magnum/src/Magnum/Vk/Instance.h

#ifndef Magnum_Vk_Instance_h
#define Magnum_Vk_Instance_h
/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021 Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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*/

/** @file
 * @brief Class @ref Magnum::Vk::Instance
 * @m_since_latest
 */

#include <Corrade/Containers/Pointer.h>

#include "Magnum/Tags.h"
#include "Magnum/Math/BoolVector.h"
#include "Magnum/Vk/TypeTraits.h"
#include "Magnum/Vk/Vk.h"
#include "Magnum/Vk/Vulkan.h"
#include "Magnum/Vk/visibility.h"

namespace Magnum { namespace Vk {

namespace Implementation {
    enum: std::size_t { InstanceExtensionCount = 16 };

    struct InstanceState;
}

/**
@brief Instance
@m_since_latest

Wraps a @type_vk_keyword{Instance} and stores instance-specific Vulkan function
pointers. An instance provides device enumeration and management of Vulkan
layers that enable additional functionality such as command validation or
tracing / debugging.

@section Vk-Instance-creation Instance creation

While an @ref Instance can be default-constructed without much fuss, it's
recommended to pass a @ref InstanceCreateInfo with at least the `argc` / `argv`
pair, which allows you to use various `--magnum-*`
@ref Vk-Instance-command-line "command-line options":

@snippet MagnumVk.cpp Instance-creation-minimal

In addition to command-line arguments, setting application info isn't strictly
required either, but may be beneficial for the driver:

@snippet MagnumVk.cpp Instance-creation

<b></b>

@m_class{m-note m-success}

@par
    The above code uses the @link Containers::Literals::operator""_s() @endlink
    literal, which lets the library know that given string is global and
    null-terminated. Such strings then don't need to be copied internally to
    keep them in scope until they're consumed by Vulkan APIs. The same is
    recommended to do for extension and layer names where possible.

The above won't enable any additional layers or extensions except for what the
engine itself needs or what's supplied on the command line. Use
@ref InstanceCreateInfo::addEnabledLayers() and
@ref InstanceCreateInfo::addEnabledExtensions() to enable them, you can use
both string names as well as predefined *instance* extensions from the
@ref Extensions namespace. Later on, presence of predefined extensions can be
checked with @ref isExtensionEnabled().

@snippet MagnumVk.cpp Instance-creation-layers-extensions

However, with the above approach, if any layer or extension isn't available,
the instance creation will abort. The recommended workflow is thus first
checking layer and extension availability using @ref enumerateLayerProperties()
and @ref enumerateInstanceExtensionProperties():

@snippet MagnumVk.cpp Instance-creation-check-supported

Next step after creating a Vulkan instance is picking and creating a
@ref Device.

@see @ref vulkan-wrapping-optimizing-properties

@section Vk-Instance-command-line Command-line options

The @ref Instance is configurable through command-line options that are passed
through the @ref InstanceCreateInfo `argc` / `argv` parameters. If those are
not passed, only the environment variables are used. A subset of these options
is reused by a subsequently created @ref Device as well.

@code{.sh}
<application> [--magnum-help]
    [--magnum-disable-workarounds LIST]
    [--magnum-disable-layers LIST]
    [--magnum-disable-extensions LIST]
    [--magnum-enable-layers LIST]
    [--magnum-enable-instance-extensions LIST]
    [--magnum-enable-extensions LIST]
    [--magnum-vulkan-version X.Y]
    [--magnum-log default|quiet|verbose]
    [--magnum-device ID|integrated|discrete|virtual|cpu] ...
@endcode

Arguments:

-   `...` --- main application arguments (see `-h` or `--help` for details)
-   `--magnum-help` --- display this help message and exit
-   `--magnum-disable-workarounds LIST` --- Vulkan driver workarounds to
    disable (see @ref vulkan-workarounds for detailed info) (environment:
    `MAGNUM_DISABLE_WORKAROUNDS`)
-   `--magnum-disable-layers LIST` --- Vulkan layers to disable, meaning
    @ref InstanceCreateInfo::addEnabledLayers() will skip them (environment:
    `MAGNUM_DISABLE_LAYERS`)
-   `--magnum-disable-extensions LIST` --- Vulkan instance or device extensions
    to disable, meaning @ref InstanceCreateInfo::addEnabledExtensions() and
    @ref DeviceCreateInfo::addEnabledExtensions() will skip them (environment:
    `MAGNUM_DISABLE_EXTENSIONS`)
-   `--magnum-enable-layers LIST` --- Vulkan layers to enable in addition to
    @ref InstanceCreateInfo defaults and what the application requests
    (environment: `MAGNUM_ENABLE_LAYERS`)
-   `--magnum-enable-instance-extensions LIST` --- Vulkan instance extensions
    to enable in addition to @ref InstanceCreateInfo defaults and what the
    application requests (environment: `MAGNUM_ENABLE_INSTANCE_EXTENSIONS`)
-   `--magnum-enable-extensions LIST` --- Vulkan device extensions to enable in
    addition to @ref DeviceCreateInfo defaults and what the application
    requests (environment: `MAGNUM_ENABLE_EXTENSIONS`)
-   `--magnum-vulkan-version X.Y` --- force @ref Instance and @ref Device
    Vulkan version instead of using what the instance / device reports as
    supported, affecting what entrypoints and extensions get used (environment:
    `MAGNUM_VULKAN_VERSION`)
-   `--magnum-log default|quiet|verbose` --- console logging (environment:
    `MAGNUM_LOG`) (default: `default`)
-   `--magnum-device ID|integrated|discrete|virtual|cpu` --- device ID or kind
    to pick in @ref pickDevice(); if a device is selected through
    @ref enumerateDevices() or any other way, this option has no effect
    (environment: `MAGNUM_DEVICE`)

@section Vk-Instance-raw Interaction with raw Vulkan code

In addition to the common properties explained in @ref vulkan-wrapping-raw, the
@ref Instance contains instance-level Vulkan function pointers, accessible
through @ref operator->():

@snippet MagnumVk.cpp Instance-function-pointers

These functions are by default not accessible globally (and neither there is a
global "current instance"), which is done in order to avoid multiple
independent instances affecting each other. Sometimes it is however desirable
to have global function pointers --- for example when a 3rd party code needs to
operate on the same instance, or when writing quick prototype code --- and then
it's possible to populate those using @ref populateGlobalFunctionPointers().
Compared to the above, the same custom code would then look like this:

@snippet MagnumVk.cpp Instance-global-function-pointers

Similarly you can use @ref Device::populateGlobalFunctionPointers() to populate
device-level global function pointers.

@section Vk-Instance-disabled-move Disabled move and delayed instance creation

Similarly to @ref Device, for safety reasons as all instance-dependent objects
internally have to keep a pointer to the originating @ref Instance to access
Vulkan function pointers, the @ref Instance class is not movable. This leads to
a difference compared to other Vulkan object wrappers, where you can use the
@ref NoCreate tag to construct an empty instance (for example as a class
member) and do a delayed creation by moving a new instance over the empty one.
Here you have to use the @ref create() function instead:

@snippet MagnumVk.cpp Instance-delayed-creation

Similar case is with @ref wrap() --- instead of being @cpp static @ce, you have
to call it on a @ref Instance(NoCreateT) "NoCreate"'d instance.
*/
class MAGNUM_VK_EXPORT Instance {
    public:
        /**
         * @brief Wrap existing Vulkan handle
         * @param handle        The @type_vk{Instance} handle
         * @param version       Vulkan version that's assumed to be used on the
         *      instance
         * @param enabledExtensions Extensions that are assumed to be enabled
         *      on the instance
         * @param flags         Handle flags
         *
         * <b></b>
         *
         * @m_class{m-note m-warning}
         *
         * @par
         *      Unlike with other Vulkan object wrappers, this isn't a
         *      @cpp static @ce function returning a new @ref Instance, instead
         *      it's expected to be called on a @ref NoCreate "NoCreate"'d
         *      instance. See @ref Vk-Instance-disabled-move for more
         *      information.
         *
         * The @p handle is expected to be of an existing Vulkan instance. The
         * @p version and @p enabledExtensions parameters populate internal
         * info about supported version and extensions and will be reflected in
         * @ref isVersionSupported() and @ref isExtensionEnabled(), among other
         * things. If @p enabledExtensions empty, the instance will behave as
         * if no extensions were enabled.
         *
         * @m_class{m-note m-danger}
         *
         * @par
         *      Due to the extension and layer list being outside of library
         *      control here, driver bug workarounds are not detected and
         *      enabled when using this function. Depending on bug severity,
         *      that may lead to crashes and unexpected behavior that wouldn't
         *      otherwise happen with an @ref Instance created the usual way.
         *
         * Note that this function retrieves all instance-specific Vulkan
         * function pointers, which is a relatively costly operation. It's thus
         * not recommended to call this function repeatedly for creating
         * short-lived instances, even though it's technically correct.
         *
         * Unlike an instance created using a constructor, the Vulkan instance
         * is by default not deleted on destruction, use @p flags for different
         * behavior.
         * @see @ref release()
         */
        void wrap(VkInstance handle, Version version, Containers::ArrayView<const Containers::StringView> enabledExtensions, HandleFlags flags = {});

        /** @overload */
        void wrap(VkInstance handle, Version version, std::initializer_list<Containers::StringView> enabledExtensions, HandleFlags flags = {});

        /**
         * @brief Constructor
         *
         * Equivalent to calling @ref Instance(NoCreateT) followed by
         * @ref create(const InstanceCreateInfo&).
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        explicit Instance(const InstanceCreateInfo& info = InstanceCreateInfo{});
        #else
        /* To avoid dependency on InstanceCreateInfo.h */
        explicit Instance(const InstanceCreateInfo& info);
        explicit Instance();
        #endif

        /**
         * @brief Construct without creating the instance
         *
         * The constructed instance is equivalent to moved-from state. Useful
         * in cases where you will overwrite the instance later anyway. Move
         * another object over it to make it useful.
         */
        explicit Instance(NoCreateT);

        /** @brief Copying is not allowed */
        Instance(const Instance&) = delete;

        /**
         * @brief Moving is not allowed
         *
         * See @ref Vk-Instance-disabled-move for more information.
         */
        Instance(Instance&&) = delete;

        /**
         * @brief Destructor
         *
         * Destroys associated @type_vk{Instance} handle, unless the instance
         * was created using @ref wrap() without @ref HandleFlag::DestroyOnDestruction
         * specified.
         * @see @fn_vk_keyword{DestroyInstance}, @ref release()
         */
        ~Instance();

        /** @brief Copying is not allowed */
        Instance& operator=(const Instance&) = delete;

        /**
         * @brief Moving is not allowed
         *
         * See @ref Vk-Instance-disabled-move for more information.
         */
        Instance& operator=(Instance&&) = delete;

        /** @brief Underlying @type_vk{Instance} handle */
        VkInstance handle() { return _handle; }
        /** @overload */
        operator VkInstance() { return _handle; }

        /** @brief Handle flags */
        HandleFlags handleFlags() const { return _flags; }

        /**
         * @brief Create an instance
         * @param info      Instance creation info
         *
         * Meant to be called on a @ref Instance(NoCreateT) "NoCreate"'d
         * instance. After creating the instance, populates instance-level
         * function pointers and runtime information about enabled extensions
         * based on @p info.
         *
         * If instance creation fails, a message is printed to error output and
         * the application exits --- if you need a different behavior, use
         * @ref tryCreate() instead.
         * @see @ref Instance(const InstanceCreateInfo&),
         *      @see @fn_vk_keyword{CreateInstance}
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        void create(const InstanceCreateInfo& info = InstanceCreateInfo{});
        #else
        /* To avoid dependency on InstanceCreateInfo.h */
        void create(const InstanceCreateInfo& info);
        void create();
        #endif

        /**
         * @brief Try to create an instance
         *
         * Unlike @ref create(), instead of exiting on error, prints a message
         * to error output and returns a corresponding result value. On success
         * returns @ref Result::Success.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        Result tryCreate(const InstanceCreateInfo& info = InstanceCreateInfo{});
        #else
        /* To avoid dependency on InstanceCreateInfo.h */
        Result tryCreate(const InstanceCreateInfo& info);
        Result tryCreate();
        #endif

        /**
         * @brief Version supported by the instance
         *
         * Unless overriden using `--magnum-vulkan-version` on the
         * @ref Vk-Device-command-line "command line", corresponds to
         * @ref enumerateInstanceVersion().
         */
        Version version() const { return _version; }

        /**
         * @brief Whether given version is supported on the instance
         *
         * Compares @p version against @ref version().
         */
        bool isVersionSupported(Version version) const {
            return _version >= version;
        }

        /**
         * @brief Whether given extension is enabled
         *
         * Accepts instance extensions from the @ref Extensions namespace,
         * listed also in the @ref vulkan-support "Vulkan support tables".
         * Search complexity is @f$ \mathcal{O}(1) @f$. Example usage:
         *
         * @snippet MagnumVk.cpp Instance-isExtensionEnabled
         *
         * Note that this returns @cpp true @ce only if given extension is
         * supported by the driver *and* it was enabled via
         * @ref InstanceCreateInfo::addEnabledExtensions(). For querying
         * extension support before creating an instance use
         * @ref InstanceExtensionProperties::isSupported().
         */
        template<class E> bool isExtensionEnabled() const {
            static_assert(Implementation::IsInstanceExtension<E>::value, "expected a Vulkan instance extension");
            return _extensionStatus[E::InstanceIndex];
        }

        /** @overload */
        bool isExtensionEnabled(const InstanceExtension& extension) const;

        /**
         * @brief Instance-specific Vulkan function pointers
         *
         * Function pointers are implicitly stored per-instance, use
         * @ref populateGlobalFunctionPointers() to populate the global `vk*`
         * functions.
         */
        const FlextVkInstance& operator*() const { return _functionPointers; }
        /** @overload */
        const FlextVkInstance* operator->() const { return &_functionPointers; }

        /**
         * @brief Release the underlying Vulkan instance
         *
         * Releases ownership of the Vulkan instance and returns its handle so
         * @fn_vk{DestroyInstance} is not called on destruction. The internal
         * state is then equivalent to moved-from state.
         * @see @ref wrap()
         */
        VkInstance release();

        /**
         * @brief Populate global instance-level function pointers to be used with third-party code
         *
         * Populates instance-level global function pointers so third-party
         * code is able to call global instance-level `vk*` functions. See
         * @ref Vk-Instance-raw for more information.
         *
         * @attention This operation is changing global state. You need to
         *      ensure that this function is not called simultaneously from
         *      multiple threads and code using those function points is
         *      calling them with the same instance as the one returned by
         *      @ref handle().
         */
        void populateGlobalFunctionPointers();

    #ifdef DOXYGEN_GENERATING_OUTPUT
    private:
    #endif
        Implementation::InstanceState& state() { return *_state; }

    private:
        template<class T> MAGNUM_VK_LOCAL void initializeExtensions(Containers::ArrayView<const T> enabledExtensions);
        MAGNUM_VK_LOCAL void initialize(Version version, Int argc, const char** argv);

        VkInstance _handle;
        HandleFlags _flags;
        Version _version;
        Math::BoolVector<Implementation::InstanceExtensionCount> _extensionStatus;
        Containers::Pointer<Implementation::InstanceState> _state;

        /* This member is bigger than you might think */
        FlextVkInstance _functionPointers;
};

}}

#endif