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M
glMap2
Chapter 11
279
v1, v2
Specify a linear mapping of ˆv, as presented to glEvalCoord2, to one of
the two variables that are evaluated by the equations specified by this
command. Initially, v1 is 0 and v2 is 1.
vstride
Specifies the number of floats or doubles between the beginning of
control point R
ij
and the beginning of control point R
i(j+1)
, where i and j
are the u and v control point indices, respectively. This allows control
points to be embedded in arbitrary data structures. The only constraint
is that the values for a particular control point must occupy contiguous
memory locations. The initial value of vstride is 0.
vorder
Specifies the dimension of the control point array in the v axis. Must be
positive. The initial value is 1.
points
Specifies a pointer to the array of control points.
Description
Evaluators provide a way to use polynomial or rational polynomial mapping to produce
vertices, normals, texture coordinates, and colors. The values produced by an evaluator
are sent on to further stages of GL processing just as if they had been presented using
glVertex, glNormal, glTexCoord, and glColor commands, except that the generated
values do not update the current normal, texture coordinates, or color.
All polynomial or rational polynomial splines of any degree (up to the maximum degree
supported by the GL implementation) can be described using evaluators. These include
almost all surfaces used in computer graphics, including B-spline surfaces, NURBS
surfaces, Bezier surfaces, and so on.
Evaluators define surfaces based on bivariate Bernstein polynomials. Define p(û, v) as
Equation 11-5
where R
ij
is a control point, B
i
n
(û) is the ith Bernstein polynomial of degree n (uorder = n
+ 1)
Equation 11-6
and B
j
m
(v) is the jth Bernstein polynomial of degree m (vorder = m + 1)
Equation 11-7
Recall that
p u
ˆ
v
ˆ
,
(
)
B
i
n
j
0
=
m
∑
u
ˆ
( )
B
j
m
v
ˆ
( )
R
ij
i
0
=
n
∑
=
B
i
n
u
ˆ
( )
n
i
u
ˆ
i
1
u
ˆ
–
(
)
n
i
–
=
B
j
m
v
ˆ
( )
m
j
v
ˆ
j
1
v
ˆ
–
(
)
m
j
–
=
Содержание c3700 - Workstation
Страница 9: ...Chapter 1 9 1 A ...
Страница 12: ...A glAccum Chapter 1 12 glLogicOp glPixelStore glPixelTransfer glReadBuffer glReadPixels glScissor glStencilOp ...
Страница 18: ...A glArrayElement Chapter 1 18 glNormalPointer glTexCoordPointer glVertexPointer ...
Страница 19: ...Chapter 2 19 2 B ...
Страница 40: ...B gluBuild2DMipmaps Chapter 2 40 ...
Страница 41: ...Chapter 3 41 3 C ...
Страница 49: ...C glXChooseVisual Chapter 3 49 See Also glXCreateContext glXGetConfig ...
Страница 73: ...C glCopyPixels Chapter 3 73 glReadBuffer glReadPixels glStencilFunc ...
Страница 84: ...C glCopyTexSubImage2D Chapter 3 84 glTexParameter glTexSubImage1D glTexSubImage2D ...
Страница 93: ...Chapter 4 93 4 D ...
Страница 99: ...D glDeleteTextures Chapter 4 99 glTexImage1D glTexImage2D glTexParameter ...
Страница 127: ...Chapter 5 127 5 E ...
Страница 148: ...E glEvalPoint Chapter 5 148 ...
Страница 149: ...Chapter 6 149 6 F ...
Страница 161: ...Chapter 7 161 7 G ...
Страница 164: ...G glGenTextures Chapter 7 164 glTexImage1D glTexImage2D glTexParameter ...
Страница 185: ...G glGet Chapter 7 185 glGetTexGen glGetTexImage glGetTexLevelParameter glGetTexParameter glIsEnabled ...
Страница 207: ...G glGetPointer Chapter 7 207 glSelectBuffer glTexCoordPointer glVertexPointer ...
Страница 224: ...G glGetTexParameter Chapter 7 224 See Also glAreTexturesResident glPrioritizeTextures glTexParameter ...
Страница 225: ...Chapter 8 225 8 H ...
Страница 228: ...H glHint Chapter 8 228 ...
Страница 229: ...Chapter 9 229 9 I ...
Страница 248: ...I glIsTexture Chapter 9 248 ...
Страница 249: ...Chapter 10 249 10 L ...
Страница 256: ...L glLightModel Chapter 10 256 See Also glLight glMaterial ...
Страница 271: ...Chapter 11 271 11 M ...
Страница 291: ...Chapter 12 291 12 N ...
Страница 312: ...N gluNurbsSurface Chapter 12 312 ...
Страница 313: ...Chapter 13 313 13 O ...
Страница 317: ...Chapter 14 317 14 P ...
Страница 345: ...P glPolygonStipple Chapter 14 345 See Also glDrawPixels glLineStipple glPixelStore glPixelTransfer ...
Страница 360: ...P glPushName Chapter 14 360 See Also glInitNames glLoadName glRenderMode glSelectBuffer ...
Страница 362: ...P gluPwlCurve Chapter 14 362 ...
Страница 363: ...Chapter 15 363 15 Q ...
Страница 372: ...Q glXQueryVersion Chapter 15 372 glXQueryVersion ...
Страница 373: ...Chapter 16 373 16 R ...
Страница 390: ...R glRotate Chapter 16 390 ...
Страница 391: ...Chapter 17 391 17 S ...
Страница 397: ...S glScissor Chapter 17 397 See Also glEnable glViewport ...
Страница 409: ...Chapter 18 409 18 T ...
Страница 430: ...T glTexEnv Chapter 18 430 glCopyTexSubImage2D glTexImage1D glTexImage2D glTexParameter glTexSubImage1D glTexSubImage2D ...
Страница 448: ...T glTexImage3DEXT Chapter 18 448 glTexGen glTexImage1D glTexImage2D glTexParameter ...
Страница 457: ...T glTexSubImage1D Chapter 18 457 glTexImage2D glTexParameter glTexSubImage2D ...
Страница 465: ...T glTranslate Chapter 18 465 See Also glMatrixMode glMultMatrix glPushMatrix glScale ...
Страница 466: ...T glTranslate Chapter 18 466 ...
Страница 467: ...Chapter 19 467 19 U ...
Страница 469: ...U gluUnProject Chapter 19 469 See Also glGet gluProject ...
Страница 471: ...U glXUseXFont Chapter 19 471 See Also glBitmap glXMakeCurrent ...
Страница 472: ...U glXUseXFont Chapter 19 472 ...
Страница 473: ...Chapter 20 473 20 V ...
Страница 482: ...V glVisibilityBufferhp Chapter 20 482 ...
Страница 483: ...Chapter 21 483 21 W ...
Страница 486: ...W glXWaitX Chapter 21 486 ...