extensions/SGIX/SGIX_cylinder_texgen.txt

Name

    SGIX_cylinder_texgen

Name Strings

    GL_SGIX_cylinder_texgen

Version

    $Date: 1999/04/03 08:40:44 $ $Revision: 1.3 $

Number

    140

Dependencies

Overview

    This extension adds two texture coordinate generation modes, both
    of which generate a texture coordinate based on an intersection
    of the reflected ray with a local cylinder.  The difference between
    the two modes lies in the coordinate space in which the reflected
    ray is assumed to reside.

New Procedures and Functions

    None

New Tokens

    Accepted by the <params> parameters of TexGeni, TexGenf, TexGend,
    TexGeniv, TexGenfv, and TexGendv:

	EYE_CYLINDER_SGIX
	OBJECT_CYLINDER_SGIX
	EYE_CYLINDER_RADIUS_SGIX
	OBJECT_CYLINDER_RADIUS_SGIX

Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)

    If TEXTURE_GEN_MODE indicates OBJECT_CYLINDER_SGIX, then the
    generating function for the coordinate indicated by <coord> is

	XXX

    In other words, compute the reflection vector in object space from
    the point P in object space, and find the intersection of this
    reflection vector with a cylinder of radius r oriented along the x
    axis in object space.  If the cylinder is cut perpendicular to its
    axis at the point where the reflected ray intersects the cylinder,
    g is the normalized arclength of the arc from the xy plane to the
    intersection point along this cross section.

    r is specified by calling TexGeni, TexGenf, or TexGend with <pname>
    set to OBJECT_CYLINDER_SGIX and <params> set to r or by calling
    TexGeniv, TexGenfv, or TexGendv set to OBJECT_CYLINDER_SGIX and
    <params> pointing to an array containing r.

    If TEXTURE_GEN_MODE indicates EYE_DISTANCE_TO_POINT_SGIS, then the
    generating function for the coordinate indicated by <coord> is the
    same as above, but ...

	XXX

    In other words, compute the reflection vector in eye space from the
    point P in eye space, and find the intersection of this reflection
    vector with a cylinder of radius r oriented along the x axis in
    eye space.  If the cylinder is cut perpendicular to its axis at the
    point where the reflected ray intersects the cylinder, g is the
    normalized arclength of the arc from the xy plane to the intersection
    point along this cross section.

    r is specified by calling TexGeni, TexGenf, or TexGend with <pname>
    set to EYE_CYLINDER_SGIX and <params> set to r or by calling
    TexGeniv, TexGenfv, or TexGendv set to EYE_CYLINDER_SGIX and <params>
    pointing to an array containing r.

Additions to Chapter 3 of the 1.1 Specification (Rasterization)

    None

Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations
and the Frame Buffer)

    None

Additions to Chapter 5 of the 1.1 Specification (Special Functions)

    None

Additions to Chapter 6 of the 1.1 Specification (State and State Requests)

    None

New State
							Initial
    Get Value			Get Command	Type	Value			Attrib
    ---------			-----------	----	-------			------
    EYE_CYLINDER_SGIX		GetTexGeniv	1 x R	{0}			texture
    OBJECT_CYLINDER_SGIX	GetTexGeniv	1 x R	{0}			texture
    EYE_CYLINDER_RADIUS_SGIX	GetTexGeniv	1 x R	{1}			texture
    OBJECT_CYLINDER_RADIUS_SGIX	GetTexGeniv	1 x R	{1}			texture