class IStateBuffer;

The IStateBuffer interface defines a state buffer for use in a shader program. State buffers are a block of memory that can contain multiple state values, and can be mapped into multiple shaders at once. Although like global state values they are still read-only within a shader, it is possible to load more data into a state buffer that can be set in individual global state values. The ability to map them into multiple shaders also simplifies state management, as updates to state values in a state buffer only need to be performed once in order to provide new values to all shaders where they are used.

A very valuable use of state buffers is to store scene-wide common state values, such as the view and project matrices, the screen size in pixels, scene light positions and characteristics, and so on. By defining these state values in state buffers, the application can manage a single set of state values for these settings, and apply changes to these settings to all shaders in the program at once.

A useful property of state buffers is the ability to define "pages", which are separate sets of values within the one state buffer. Each page of the state buffer shares the same layout, or in other words has the same number and type of fields in it, but each page can hold a distinct set of values for those fields. Separate pages of the state buffer can be bound at different times, even to the point of providing a unique state buffer page per renderable object if desired. Through the use of the SetPageSettings method, it is also possible to allow the number of pages in the state buffer to be modified after creation, by calling the ResizePageCount method. This is well suited to using paged state buffers to provide large sets of per-object state. The application can allocate page numbers to each renderable object, and update each page with the correct state values per object prior to drawing, with the number of pages growing or shrinking as required as the content of the scene changes.

Initialization methods

	Name	Description
	Delete	Schedules the object for deletion. After calling this method, the object will be destroyed after the current frame completes drawing.
	AllocateMemory	Attempts to allocate memory for the buffer using the defined buffer layout and page settings

Usage methods

	Name	Description
	SetPerformanceHints	Provides hints to the renderer about how this object will be used. Correct use of hints is important to optimize performance.

Format methods

	Name	Description
	SetManualPageSize	Defines a manual page size for the buffer. This can be used instead of calling BindBufferLayout.
	BindBufferLayout	Binds the specified state buffer layout to the state buffer. A layout must be defined using this method or SetManualPageSize before calling AllocateMemory, and cannot be changed afterwards.
	SetPageSettings	Sets the page settings to use for the state buffer
	ResizePageCount	If the state buffer allows resizing, this allows the number of pages in the buffer to be changed.

State value methods

	Name	Description
	GetStateValueId	Retrieves an ID for the given state value
	SetStateValue	Updates the target state variable in the first page of the buffer with the supplied value
	SetStateValueForPage	Updates the target state variable in the specified page of the buffer with the supplied value
	SetRawPageData	Writes the specified raw byte data directly into the state buffer at the specified location

• IStateBufferLayout
• IShaderProgram