Unix/Linux Go Back    


SuSE 11.3 - man page for gltexgeni (suse section 3G)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


GLTEXGEN(3G)									     GLTEXGEN(3G)

NAME
       glTexGend,  glTexGenf, glTexGeni, glTexGendv, glTexGenfv, glTexGeniv - control the genera-
       tion of texture coordinates

C SPECIFICATION
       void glTexGend( GLenum coord,
		       GLenum pname,
		       GLdouble param )
       void glTexGenf( GLenum coord,
		       GLenum pname,
		       GLfloat param )
       void glTexGeni( GLenum coord,
		       GLenum pname,
		       GLint param )

PARAMETERS
       coord   Specifies a texture coordinate.	Must be one of GL_S, GL_T, GL_R, or GL_Q.

       pname   Specifies the symbolic name of the texture-coordinate generation  function.   Must
	       be GL_TEXTURE_GEN_MODE.

       param   Specifies  a  single-valued texture generation parameter, one of GL_OBJECT_LINEAR,
	       GL_EYE_LINEAR, or GL_SPHERE_MAP.

C SPECIFICATION
       void glTexGendv( GLenum coord,
			GLenum pname,
			const GLdouble *params )
       void glTexGenfv( GLenum coord,
			GLenum pname,
			const GLfloat *params )
       void glTexGeniv( GLenum coord,
			GLenum pname,
			const GLint *params )

PARAMETERS
       coord  Specifies a texture coordinate.  Must be one of GL_S, GL_T, GL_R, or GL_Q.

       pname  Specifies the symbolic name of the texture-coordinate generation function or  func-
	      tion parameters.	Must be GL_TEXTURE_GEN_MODE, GL_OBJECT_PLANE, or GL_EYE_PLANE.

       params Specifies  a  pointer  to  an  array of texture generation parameters.  If pname is
	      GL_TEXTURE_GEN_MODE, then the array must contain a single symbolic constant, one of
	      GL_OBJECT_LINEAR,  GL_EYE_LINEAR,  or  GL_SPHERE_MAP.   Otherwise, params holds the
	      coefficients for the texture-coordinate generation function specified by pname.

DESCRIPTION
       glTexGen selects a texture-coordinate generation function or supplies coefficients for one
       of the functions.  coord names one of the (s, t, r, q) texture coordinates; it must be one
       of the symbols GL_S, GL_T, GL_R, or GL_Q.  pname must be one of three symbolic  constants:
       GL_TEXTURE_GEN_MODE,  GL_OBJECT_PLANE,  or GL_EYE_PLANE.  If pname is GL_TEXTURE_GEN_MODE,
       then params chooses a mode, one of GL_OBJECT_LINEAR, GL_EYE_LINEAR, or GL_SPHERE_MAP.   If
       pname is either GL_OBJECT_PLANE or GL_EYE_PLANE, params contains coefficients for the cor-
       responding texture generation function.

       If the texture generation function is GL_OBJECT_LINEAR, the function

					 g=p1xo+p2yo+p3zo+p4wo

       is used, where g is the value computed for the coordinate named in coord, p1, p2, p3,  and
       p4  are	the four values supplied in params, and xo, yo, zo, and wo are the object coordi-
       nates of the vertex.  This function can be used, for example, to texture-map terrain using
       sea level as a reference plane (defined by p1, p2, p3, and p4).	The altitude of a terrain
       vertex is computed by the GL_OBJECT_LINEAR coordinate generation function as its  distance
       from  sea  level;  that	altitude can then be used to index the texture image to map white
       snow onto peaks and green grass onto foothills.

       If the texture generation function is GL_EYE_LINEAR, the function

					 g=p1xe+p2ye+p3ze+p4we

       is used, where

					(p1p2p3p4)=(p1p2p3p4)M-1

       and xe, ye, ze, and we are the eye coordinates of the vertex, p1, p2, p3, and p4  are  the
       values  supplied  in params, and M is the modelview matrix when glTexGen is invoked.  If M
       is poorly conditioned or singular, texture coordinates generated by the resulting function
       may be inaccurate or undefined.

       Note that the values in params define a reference plane in eye coordinates.  The modelview
       matrix that is applied to them may not be the same one in effect when the polygon vertices
       are  transformed.   This function establishes a field of texture coordinates that can pro-
       duce dynamic contour lines on moving objects.

       If pname is GL_SPHERE_MAP and coord is either GL_S or GL_T, s and  t  texture  coordinates
       are  generated as follows.  Let u be the unit vector pointing from the origin to the poly-
       gon vertex (in eye coordinates).  Let n sup prime be the current normal, after transforma-
       tion to eye coordinates.  Let

					      f=(fxfyfz)T
       be the reflection vector such that

					      f=u-2n'n'Tu

       Finally,  let  m=2fx+fy+(fz+1)2.   Then the values assigned to the s and t texture coordi-
       nates are

						 s=__+_

						 t=__+_

       To enable or disable a texture-coordinate generation function, call glEnable or	glDisable
       with  one  of  the  symbolic texture-coordinate names (GL_TEXTURE_GEN_S, GL_TEXTURE_GEN_T,
       GL_TEXTURE_GEN_R, or GL_TEXTURE_GEN_Q) as the argument.	When enabled, the specified  tex-
       ture  coordinate  is  computed  according  to the generating function associated with that
       coordinate.  When disabled, subsequent vertices take the specified texture coordinate from
       the  current  set  of texture coordinates. Initially, all texture generation functions are
       set to GL_EYE_LINEAR and are disabled.  Both s plane equations are (1, 0, 0,  0),  both	t
       plane equations are (0, 1, 0, 0), and all r and q plane equations are (0, 0, 0, 0).

       When  the  GL_ARB_multitexture extension is supported, glTexGen set the texture generation
       parameters for the currently active texture unit, selected with glActiveTextureARB.

ERRORS
       GL_INVALID_ENUM is generated when coord or pname is not an accepted defined value, or when
       pname is GL_TEXTURE_GEN_MODE and params is not an accepted defined value.

       GL_INVALID_ENUM	is  generated when pname is GL_TEXTURE_GEN_MODE, params is GL_SPHERE_MAP,
       and coord is either GL_R or GL_Q.

       GL_INVALID_OPERATION is generated if glTexGen is executed between the execution of glBegin
       and the corresponding execution of glEnd.

ASSOCIATED GETS
       glGetTexGen
       glIsEnabled with argument GL_TEXTURE_GEN_S
       glIsEnabled with argument GL_TEXTURE_GEN_T
       glIsEnabled with argument GL_TEXTURE_GEN_R
       glIsEnabled with argument GL_TEXTURE_GEN_Q

SEE ALSO
       glActiveTextureARB(3G),	glCopyPixels(3G),  glCopyTexImage2D(3G), glCopyTexSubImage1D(3G),
       glCopyTexSubImage2D(3G),    glCopyTexSubImage3D(3G),    glTexEnv(3G),	glTexImage1D(3G),
       glTexImage2D(3G),      glTexImage3D(3G),      glTexParameter(3G),     glTexSubImage1D(3G),
       glTexSubImage2D(3G), glTexSubImage3D(3G)

										     GLTEXGEN(3G)
Unix & Linux Commands & Man Pages : 2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 12:36 PM.