1 files changed, 116 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_shadow_catcher.h b/intern/cycles/kernel/kernel_shadow_catcher.h
new file mode 100644
index 00000000000..824749818a4
--- /dev/null
+++ b/intern/cycles/kernel/kernel_shadow_catcher.h
@@ -0,0 +1,116 @@
+/*
+ * 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
+
+#include "kernel/integrator/integrator_state_util.h"
+#include "kernel/kernel_path_state.h"
+
+CCL_NAMESPACE_BEGIN
+
+/* Check whether current surface bounce is where path is to be split for the shadow catcher. */
+ccl_device_inline bool kernel_shadow_catcher_is_path_split_bounce(INTEGRATOR_STATE_ARGS,
+                                                                  const int object_flag)
+{
+#ifdef __SHADOW_CATCHER__
+  if (!kernel_data.integrator.has_shadow_catcher) {
+    return false;
+  }
+
+  /* Check the flag first, avoiding fetches form global memory. */
+  if ((object_flag & SD_OBJECT_SHADOW_CATCHER) == 0) {
+    return false;
+  }
+  if (object_flag & SD_OBJECT_HOLDOUT_MASK) {
+    return false;
+  }
+
+  const int path_flag = INTEGRATOR_STATE(path, flag);
+
+  if ((path_flag & PATH_RAY_TRANSPARENT_BACKGROUND) == 0) {
+    /* Split only on primary rays, secondary bounces are to treat shadow catcher as a regular
+     * object. */
+    return false;
+  }
+
+  if (path_flag & PATH_RAY_SHADOW_CATCHER_PASS) {
+    return false;
+  }
+
+  return true;
+#else
+  (void)object_flag;
+  return false;
+#endif
+}
+
+/* Check whether the current path can still split. */
+ccl_device_inline bool kernel_shadow_catcher_path_can_split(INTEGRATOR_STATE_CONST_ARGS)
+{
+  if (INTEGRATOR_PATH_IS_TERMINATED && INTEGRATOR_SHADOW_PATH_IS_TERMINATED) {
+    return false;
+  }
+
+  const int path_flag = INTEGRATOR_STATE(path, flag);
+
+  if (path_flag & PATH_RAY_SHADOW_CATCHER_HIT) {
+    /* Shadow catcher was already hit and the state was split. No further split is allowed. */
+    return false;
+  }
+
+  return (path_flag & PATH_RAY_TRANSPARENT_BACKGROUND) != 0;
+}
+
+/* NOTE: Leaves kernel scheduling information untouched. Use INIT semantic for one of the paths
+ * after this function. */
+ccl_device_inline bool kernel_shadow_catcher_split(INTEGRATOR_STATE_ARGS, const int object_flags)
+{
+#ifdef __SHADOW_CATCHER__
+
+  if (!kernel_shadow_catcher_is_path_split_bounce(INTEGRATOR_STATE_PASS, object_flags)) {
+    return false;
+  }
+
+  /* The split is to be done. Mark the current state as such, so that it stops contributing to the
+   * shadow catcher matte pass, but keeps contributing to the combined pass. */
+  INTEGRATOR_STATE_WRITE(path, flag) |= PATH_RAY_SHADOW_CATCHER_HIT;
+
+  /* Split new state from the current one. This new state will only track contribution of shadow
+   * catcher objects ignoring non-catcher objects. */
+  integrator_state_shadow_catcher_split(INTEGRATOR_STATE_PASS);
+
+  return true;
+#else
+  (void)object_flags;
+  return false;
+#endif
+}
+
+#ifdef __SHADOW_CATCHER__
+
+ccl_device_forceinline bool kernel_shadow_catcher_is_matte_path(INTEGRATOR_STATE_CONST_ARGS)
+{
+  return (INTEGRATOR_STATE(path, flag) & PATH_RAY_SHADOW_CATCHER_HIT) == 0;
+}
+
+ccl_device_forceinline bool kernel_shadow_catcher_is_object_pass(INTEGRATOR_STATE_CONST_ARGS)
+{
+  return INTEGRATOR_STATE(path, flag) & PATH_RAY_SHADOW_CATCHER_PASS;
+}
+
+#endif /* __SHADOW_CATCHER__ */
+
+CCL_NAMESPACE_END