glTexCoordPointerEXT(3G) OpenGL Reference glTexCoordPointerEXT(3G)
NAME
glTexCoordPointerEXT - define an array of texture coordinates
C SPECIFICATION
void glTexCoordPointerEXT( GLint size,
GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
PARAMETERS
size Specifies the number of coordinates per array element. It must
be 1, 2, 3 or 4.
type Specifies the data type of each texture coordinate. Symbolic
constants GLSHORT, GLINT, GLFLOAT, or GLDOUBLEEXT, are
accepted.
stride Specifies the byte offset between consecutive array elements.
If stride is zero the array elements are understood to be
tightly packed.
count Specifies the number of array elements, counting from the first,
that are static.
pointer Specifies a pointer to the first coordinate of the first element
in the array.
DESCRIPTION
glTexCoordPointerEXT specifies the location and data format of an array
of texture coordinates to use when rendering using the vertex array
extension. 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 gives 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.) count indicates the number of array elements
(counting from the first) that are static. Static elements may be
modified by the application, but once they are modified, the application
must explicitly respecify the array before using it for any rendering.
When a texture coordinate array is specified, size, type, stride, count,
and pointer are saved as client-side state, and static array elements may
be cached by the implementation.
The texture coordinate array is enabled and disabled using glEnable and
glDisable with the argument GLTEXTURECOORDARRAYEXT. If enabled, the
texture coordinate array is used when glDrawArraysEXT or
glArrayElementEXT is called.
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glTexCoordPointerEXT(3G) OpenGL Reference glTexCoordPointerEXT(3G)
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
NOTES
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the texture coordinate array is disabled and it won't be
accessed when glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glTexCoordPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the
results are undefined.
glTexCoordPointerEXT will typically be implemented on the client side
with no protocol.
Since the texture coordinate array parameters are client side state, they
are not saved or restored by glPushAttrib and glPopAttrib.
glTexCoordPointerEXT commands are not entered into display lists.
glTexCoordPointerEXT is part of the EXTvertexarray extension, not part
of the core GL command set. If GLEXTvertexarray is included in the
string returned by glGetString, when called with argument GLEXTENSIONS,
extension EXTvertexarray is supported.
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 or count is negative
ASSOCIATED GETS
glIsEnabled with argument GLTEXTURECOORDARRAYEXT
glGet with argument GLTEXTURECOORDARRAYSIZEEXT
glGet with argument GLTEXTURECOORDARRAYTYPEEXT
glGet with argument GLTEXTURECOORDARRAYSTRIDEEXT
glGet with argument GLTEXTURECOORDARRAYCOUNTEXT
glGetPointervEXT with argument GLTEXTURECOORDARRAYPOINTEREXT
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glTexCoordPointerEXT(3G) OpenGL Reference glTexCoordPointerEXT(3G)
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.)
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.
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glTexCoordPointerEXT(3G) OpenGL Reference glTexCoordPointerEXT(3G)
SEE ALSO
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glEnable, glGetPointervEXT, glIndexPointerEXT,
glNormalPointerEXT, glVertexPointerEXT
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