GPUTexture: GL Backend Isolation

This is a massive cleanup needed for vulkan support T68990. It provides:

- More meaningful enums with conversion functions.
- Less hacky supports of arrays and cubemaps (all considered layered).
- More inline with the stateless design of vulkan and modern GL.
- Methods Fallbacks are using framebuffer functions that are wrapped
  instead of implementing inside the texture module.

What is not in there:
- API change.
- Samplers support (breaks a few effects).

# Conflicts:
#	source/blender/gpu/GPU_texture.h

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/gpu/opengl/gl_context.hh b/source/blender/gpu/opengl/gl_context.hh
index bc7e2060804..9e6359fabad 100644
--- a/source/blender/gpu/opengl/gl_context.hh
+++ b/source/blender/gpu/opengl/gl_context.hh
@@ -30,6 +30,8 @@
 #include "BLI_set.hh"
 #include "BLI_vector.hh"
 
+#include "gl_state.hh"
+
 #include "glew-mx.h"
 
 #include <mutex>
@@ -83,6 +85,12 @@ class GLContext : public GPUContext {
   void activate(void) override;
   void deactivate(void) override;
 
+  static inline GLStateManager *state_manager_active_get()
+  {
+    GLContext *ctx = static_cast<GLContext *>(GPU_context_active_get());
+    return static_cast<GLStateManager *>(ctx->state_manager);
+  };
+
   /* TODO(fclem) these needs to become private. */
  public:
   void orphans_add(Vector<GLuint> &orphan_list, std::mutex &list_mutex, GLuint id);