Cryptomatte: Data structure in compositor node

This changes the way how the mattes are stored in the compositor node. This used to
be a single string what was decoded/encoded when needed. The new data structure
stores all entries in `CryptomatteEntry` and is converted to the old `matte_id`
property on the fly.

This is done for some future changes in the workflow where a more structured
approach leads to less confusing and easier to read code.

4 files changed, 201 insertions, 88 deletions

diff --git a/source/blender/blenkernel/BKE_cryptomatte.h b/source/blender/blenkernel/BKE_cryptomatte.h
index 929266d1b89..c3c17f72cae 100644
--- a/source/blender/blenkernel/BKE_cryptomatte.h
+++ b/source/blender/blenkernel/BKE_cryptomatte.h
@@ -25,18 +25,28 @@
 
 #include "BLI_sys_types.h"
 
+#include "DNA_layer_types.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 struct Object;
 struct Material;
+struct ID;
+struct Main;
 
+uint32_t BKE_cryptomatte_hash(const char *name, int name_len);
 uint32_t BKE_cryptomatte_object_hash(const struct Object *object);
 uint32_t BKE_cryptomatte_material_hash(const struct Material *material);
 uint32_t BKE_cryptomatte_asset_hash(const struct Object *object);
 float BKE_cryptomatte_hash_to_float(uint32_t cryptomatte_hash);
 
+char *BKE_cryptomatte_entries_to_matte_id(struct NodeCryptomatte *node_storage);
+void BKE_cryptomatte_matte_id_to_entries(const struct Main *bmain,
+                                         struct NodeCryptomatte *node_storage,
+                                         const char *matte_id);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 5b10f734d71..d440d3e4d64 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -101,7 +101,7 @@ set(SRC
   intern/constraint.c
   intern/context.c
   intern/crazyspace.c
-  intern/cryptomatte.c
+  intern/cryptomatte.cc
   intern/curve.c
   intern/curve_bevel.c
   intern/curve_decimate.c
diff --git a/source/blender/blenkernel/intern/cryptomatte.c b/source/blender/blenkernel/intern/cryptomatte.c
deleted file mode 100644
index 6570ffce920..00000000000
--- a/source/blender/blenkernel/intern/cryptomatte.c
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * The Original Code is Copyright (C) 2008 Blender Foundation.
- * All rights reserved.
- */
-
-/** \file
- * \ingroup bke
- */
-
-#include "BKE_cryptomatte.h"
-
-#include "DNA_material_types.h"
-#include "DNA_object_types.h"
-
-#include "BLI_compiler_attrs.h"
-#include "BLI_hash_mm3.h"
-#include "BLI_string.h"
-#include <string.h>
-
-static uint32_t cryptomatte_hash(const ID *id)
-{
-  const char *name = &id->name[2];
-  const int len = BLI_strnlen(name, MAX_NAME - 2);
-  uint32_t cryptohash_int = BLI_hash_mm3((const unsigned char *)name, len, 0);
-  return cryptohash_int;
-}
-
-uint32_t BKE_cryptomatte_object_hash(const Object *object)
-{
-  return cryptomatte_hash(&object->id);
-}
-
-uint32_t BKE_cryptomatte_material_hash(const Material *material)
-{
-  if (material == NULL) {
-    return 0.0f;
-  }
-  return cryptomatte_hash(&material->id);
-}
-
-uint32_t BKE_cryptomatte_asset_hash(const Object *object)
-{
-  const Object *asset_object = object;
-  while (asset_object->parent != NULL) {
-    asset_object = asset_object->parent;
-  }
-  return cryptomatte_hash(&asset_object->id);
-}
-
-/* Convert a cryptomatte hash to a float.
- *
- * Cryptomatte hashes are stored in float textures and images. The conversion is taken from the
- * cryptomatte specification. See Floating point conversion section in
- * https://github.com/Psyop/Cryptomatte/blob/master/specification/cryptomatte_specification.pdf.
- *
- * The conversion uses as many 32 bit floating point values as possible to minimize hash
- * collisions. Unfortunately not all 32 bits can be as NaN and Inf can be problematic.
- *
- * Note that this conversion assumes to be running on a L-endian system. */
-float BKE_cryptomatte_hash_to_float(uint32_t cryptomatte_hash)
-{
-  uint32_t mantissa = cryptomatte_hash & ((1 << 23) - 1);
-  uint32_t exponent = (cryptomatte_hash >> 23) & ((1 << 8) - 1);
-  exponent = MAX2(exponent, (uint32_t)1);
-  exponent = MIN2(exponent, (uint32_t)254);
-  exponent = exponent << 23;
-  uint32_t sign = (cryptomatte_hash >> 31);
-  sign = sign << 31;
-  uint32_t float_bits = sign | exponent | mantissa;
-  float f;
-  memcpy(&f, &float_bits, sizeof(uint32_t));
-  return f;
-}
diff --git a/source/blender/blenkernel/intern/cryptomatte.cc b/source/blender/blenkernel/intern/cryptomatte.cc
new file mode 100644
index 00000000000..4bbeb088628
--- /dev/null
+++ b/source/blender/blenkernel/intern/cryptomatte.cc
@@ -0,0 +1,190 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2020 Blender Foundation.
+ * All rights reserved.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#include "BKE_cryptomatte.h"
+#include "BKE_main.h"
+
+#include "DNA_material_types.h"
+#include "DNA_node_types.h"
+#include "DNA_object_types.h"
+
+#include "BLI_compiler_attrs.h"
+#include "BLI_dynstr.h"
+#include "BLI_hash_mm3.h"
+#include "BLI_listbase.h"
+#include "BLI_string.h"
+
+#include "MEM_guardedalloc.h"
+
+#include <cstring>
+#include <sstream>
+#include <string>
+
+static uint32_t cryptomatte_hash(const ID *id)
+{
+  const char *name = &id->name[2];
+  const int name_len = BLI_strnlen(name, MAX_NAME);
+  uint32_t cryptohash_int = BKE_cryptomatte_hash(name, name_len);
+  return cryptohash_int;
+}
+
+uint32_t BKE_cryptomatte_hash(const char *name, int name_len)
+{
+  uint32_t cryptohash_int = BLI_hash_mm3((const unsigned char *)name, name_len, 0);
+  return cryptohash_int;
+}
+
+uint32_t BKE_cryptomatte_object_hash(const Object *object)
+{
+  return cryptomatte_hash(&object->id);
+}
+
+uint32_t BKE_cryptomatte_material_hash(const Material *material)
+{
+  if (material == nullptr) {
+    return 0.0f;
+  }
+  return cryptomatte_hash(&material->id);
+}
+
+uint32_t BKE_cryptomatte_asset_hash(const Object *object)
+{
+  const Object *asset_object = object;
+  while (asset_object->parent != nullptr) {
+    asset_object = asset_object->parent;
+  }
+  return cryptomatte_hash(&asset_object->id);
+}
+
+/* Convert a cryptomatte hash to a float.
+ *
+ * Cryptomatte hashes are stored in float textures and images. The conversion is taken from the
+ * cryptomatte specification. See Floating point conversion section in
+ * https://github.com/Psyop/Cryptomatte/blob/master/specification/cryptomatte_specification.pdf.
+ *
+ * The conversion uses as many 32 bit floating point values as possible to minimize hash
+ * collisions. Unfortunately not all 32 bits can be as NaN and Inf can be problematic.
+ *
+ * Note that this conversion assumes to be running on a L-endian system. */
+float BKE_cryptomatte_hash_to_float(uint32_t cryptomatte_hash)
+{
+  uint32_t mantissa = cryptomatte_hash & ((1 << 23) - 1);
+  uint32_t exponent = (cryptomatte_hash >> 23) & ((1 << 8) - 1);
+  exponent = MAX2(exponent, (uint32_t)1);
+  exponent = MIN2(exponent, (uint32_t)254);
+  exponent = exponent << 23;
+  uint32_t sign = (cryptomatte_hash >> 31);
+  sign = sign << 31;
+  uint32_t float_bits = sign | exponent | mantissa;
+  float f;
+  memcpy(&f, &float_bits, sizeof(uint32_t));
+  return f;
+}
+
+static ID *cryptomatte_find_id(const ListBase *ids, const float encoded_hash)
+{
+  LISTBASE_FOREACH (ID *, id, ids) {
+    uint32_t hash = BKE_cryptomatte_hash((id->name + 2), BLI_strnlen(id->name + 2, MAX_NAME));
+    if (BKE_cryptomatte_hash_to_float(hash) == encoded_hash) {
+      return id;
+    }
+  }
+  return nullptr;
+}
+
+/* Find an ID in the given main that matches the given encoded float. */
+static struct ID *BKE_cryptomatte_find_id(const Main *bmain, const float encoded_hash)
+{
+  ID *result;
+  result = cryptomatte_find_id(&bmain->objects, encoded_hash);
+  if (result == nullptr) {
+    result = cryptomatte_find_id(&bmain->materials, encoded_hash);
+  }
+  return result;
+}
+
+char *BKE_cryptomatte_entries_to_matte_id(NodeCryptomatte *node_storage)
+{
+  DynStr *matte_id = BLI_dynstr_new();
+  bool first = true;
+  LISTBASE_FOREACH (CryptomatteEntry *, entry, &node_storage->entries) {
+    if (!first) {
+      BLI_dynstr_append(matte_id, ",");
+    }
+    if (BLI_strnlen(entry->name, sizeof(entry->name)) != 0) {
+      BLI_dynstr_nappend(matte_id, entry->name, sizeof(entry->name));
+    }
+    else {
+      BLI_dynstr_appendf(matte_id, "<%.9g>", entry->encoded_hash);
+    }
+    first = false;
+  }
+  char *result = BLI_dynstr_get_cstring(matte_id);
+  BLI_dynstr_free(matte_id);
+  return result;
+}
+
+void BKE_cryptomatte_matte_id_to_entries(const Main *bmain,
+                                         NodeCryptomatte *node_storage,
+                                         const char *matte_id)
+{
+  BLI_freelistN(&node_storage->entries);
+
+  std::istringstream ss(matte_id);
+  while (ss.good()) {
+    CryptomatteEntry *entry = nullptr;
+    std::string token;
+    getline(ss, token, ',');
+    /* Ignore empty tokens. */
+    if (token.length() > 0) {
+      size_t first = token.find_first_not_of(' ');
+      size_t last = token.find_last_not_of(' ');
+      if (first == std::string::npos || last == std::string::npos) {
+        break;
+      }
+      token = token.substr(first, (last - first + 1));
+      if (*token.begin() == '<' && *(--token.end()) == '>') {
+        float encoded_hash = atof(token.substr(1, token.length() - 2).c_str());
+        entry = (CryptomatteEntry *)MEM_callocN(sizeof(CryptomatteEntry), __func__);
+        entry->encoded_hash = encoded_hash;
+        if (bmain) {
+          ID *id = BKE_cryptomatte_find_id(bmain, encoded_hash);
+          if (id != nullptr) {
+            BLI_strncpy(entry->name, id->name + 2, sizeof(entry->name));
+          }
+        }
+      }
+      else {
+        const char *name = token.c_str();
+        int name_len = token.length();
+        entry = (CryptomatteEntry *)MEM_callocN(sizeof(CryptomatteEntry), __func__);
+        BLI_strncpy(entry->name, name, sizeof(entry->name));
+        uint32_t hash = BKE_cryptomatte_hash(name, name_len);
+        entry->encoded_hash = BKE_cryptomatte_hash_to_float(hash);
+      }
+    }
+    if (entry != nullptr) {
+      BLI_addtail(&node_storage->entries, entry);
+    }
+  }
+}
\ No newline at end of file