glGetActiveUniformsiv

From OpenGL Reference
Jump to navigation Jump to search

Returns information about several active uniform variables for the specified program object.

C Specification[edit]

void glGetActiveUniformsiv( GLuint program, GLsizei uniformCount, const GLuint * uniformIndices, GLenum pname, GLint * params );


Parameters[edit]

program - Specifies the program object to be queried.
uniformCount - Specifies both the number of elements in the array of indices uniformIndices and the number of parameters written to params upon successful return.
uniformIndices - Specifies the address of an array of uniformCount integers containing the indices of uniforms within program whose parameter pname should be queried.
pname - Specifies the property of each uniform in uniformIndices that should be written into the corresponding element of params .
params - Specifies the address of an array of uniformCount integers which are to receive the value of pname for each uniform in uniformIndices .


Description[edit]

 glGetActiveUniformsiv queries the value of the parameter named pname for each of the uniforms within program whose indices are specified in the array of uniformCount unsigned integers uniformIndices . Upon success, the value of the parameter for each uniform is written into the corresponding entry in the array whose address is given in params . If an error is generated, nothing is written into params .

If pname is GL_UNIFORM_TYPE , then an array identifying the types of uniforms specified by the corresponding array of uniformIndices is returned. The returned types can be any of the values from the following table:

Returned Symbolic Contant Shader Uniform Type
GL_FLOAT  float 
GL_FLOAT_VEC2  vec2 
GL_FLOAT_VEC3  vec3 
GL_FLOAT_VEC4  vec4 
GL_DOUBLE  double 
GL_DOUBLE_VEC2  dvec2 
GL_DOUBLE_VEC3  dvec3 
GL_DOUBLE_VEC4  dvec4 
GL_INT  int 
GL_INT_VEC2  ivec2 
GL_INT_VEC3  ivec3 
GL_INT_VEC4  ivec4 
GL_UNSIGNED_INT  unsigned int 
GL_UNSIGNED_INT_VEC2  uvec2 
GL_UNSIGNED_INT_VEC3  uvec3 
GL_UNSIGNED_INT_VEC4  uvec4 
GL_BOOL  bool 
GL_BOOL_VEC2  bvec2 
GL_BOOL_VEC3  bvec3 
GL_BOOL_VEC4  bvec4 
GL_FLOAT_MAT2  mat2 
GL_FLOAT_MAT3  mat3 
GL_FLOAT_MAT4  mat4 
GL_FLOAT_MAT2x3  mat2x3 
GL_FLOAT_MAT2x4  mat2x4 
GL_FLOAT_MAT3x2  mat3x2 
GL_FLOAT_MAT3x4  mat3x4 
GL_FLOAT_MAT4x2  mat4x2 
GL_FLOAT_MAT4x3  mat4x3 
GL_DOUBLE_MAT2  dmat2 
GL_DOUBLE_MAT3  dmat3 
GL_DOUBLE_MAT4  dmat4 
GL_DOUBLE_MAT2x3  dmat2x3 
GL_DOUBLE_MAT2x4  dmat2x4 
GL_DOUBLE_MAT3x2  dmat3x2 
GL_DOUBLE_MAT3x4  dmat3x4 
GL_DOUBLE_MAT4x2  dmat4x2 
GL_DOUBLE_MAT4x3  dmat4x3 
GL_SAMPLER_1D  sampler1D 
GL_SAMPLER_2D  sampler2D 
GL_SAMPLER_3D  sampler3D 
GL_SAMPLER_CUBE  samplerCube 
GL_SAMPLER_1D_SHADOW  sampler1DShadow 
GL_SAMPLER_2D_SHADOW  sampler2DShadow 
GL_SAMPLER_1D_ARRAY  sampler1DArray 
GL_SAMPLER_2D_ARRAY  sampler2DArray 
GL_SAMPLER_1D_ARRAY_SHADOW  sampler1DArrayShadow 
GL_SAMPLER_2D_ARRAY_SHADOW  sampler2DArrayShadow 
GL_SAMPLER_2D_MULTISAMPLE  sampler2DMS 
GL_SAMPLER_2D_MULTISAMPLE_ARRAY  sampler2DMSArray 
GL_SAMPLER_CUBE_SHADOW  samplerCubeShadow 
GL_SAMPLER_BUFFER  samplerBuffer 
GL_SAMPLER_2D_RECT  sampler2DRect 
GL_SAMPLER_2D_RECT_SHADOW  sampler2DRectShadow 
GL_INT_SAMPLER_1D  isampler1D 
GL_INT_SAMPLER_2D  isampler2D 
GL_INT_SAMPLER_3D  isampler3D 
GL_INT_SAMPLER_CUBE  isamplerCube 
GL_INT_SAMPLER_1D_ARRAY  isampler1DArray 
GL_INT_SAMPLER_2D_ARRAY  isampler2DArray 
GL_INT_SAMPLER_2D_MULTISAMPLE  isampler2DMS 
GL_INT_SAMPLER_2D_MULTISAMPLE_ARRAY  isampler2DMSArray 
GL_INT_SAMPLER_BUFFER  isamplerBuffer 
GL_INT_SAMPLER_2D_RECT  isampler2DRect 
GL_UNSIGNED_INT_SAMPLER_1D  usampler1D 
GL_UNSIGNED_INT_SAMPLER_2D  usampler2D 
GL_UNSIGNED_INT_SAMPLER_3D  usampler3D 
GL_UNSIGNED_INT_SAMPLER_CUBE  usamplerCube 
GL_UNSIGNED_INT_SAMPLER_1D_ARRAY  usampler2DArray 
GL_UNSIGNED_INT_SAMPLER_2D_ARRAY  usampler2DArray 
GL_UNSIGNED_INT_SAMPLER_2D_MULTISAMPLE  usampler2DMS 
GL_UNSIGNED_INT_SAMPLER_2D_MULTISAMPLE_ARRAY  usampler2DMSArray 
GL_UNSIGNED_INT_SAMPLER_BUFFER  usamplerBuffer 
GL_UNSIGNED_INT_SAMPLER_2D_RECT  usampler2DRect 

If pname is GL_UNIFORM_SIZE , then an array identifying the size of the uniforms specified by the corresponding array of uniformIndices is returned. The sizes returned are in units of the type returned by a query of GL_UNIFORM_TYPE . For active uniforms that are arrays, the size is the number of active elements in the array; for all other uniforms, the size is one.

If pname is GL_UNIFORM_NAME_LENGTH , then an array identifying the length, including the terminating null character, of the uniform name strings specified by the corresponding array of uniformIndices is returned.

If pname is GL_UNIFORM_BLOCK_INDEX , then an array identifying the uniform block index of each of the uniforms specified by the corresponding array of uniformIndices is returned. The uniform block index of a uniform associated with the default uniform block is -1.

If pname is GL_UNIFORM_OFFSET , then an array of uniform buffer offsets is returned. For uniforms in a named uniform block, the returned value will be its offset, in basic machine units, relative to the beginning of the uniform block in the buffer object data store. For atomic counter uniforms, the returned value will be its offset relative to the beginning of its active atomic counter buffer. For all other uniforms, -1 will be returned.

If pname is GL_UNIFORM_ARRAY_STRIDE , then an array identifying the stride between elements of each of the uniforms specified by the corresponding array of uniformIndices is returned. For uniforms in named uniform blocks and for uniforms declared as atomic counters, the stride is the difference, in basic machine units, of consecutive elements in an array, or zero for uniforms not declared as an array. For all other uniforms, a stride of -1 will be returned.

If pname is GL_UNIFORM_MATRIX_STRIDE , then an array identifying the stride between columns of a column-major matrix or rows of a row-major matrix, in basic machine units, of each of the uniforms specified by the corresponding array of uniformIndices is returned. The matrix stride of a uniform associated with the default uniform block is -1. Note that this information only makes sense for uniforms that are matrices. For uniforms that are not matrices, but are declared in a named uniform block, a matrix stride of zero is returned.

If pname is GL_UNIFORM_IS_ROW_MAJOR , then an array identifying whether each of the uniforms specified by the corresponding array of uniformIndices is a row-major matrix or not is returned. A value of one indicates a row-major matrix, and a value of zero indicates a column-major matrix, a matrix in the default uniform block, or a non-matrix.

If pname is GL_UNIFORM_ATOMIC_COUNTER_BUFFER_INDEX , then an array identifying the active atomic counter buffer index of each of the uniforms specified by the corresponding array of uniformIndices is returned. For uniforms other than atomic counters, the returned buffer index is -1. The returned indices may be passed to glGetActiveAtomicCounterBufferiv to query the properties of the associated buffer, and not necessarily the binding point specified in the uniform declaration.


Notes[edit]

The double types, GL_DOUBLE , GL_DOUBLE_VEC2 , GL_DOUBLE_VEC3 , GL_DOUBLE_VEC4 , GL_DOUBLE_MAT2 , GL_DOUBLE_MAT3 , GL_DOUBLE_MAT4 , GL_DOUBLE_MAT2x3 , GL_DOUBLE_MAT2x4 , GL_DOUBLE_MAT3x2 , GL_DOUBLE_MAT3x4 , GL_DOUBLE_MAT4x2 , and GL_DOUBLE_MAT4x3 are only available if the GL version is 4.1 or higher.

 GL_UNIFORM_ATOMIC_COUNTER_BUFFER_INDEX is only accepted by pname if the GL version is 4.2 or higher.


Errors[edit]

 GL_INVALID_VALUE is generated if program is not a value generated by OpenGL.

 GL_INVALID_OPERATION is generated if program is not a program object.

 GL_INVALID_VALUE is generated if uniformCount is greater than or equal to the value of GL_ACTIVE_UNIFORMS for program .

 GL_INVALID_ENUM is generated if pname is not an accepted token.


Associated Gets[edit]

 glGet with argument GL_MAX_VERTEX_UNIFORM_COMPONENTS , GL_MAX_TESS_CONTROL_UNIFORM_COMPONENTS , GL_MAX_TESS_EVALUATION_UNIFORM_COMPONENTS , GL_MAX_GEOMETRY_UNIFORM_COMPONENTS , GL_MAX_FRAGMENT_UNIFORM_COMPONENTS , or GL_MAX_COMBINED_UNIFORM_COMPONENTS .

 glGetProgram with argument GL_ACTIVE_UNIFORMS or GL_ACTIVE_UNIFORM_MAX_LENGTH .

 glIsProgram 


Version Support[edit]

 glGetActiveUniformsiv  3.1+

See Also[edit]

 glGetUniform , glGetActiveUniform , glGetUniformLocation , glLinkProgram , glUniform , glUseProgram 


Copyright[edit]

Copyright© 2011-2014 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/.