Install Now
sampler_t - A type used to control how elements of an image object are read by read_image{f|i|ui}.
Contents
Copyright
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and/or
associated documentation files (the "Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Materials, and to permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included in all copies or
substantial portions of the Materials.
Description
The image read functions take a sampler argument. The sampler can be passed as an argument to the kernel
using clSetKernelArg(3clc), or can be declared in the outermost scope of kernel functions, or it can be a
constant variable of type sampler_t declared in the program source.
Sampler variables in a program are declared to be of type sampler_t. A variable of sampler_t type
declared in the program source must be initialized with a 32-bit unsigned integer constant, which is
interpreted as a bit-field specifiying the following properties:
• Addressing Mode
• Filter Mode
• Normalized Coordinates
These properties control how elements of an image object are read by imageFunctions(3clc).
Samplers can also be declared as global constants in the program source using the syntax shown at the top
of this page.
The sampler fields are described in the table below:
┌────────────────────────────┬──────────────────────────────────────────┐
│ SamplerState │ Description │
├────────────────────────────┼──────────────────────────────────────────┤
│ │ │
│ <normalizedcoords> │ Specifies whether the x, y and │
│ │ z coordinates are passed in as │
│ │ normalized or unnormalized │
│ │ values. This must be a literal │
│ │ value and can be one of the │
│ │ following predefined enums: │
│ │ │
│ │ │
│ │ │
│ │ CLK_NORMALIZED_COORDS_TRUE or │
│ │ CLK_NORMALIZED_COORDS_FALSE. │
│ │ │
│ │ │
│ │ │
│ │ The samplers used with an │
│ │ image in multiple calls to │
│ │ imageFunctions(3clc){f|i|ui} │
│ │ declared in a kernel must use │
│ │ the same value for <normalized │
│ │ coords>. │
├────────────────────────────┼──────────────────────────────────────────┤
│ │ │
│ <addressingmode> │ Specifies the image │
│ │ addressing-mode i.e. how │
│ │ out-of-range image coordinates │
│ │ are handled. This must be a │
│ │ literal value and can be one of │
│ │ the following predefined enums: │
│ │ │
│ │ │
│ │ │
│ │ CLK_ADDRESS_MIRRORED_REPEAT - │
│ │ Flip the image coordinate at │
│ │ every integer junction. This │
│ │ addressing mode can only be used │
│ │ with normalized coordinates. If │
│ │ normalized coordinates are not │
│ │ used, this addressing mode may │
│ │ generate image coordinates that │
│ │ are undefined. │
│ │ │
│ │ │
│ │ │
│ │ CLK_ADDRESS_REPEAT - out-of-range │
│ │ image coordinates are wrapped to │
│ │ the valid range. This address │
│ │ mode can only be used with │
│ │ normalized coordinates. If │
│ │ normalized coordinates are not │
│ │ used, this addressing mode may │
│ │ generate image coordinates that │
│ │ are undefined. │
│ │ │
│ │ │
│ │ │
│ │ CLK_ADDRESS_CLAMP_TO_EDGE - │
│ │ out-of-range image coordinates │
│ │ are clamped to the extent. │
│ │ │
│ │ │
│ │ │
│ │ CLK_ADDRESS_CLAMP - out-of-range │
│ │ image coordinates will return a │
│ │ border color. This is similar to │
│ │ the GL_ADDRESS_CLAMP_TO_BORDER │
│ │ addressing mode. │
│ │ │
│ │ │
│ │ │
│ │ CLK_ADDRESS_NONE - for this │
│ │ addressing mode the programmer │
│ │ guarantees that the image │
│ │ coordinates used to sample │
│ │ elements of the image refer to a │
│ │ location inside the image; │
│ │ otherwise the results are │
│ │ undefined. │
│ │ │
│ │ │
│ │ │
│ │ For 1D and 2D image arrays, the │
│ │ addressing mode applies only to │
│ │ the x and (x,y) coordinates. The │
│ │ addressing mode for the │
│ │ coordinate which specifies the │
│ │ array index is always │
│ │ CLK_ADDRESS_CLAMP_TO_EDGE │
├────────────────────────────┼──────────────────────────────────────────┤
│ │ │
│ <filtermode> │ Specifies the filtering mode to │
│ │ use. This must be a literal value │
│ │ and can be one of the following │
│ │ predefined enums: │
│ │ CLK_FILTER_NEAREST or │
│ │ CLK_FILTER_LINEAR. Refer to │
│ │ section 8.2 for a description of │
│ │ these filter modes. │
└────────────────────────────┴──────────────────────────────────────────┘
Name
sampler_t - A type used to control how elements of an image object are read by read_image{f|i|ui}.
const sampler_t <sampler name> = <value> constant
sampler_t <sampler name> = <value> __constant sampler_t
<sampler name> = <value>
Notes
1. OpenCL Specification
page 292, section 6.12.14.1 - Samplers
The Khronos Group 11/18/2024 SAMPLER_T(3clc)
See Also
otherDataTypes(3clc), imageFunctions(3clc), classDiagram(3clc)
Specification
OpenCLSpecification[1]
PNG Icons
Emojis