations over the course of 30 seconds.

• platform/graphics/transforms/RotateTransformOperation.h:

Instead of calling rotate3d, just have rotate directly call multiply with the following
TransformationMatrix:
`
[[ cos(z) sin(z) 0 0 ]

[ -sin(z) cos(z) 0 0 ]
[ 0 0 1 0 ]
[ 0 0 0 1 ]]

`
...where z is the angle of rotation, in radians.

• platform/graphics/transforms/TransformationMatrix.cpp:

(WebCore::TransformationMatrix::rotate):

• platform/graphics/transforms/TransformationMatrix.h:

(WebCore::TransformationMatrix::rotate): Deleted.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/transforms/RotateTransformOperation.h (modified) (1 diff)
• platform/graphics/transforms/TransformationMatrix.cpp (modified) (1 diff)
• platform/graphics/transforms/TransformationMatrix.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2020-08-31  Wenson Hsieh  <wenson_hsieh@apple.com>
+
+        Optimize the implementation of TransformationMatrix::rotate(double)
+        https://bugs.webkit.org/show_bug.cgi?id=215994
+
+        Reviewed by Tim Horton.
+
+        TransformationMatrix::rotate(angle) currently just calls TransformationMatrix::rotate3d(0, 0, 1, angle), which
+        has a fast path for the case where we're rotating about the z-axis. However, we can make this *slightly* faster
+        by omitting the hypotenuse computation, several floating point comparisons, and several assignments in this case
+        because we already know that we're just rotating about the z-axis.
+
+        This is a small (but measurable) improvement on the Multiply subtest of MotionMark, which applies a little over
+        3 million rotation transformations over the course of 30 seconds.
+
+        * platform/graphics/transforms/RotateTransformOperation.h:
+
+        Instead of calling `rotate3d`, just have `rotate` directly call `multiply` with the following
+        `TransformationMatrix`:
+        ```
+        [[  cos(z)  sin(z)  0   0 ]
+         [  -sin(z) cos(z)  0   0 ]
+         [  0       0       1   0 ]
+         [  0       0       0   1 ]]
+        ```
+        ...where `z` is the angle of rotation, in radians.
+
+        * platform/graphics/transforms/TransformationMatrix.cpp:
+        (WebCore::TransformationMatrix::rotate):
+        * platform/graphics/transforms/TransformationMatrix.h:
+        (WebCore::TransformationMatrix::rotate): Deleted.
+
 2020-08-31  Aditya Keerthi  <akeerthi@apple.com>
 

trunk/Source/WebCore/platform/graphics/transforms/RotateTransformOperation.h

@@ -61 +61 @@
     bool apply(TransformationMatrix& transform, const FloatSize& /*borderBoxSize*/) const override
     {
-        transform.rotate3d(m_x, m_y, m_z, m_angle);
+        if (type() == TransformOperation::ROTATE)
+            transform.rotate(m_angle);
+        else
+            transform.rotate3d(m_x, m_y, m_z, m_angle);
         return false;
     }

trunk/Source/WebCore/platform/graphics/transforms/TransformationMatrix.cpp

@@ -898 +898 @@
 }
 
+TransformationMatrix& TransformationMatrix::rotate(double angle)
+{
+    angle = deg2rad(angle);
+    double sinZ = sin(angle);
+    double cosZ = cos(angle);
+    multiply({ cosZ, sinZ, -sinZ, cosZ, 0, 0 });
+    return *this;
+}
+
 TransformationMatrix& TransformationMatrix::rotate3d(double rx, double ry, double rz)
 {

trunk/Source/WebCore/platform/graphics/transforms/TransformationMatrix.h

@@ -254 +254 @@
 
     // Angle is in degrees.
-    TransformationMatrix& rotate(double d) { return rotate3d(0, 0, d); }
+    WEBCORE_EXPORT TransformationMatrix& rotate(double);
     TransformationMatrix& rotateFromVector(double x, double y);
     WEBCORE_EXPORT TransformationMatrix& rotate3d(double rx, double ry, double rz);