Split and augment reftests for rotation interpolation.

Divided the rotation tests into two groups: one for common axis,
second for interpolated axis + angle (SLERP).  By separating in this
way, it is easier to match up the tests with the corresponding images.

The 0 -> 90 degree tests for common-axis rotations were changed to
30 -> 90 since a zero degree rotation matches any non-zero counterpart.

Tests added to both groups to verify the following:

* rotation with scaled axis
* rotate -> rotateZ
* special case of a zero rotation angle
* counter-rotation with negative angle
* counter-rotation with inverted axis
* axis+angle interpolation (SLERP)

Bug: 998175, 929841
Change-Id: Iefcfa9bf0d55b6df7f459f51c8b900dd991ab890
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2513796Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823746}

third_party/blink/web_tests/TestExpectations

@@ -6228,3 +6228,10 @@ crbug.com/1144537 external/wpt/xhr/responsexml-document-properties.htm [ Pass Fa
 
 # Sheriff 2020-11-03
 crbug.com/1145019 [ Win7 ] fast/events/updateLayoutForHitTest.html [ Failure ]
+
+# Lack of support for reftest fuzzy matching
+# Reftests have minor pixel differences due to antialiasing.
+crbug.com/997202 [ Mac ] external/wpt/css/css-transforms/animation/transform-interpolation-rotate-slerp.html [ Failure ]
+crbug.com/997202 [ Mac ] virtual/composite-relative-keyframes/external/wpt/css/css-transforms/animation/transform-interpolation-rotate-slerp.html [ Failure ]
+crbug.com/997202 [ Mac ] virtual/threaded/external/wpt/css/css-transforms/animation/transform-interpolation-rotate-slerp.html [ Failure ]
+crbug.com/997202 [ Mac ] virtual/transform-interop/external/wpt/css/css-transforms/animation/transform-interpolation-rotate-slerp.html [ Failure ]

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/support/transform-interpolation-reftests.js

@@ -18,13 +18,43 @@ const transformTests = {
     ['translateX(50%)', 'translateX(calc(25% - 2em))', 'translateX(-4em)']
   ],
   rotate: [
-    ['rotate(0deg)', 'rotate(45deg)', 'rotate(90deg)'],
-    ['rotateX(0deg)', 'rotateX(45deg)', 'rotateX(90deg)'],
-    ['rotateY(0deg)', 'rotateY(45deg)', 'rotateY(90deg)'],
+    // Rotation about named-axis.
+    ['rotate(30deg)', 'rotate(60deg)', 'rotate(90deg)'],
+    ['rotateX(30deg)', 'rotateX(60deg)', 'rotateX(90deg)'],
+    ['rotateY(30deg)', 'rotateY(60deg)', 'rotateY(90deg)'],
+    ['rotate(30deg)', 'rotate(60deg)', 'rotateZ(90deg)'],
     ['rotate(0deg)', 'rotate(180deg)', 'rotate(360deg)'],
+    // Common axis rotations.
     ['rotate3d(7, 8, 9, 0deg)', 'rotate3d(7, 8, 9, 45deg)', 'rotate3d(7, 8, 9, 90deg)'],
+    ['rotate3d(1, 2, 3, 0deg)', 'rotate3d(3, 6, 9, 45deg)', 'rotate3d(2, 4, 6, 90deg)'],
+    // Axis is arbitrary if angle is zero. Use non-zero rotation to determine
+    // the rotation axis.
+    ['rotateX(0deg)', 'rotate(45deg)', 'rotate(90deg)'],
+    ['rotateX(90deg)', 'rotateX(45deg)', 'rotate(0deg)']
+  ],
+  rotateSlerp: [
     // First endpoint is the same rotation as rotateZ(0deg) but triggers SLERP
-    ['rotateX(360deg)', 'rotateZ(45deg)', 'rotateZ(90deg)']
+    ['rotateX(360deg)', 'rotateZ(45deg)', 'rotateZ(90deg)'],
+    // Interpolation with inverse. Second case is a common-axis case, but
+    // included here to group it with its equivalent SLERP test.
+    ['rotate(45deg)', 'rotate(0deg)', 'rotate3d(0, 0, -1, 45deg)'],
+    ['rotate(45deg)', 'rotate(0deg)', 'rotate(-45deg)'],
+    // Interpolate axis and angle of rotation.
+    // 70.5288deg = acos(1/3).
+    ['rotateX(90deg)', 'rotate3d(1, 1, 0, 70.5288deg)', 'rotateY(90deg)'],
+    // Not nice analytical solution for this last one.
+    // (1, 1, 0, 90deg) --> (x, y, z, w) = (1/2, 1/2, 0, 1/root2)
+    // (0, 1, 1, 180deg) --> (x, y, z, w) = (0, 1/root2, 1/root2, 0)
+    // Trace of the "to" transformation matrix is -1. Requires special handling
+    // to ensure correctness of the quaternion.
+    // SLERP @0.5: (x, y, z, w) = (0.30389062997686395,
+    //                             0.7336568918027127,
+    //                             0.4297662618258487,
+    //                             0.4297662618258487)
+    // --> rotate3d(0.3365568, 0.8125199, 0.4759632, 129.094547486deg)
+    ['rotate3d(1, 1, 0, 90deg)',
+     'rotate3d(0.3365568, 0.8125199, 0.4759632, 129.094547486deg)',
+     'rotate3d(0, 1, 1, 180deg)'],
   ],
   scale: [
     ['scaleX(0.5)', 'scaleX(0.75)', 'scaleX(1)'],

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/transform-interpolation-rotate-slerp.html

+<!DOCTYPE html>
+<html class="reftest-wait">
+<link rel="match" href="transform-interpolation-ref.html?rotateSlerp">
+<link rel="help" href="https://drafts.csswg.org/css-transforms/">
+
+<script src="../../../common/reftest-wait.js"></script>
+<script src="support/transform-interpolation-reftests.js"></script>
+
+<body>
+<script>
+createTests(transformTests.rotateSlerp);
+</script>