glUniform

3G
glUniform

glUniform1f

glUniform2f

glUniform3f

glUniform4f

glUniform1i

glUniform2i

glUniform3i

glUniform4i

glUniform1fv

glUniform2fv

glUniform3fv

glUniform4fv

glUniform1iv

glUniform2iv

glUniform3iv

glUniform4iv

glUniformMatrix2fv

glUniformMatrix3fv

glUniformMatrix4fv

specify the value of a uniform variable for the current program object

# C Specification

    		void glUniform1f
    		GLint location
    		GLfloat v0

    		void glUniform2f
    		GLint location
    		GLfloat v0
    		GLfloat v1

    		void glUniform3f
    		GLint location
    		GLfloat v0
    		GLfloat v1
    		GLfloat v2

    		void glUniform4f
    		GLint location
    		GLfloat v0
    		GLfloat v1
    		GLfloat v2
    		GLfloat v3

    		void glUniform1i
    		GLint location
    		GLint v0

    		void glUniform2i
    		GLint location
    		GLint v0
    		GLint v1

    		void glUniform3i
    		GLint location
    		GLint v0
    		GLint v1
    		GLint v2

    		void glUniform4i
    		GLint location
    		GLint v0
    		GLint v1
    		GLint v2
    		GLint v3

## 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.

## C Specification

    		void glUniform1fv
    		GLint location
    		GLsizei count
    		const GLfloat *value

    		void glUniform2fv
    		GLint location
    		GLsizei count
    		const GLfloat *value

    		void glUniform3fv
    		GLint location
    		GLsizei count
    		const GLfloat *value

    		void glUniform4fv
    		GLint location
    		GLsizei count
    		const GLfloat *value

    		void glUniform1iv
    		GLint location
    		GLsizei count
    		const GLint *value

    		void glUniform2iv
    		GLint location
    		GLsizei count
    		const GLint *value

    		void glUniform3iv
    		GLint location
    		GLsizei count
    		const GLint *value

    		void glUniform4iv
    		GLint location
    		GLsizei count
    		const GLint *value

## 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.

## C Specification

    		void glUniformMatrix2fv
    		GLint location
    		GLsizei count
    		GLboolean transpose
    		const GLfloat *value

    		void glUniformMatrix3fv
    		GLint location
    		GLsizei count
    		GLboolean transpose
    		const GLfloat *value

    		void glUniformMatrix4fv
    		GLint location
    		GLsizei count
    		GLboolean transpose
    		const GLfloat *value

## 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. Must be `GL_FALSE`.

`value`

- Specifies a pointer to an array of `count` values that will be used to update the specified uniform variable.

## Description

`glUniform` 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

glGetUniformLocation

. `glUniform` operates on the program object that was made part of current state by calling

glUseProgram

.

The commands `glUniform{1|2|3|4}{f|i}` 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, bool; `2` for vec2, ivec2, bvec2, etc.). The suffix `f` indicates that floating-point values are being passed; the suffix `i` indicates that 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 `f` variants should be used to provide values for uniform variables of type float, vec2, vec3, vec4, or arrays of these. Either the `i` or the `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 `glUniform` until the next successful link operation occurs on the program object, when they are once again initialized to 0.

The commands `glUniform{1|2|3|4}{f|i}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 `glUniform{1|2|3|4}{f|i}`.

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., `glUniform3f` or `glUniform3fv` 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 `glUniformMatrix{2|3|4}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). Each matrix is assumed to be supplied in column 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

`glUniform1i` and `glUniform1iv` 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 `glUniform` command.

`GL_INVALID_OPERATION` is generated if one of the 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, or 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_VALUE` is generated if `transpose` is not `GL_FALSE`.

`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 `glUniform1i` and `glUniform1iv`.

## Associated Gets

glGet

with the argument `GL_CURRENT_PROGRAM`

glGetActiveUniform

with the handle of a program object and the index of an active uniform variable

glGetUniform

with the handle of a program object and the location of a uniform variable

glGetUniformLocation

with the handle of a program object and the name of a uniform variable

## See Also

glLinkProgram

,

glUseProgram

## Copyright

Copyright 2003-2005 3Dlabs Inc. Ltd. 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/.