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 GL_SHORT, GL_INT, GL_FLOAT, or GL_DOUBLE_EXT, 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 vertices 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 GL_TEXTURE_COORD_ARRAY_EXT. If enabled, the
     texture coordinate array is used when glDrawArraysEXT or
     glArrayElementEXT is called.
     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 vertices 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 EXT_vertex_array extension, not part
     of the core GL command set. If GL_EXT_vertex_array is included in the
     string returned by glGetString, when called with argument GL_EXTENSIONS,
     extension EXT_vertex_array is supported.

ERRORS
     GL_INVALID_VALUE is generated if size is not 1, 2, 3, or 4.

     GL_INVALID_ENUM is generated if type is not an accepted value.

     GL_INVALID_VALUE is generated if stride or count  is negative


ASSOCIATED GETS
     glIsEnabled with argument GL_TEXTURE_COORD_ARRAY_EXT
     glGet with argument GL_TEXTURE_COORD_ARRAY_SIZE_EXT
     glGet with argument GL_TEXTURE_COORD_ARRAY_TYPE_EXT
     glGet with argument GL_TEXTURE_COORD_ARRAY_STRIDE_EXT
     glGet with argument GL_TEXTURE_COORD_ARRAY_COUNT_EXT
     glGetPointervEXT with argument GL_TEXTURE_COORD_ARRAY_POINTER_EXT

MACHINE DEPENDENCIES
     On RealityEngine, RealityEngine2, and VTX systems, do not enable or
     disable GL_VERTEX_ARRAY, GL_VERTEX_ARRAY_EXT, GL_NORMAL_ARRAY,
     GL_NORMAL_ARRAY_EXT, GL_COLOR_ARRAY, GL_COLOR_ARRAY_EXT,
     GL_INDEX_ARRAY,GL_INDEX_ARRAY_EXT, GL_TEXTURE_COORD_ARRAY,
     GL_TEXTURE_COORD_ARRAY_EXT, GL_EDGE_FLAG_ARRAY or GL_EDGE_FLAG_ARRAY_EXT
     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 EXT_vertex_array 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
     GL_OBJECT_LINEAR 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
     glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
     glEdgeFlagPointerEXT, glEnable, glGetPointervEXT, glIndexPointerEXT,
     glNormalPointerEXT, glVertexPointerEXT