Fix translationZ matrix computation

bug:14259972

Ensure that translationZ is applied for true3dTransform property
transformations, even if the node doesn't have any other
transformation properties set.

Additionally, use fuzzy compare for translationZ, similar to
rotationX/Y, since they're expenive to leave set in rounding error
cases.

Change-Id: Idafa4423cc7751a8f433237b1f576aa7abb74f6e
diff --git a/libs/hwui/utils/MathUtils.h b/libs/hwui/utils/MathUtils.h
new file mode 100644
index 0000000..57ba8fa
--- /dev/null
+++ b/libs/hwui/utils/MathUtils.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MATHUTILS_H
+#define MATHUTILS_H
+
+namespace android {
+namespace uirenderer {
+
+class MathUtils {
+private:
+    static const float gNonZeroEpsilon = 0.001f;
+public:
+    /**
+     * Check for floats that are close enough to zero.
+     */
+    inline static bool isZero(float value) {
+        return (value >= -gNonZeroEpsilon) && (value <= gNonZeroEpsilon);
+    }
+}; // class MathUtils
+
+} /* namespace uirenderer */
+} /* namespace android */
+
+#endif /* RENDERNODE_H */