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GLfloatvoidparam)

GLintparam)

*pname*-
Specifies a single-valued fog parameter.
**GL_FOG_MODE**,**GL_FOG_DENSITY**,**GL_FOG_START**,**GL_FOG_END**, and**GL_FOG_INDEX**are accepted. *param*-
Specifies the value that
*pname*will be set to.

const GLfloatvoid*params)

const GLint*params)

*pname*-
Specifies a fog parameter.
**GL_FOG_MODE**,**GL_FOG_DENSITY**,**GL_FOG_START**,**GL_FOG_END**,**GL_FOG_INDEX**, and**GL_FOG_COLOR**are accepted. *params*-
Specifies the value or values to be assigned to
*pname*.**GL_FOG_COLOR**requires an array of four values. All other parameters accept an array containing only a single value.

**GL_FOG_MODE**-
*params*is a single integer or floating-point value that specifies the equation to be used to compute the fog blend factor, $f$. Three symbolic constants are accepted:**GL_LINEAR**,**GL_EXP**, and**GL_EXP2**. The equations corresponding to these symbolic constants are defined below. The initial fog mode is**GL_EXP**. **GL_FOG_DENSITY**-
*params*is a single integer or floating-point value that specifies $density$, the fog density used in both exponential fog equations. Only nonnegative densities are accepted. The initial fog density is 1. **GL_FOG_START**-
*params*is a single integer or floating-point value that specifies $start$, the near distance used in the linear fog equation. The initial near distance is 0. **GL_FOG_END**-
*params*is a single integer or floating-point value that specifies $end$, the far distance used in the linear fog equation. The initial far distance is 1. **GL_FOG_INDEX**-
*params*is a single integer or floating-point value that specifies $i sub f$, the fog color index. The initial fog index is 0. **GL_FOG_COLOR**-
*params*contains four integer or floating-point values that specify $C sub f$, the fog color. Integer values are mapped linearly such that the most positive representable value maps to 1.0, and the most negative representable value maps to -1.0. Floating-point values are mapped directly. After conversion, all color components are clamped to the range [0,1]. The initial fog color is (0, 0, 0, 0). Fog blends a fog color with each rasterized pixel fragment's posttexturing color using a blending factor $f$. Factor $f$ is computed in one of three ways, depending on the fog mode. Let $z$ be the distance in eye coordinates from the origin to the fragment being fogged. The equation for**GL_LINEAR**fog is

The equation for

**GL_EXP**fog is

The equation for

**GL_EXP2**fog is

Regardless of the fog mode, $f$ is clamped to the range [0, 1] after it is computed. Then, if the GL is in RGBA color mode, the fragment's red, green, and blue colors, represented by $C sub r$, are replaced by

Fog does not affect a fragment's alpha component. In color index mode, the fragment's color index $i sub r$ is replaced by

- NAME
- C SPECIFICATION
- PARAMETERS
- C SPECIFICATION
- PARAMETERS
- DESCRIPTION
- ERRORS
- ASSOCIATED GETS
- SEE ALSO