Specifies the value of a generic vertex attribute
Signature
glVertexAttribP1ui(
GLuint (
index
)
,
GLenum (
type
)
,
GLboolean (
normalized
)
,
GLuint (
value
)
)-> void
glVertexAttribP2ui(
GLuint (
index
)
,
GLenum (
type
)
,
GLboolean (
normalized
)
,
GLuint (
value
)
)-> void
glVertexAttribP3ui(
GLuint (
index
)
,
GLenum (
type
)
,
GLboolean (
normalized
)
,
GLuint (
value
)
)-> void
glVertexAttribP4ui(
GLuint (
index
)
,
GLenum (
type
)
,
GLboolean (
normalized
)
,
GLuint (
value
)
)-> void
Parameters
| Variables | Description |
|---|---|
| index |
Specifies the index of the generic vertex
attribute to be modified.
|
| v0, v1, v2, v3 |
Specifies the new values to be used for the
specified vertex attribute.
|
Parameters
Parameters
- index
-
Specifies the index of the generic vertex attribute to be modified.
- type
-
Type of packing used on the data. This parameter must be GL_INT_10_10_10_2 or GL_UNSIGNED_INT_10_10_10_2 to specify signed or unsigned data, respectively.
- normalized
-
If GL_TRUE , then the values are to be converted to floating point values by normalizing. Otherwise, they are converted directly to floating point values.
- value
-
Specifies the new packed value to be used for the specified vertex attribute.
Description
The
glVertexAttrib
family of entry points
allows an application to pass generic vertex attributes in
numbered locations.
Generic attributes are defined as four-component values
that are organized into an array. The first entry of this array
is numbered 0, and the size of the array is specified by the
implementation-dependent constant
GL_MAX_VERTEX_ATTRIBS
. Individual elements
of this array can be modified with a
glVertexAttrib
call that specifies the
index of the element to be modified and a value for that
element.
These commands can be used to specify one, two, three, or
all four components of the generic vertex attribute specified by
index
. A
1
in the
name of the command indicates that only one value is passed, and
it will be used to modify the first component of the generic
vertex attribute. The second and third components will be set to
0, and the fourth component will be set to 1. Similarly, a
2
in the name of the command indicates that
values are provided for the first two components, the third
component will be set to 0, and the fourth component will be set
to 1. A
3
in the name of the command
indicates that values are provided for the first three
components and the fourth component will be set to 1, whereas a
4
in the name indicates that values are
provided for all four components.
The letters
s
,
f
,
i
,
d
,
ub
,
us
, and
ui
indicate
whether the arguments are of type short, float, int, double,
unsigned byte, unsigned short, or unsigned int. When
v
is appended to the name, the commands can
take a pointer to an array of such values.
Additional capitalized letters can indicate further alterations
to the default behavior of the glVertexAttrib function:
The commands containing
N
indicate that
the arguments will be passed as fixed-point values that are
scaled to a normalized range according to the component
conversion rules defined by the OpenGL specification. Signed
values are understood to represent fixed-point values in the
range [-1,1], and unsigned values are understood to represent
fixed-point values in the range [0,1].
The commands containing
I
indicate that
the arguments are extended to full signed or unsigned integers.
The commands containing
P
indicate that
the arguments are stored as packed components within a larger
natural type.
The commands containing
L
indicate that
the arguments are full 64-bit quantities and should be passed directly
to shader inputs declared as 64-bit double precision types.
OpenGL Shading Language attribute variables are allowed to
be of type mat2, mat3, or mat4. Attributes of these types may be
loaded using the
glVertexAttrib
entry
points. Matrices must be loaded into successive generic
attribute slots in column major order, with one column of the
matrix in each generic attribute slot.
A user-defined attribute variable declared in a vertex
shader can be bound to a generic attribute index by calling
glBindAttribLocation
.
This allows an application to use more descriptive variable
names in a vertex shader. A subsequent change to the specified
generic vertex attribute will be immediately reflected as a
change to the corresponding attribute variable in the vertex
shader.
The binding between a generic vertex attribute index and a
user-defined attribute variable in a vertex shader is part of
the state of a program object, but the current value of the
generic vertex attribute is not. The value of each generic
vertex attribute is part of current state, just like standard
vertex attributes, and it is maintained even if a different
program object is used.
An application may freely modify generic vertex attributes
that are not bound to a named vertex shader attribute variable.
These values are simply maintained as part of current state and
will not be accessed by the vertex shader. If a generic vertex
attribute bound to an attribute variable in a vertex shader is
not updated while the vertex shader is executing, the vertex
shader will repeatedly use the current value for the generic
vertex attribute.
Notes
Generic vertex attributes can be updated at any time.
It is possible for an application to bind more than one
attribute name to the same generic vertex attribute index. This
is referred to as aliasing, and it is allowed only if just one
of the aliased attribute variables is active in the vertex
shader, or if no path through the vertex shader consumes more
than one of the attributes aliased to the same location. OpenGL
implementations are not required to do error checking to detect
aliasing, they are allowed to assume that aliasing will not
occur, and they are allowed to employ optimizations that work
only in the absence of aliasing.
There is no provision for binding standard vertex
attributes; therefore, it is not possible to alias generic
attributes with standard attributes.
glVertexAttribL
versions are available only if the GL version is 4.1 or higher.
Errors
GL_INVALID_ENUM
is generated if
glVertexAttribP
is used with a
type
other than
GL_INT_10_10_10_2
or
GL_UNSIGNED_INT_10_10_10_2
.
Associated Gets
glGet
with the argument
GL_CURRENT_PROGRAM
glGetActiveAttrib
with argument
program
and the index of an active
attribute variable
glGetAttribLocation
with argument
program
and an attribute
variable name
See Also
Copyright
Copyright
2003-2005 3Dlabs Inc. Ltd.
Copyright
2010 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
http://opencontent.org/openpub/
.