Name
ARB_gpu_shader_int64
Name Strings
GL_ARB_gpu_shader_int64
Contact
Daniel Rakos, AMD (daniel.rakos 'at' amd.com)
Contributors
Daniel Rakos, AMD
Graham Sellers, AMD
Notice
Copyright (c) 2015 The Khronos Group Inc. Copyright terms at
http://www.khronos.org/registry/speccopyright.html
Status
Complete. Approved by the ARB on June 26, 2015.
Ratified by the Khronos Board of Promoters on August 7, 2015.
Version
Last Modified Date: 02/03/2015
Author Revision: 1
Number
ARB Extension #178
Dependencies
This extension is written against the OpenGL 4.5 (Core Profile)
Specification.
This extension is written against version 4.50 of the OpenGL Shading
Language Specification.
OpenGL 4.0 and GLSL 4.00 are required.
This extension interacts with AMD_gpu_shader_int64.
This extension interacts with NV_gpu_shader5.
This extension interacts with NV_shader_buffer_load.
This extension interacts with NV_vertex_attrib_integer_64bit.
Overview
The extension introduces the following features for all shader types:
* support for 64-bit scalar and vector integer data types, including
uniform API, uniform buffer object, transform feedback, and shader
input and output support;
* new built-in functions to pack and unpack 64-bit integer types into a
two-component 32-bit integer vector;
* new built-in functions to convert double-precision floating-point
values to or from their 64-bit integer bit encodings;
* vector relational functions supporting comparisons of vectors of
64-bit integer types; and
* common functions abs, sign, min, max, clamp, and mix supporting
arguments of 64-bit integer types.
New Procedures and Functions
void Uniform1i64ARB(int location, int64 x);
void Uniform2i64ARB(int location, int64 x, int64 y);
void Uniform3i64ARB(int location, int64 x, int64 y, int64 z);
void Uniform4i64ARB(int location, int64 x, int64 y, int64 z, int64 w);
void Uniform1i64vARB(int location, sizei count, const int64 *value);
void Uniform2i64vARB(int location, sizei count, const int64 *value);
void Uniform3i64vARB(int location, sizei count, const int64 *value);
void Uniform4i64vARB(int location, sizei count, const int64 *value);
void Uniform1ui64ARB(int location, uint64 x);
void Uniform2ui64ARB(int location, uint64 x, uint64 y);
void Uniform3ui64ARB(int location, uint64 x, uint64 y, uint64 z);
void Uniform4ui64ARB(int location, uint64 x, uint64 y, uint64 z, uint64 w);
void Uniform1ui64vARB(int location, sizei count, const uint64 *value);
void Uniform2ui64vARB(int location, sizei count, const uint64 *value);
void Uniform3ui64vARB(int location, sizei count, const uint64 *value);
void Uniform4ui64vARB(int location, sizei count, const uint64 *value);
void GetUniformi64vARB(uint program, int location, int64 *params);
void GetUniformui64vARB(uint program, int location, uint64 *params);
void GetnUniformi64vARB(uint program, int location, sizei bufSize,
int64 *params);
void GetnUniformui64vARB(uint program, int location, sizei bufSize,
uint64 *params);
void ProgramUniform1i64ARB(uint program, int location, int64 x);
void ProgramUniform2i64ARB(uint program, int location, int64 x, int64 y);
void ProgramUniform3i64ARB(uint program, int location, int64 x, int64 y,
int64 z);
void ProgramUniform4i64ARB(uint program, int location, int64 x, int64 y,
int64 z, int64 w);
void ProgramUniform1i64vARB(uint program, int location, sizei count,
const int64 *value);
void ProgramUniform2i64vARB(uint program, int location, sizei count,
const int64 *value);
void ProgramUniform3i64vARB(uint program, int location, sizei count,
const int64 *value);
void ProgramUniform4i64vARB(uint program, int location, sizei count,
const int64 *value);
void ProgramUniform1ui64ARB(uint program, int location, uint64 x);
void ProgramUniform2ui64ARB(uint program, int location, uint64 x, uint64 y);
void ProgramUniform3ui64ARB(uint program, int location, uint64 x, uint64 y,
uint64 z);
void ProgramUniform4ui64ARB(uint program, int location, uint64 x, uint64 y,
uint64 z, uint64 w);
void ProgramUniform1ui64vARB(uint program, int location, sizei count,
const uint64 *value);
void ProgramUniform2ui64vARB(uint program, int location, sizei count,
const uint64 *value);
void ProgramUniform3ui64vARB(uint program, int location, sizei count,
const uint64 *value);
void ProgramUniform4ui64vARB(uint program, int location, sizei count,
const uint64 *value);
New Tokens
Returned by the parameter of GetActiveAttrib, GetActiveUniform, and
GetTransformFeedbackVarying:
INT64_ARB 0x140E
UNSIGNED_INT64_ARB 0x140F
INT64_VEC2_ARB 0x8FE9
INT64_VEC3_ARB 0x8FEA
INT64_VEC4_ARB 0x8FEB
UNSIGNED_INT64_VEC2_ARB 0x8FF5
UNSIGNED_INT64_VEC3_ARB 0x8FF6
UNSIGNED_INT64_VEC4_ARB 0x8FF7
Additions to Chapter 7 of the OpenGL 4.5 (Core Profile) Specification
(Program Objects)
Modify Section 7.3.1, Program Interfaces
(add to Table 7.3, OpenGL Shading Language type tokens, p. 112)
+----------------------------+--------------+--------+--------+--------+
| Type Name Token | Keyword | Attrib | Xfb | Buffer |
+----------------------------+--------------+--------+--------+--------+
| INT64_ARB | int64_t | * | * | * |
| INT64_VEC2_ARB | i64vec2 | * | * | * |
| INT64_VEC3_ARB | i64vec3 | * | * | * |
| INT64_VEC4_ARB | i64vec4 | * | * | * |
| UNSIGNED_INT64_ARB | uint64_t | * | * | * |
| UNSIGNED_INT64_VEC2_ARB | u64vec2 | * | * | * |
| UNSIGNED_INT64_VEC3_ARB | u64vec3 | * | * | * |
| UNSIGNED_INT64_VEC4_ARB | u64vec4 | * | * | * |
+----------------------------+--------------+--------+--------+--------+
Modify Section 7.6, Uniform Variables
(modify second paragraph on p. 125)
Scalar, vector, and matrix uniforms with double-precision components,
and scalar and vector uniforms with 64-bit integer components will consume
no more than twice the number of components of equivalent uniforms with
single-precision components.
Modify Section 7.6.1, Loading Uniform Variables
(add to the list of commands in first paragraph on p. 132)
void Uniform{1,2,3,4}{i64,ui64}ARB(int location, T value);
void Uniform{1,2,3,4}{i64,ui64}vARB(int location, const T *value);
(insert after sixth paragraph on p. 132)
The Uniform*i64{v}ARB and Uniform*ui{v}ARB commands will load count sets
of one to four 64-bit signed or unsigned integer values into a uniform
location defined as a 64-bit signed or unsigned integer scalar or vector
types.
(add to the list of commands in first paragraph on p. 134)
void ProgramUniform{1,2,3,4}{i64,ui64}ARB(uint program, int location,
T value);
void ProgramUniform{1,2,3,4}{i64,ui64}vARB(uint program, int location,
const T *value);
Modify Section 7.6.2.1, Uniform Buffer Object Storage
(modify the first two bullets of the first paragraph on p. 136)
* Members of type bool int, uint, float, double, int64_t, and uint64_t
are respectively extracted from a buffer object by reading a single
uint, int, uint, float, double, int64_t, or uint64_t value at the
specified offset.
* Vectors with N elements with basic data types of bool, int, uint,
float, double, int64_t, or uint64_t are extracted as N values in
consecutive memory locations beginning at the specified offset, with
components stored in order with the first (X) component at the
lowest offset. The GL data type used for component extraction is
derived according to the rules for scalar members above.
Modify Section 7.13, Shader, Program, and Program Pipeline Queries
(add to the list of commands in last paragraph on p. 162)
void GetUniformi64vARB(uint program, int location, int64 *params);
void GetUniformui64vARB(uint program, int location, uint64 *params);
void GetnUniformi64vARB(uint program, int location, sizei bufSize,
int64 *params);
void GetnUniformui64vARB(uint program, int location, sizei bufSize,
uint64 *params);
Additions to Chapter 11 of the OpenGL 4.5 (Core Profile) Specification
(Programmable Vertex Processing)
Modify Section 11.1.1, Vertex Attributes
(modify third sentence of second paragraph on p. 368)
... hardware resources. For the purposes of this test, attribute variables
of the type dvec3, dvec4, dmat2x3, dmat2x3, dmat3, dmat3x4, dmat4x3,
dmat4, i64vec3, i64vec4, u64vec3, and u64vec4 may count as consuming twice
as many attributes as equivalent single-precision types. While these types
use the same number of generic attributes as their single-precision
vectors of internal storage for each three- or four-component
double-precision or 64-bit integer vector.
Modify Section 11.1.2.1, Output Variables
(modify last sentence of fourth paragraph on p. 369)
... multiple components. Each component of variables declared as double-
precision floating point scalars, vectors, or matrices, or declared as
64-bit integer scalars or vectors may be counted as consuming two
components.
(modify third bullet of the first paragraph on p. 373)
* any variable containing double-precision floating-point or 64-bit
integer components
- has an xfb_offset layout qualifier that is not a multiple of eight;
or
- is associated with a binding point with an xfb_stride layout
qualifier that is not a multiple of eight;
(modify second paragraph on p. 373)
For transform feedback purposes, each component of outputs declared as
double-precision floating-point scalars, vectors, or matrices, or 64-bit
integer scalars or vectors are considered to consume eight basic machine
units, and each component of any other type is considered to consume four
basic machine units.
Modifications to the OpenGL Shading Language Specification, Version 4.50
Including the following line in a shader can be used to control the
language features described in this extension:
#extension GL_ARB_gpu_shader_int64 :
where is as specified in section 3.3.
New preprocessor #defines are added to the OpenGL Shading Language:
#define GL_ARB_gpu_shader_int64 1
Additions to Chapter 3 of the OpenGL Shading Language Specification (Basics)
Modify Section 3.6, Keywords
(add the following to the list of reserved keywords at p. 17)
int64_t i64vec2 i64vec3 i64vec4 uint64_t u64vec2 u64vec3 u64vec4
Additions to Chapter 4 of the OpenGL Shading Language Specification
(Variables and Types)
Modify Section 4.1, Basic Types
(add to the basic "Transparent Types" table, p. 21)
+-----------+------------------------------------------------------------+
| Type | Meaning |
+-----------+------------------------------------------------------------+
| int64_t | a 64-bit signed integer |
| uint64_t | a 64-bit unsigned integer |
| i64vec2 | a two-component 64-bit signed integer vector |
| i64vec3 | a three-component 64-bit signed integer vector |
| i64vec4 | a four-component 64-bit signed integer vector |
| u64vec2 | a two-component 64-bit unsigned integer vector |
| u64vec3 | a three-component 64-bit unsigned integer vector |
| u64vec4 | a four-component 64-bit unsigned integer vector |
+-----------+------------------------------------------------------------+
Modify Section 4.1.3, Integers
(replace first paragraph of the section, p. 25)
Signed and unsigned integer variables are fully supported. In this
document, the term integer is meant to generally include both signed and
unsigned integers, including both 32-bit and 64-bit integers. Unsigned
integers of type uint, uvec2, uvec3, and uvec4 have exactly 32 bits of
precision, while unsigned integers of type uint64_t, u64vec2, u64vec3, and
u64vec4 have exactly 64 bits of precision. Signed integers of type int,
ivec2, ivec3, and ivec4 have exactly 32 bits of precision, while signed
integers of type int64_t, i64vec2, i64vec3, and i64vec4 have exactly
64 bits of precision. Addition, subtraction, and shift operations
resulting in overflow or underflow will not cause any exceptions, nor
will they saturate, rather they will "wrap" to yield the low-order bits
of the result. Divison and multiplication operations resulting in overflow
or underflow will not cause any exception but will result in an undefined
value.
(add after the first paragraph of the section, p. 25)
Variables with the types "int64_t" and "uint64_t" represent signed and
unsigned integer values, respectively, with exactly 64 bits of precision.
(modify grammar rule for "integer-suffix", p. 26)
integer-suffix: one of
u U l L ul UL
(modify first sentence of second paragraph on p. 26)
No white space is allowed between the digits of an integer constant,
including after the leading 0 or after the leading 0x or 0X of a constant,
or before the suffix u, U, l, L, ul, or UL.
(modify third sentence of second paragraph on p. 26)
When the suffix u or U is present, the literal has type uint. When the
suffix l or L is present, the literal has type int64_t. When the suffix
ul or UL is present, the literal has type uint64_t. Otherwise, the type is
int.
Modify Section 4.1.10, Implicit Conversions
(modify table of implicit conversions on p. 35)
+----------------------+-------------------------------------------------+
| Type of expression | Can be implicitly converted to |
+----------------------+-------------------------------------------------+
| int | uint, int64_t, uint64_t, float, double |
| uint | uint64_t, float, double |
| int64_t | uint64_t, double |
| uint64_t | double |
| ivec2 | uvec2, i64vec2, u64vec2, vec2, dvec2 |
| ivec3 | uvec3, i64vec3, u64vec3, vec3, dvec3 |
| ivec4 | uvec4, i64vec4, u64vec4, vec4, dvec4 |
| uvec2 | u64vec2, vec2, dvec2 |
| uvec3 | u64vec3, vec3, dvec3 |
| uvec4 | u64vec4, vec4, dvec4 |
| i64vec2 | u64vec2, dvec2 |
| i64vec3 | u64vec3, dvec3 |
| i64vec4 | u64vec4, dvec4 |
| u64vec2 | dvec2 |
| u64vec3 | dvec3 |
| u64vec4 | dvec4 |
+----------------------+-------------------------------------------------+
Modify Section 4.3.6, Output Variables
(add new bullet to the list in the second paragraph on p. 49)
* A 64-bit integer scalar or vector (int64_t, uint64_t, i64vec2, i64vec3,
i64vec4, u64vec2, u64vec3, u64vec4)
Additions to Chapter 5 of the OpenGL Shading Language Specification
(Operators and Expressions)
Modify Section 5.4.1, Conversion and Scalar Constructors
(add to the constructor propotype list on p. 95)
int(int64_t) // converts a 64-bit signed integer to a 32-bit signed integer
int(uint64_t) // converts a 64-bit unsigned integer to a 32-bit signed integer
uint(int64_t) // converts a 64-bit signed integer to a 32-bit unsigned integer
uint(uint64_t) // converts a 64-bit unsigned integer to a 32-bit unsigned integer
bool(int64_t) // converts a 64-bit signed integer to a Boolean
bool(uint64_t) // converts a 64-bit unsigned integer to a Boolean
float(int64_t) // converts a 64-bit signed integer to a float
float(uint64_t) // converts a 64-bit unsigned integer to a float
double(int64_t) // converts a 64-bit signed integer to a double
double(uint64_t) // converts a 64-bit unsigned integer to a double
int64_t(int) // converts a 32-bit signed integer to a 64-bit signed integer
int64_t(uint) // converts a 32-bit unsigned integer to a 64-bit signed integer
int64_t(bool) // converts a Boolean to a 64-bit signed integer
int64_t(float) // converts a float to a 64-bit signed integer
int64_t(double) // converts a double to a 64-bit signed integer
uint64_t(int) // converts a 32-bit signed integer to a 64-bit unsigned integer
uint64_t(uint) // converts a 32-bit unsigned integer to a 64-bit unsigned integer
uint64_t(bool) // converts a Boolean to a 64-bit unsigned integer
uint64_t(float) // converts a float to a 64-bit unsigned integer
uint64_t(double) // converts a double to a 64-bit unsigned integer
(modify second sentence of first paragraph on p. 96)
... is dropped. It is undefined to convert a negative floating-point value
to an uint or uint64_t.
(replace third paragraph on p. 96)
The constructors int(uint) and int64_t(uint64_t) preserve the bit pattern
in the argument, which will change the argument's value if its sign bit is
set. The constructor uint(int) and uint64_t(int64_t) preserve the bit
pattern in the argument, which will change its value if it is negative.
Additions to Chapter 6 of the OpenGL Shading Language Specification
(Statements and Structure)
Modify Section 6.1, Function Defintions
(replace second rule in third paragraph on p. 111)
2. A match involving a conversion from a signed integer, unsigned
integer, or floating-point type to a similar type having a larger
number of bits is better than a match involving any other implicit
conversion.
Additions to Chapter 8 of the OpenGL Shading Language Specification
(Built-in Functions)
(insert after third sentence of last paragraph on p. 138)
... genUType is used as the argument. Where the input arguments (and
corresponding output) can be int64_t, i64vec2, i64vec3, i64vec4,
genI64Type is used as the argument. Where the input arguments (and
corresponding output) can be uint64_t, u64vec2, u64vec3, u64vec4,
genU64Type is used as the argument.
Modify Section 8.3, Common Functions
(add to the table of common functions on p. 142)
+------------------------------------------------+----------------------------------------------------+
| Syntax | Desciption |
+------------------------------------------------+----------------------------------------------------+
| genI64Type abs(genI64Type x) | Returns x if x >= 0; otherwise it returns -x. |
+------------------------------------------------+----------------------------------------------------+
| genI64Type sign(genI64Type x) | Returns 1 if x > 0, 0 if x = 0, or -1 if x < 0. |
+------------------------------------------------+----------------------------------------------------+
| genI64Type min(genI64Type x, | Returns y if y < x; otherwise it returns x. |
| genI64Type y) | |
| genI64Type min(genI64Type x, | |
| int64_t y) | |
| genU64Type min(genU64Type x, | |
| genU64Type y) | |
| genU64Type min(genU64Type x, | |
| uint64_t y) | |
+------------------------------------------------+----------------------------------------------------+
| genI64Type max(genI64Type x, | Returns y if x < y; otherwise it returns x. |
| genI64Type y) | |
| genI64Type max(genI64Type x, | |
| int64_t y) | |
| genU64Type max(genU64Type x, | |
| genU64Type y) | |
| genU64Type max(genU64Type x, | |
| uint64_t y) | |
+------------------------------------------------+----------------------------------------------------+
| genI64Type clamp(genI64Type x, | Returns min(max(x, minVal), maxVal). |
| genI64Type minVal, | |
| genI64Type maxVal) | Results are undefined if minVal > maxVal. |
| genI64Type clamp(genI64Type x, | |
| int64_t minVal, | |
| int64_t maxVal) | |
| genU64Type clamp(genU64Type x, | |
| genU64Type minVal, | |
| genU64Type maxVal) | |
| genU64Type clamp(genU64Type x, | |
| uint64_t minVal, | |
| uint64_t maxVal) | |
+------------------------------------------------+----------------------------------------------------+
| genI64Type mix(genI64Type x, | Selects which vector each returned component comes |
| genI64Type y, | from. For a component of a that is false, the |
| genBType a) | corresponding component of x is returned. For a |
| genU64Type mix(genU64Type x, | component of a that is true, the corresponding |
| genU64Type y, | component of y is returned. |
| genBType a) | |
+------------------------------------------------+----------------------------------------------------+
| genI64Type doubleBitsToInt64(genDType value) | Returns a signed or unsigned 64-bit integer value |
| genU64Type doubleBitsToUint64(genDType value) | representing the encoding of a double. The double |
| | value's bit-level representation is preserved |
+------------------------------------------------+----------------------------------------------------+
| genDType int64BitsToDouble(genI64Type value) | Returns a double value corresponding to a signed |
| genDType uint64BitsToDouble(genU64Type value) | or unsigned integer encoding of a double. If a NaN |
| | is passed in, it will not signal, and the |
| | resulting value is unspecified. If an Inf is |
| | passed in, the resulting value is the |
| | corresponding Inf. |
+------------------------------------------------+----------------------------------------------------+
Rename Section 8.4, Floating-Point Pack and Unpack Functions to
8.4, Floating-Point and Integer Pack and Unpack Functions
Modify Section 8.4, Floating-Point and Integer Pack and Unpack Functions
(add to the table of pack and unpack functions on p. 147)
+-----------------------------------+------------------------------------------------------+
| Syntax | Desciption |
+-----------------------------------+------------------------------------------------------+
| int64_t packInt2x32(ivec2 v) | Returns a signed or unsigned 64-bit integer obtained |
| uint64_t packUint2x32(uvec2 v) | by packing the components of a two-component signed |
| | or unsigned integer vector, respectively. The first |
| | vector component specifies the 32 least significant |
| | bits; the second component specifies the 32 most |
| | significant bits. |
+-----------------------------------+------------------------------------------------------+
| ivec2 unpackInt2x32(int64_t v) | Returns a signed or unsigned integer vector built |
| uvec2 unpackUint2x32(uint64_t v) | from a 64-bit signed or unsigned integer scalar, |
| | respectively. The first component of the vector |
| | contains the 32 least significant bits of the input; |
| | the second component contains the 32 most |
| | significant bits. |
+-----------------------------------+------------------------------------------------------+
Modify Section, 8.7, Vector Relational Functions
(add to the table of placeholders at the top of p. 154)
+-------------+-----------------------------+
| Placeholder | Specific Types Allowed |
+-------------+-----------------------------+
| i64vec | i64vec2, i64vec3, i64vec4 |
| u64vec | u64vec2, u64vec3, u64vec4 |
+-------------+-----------------------------+
(add to the table of vector relational functions at the bottom of p. 154)
+-------------------------------------------+-----------------------------------------------+
| Syntax | Desciption |
+-------------------------------------------+-----------------------------------------------+
| bvec lessThan(i64vec x, i64vec y) | Returns the component-wise compare of x < y. |
| bvec lessThan(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
| bvec lessThanEqual(i64vec x, i64vec y) | Returns the component-wise compare of x <= y. |
| bvec lessThanEqual(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
| bvec greaterThan(i64vec x, i64vec y) | Returns the component-wise compare of x > y. |
| bvec greaterThan(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
| bvec greaterThanEqual(i64vec x, i64vec y) | Returns the component-wise compare of x >= y. |
| bvec greaterThanEqual(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
| bvec equal(i64vec x, i64vec y) | Returns the component-wise compare of x == y. |
| bvec equal(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
| bvec notEqual(i64vec x, i64vec y) | Returns the component-wise compare of x != y. |
| bvec notEqual(u64vec x, u64vec y) | |
+-------------------------------------------+-----------------------------------------------+
Modify Section 9, Shading Language Grammar for Core Profile
(add to the list of tokens on p. 187)
...
INT64 UINT64 I64VEC2 I64VEC3 I64VEC4 U64VEC2 U64VEC3 U64VEC4
...
INT64CONSTANT UINT64CONSTANT
(add to the rule of "primary_expression" on p. 188)
primary_expression:
...
INT64CONSTANT
UINT64CONSTANT
...
(add to the rule of "type_specifier_nonarray" on p. 195)
type_specifier_nonarray:
...
INT64
UINT64
...
I64VEC2
I64VEC3
I64VEC4
U64VEC2
U64VEC3
U64VEC4
...
Dependencies on NV_gpu_shader5
If the shader enables only NV_gpu_shader5, but not ARB_gpu_shader_int64
then the overloaded built-in functions abs, sign, min, max, clamp, and mix
are not available.
Dependencies on NV_shader_buffer_load
If NV_shader_buffer_load is supported, that specification should be edited
as follows, to allow pointers to dereference the new data types added by
this extension.
Modify "Section 2.20.X, Shader Memory Access" from NV_shader_buffer_load.
(add rules for loads of variables having the new data types from this
extension to the list of bullets following "When a shader dereferences a
pointer variable")
- Data of type int64_t and uint64_t are read from or written to memory as
a signel 64-bit signed and unsigned integer value, respectively, at the
specified GPU address.
Dependencies on NV_vertex_attrib_integer_64bit
This extension only provides the ability to specify 64-bit integer input
variables in a GLSL vertex shader, but does not provide a way to specify
the values of the corresponding vertex attributes via the OpenGL API.
The NV_vertex_attrib_integer_64bit extension exactly provides that
functionality.
Errors
None.
New State
None.
New Implementation Dependent State
None.
Issues
(1) How the functionality in this extension is different than the 64-bit
integer support introduced by NV_gpu_shader5 and AMD_gpu_shader_int64?
RESOLVED: This extension is a functional superset of the 64-bit integer
support in NV_gpu_shader5 with the following additions:
* support for overloaded versions of the functions abs, sign, min,
max, clamp, and mix that accept 64-bit integers as parameters.
Also, this extension is equivalent with AMD_gpu_shader_int64, except that
the entry points now have an ARB suffix.
(2) How do the implicit conversions impact binary operators?
RESOLVED: For binary operators, we prefer converting to a common type
that is as close as possible in size and type to the original
expression.
(3) How do the implicit conversions impact function overloading rules?
RESOLVED: We extend the preference rules in core OpenGL to account
for the new data types, adding a rule to favor conversion from 32-bit
integers to 64-bit integers over coversions to floating-point values.
(4) What should be done to distinguish between 32- and 64-bit integer
constants?
RESOLVED: We will use "L" and "UL" to identify signed and unsigned
64-bit integer constants; the use of "L" matches a similar ("long")
suffix in the C programming language. C leaves the size of integer
types implementation-dependent, and many implementations require an "LL"
suffix to declare 64-bit integer constants. With our size definitions,
"L" will be considered sufficient to make an integer constant 64-bit.
(5) Should provide support for vertex attributes with 64-bit components,
and if so, how should the support be provided in the OpenGL API?
RESOLVED: Yes, but in order to specify 64-bit vertex attribute values
in the OpenGL API support for NV_vertex_attrib_integer_64bit or a
similar extension is also required.
(6) Should we support 64-bit integer uniforms in the default uniform
block?
RESOLVED: Yes, for completeness.
(7) Should we support 64-bit integer types as members of uniform blocks,
shader storage buffer blocks, or as transform feedback varyings?
RESOLVED: Yes, support all of them. 64-bit integers will consume eight
basic machine units just like double-precision floating-point variables.
(8) How do the uniform loading commands introduced by this extension
interact similar commands added by NV_shader_buffer_load?
RESOLVED: NV_shader_buffer_load provided the command Uniformui64NV to
load pointer uniforms with a single 64-bit unsigned integer. This
extension provides vectors of 64-bit unsigned integers, so we needed
Uniform{2,3,4}ui64NV commands. We chose to provide a Uniform1ui64NV
command, which will be functionally equivalent to Uniformui64NV.
(9) Should we provide distinct sized types for 32-bit integers, floats,
and doubles?
RESOLVED: No. While NV_gpu_shader5 does add such types, it seems there
isn't much value in adding those in this extension, especially because
this extension strictly focuses on supporting 64-bit integers.
(10) Can the 64-bit uniform APIs be used to load values for uniforms of
type "bool", "bvec2", "bvec3", or "bvec4"?
RESOLVED: No. OpenGL 2.0 and beyond did allow "bool" variable to be
set with Uniform*i* and Uniform*f APIs, and OpenGL 3.0 extended that
support to Uniform*ui* for orthogonality. But it seems pointless to
extended this capability forward to 64-bit Uniform APIs as well.
(11) There exists both an UNSIGNED_INT64_AMD and UNSIGNED_INT64_NV token
with different values (the former existed earlier) so which token
value this extension should reuse?
DISCUSSION: No functions in this extension accept these values as
inputs, they only should return one of these in various scenarios.
RESOLVED: This extension will reuse the value of UNSIGNED_INT64_NV to
stay source code compatible with NV_gpu_shader5 and AMD_gpu_shader_int64.
Revision History
Rev. Date Author Changes
---- -------- -------- -------------------------------------------------
1 02/03/15 drakos Draft based on AMD_gpu_shader_int64.
Rebased language for GL 4.5 and GLSL 4.50.