1 files changed, 140 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_texture_pool.cc b/source/blender/draw/intern/draw_texture_pool.cc
new file mode 100644
index 00000000000..544a763ddb9
--- /dev/null
+++ b/source/blender/draw/intern/draw_texture_pool.cc
@@ -0,0 +1,140 @@
+/*
+ * 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.
+ *
+ * Copyright 2021, Blender Foundation.
+ */
+
+/** \file
+ * \ingroup draw
+ */
+
+#include "BKE_global.h"
+
+#include "BLI_vector.hh"
+
+#include "draw_texture_pool.h"
+
+using namespace blender;
+
+typedef struct DRWTexturePoolHandle {
+  uint64_t users_bits;
+  GPUTexture *texture;
+} DRWTexturePoolHandle;
+
+struct DRWTexturePool {
+  Vector<void *, 16> users;
+  Vector<DRWTexturePoolHandle> handles;
+  /* Cache last result to avoid linear search each time. */
+  int last_user_id = -1;
+};
+
+DRWTexturePool *DRW_texture_pool_create(void)
+{
+  return new DRWTexturePool();
+}
+
+void DRW_texture_pool_free(DRWTexturePool *pool)
+{
+  /* Reseting the pool twice will effectively free all textures. */
+  DRW_texture_pool_reset(pool);
+  DRW_texture_pool_reset(pool);
+  delete pool;
+}
+
+/**
+ * Try to find a texture corresponding to params into the texture pool.
+ * If no texture was found, create one and add it to the pool.
+ */
+GPUTexture *DRW_texture_pool_query(
+    DRWTexturePool *pool, int width, int height, eGPUTextureFormat format, void *user)
+{
+  int user_id = pool->last_user_id;
+  /* Try cached value. */
+  if (user_id != -1) {
+    if (pool->users[user_id] != user) {
+      user_id = -1;
+    }
+  }
+  /* Try to find inside previous users. */
+  if (user_id == -1) {
+    user_id = pool->users.first_index_of_try(user);
+  }
+  /* No chance, needs to add it to the user list. */
+  if (user_id == -1) {
+    user_id = pool->users.size();
+    pool->users.append(user);
+    /* If there is more than 63 users, better refactor this system. */
+    BLI_assert(user_id < 64);
+  }
+  pool->last_user_id = user_id;
+
+  uint64_t user_bit = 1llu << user_id;
+  for (DRWTexturePoolHandle &handle : pool->handles) {
+    /* Skip if the user is already using this texture. */
+    if (user_bit & handle.users_bits) {
+      continue;
+    }
+    /* If everthing matches reuse the texture. */
+    if ((GPU_texture_format(handle.texture) == format) &&
+        (GPU_texture_width(handle.texture) == width) &&
+        (GPU_texture_height(handle.texture) == height)) {
+      handle.users_bits |= user_bit;
+      return handle.texture;
+    }
+  }
+
+  char name[16] = "DRW_tex_pool";
+  if (G.debug & G_DEBUG_GPU) {
+    int texture_id = pool->handles.size();
+    SNPRINTF(name, "DRW_tex_pool_%d", texture_id);
+  }
+
+  DRWTexturePoolHandle handle;
+  handle.users_bits = user_bit;
+  handle.texture = GPU_texture_create_2d(name, width, height, 1, format, nullptr);
+  pool->handles.append(handle);
+  /* Doing filtering for depth does not make sense when not doing shadow mapping,
+   * and enabling texture filtering on integer texture make them unreadable. */
+  bool do_filter = !GPU_texture_depth(handle.texture) && !GPU_texture_integer(handle.texture);
+  GPU_texture_filter_mode(handle.texture, do_filter);
+
+  return handle.texture;
+}
+
+/* Resets the user bits for each texture in the pool and delete unused ones. */
+void DRW_texture_pool_reset(DRWTexturePool *pool)
+{
+  pool->last_user_id = -1;
+
+  for (auto it = pool->handles.rbegin(); it != pool->handles.rend(); ++it) {
+    DRWTexturePoolHandle &handle = *it;
+    if (handle.users_bits == 0) {
+      if (handle.texture) {
+        GPU_texture_free(handle.texture);
+        handle.texture = nullptr;
+      }
+    }
+    else {
+      handle.users_bits = 0;
+    }
+  }
+
+  /* Reverse iteration to make sure we only reorder with known good handles. */
+  for (int i = pool->handles.size() - 1; i >= 0; i--) {
+    if (!pool->handles[i].texture) {
+      pool->handles.remove_and_reorder(i);
+    }
+  }
+}
\ No newline at end of file