glGetShaderPrecisionFormat

3G

glGetShaderPrecisionFormat

return the range and precision for different shader numeric formats

# C Specification

    		void glGetShaderPrecisionFormat
    		GLenum shaderType
    		GLenum precisionType
    		GLint *range
    		GLint *precision

## Parameters

`shaderType`

- Specifies the type of shader to query. Must be either `GL_VERTEX_SHADER` or `GL_FRAGMENT_SHADER`.

`precisionType`

- Specifies the numeric format to query, corresponding to a shader precision qualifier and variable type. Must be one of `GL_LOW_FLOAT`, `GL_MEDIUM_FLOAT`, `GL_HIGH_FLOAT`, `GL_LOW_INT`, `GL_MEDIUM_INT`, or `GL_HIGH_INT`.

`range`

- Specifies a pointer to the two-element array in which the log 2 of the minimum and maximum representable magnitudes of the format are returned.

`precision`

- Specifies a pointer to the location in which the log 2 of the precision of the format is returned.

## Description

`glGetShaderPrecisionFormat` returns range and precision limits for floating-point and integer shader variable formats with low, medium, and high precision qualifiers. When minRep and maxRep are the minimum and maximum representable values of the format, floor ⁡ log 2 ⁡ minRep and floor ⁡ log 2 ⁡ maxRep are returned in `range` as the first and second elements, respectively.

If the smallest representable value greater than 1 is 1 + ε then floor ⁡ - log 2 ⁡ ε is returned in `precision`. An integer format will have an ε of 1, and thus will return 0. Floating-point formats will return values greater than 0.

## Notes

The minimum range and precision required for different formats is described in the OpenGL ES Shading Language Specification.

If a high precision floating-point format is not supported for fragment shaders, calling `glGetShaderPrecisionFormat` with arguments `GL_FRAGMENT_SHADER` and `GL_HIGH_FLOAT` will return 0 for both `range` and `precision`. Support for a high precision floating-point format is mandatory for vertex shaders.

Shader compiler support is optional, and thus must be queried before use by calling

glGet

with argument `GL_SHADER_COMPILER`.

glShaderSource

,

glCompileShader

, `glGetShaderPrecisionFormat`, and

glReleaseShaderCompiler

will each generate `GL_INVALID_OPERATION` on implementations that do not support a shader compiler. Such implementations instead offer the

glShaderBinary

alternative for supplying a pre-compiled shader binary.

If an error is generated, no change is made to the contents of `range` or `precision`.

## Errors

`GL_INVALID_OPERATION` is generated if a shader compiler is not supported.

`GL_INVALID_ENUM` is generated if `shaderType` or `precisionType` is not an accepted value.

## Associated Gets

glGet

with argument `GL_SHADER_COMPILER`

## See Also

glCompileShader

,

glShaderSource

## Copyright

Copyright 2008 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/.