Gl.Uniform1f (gb.opengl.glsl)
Static Sub Uniform1f ( Location As Integer, V0 As Float )
Specify the value of a uniform variable for the current program object.
Parameters
- location
-
Specifies the location of the uniform variable
to be modified.
-
v0,
v1,
v2,
v3
-
Specifies the new values to be used for the
specified uniform variable.
Parameters
- location
-
Specifies the location of the uniform value to
be modified.
- count
-
Specifies the number of elements that are to
be modified. This should be 1 if the targeted
uniform variable is not an array, and 1 or more if it is
an array.
- value
-
Specifies a pointer to an array of
count values that will be
used to update the specified uniform
variable.
Parameters
- location
-
Specifies the location of the uniform value to
be modified.
- count
-
Specifies the number of matrices that are to
be modified. This should be 1 if the targeted
uniform variable is not an array of matrices, and 1 or more if it is
an array of matrices.
- transpose
-
Specifies whether to transpose the matrix as
the values are loaded into the uniform
variable.
- value
-
Specifies a pointer to an array of
count values that will be
used to update the specified uniform
variable.
Description
Gl.Uniform modifies the value of a
uniform variable or a uniform variable array. The location of
the uniform variable to be modified is specified by
location, which should be a value
returned by
Gl.GetUniformLocation.
Gl.Uniform operates on the program object
that was made part of current state by calling
Gl.UseProgram.
The commands
Gl.Uniform{1|2|3|4}{f|i|ui}
are used to change the value of the uniform variable specified
by
location using the values passed as
arguments. The number specified in the command should match the
number of components in the data type of the specified uniform
variable (e.g.,
1 for float, int, unsigned int, bool;
2 for vec2, ivec2, uvec2, bvec2, etc.). The suffix
f indicates that floating-point values are
being passed; the suffix
i indicates that
integer values are being passed; the suffix
ui indicates that
unsigned integer values are being passed, and this type should also match
the data type of the specified uniform variable. The
i variants of this function should be used
to provide values for uniform variables defined as int, ivec2,
ivec3, ivec4, or arrays of these. The
ui variants of this function should be used
to provide values for uniform variables defined as unsigned int, uvec2,
uvec3, uvec4, or arrays of these. The
f
variants should be used to provide values for uniform variables
of type float, vec2, vec3, vec4, or arrays of these. Either the
i,
ui or
f variants
may be used to provide values for uniform variables of type
bool, bvec2, bvec3, bvec4, or arrays of these. The uniform
variable will be set to false if the input value is 0 or 0.0f,
and it will be set to true otherwise.
All active uniform variables defined in a program object
are initialized to 0 when the program object is linked
successfully. They retain the values assigned to them by a call
to
Gl.Uniform * until the next successful
link operation occurs on the program object, when they are once
again initialized to 0.
The commands
Gl.Uniform{1|2|3|4}{f|i|ui}v
can be used to modify a single uniform variable or a uniform
variable array. These commands pass a count and a pointer to the
values to be loaded into a uniform variable or a uniform
variable array. A count of 1 should be used if modifying the
value of a single uniform variable, and a count of 1 or greater
can be used to modify an entire array or part of an array. When
loading
n elements starting at an arbitrary
position
m in a uniform variable array,
elements
m +
n - 1 in
the array will be replaced with the new values. If
m +
n - 1 is
larger than the size of the uniform variable array, values for
all array elements beyond the end of the array will be ignored.
The number specified in the name of the command indicates the
number of components for each element in
value, and it should match the number of
components in the data type of the specified uniform variable
(e.g.,
1 for float, int, bool;
2 for vec2, ivec2, bvec2, etc.). The data
type specified in the name of the command must match the data
type for the specified uniform variable as described previously
for
Gl.Uniform{1|2|3|4}{f|i|ui}.
For uniform variable arrays, each element of the array is
considered to be of the type indicated in the name of the
command (e.g.,
Gl.Uniform3f or
Gl.Uniform3fv can be used to load a uniform
variable array of type vec3). The number of elements of the
uniform variable array to be modified is specified by
count
The commands
Gl.UniformMatrix{2|3|4|2x3|3x2|2x4|4x2|3x4|4x3}fv
are used to modify a matrix or an array of matrices. The numbers in the
command name are interpreted as the dimensionality of the matrix.
The number
2 indicates a 2 × 2 matrix
(i.e., 4 values), the number
3 indicates a
3 × 3 matrix (i.e., 9 values), and the number
4 indicates a 4 × 4 matrix (i.e., 16
values). Non-square matrix dimensionality is explicit, with the first
number representing the number of columns and the second number
representing the number of rows. For example,
2x4 indicates a 2 × 4 matrix with 2 columns
and 4 rows (i.e., 8 values).
If
transpose is
Gl.FALSE, each matrix is assumed to be
supplied in column major order. If
transpose is
Gl.TRUE, each matrix is assumed to be
supplied in row major order. The
count
argument indicates the number of matrices to be passed. A count
of 1 should be used if modifying the value of a single matrix,
and a count greater than 1 can be used to modify an array of
matrices.
Notes
Gl.Uniform1i and
Gl.Uniform1iv are the only two functions
that may be used to load uniform variables defined as sampler
types. Loading samplers with any other function will result in a
Gl.INVALID_OPERATION error.
If
count is greater than 1 and the
indicated uniform variable is not an array, a
Gl.INVALID_OPERATION error is generated and the
specified uniform variable will remain unchanged.
Other than the preceding exceptions, if the type and size
of the uniform variable as defined in the shader do not match
the type and size specified in the name of the command used to
load its value, a Gl.INVALID_OPERATION error will
be generated and the specified uniform variable will remain
unchanged.
If
location is a value other than
-1 and it does not represent a valid uniform variable location
in the current program object, an error will be generated, and
no changes will be made to the uniform variable storage of the
current program object. If
location is
equal to -1, the data passed in will be silently ignored and the
specified uniform variable will not be changed.
Errors
Gl.INVALID_OPERATION is generated if there
is no current program object.
Gl.INVALID_OPERATION is generated if the
size of the uniform variable declared in the shader does not
match the size indicated by the
Gl.Uniform
command.
Gl.INVALID_OPERATION is generated if one of
the signed or unsigned integer variants of this function is used to load a uniform
variable of type float, vec2, vec3, vec4, or an array of these,
or if one of the floating-point variants of this function is
used to load a uniform variable of type int, ivec2, ivec3,
ivec4, unsigned int, uvec2, uvec3,
uvec4, or an array of these.
Gl.INVALID_OPERATION is generated if one of
the signed integer variants of this function is used to load a uniform
variable of type unsigned int, uvec2, uvec3,
uvec4, or an array of these.
Gl.INVALID_OPERATION is generated if one of
the unsigned integer variants of this function is used to load a uniform
variable of type int, ivec2, ivec3,
ivec4, or an array of these.
Gl.INVALID_OPERATION is generated if
location is an invalid uniform location
for the current program object and
location is not equal to -1.
Gl.INVALID_VALUE is generated if
count is less than 0.
Gl.INVALID_OPERATION is generated if
count is greater than 1 and the indicated
uniform variable is not an array variable.
Gl.INVALID_OPERATION is generated if a
sampler is loaded using a command other than
Gl.Uniform1i and
Gl.Uniform1iv.
Associated Gets
Gl.Get
with the argument Gl.CURRENT_PROGRAM
Gl.GetActiveUniform
with the handle of a program object and the index of an active uniform variable
Gl.GetUniform
with the handle of a program object and the location of a
uniform variable
Gl.GetUniformLocation
with the handle of a program object and the name of a uniform
variable
See also
See original documentation on OpenGL website