基类-帧缓冲纹理数据

并提供通过id来到纹理数据的方法

    enum class FramebufferTextureFormat
    {
        None = 0,
        // Color
        RGBA8,
        // Depth/stencil
        DEPTH24STENCIL8,
        // Defaults
        Depth = DEPTH24STENCIL8
    };
    struct FramebufferTextureSpecification
    {
        FramebufferTextureSpecification() = default;
        FramebufferTextureSpecification(FramebufferTextureFormat format)
            : TextureFormat(format) {}
        FramebufferTextureFormat TextureFormat = FramebufferTextureFormat::None;
        // TODO: filtering/wrap
    };
    struct FramebufferAttachmentSpecification
    {
        FramebufferAttachmentSpecification() = default;
        FramebufferAttachmentSpecification(std::initializer_list<FramebufferTextureSpecification> attachments)
            : Attachments(attachments) {}
        std::vector<FramebufferTextureSpecification> Attachments;
    };

    struct FramebufferSpecification
    {
        uint32_t Width = 0, Height = 0;
        FramebufferAttachmentSpecification Attachments;
        uint32_t Samples = 1;
        bool SwapChainTarget = false;
    };


        virtual uint32_t GetColorAttachmentRendererID(uint32_t index = 0) const = 0;

Opengl的帧缓冲

    virtual uint32_t GetColorAttachmentRendererID(uint32_t index = 0) const override { CORE_DEBUG_ASSERT(index < m_ColorAttachments.size()); return m_ColorAttachments[index]; }

private:
        std::vector<FramebufferTextureSpecification> m_ColorAttachmentSpecifications;
        FramebufferTextureSpecification m_DepthAttachmentSpecification = FramebufferTextureFormat::None;
        std::vector<uint32_t> m_ColorAttachments;
        uint32_t m_DepthAttachment = 0;

工具

纹理目标：多样本纹理（一般用于MSAA）\2D纹理 创建纹理： 绑定纹理： 附加颜色纹理： 附加深度纹理： 是否为深度格式

static const uint32_t s_MaxFramebufferSize = 8192;
    namespace Utils {
        static GLenum TextureTarget(bool multisampled)
        {
            return multisampled ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D;
        }
        static void CreateTextures(bool multisampled, uint32_t* outID, uint32_t count)
        {
            glCreateTextures(TextureTarget(multisampled), count, outID);
        }
        static void BindTexture(bool multisampled, uint32_t id)
        {
            glBindTexture(TextureTarget(multisampled), id);
        }
        static void AttachColorTexture(uint32_t id, int samples, GLenum format, uint32_t width, uint32_t height, int index)
        {
            bool multisampled = samples > 1;
            if (multisampled)
            {
                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, format, width, height, GL_FALSE);
            }
            else
            {
                glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            }
            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + index, TextureTarget(multisampled), id, 0);
        }
        static void AttachDepthTexture(uint32_t id, int samples, GLenum format, GLenum attachmentType, uint32_t width, uint32_t height)
        {
            bool multisampled = samples > 1;
            if (multisampled)
            {
                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, format, width, height, GL_FALSE);
            }
            else
            {
                glTexStorage2D(GL_TEXTURE_2D, 1, format, width, height);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            }
            glFramebufferTexture2D(GL_FRAMEBUFFER, attachmentType, TextureTarget(multisampled), id, 0);
        }
        static bool IsDepthFormat(FramebufferTextureFormat format)
        {
            switch (format)
            {
            case FramebufferTextureFormat::DEPTH24STENCIL8:  return true;
            }
            return false;
        }
    }

构造帧缓冲

不是深度纹理，加入到颜色规格数组中 是的话，规格就设置成当前深度纹理

    OpenGLFramebuffer::OpenGLFramebuffer(const FramebufferSpecification& spec)
        : m_Specification(spec)
    {
        for (auto spec : m_Specification.Attachments.Attachments)
        {
            if (!Utils::IsDepthFormat(spec.TextureFormat))
                m_ColorAttachmentSpecifications.emplace_back(spec);
            else
                m_DepthAttachmentSpecification = spec;
        }
        Invalidate();
    }

删除

一次性删除所有颜色渲染目标

glDeleteTextures(m_ColorAttachments.size(), m_ColorAttachments.data());

确保颜色附件不超过四个

        //多颜色纹理
        if (m_ColorAttachments.size() > 1)
        {
            CORE_DEBUG_ASSERT(m_ColorAttachments.size() <= 4);
            GLenum buffers[4] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3 };
            glDrawBuffers(m_ColorAttachments.size(), buffers);
        }
        else if (m_ColorAttachments.empty())
        {
            // Only depth-pass
            glDrawBuffer(GL_NONE);
        }