buffer

Tag: buffer
Parent tag: buffers
Attributes: name (string)

Child tags:

• SIZE (int) – the size in bytes
• DIM (uivec3) – the number of structs in each dimension, like a 3D array. To be used in combination with structure
• structure – the definition of the structure.
• CLEAR (enum) – {NEVER (default), BY_FRAME}. If BY_FRAME is specified the buffer will be filled with zeroes at the beginning of each frame.
• file (string) – a file name for the buffer initial contents.

This tag defines a buffer that can later be used in a material.

The buffer’s size can be specified either in bytes or using a friendlier notation based on a structure. This last approach requires the definition of a structure with the types of each field, and the definition of dimensions (x, y, and z).

In the example below, buffers hits and hits2 have the same size.

Example:

	
<buffer name="hits">
	<SIZE value=150994944 /> 
</buffer>	

<buffer name="hits2">
	<DIM x=1024 y=1024 z=9 />
	<structure>
		<field value="FLOAT" />
		<field value="INT" />
		<field value="FLOAT" />
		<field value="FLOAT" />
	</structure>	
</buffer>	

<buffer name="atomicsBuffer">
	<SIZE value=16 />
	<CLEAR value="BY_FRAME" />
</buffer>

The initial buffer contents can also be loaded from a text file. In this case the DIM and structure are required to describe the file structure. For instance consider the following buffer definition:

	
<buffer name="myBuffer">
	<DIM x=5 y=1 z=1 />
	<structure>
		<field value="FLOAT" />
		<field value="INT" />
	</structure>	
	<file name="myBufferContents.txt" />
</buffer>	

The DIM field specifies that there will be 5 items. Each item will have a float and a int according to the filed structure. An example of such a file is:

5.0 1
4.0 2
3.0 3
2.0 4
1.0 5