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diff --git a/intern/cycles/integrator/adaptive_sampling.h b/intern/cycles/integrator/adaptive_sampling.h
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+/*
+ * Copyright 2011-2021 Blender Foundation
+ *
+ * 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.
+ */
+
+#pragma once
+
+CCL_NAMESPACE_BEGIN
+
+class AdaptiveSampling {
+ public:
+  AdaptiveSampling();
+
+  /* Align number of samples so that they align with the adaptive filtering.
+   *
+   * Returns the new value for the `num_samples` so that after rendering so many samples on top
+   * of `start_sample` filtering is required.
+   *
+   * The alignment happens in a way that allows to render as many samples as possible without
+   * missing any filtering point. This means that the result is "clamped" by the nearest sample
+   * at which filtering is needed. This is part of mechanism which ensures that all devices will
+   * perform same exact filtering and adaptive sampling, regardless of their performance.
+   *
+   * `start_sample` is the 0-based index of sample.
+   *
+   * NOTE: The start sample is included into the number of samples to render. This means that
+   * if the number of samples is 1, then the path tracer will render samples [align_samples],
+   * if the number of samples is 2, then the path tracer will render samples [align_samples,
+   * align_samples + 1] and so on. */
+  int align_samples(int start_sample, int num_samples) const;
+
+  /* Check whether adaptive sampling filter should happen at this sample.
+   * Returns false if the adaptive sampling is not use.
+   *
+   * `sample` is the 0-based index of sample. */
+  bool need_filter(int sample) const;
+
+  bool use = false;
+  int adaptive_step = 0;
+  int min_samples = 0;
+  float threshold = 0.0f;
+};
+
+CCL_NAMESPACE_END