axmol/core/renderer/backend/metal/DeviceMTL.h

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 Copyright (c) 2018-2019 Xiamen Yaji Software Co., Ltd.

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#pragma once

#include "../Device.h"
#import <Metal/Metal.h>
#import <QuartzCore/CAMetalLayer.h>

NS_AX_BACKEND_BEGIN

/**
 * @addtogroup _metal
 * @{
 */

/**
 * Create resources from MTLDevice.
 */
class DeviceMTL : public Device
{
public:
    /* The max vertex attribs, it's not how many device supports which may be lower. */
    static constexpr uint32_t MAX_VERTEX_ATTRIBS = 16;

    /* The vertex data buffers binding index start, the glslcc(SPIRV-Cross) compiled MSL uniform buffer index=0 */
    static constexpr uint32_t VBO_BINDING_INDEX_START = 0;

    /* The default attribs binding index */
    static constexpr uint32_t DEFAULT_ATTRIBS_BINDING_INDEX = VBO_BINDING_INDEX_START + MAX_VERTEX_ATTRIBS;

    /**
     * Set CAMetalLayer.
     * @param metalLayer A CAMetalLayer object.
     */
    static void setCAMetalLayer(CAMetalLayer* metalLayer);

    /**
     * Invoke by engine internally at the beginning of rendering a new frame.
     */
    static void updateDrawable();

    /**
     * Get a CAMetalLayer.
     * @return A CAMetalLayer object.
     */
    static CAMetalLayer* getCAMetalLayer() { return DeviceMTL::_metalLayer; }

    /**
     * Get available Drawable.
     * @return an available drawable.
     */
    static id<CAMetalDrawable> getCurrentDrawable();

    /**
     * Reset current drawable to nil.
     */
    static void resetCurrentDrawable();

    /// @name Constructor, Destructor and Initializers
    DeviceMTL();
    ~DeviceMTL();

    /// @name Setters & Getters
    /**
     * New a CommandBuffer object.
     * @return A CommandBuffer object.
     */
    virtual CommandBuffer* newCommandBuffer() override;

    /**
     * New a Buffer object.
     * @param size Specifies the size in bytes of the buffer object's new data store.
     * @param type Specifies the target buffer object. The symbolic constant must be BufferType::VERTEX or
     * BufferType::INDEX.
     * @param usage Specifies the expected usage pattern of the data store. The symbolic constant must be
     * BufferUsage::STATIC, BufferUsage::DYNAMIC.
     * @return A Buffer object.
     */
    virtual Buffer* newBuffer(std::size_t size, BufferType type, BufferUsage usage) override;

    /**
     * New a TextureBackend object.
     * @param descriptor Specifies texture description.
     * @return A TextureBackend object.
     */
    virtual TextureBackend* newTexture(const TextureDescriptor& descriptor) override;

    RenderTarget* newDefaultRenderTarget(TargetBufferFlags rtf) override;
    RenderTarget* newRenderTarget(TargetBufferFlags rtf,
                                  TextureBackend* colorAttachment,
                                  TextureBackend* depthAttachment,
                                  TextureBackend* stencilAttachhment) override;

    /**
     * New a DepthStencilState object.
     */
    virtual DepthStencilState* newDepthStencilState() override;

    /**
     * New a RenderPipeline object.
     * @param descriptor Specifies render pipeline description.
     * @return A RenderPipeline object.
     */
    virtual RenderPipeline* newRenderPipeline() override;

    /**
     * This property controls whether or not the drawables'
     * MTLTextures may only be used for framebuffer attachments (YES) or
     * whether they may also be used for texture sampling and pixel
     * read/write operations (NO).
     * @param frameBufferOnly A value of YES allows CAMetalLayer to allocate the MTLTexture objects in ways that are
     * optimized for display purposes that makes them unsuitable for sampling. The recommended value for most
     * applications is YES.
     */
    virtual void setFrameBufferOnly(bool frameBufferOnly) override;

    /**
     * New a Program, not auto release.
     * @param vertexShader Specifes this is a vertex shader source.
     * @param fragmentShader Specifes this is a fragment shader source.
     * @return A Program instance.
     */
    virtual Program* newProgram(std::string_view vertexShader, std::string_view fragmentShader) override;

    /**
     * Get a MTLDevice object.
     * @return A MTLDevice object.
     */
    inline id<MTLDevice> getMTLDevice() const { return _mtlDevice; }

    /**
     * Get a MTLCommandQueue object.
     * @return A MTLCommandQueue object.
     */
    inline id<MTLCommandQueue> getMTLCommandQueue() const { return _mtlCommandQueue; }

protected:
    /**
     * New a shaderModule.
     * @param stage Specifies whether is vertex shader or fragment shader.
     * @param source Specifies shader source.
     * @return A ShaderModule object.
     */
    virtual ShaderModule* newShaderModule(ShaderStage stage, std::string_view source) override;

private:
    static CAMetalLayer* _metalLayer;
    static id<CAMetalDrawable> _currentDrawable;

    id<MTLDevice> _mtlDevice             = nil;
    id<MTLCommandQueue> _mtlCommandQueue = nil;
};

// end of _metal group
/// @}
NS_AX_BACKEND_END