DRW: Move buffer & temp textures & framebuffer management to DrawManager

This is a necessary step for EEVEE's new arch. This moves more data
to the draw manager. This makes it easier to have the render or draw
engines manage their own data.

This makes more sense and cleans-up what the GPUViewport holds

Also rewrites the Texture pool manager to be in C++.

This also move the DefaultFramebuffer/TextureList and the engine related
data to a new `DRWViewData` struct. This struct manages the per view
(as in stereo view) engine data.

There is a bit of cleanup in the way the draw manager is setup.
We now use a temporary DRWData instead of creating a dummy viewport.

Development: fclem, jbakker

Differential Revision: https://developer.blender.org/D11966

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