OffscreenSubpass.h

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#pragma once

#include "Subpass.h"

namespace Fling
{
    class CommandBuffer;
    class LogicalDevice;
    class FrameBuffer;  
    class MeshRenderer;
    class Swapchain;
    class FirstPersonCamera;

    struct alignas(16) OffscreenUBO
    {
        glm::mat4 Projection;
        glm::mat4 Model;
        glm::mat4 View;
        glm::vec3 ObjPos;
    };

    // Uses the MRT shaders (mulitple render targets)
    class OffscreenSubpass : public Subpass
    {
    public:
        OffscreenSubpass(
            const LogicalDevice* t_Dev,
            const Swapchain* t_Swap,
            entt::registry& t_reg,
            FirstPersonCamera* t_Cam,
            std::shared_ptr<Fling::Shader> t_Vert,
            std::shared_ptr<Fling::Shader> t_Frag
        );

        virtual ~OffscreenSubpass();

        FrameBuffer* GetOffscreenFrameBuffer() const { return m_OffscreenFrameBuf; }

        void Draw(CommandBuffer& t_CmdBuf, VkFramebuffer t_PresentFrameBuf, UINT32 t_ActiveSwapImage, entt::registry& t_reg, float DeltaTime) override;

        void CreateDescriptorSets(VkDescriptorPool t_Pool, entt::registry& t_reg) override;

        void PrepareAttachments() override;

        void CreateGraphicsPipeline() override;

        void GatherPresentDependencies(
            std::vector<CommandBuffer*>& t_CmdBuffs,
            std::vector<VkSemaphore>& t_Deps,
            UINT32 t_ActiveFrameIndex,
            UINT32 t_CurrentFrameInFlight) override;

        void CleanUp(entt::registry& t_reg) override;

    private:

        void OnMeshRendererAdded(entt::entity t_Ent, entt::registry& t_Reg, MeshRenderer& t_MeshRend);

        void CreateMeshDescriptorSet(MeshRenderer& t_MeshRend, VkDescriptorPool t_Pool, FrameBuffer& t_FrameBuf);

        void BuildOffscreenCommandBuffer(entt::registry& t_reg, UINT32 t_ActiveFrameInFlight);

        // We need an offscreen semaphore for each possible frame in flight because the swap chain
        // presentation will depend on this command buffer being complete
        std::vector<VkSemaphore> m_OffscreenSemaphores;

        VkCommandPool m_CommandPool = VK_NULL_HANDLE;

        // Offscreen command buffers for populating the GBuffer
        std::vector<CommandBuffer*> m_OffscreenCmdBufs;

        FrameBuffer* m_OffscreenFrameBuf = nullptr;

        const FirstPersonCamera* m_Camera;

        VkDescriptorPool m_DescriptorPool = VK_NULL_HANDLE;
    };
}   // namespace Fling