glTexCoordPointer(3G) OpenGL Reference glTexCoordPointer(3G)
NAME
glTexCoordPointer - define an array of texture coordinates
C SPECIFICATION
void glTexCoordPointer( GLint size,
GLenum type,
GLsizei stride,
const GLvoid *pointer )
PARAMETERS
size Specifies the number of coordinates per array element. Must be
1, 2, 3 or 4. The initial value is 4.
type Specifies the data type of each texture coordinate. Symbolic
constants GLSHORT, GLINT, GLFLOAT, or GLDOUBLE are accepted.
The initial value is GLFLOAT.
stride Specifies the byte offset between consecutive array elements.
If stride is 0, the array elements are understood to be tightly
packed. The initial value is 0.
pointer Specifies a pointer to the first coordinate of the first element
in the array.
DESCRIPTION
glTexCoordPointer specifies the location and data format of an array of
texture coordinates to use when rendering. size specifies the number of
coordinates per element, and must be 1, 2, 3, or 4. type specifies the
data type of each texture coordinate and stride specifies the byte stride
from one array element to the next allowing vertexes and attributes to be
packed into a single array or stored in separate arrays. (Single-array
storage may be more efficient on some implementations; see
glInterleavedArrays.) When a texture coordinate array is specified,
size, type, stride, and pointer are saved client-side state.
To enable and disable the texture coordinate array, call
glEnableClientState and glDisableClientState with the argument
GLTEXTURECOORDARRAY. If enabled, the texture coordinate array is used
when glDrawArrays, glDrawElements or
glArrayElement is called.
Use glDrawArrays to construct a sequence of primitives (all of the same
type) from prespecified vertex and vertex attribute arrays. Use
glArrayElement to specify primitives by indexing vertexes and vertex
attributes and glDrawElements to construct a sequence of primitives by
indexing vertexes and vertex attributes.
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glTexCoordPointer(3G) OpenGL Reference glTexCoordPointer(3G)
NOTES
glTexCoordPointer is available only if the GL version is 1.1 or greater.
The texture coordinate array is initially disabled and it won't be
accessed when
glArrayElement, glDrawElements or glDrawArrays is called.
Execution of glTexCoordPointer is not allowed between the execution of
glBegin and the corresponding execution of glEnd, but an error may or may
not be generated. If no error is generated, the operation is undefined.
glTexCoordPointer is typically implemented on the client side with no
protocol.
The texture coordinate array parameters are client-side state and are
therefore not saved or restored by glPushAttrib and glPopAttrib. Use
glPushClientAttrib and
glPopClientAttrib instead.
ERRORS
GLINVALIDVALUE is generated if size is not 1, 2, 3, or 4.
GLINVALIDENUM is generated if type is not an accepted value.
GLINVALIDVALUE is generated if stride is negative.
ASSOCIATED GETS
glIsEnabled with argument GLTEXTURECOORDARRAY
glGet with argument GLTEXTURECOORDARRAYSIZE
glGet with argument GLTEXTURECOORDARRAYTYPE
glGetPointerv with argument GLTEXTURECOORDARRAYPOINTER
MACHINE DEPENDENCIES
On RealityEngine, RealityEngine2, and VTX systems, do not enable or
disable GLVERTEXARRAY, GLVERTEXARRAYEXT, GLNORMALARRAY,
GLNORMALARRAYEXT, GLCOLORARRAY, GLCOLORARRAYEXT,
GLINDEXARRAY,GLINDEXARRAYEXT, GLTEXTURECOORDARRAY,
GLTEXTURECOORDARRAYEXT, GLEDGEFLAGARRAY or GLEDGEFLAGARRAYEXT
between a call to glNewList and the corresponding call to glEndList.
Instead, enable or disable before the call to glNewList.
On InfiniteReality systems it is particularly important to minimize the
amount of data transferred from the application to the graphics pipe,
since the host-to-pipe bandwidth limit can cause a performance
bottleneck. One way to reduce the amount of data transferred per vertex
is to use properly-aligned byte and short data types whenever possible.
Accordingly, the EXTvertexarray extension on InfiniteReality systems
has been optimized for vertex information packed into the following data
structures. (Note: v represents vertex coordinates, c represents color
components, n represents normal coordinates, and t represents texture
coordinates. Normals must have unit length.)
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glTexCoordPointer(3G) OpenGL Reference glTexCoordPointer(3G)
struct {GLfloat v[3];}
struct {GLubyte c[4]; GLfloat v[3];}
struct {GLshort n[3]; GLfloat v[3];}
struct {GLubyte c[4]; GLshort n[3]; GLfloat v[3];}
struct {GLshort t[2]; GLfloat v[3];}
struct {GLshort t[2]; GLubyte c[4]; GLfloat v[3];}
struct {GLshort t[2]; GLshort n[3]; GLfloat v[3];}
struct {GLshort t[2]; GLubyte c[4]; GLshort n[3]; GLfloat v[3];}
struct {GLfloat t[2]; GLfloat v[3];}
struct {GLfloat t[2]; GLubyte c[4]; GLfloat v[3];}
struct {GLfloat t[2]; GLshort n[3]; GLfloat v[3];}
struct {GLfloat t[2]; GLubyte c[4]; GLshort n[3]; GLfloat v[3];}
Application-specific fields may be added to these structures, provided
that all the fields described above retain their relative order and word
alignment.
An additional constraint applies when glTexGen is being used. The
implementation normally generates all four texture coordinates in
parallel, and must take special action to generate just a subset of the
four coordinates. Therefore performance is best when none of the texture
coordinates are being generated, or when all of them are being generated.
For example, when using 2D texturing (generating s and t coordinates) it
will be faster to enable texture coordinate generation for the r and q
coordinates as well as s and t. Choose a texture generation mode of
GLOBJECTLINEAR and use the plane equations (0,0,0,0) and (0,0,0,1) for
r and q, respectively.
Using these structures on InfiniteReality systems can improve performance
considerably, compared to structures in which all values are single-
precision floating point.
SEE ALSO
glArrayElement, glColorPointer, glDrawArrays, glDrawElements,
glEdgeFlagPointer, glEnable, glGetPointerv, glIndexPointer,
glNormalPointer, glPopClientAttrib, glPushClientAttrib, glTexCoord,
glVertexPointer
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