GPUUniformBuf: GL backend isolation

This is in preparation of vulkan backend. We move all opengl
functionnalities behind an abstract class.

This also cleansup the "dynamic" ubo create and rename it to
`GPU_uniformbuf_from_list()`

Contains, no functional change.

Part of T68990 Vulkan support.

source/blender/gpu/opengl/gl_backend.hh

@@ -31,6 +31,7 @@
 #include "gl_context.hh"
 #include "gl_drawlist.hh"
 #include "gl_shader.hh"
+#include "gl_uniform_buffer.hh"
 
 namespace blender {
 namespace gpu {
@@ -40,6 +41,11 @@ class GLBackend : public GPUBackend {
   GLSharedOrphanLists shared_orphan_list_;
 
  public:
+  static GLBackend *get(void)
+  {
+    return static_cast<GLBackend *>(GPUBackend::get());
+  }
+
   GPUContext *context_alloc(void *ghost_window)
   {
     return new GLContext(ghost_window, shared_orphan_list_);
@@ -60,6 +66,11 @@ class GLBackend : public GPUBackend {
     return new GLShader(name);
   };
 
+  UniformBuf *uniformbuf_alloc(int size, const char *name)
+  {
+    return new GLUniformBuf(size, name);
+  };
+
   /* TODO remove */
   void buf_free(GLuint buf_id);
   void tex_free(GLuint tex_id);

source/blender/gpu/opengl/gl_batch.hh

@@ -35,6 +35,7 @@
 namespace blender {
 namespace gpu {
 
+class GLContext;
 class GLShaderInterface;
 
 #define GPU_VAO_STATIC_LEN 3
@@ -45,7 +46,7 @@ class GLShaderInterface;
 class GLVaoCache {
  private:
   /** Context for which the vao_cache_ was generated. */
-  struct GLContext *context_ = NULL;
+  GLContext *context_ = NULL;
   /** Last interface this batch was drawn with. */
   GLShaderInterface *interface_ = NULL;
   /** Cached vao for the last interface. */

source/blender/gpu/opengl/gl_context.hh

@@ -32,13 +32,13 @@
 
 #include "glew-mx.h"
 
-#include "gl_batch.hh"
-
 #include <mutex>
 
 namespace blender {
 namespace gpu {
 
+class GLVaoCache;
+
 class GLSharedOrphanLists {
  public:
   /** Mutex for the bellow structures. */
@@ -51,7 +51,7 @@ class GLSharedOrphanLists {
   void orphans_clear(void);
 };
 
-struct GLContext : public GPUContext {
+class GLContext : public GPUContext {
   /* TODO(fclem) these needs to become private. */
  public:
   /** Default VAO for procedural draw calls. */

source/blender/gpu/opengl/gl_shader.cc

@@ -49,7 +49,7 @@ GLShader::GLShader(const char *name) : Shader(name)
 #ifndef __APPLE__
   if ((G.debug & G_DEBUG_GPU) && (GLEW_VERSION_4_3 || GLEW_KHR_debug)) {
     char sh_name[64];
-    BLI_snprintf(sh_name, sizeof(sh_name), "ShaderProgram-%s", name);
+    SNPRINTF(sh_name, "ShaderProgram-%s", name);
     glObjectLabel(GL_PROGRAM, shader_program_, -1, sh_name);
   }
 #endif

source/blender/gpu/opengl/gl_uniform_buffer.cc

@@ -0,0 +1,126 @@
+/*
+ * 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 gpu
+ */
+
+#include "BKE_global.h"
+
+#include "BLI_string.h"
+
+#include "GPU_extensions.h"
+
+#include "gpu_backend.hh"
+#include "gpu_context_private.hh"
+
+#include "gl_backend.hh"
+#include "gl_uniform_buffer.hh"
+
+namespace blender::gpu {
+
+/* -------------------------------------------------------------------- */
+/** \name Creation & Deletion
+ * \{ */
+
+GLUniformBuf::GLUniformBuf(size_t size, const char *name) : UniformBuf(size, name)
+{
+  /* Do not create ubo GL buffer here to allow allocation from any thread. */
+}
+
+GLUniformBuf::~GLUniformBuf()
+{
+  GLBackend::get()->buf_free(ubo_id_);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Data upload / update
+ * \{ */
+
+void GLUniformBuf::init(void)
+{
+  BLI_assert(GPU_context_active_get());
+
+  glGenBuffers(1, &ubo_id_);
+  glBindBuffer(GL_UNIFORM_BUFFER, ubo_id_);
+  glBufferData(GL_UNIFORM_BUFFER, size_in_bytes_, NULL, GL_DYNAMIC_DRAW);
+
+#ifndef __APPLE__
+  if ((G.debug & G_DEBUG_GPU) && (GLEW_VERSION_4_3 || GLEW_KHR_debug)) {
+    char sh_name[64];
+    SNPRINTF(sh_name, "UBO-%s", name_);
+    glObjectLabel(GL_BUFFER, ubo_id_, -1, sh_name);
+  }
+#endif
+}
+
+void GLUniformBuf::update(const void *data)
+{
+  if (ubo_id_ == 0) {
+    this->init();
+  }
+  glBindBuffer(GL_UNIFORM_BUFFER, ubo_id_);
+  glBufferSubData(GL_UNIFORM_BUFFER, 0, size_in_bytes_, data);
+  glBindBuffer(GL_UNIFORM_BUFFER, 0);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Usage
+ * \{ */
+
+void GLUniformBuf::bind(int slot)
+{
+  if (slot >= GPU_max_ubo_binds()) {
+    fprintf(stderr,
+            "Error: Trying to bind \"%s\" ubo to slot %d which is above the reported limit of %d.",
+            name_,
+            slot,
+            GPU_max_ubo_binds());
+    return;
+  }
+
+  if (ubo_id_ == 0) {
+    this->init();
+  }
+
+  if (data_ != NULL) {
+    this->update(data_);
+    MEM_SAFE_FREE(data_);
+  }
+
+  slot_ = slot;
+  glBindBufferBase(GL_UNIFORM_BUFFER, slot_, ubo_id_);
+}
+
+void GLUniformBuf::unbind(void)
+{
+#ifdef DEBUG
+  /* NOTE: This only unbinds the last bound slot. */
+  glBindBufferBase(GL_UNIFORM_BUFFER, slot_, 0);
+#endif
+  slot_ = 0;
+}
+
+/** \} */
+
+}  // namespace blender::gpu

source/blender/gpu/opengl/gl_uniform_buffer.hh

@@ -0,0 +1,55 @@
+/*
+ * 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 gpu
+ */
+
+#pragma once
+
+#include "MEM_guardedalloc.h"
+
+#include "gpu_uniform_buffer_private.hh"
+
+#include "glew-mx.h"
+
+namespace blender {
+namespace gpu {
+
+class GLUniformBuf : public UniformBuf {
+ private:
+  int slot_ = -1;
+  GLuint ubo_id_ = 0;
+
+ public:
+  GLUniformBuf(size_t size, const char *name);
+  ~GLUniformBuf();
+
+  void update(const void *data) override;
+  void bind(int slot) override;
+  void unbind(void) override;
+
+ private:
+  void init(void);
+
+  MEM_CXX_CLASS_ALLOC_FUNCS("GLUniformBuf");
+};
+
+}  // namespace gpu
+}  // namespace blender