spark::render::PushConstantsLayout< PushConstantsRangeType > Class Template Reference

Describes the layout of the pipelines push constant ranges. More...

#include <PushConstantsLayout.h>

Inheritance diagram for spark::render::PushConstantsLayout< PushConstantsRangeType >:

Public Types
using	PushConstantsRange = PushConstantsRangeType

Public Member Functions
const PushConstantsRangeType &	range (ShaderStage stage) const override=0
	Get the push constants range associated with the shader stage provided.
virtual std::vector< const PushConstantsRangeType * >	ranges () const noexcept=0
	Get all push constants ranges .
Public Member Functions inherited from spark::render::IPushConstantsLayout
virtual unsigned int	size () const noexcept=0
	Get the size (in bytes) of the push constants backing memory.
std::vector< const IPushConstantsRange * >	ranges () const noexcept
	Get all push constants ranges .

Detailed Description

template<typename PushConstantsRangeType>
class spark::render::PushConstantsLayout< PushConstantsRangeType >

Describes the layout of the pipelines push constant ranges.

Template Parameters

PushConstantsRangeType

The type of the push constant ranges (inherits from IPushConstantsRange).

Push constants are very efficient, yet quite limited ways of passing per-draw data to shaders. They are mapped directly, so no buffer must be created or transitioned in order to use them. Conceptually a push constant is a single piece of memory that gets transferred to a command buffer directly. Each shader stage has a view into this piece of memory, described by an offset and a size. Since the memory is directly dumped in the command buffer, the backing memory can be incrementally updated and there is no need to store an array of buffers, as long as updates happen sequentially from the same thread.

However, there are certain restrictions when using push constants:

• Only one push constant layout per pipeline layout is supported.
• A push constant layout may not define a overall memory size larger than 128 bytes. This is a soft restriction that will issue a warning, however it might be supported on some hardware or for some back-ends.
• The elements and offsets of a push constant memory block must be aligned to 4 bytes.
• Accordingly, the size of a push constant layout must align to 4 bytes.
• Only one IPushConstantsRange per shader stage is permitted. Shader stages can be combined together, however in this case, no other ranges must be defined for the stages.

Push constants can be updated by calling ICommandBuffer::pushConstants() and are visible to subsequent draw calls immediately, until another update is performed or the command buffer is ended.

Member Function Documentation

range()

template<typename PushConstantsRangeType >

const PushConstantsRangeType & spark::render::PushConstantsLayout< PushConstantsRangeType >::range ( ShaderStage stage ) const

nodiscardoverridepure virtual

Get the push constants range associated with the shader stage provided.

Returns

The push constants range associated with the shader stage provided.

Exceptions

spark::base::ArgumentOutOfRangeException	if no range is mapped to the provided shader stage.
spark::base::BadArgumentException	if stage contains multiple shader stages.

Implements spark::render::IPushConstantsLayout.

Implemented in spark::render::vk::VulkanPushConstantsLayout.

ranges()

template<typename PushConstantsRangeType >

virtual std::vector< const PushConstantsRangeType * > spark::render::PushConstantsLayout< PushConstantsRangeType >::ranges ( ) const

nodiscardpure virtualnoexcept

Get all push constants ranges .

Returns

All push constants ranges .

Implemented in spark::render::vk::VulkanPushConstantsLayout.