_t_a_r_g_e_t The target to which the scaling function will be applied. Must
be one of GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____1111DDDD, GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____2222DDDD, or GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____3333DDDD____EEEEXXXXTTTT.
_n The number of scaling function samples in _p_o_i_n_t_s.
_p_o_i_n_t_s An array of scaling function samples, each of which is a (_l_e_v_e_l-
The sharpen texture extension defines three additional texture
magnification filters. These filters are selected by choosing one of the
values GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____SSSSGGGGIIIISSSS, GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____AAAALLLLPPPPHHHHAAAA____SSSSGGGGIIIISSSS, or
GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____CCCCOOOOLLLLOOOORRRR____SSSSGGGGIIIISSSS for the current 1D, 2D, or 3D texture's
All three filters sample the level zero texture array exactly as it would
be sampled with filter mode GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR. If both texture levels 0 and 1
are complete, the level 1 array of the texture is also linearly sampled,
just as though mipmap minification was being performed with _L_O_D (the
level of detail parameter) valued near 1.0. If levels 0 and 1 are not
complete, it is as though the magnification texture filter was GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR.
(Although querying the magnification filter value will return the value
as specified.)
The texture value computed from the level 0 array (_T_0) and the value
computed from the level one array (_T_1) are combined to compute the final
texture value (_T):
T' = ((1 + F(LOD)) * T0) - (F(LOD) * T1)
T = 0 if T' < 0
T' if 0 <= T' <= 1
1 if T' > 1
ggggllllSSSShhhhaaaarrrrppppeeeennnnTTTTeeeexxxxFFFFuuuunnnnccccSSSSGGGGIIIISSSS is used to specify the scaling function _F. _t_a_r_g_e_t
must be GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____1111DDDD, GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____2222DDDD, or GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____3333DDDD____EEEEXXXXTTTT. _n specifies
the number of pairs of values in _p_o_i_n_t_s. _p_o_i_n_t_s points to an array of
pairs of floating point values. The first value of each pair specifies a
value of _L_O_D, and the second value of each pair specifies the correspond-
ing function value. The order in which the points are specified is not
significant. The _n value pairs in _p_o_i_n_t_s completely specify the
function, replacing any previous specification that may have existed.
The function _F is evaluated by fitting a curve through the sample points
specified in _p_o_i_n_t_s. This curve may be linear between adjacent points,
or it may be smoothed, but it will pass exactly through the points, lim-
ited only by the resolution of the implementation. The value pair with
the lowest _L_O_D value specifies the function value _F for all values of _L_O_D
less than or equal to that pair's _L_O_D. Likewise, the value pair with the
greatest _L_O_D value specifies the function value _F for all values of _L_O_D
greater than or equal to that pair's _L_O_D.
Note that negative values of LOD correspond to magnification, and posi-
tive values correspond to minification. Hence, an LOD of -4 corresponds
to a magnification by a factor of 2**4, or 16. The default function
points are (0,0) and (-4,1).
If the texture magnification filter is GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____SSSSGGGGIIIISSSS, then both
the color and the alpha components of _T are computed as described in the
equations above. If the filter is GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____CCCCOOOOLLLLOOOORRRR____SSSSGGGGIIIISSSS, then all
components of _T other than alpha are computed as described above, and the
alpha component of _T is computed as if the texture magnification filter
were GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR. Finally, if the filter is GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____SSSSHHHHAAAARRRRPPPPEEEENNNN____AAAALLLLPPPPHHHHAAAA____SSSSGGGGIIIISSSS,
the alpha component of _T is computed as described in the equations above,
and all other components of _T are computed as if the texture magnifica-
tion filter were GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR.
EEEERRRRRRRROOOORRRRSSSS
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____EEEENNNNUUUUMMMM is generated if _t_a_r_g_e_t is not one of the allowable
values.
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____VVVVAAAALLLLUUUUEEEE is generated if _n is negative.
GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ggggllllSSSShhhhaaaarrrrppppeeeennnnTTTTeeeexxxxFFFFuuuunnnnccccSSSSGGGGIIIISSSS is executed
between the execution of ggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of
