Vulkan: Add Initial VKFrameBuffer.

This was backported from tmp-vulkan. When disabling the fence check
in ghost it is able to start blender. It will show a black screen
so not usable for users.

source/blender/gpu/vulkan/vk_buffer.hh

@@ -12,8 +12,6 @@
 #include "vk_common.hh"
 #include "vk_context.hh"
 
-#include "vk_mem_alloc.h"
-
 namespace blender::gpu {
 
 /**

source/blender/gpu/vulkan/vk_common.hh

@@ -13,6 +13,8 @@
 #  include <vulkan/vulkan.h>
 #endif
 
+#include "vk_mem_alloc.h"
+
 #include "gpu_texture_private.hh"
 
 namespace blender::gpu {

source/blender/gpu/vulkan/vk_context.cc

@@ -8,6 +8,7 @@
 #include "vk_context.hh"
 
 #include "vk_backend.hh"
+#include "vk_framebuffer.hh"
 #include "vk_memory.hh"
 #include "vk_state_manager.hh"
 
@@ -48,6 +49,9 @@ VKContext::VKContext(void *ghost_window, void *ghost_context)
   state_manager = new VKStateManager();
 
   VKBackend::capabilities_init(*this);
+
+  /* For offscreen contexts. Default framebuffer is empty. */
+  active_fb = back_left = new VKFrameBuffer("back_left");
 }
 
 VKContext::~VKContext()
@@ -65,6 +69,22 @@ void VKContext::init_physical_device_limits()
 
 void VKContext::activate()
 {
+  if (ghost_window_) {
+    VkImage image; /* TODO will be used for reading later... */
+    VkFramebuffer framebuffer;
+    VkRenderPass render_pass;
+    VkExtent2D extent;
+    uint32_t fb_id;
+
+    GHOST_GetVulkanBackbuffer(
+        (GHOST_WindowHandle)ghost_window_, &image, &framebuffer, &render_pass, &extent, &fb_id);
+
+    /* Recreate the gpu::VKFrameBuffer wrapper after every swap. */
+    delete back_left;
+
+    back_left = new VKFrameBuffer("back_left", framebuffer, render_pass, extent);
+    active_fb = back_left;
+  }
 }
 
 void VKContext::deactivate()

source/blender/gpu/vulkan/vk_context.hh

@@ -12,8 +12,6 @@
 #include "vk_command_buffer.hh"
 #include "vk_descriptor_pools.hh"
 
-#include "vk_mem_alloc.h"
-
 namespace blender::gpu {
 
 class VKContext : public Context {

source/blender/gpu/vulkan/vk_framebuffer.cc

@@ -9,6 +9,43 @@
 
 namespace blender::gpu {
 
+/* -------------------------------------------------------------------- */
+/** \name Creation & Deletion
+ * \{ */
+
+VKFrameBuffer::VKFrameBuffer(const char *name) : FrameBuffer(name)
+{
+  immutable_ = false;
+}
+
+VKFrameBuffer::VKFrameBuffer(const char *name,
+                             VkFramebuffer vk_framebuffer,
+                             VkRenderPass /*vk_render_pass*/,
+                             VkExtent2D vk_extent)
+    : FrameBuffer(name)
+{
+  immutable_ = true;
+  /* Never update an internal frame-buffer. */
+  dirty_attachments_ = false;
+  width_ = vk_extent.width;
+  height_ = vk_extent.height;
+  vk_framebuffer_ = vk_framebuffer;
+
+  viewport_[0] = scissor_[0] = 0;
+  viewport_[1] = scissor_[1] = 0;
+  viewport_[2] = scissor_[2] = width_;
+  viewport_[3] = scissor_[3] = height_;
+}
+
+VKFrameBuffer::~VKFrameBuffer()
+{
+  if (!immutable_ && vk_framebuffer_ != VK_NULL_HANDLE) {
+    vkDestroyFramebuffer(vk_device_, vk_framebuffer_, NULL);
+  }
+}
+
+/** \} */
+
 void VKFrameBuffer::bind(bool /*enabled_srgb*/)
 {
 }

source/blender/gpu/vulkan/vk_framebuffer.hh

@@ -9,13 +9,39 @@
 
 #include "gpu_framebuffer_private.hh"
 
+#include "vk_common.hh"
+
 namespace blender::gpu {
 
 class VKFrameBuffer : public FrameBuffer {
+ private:
+  /* Vulkan object handle. */
+  VkFramebuffer vk_framebuffer_ = VK_NULL_HANDLE;
+  /* Vulkan device who created the handle. */
+  VkDevice vk_device_ = VK_NULL_HANDLE;
+  /* Base render pass used for framebuffer creation. */
+  VkRenderPass render_pass_ = VK_NULL_HANDLE;
+  /* Number of layers if the attachments are layered textures. */
+  int depth_ = 1;
+  /** Internal frame-buffers are immutable. */
+  bool immutable_;
+
  public:
-  VKFrameBuffer(const char *name) : FrameBuffer(name)
-  {
-  }
+  /**
+   * Create a conventional framebuffer to attach texture to.
+   **/
+  VKFrameBuffer(const char *name);
+
+  /**
+   * Special frame-buffer encapsulating internal window frame-buffer.
+   * This just act as a wrapper, the actual allocations are done by GHOST_ContextVK.
+   **/
+  VKFrameBuffer(const char *name,
+                VkFramebuffer vk_framebuffer,
+                VkRenderPass vk_render_pass,
+                VkExtent2D vk_extent);
+
+  ~VKFrameBuffer();
 
   void bind(bool enabled_srgb) override;
   bool check(char err_out[256]) override;

source/blender/gpu/vulkan/vk_texture.hh

@@ -10,8 +10,6 @@
 #include "gpu_texture_private.hh"
 #include "vk_context.hh"
 
-#include "vk_mem_alloc.h"
-
 namespace blender::gpu {
 
 class VKTexture : public Texture {