fglTexCoordPointer(3G)

NAME
     fglTexCoordPointer - define an array of texture coordinates


FORTRAN SPECIFICATION
     SUBROUTINE fglTexCoordPointer( INTEGER*4 size,
                                    INTEGER*4 type,
                                    INTEGER*4 stride,
                                    CHARACTER*8 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 GL_SHORT, GL_INT, GL_FLOAT, or GL_DOUBLE are accepted.
              The initial value is GL_FLOAT.

     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.  The initial value is 0.

DESCRIPTION
     fglTexCoordPointer 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 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; see
     fglInterleavedArrays.)  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
     fglEnableClientState and fglDisableClientState with the argument
     GL_TEXTURE_COORD_ARRAY. If enabled, the texture coordinate array is used
     when fglDrawArrays, fglDrawElements, fglDrawRangeElements or
     fglArrayElement is called.

     Use fglDrawArrays to construct a sequence of primitives (all of the same
     type) from prespecified vertex and vertex attribute arrays.  Use
     fglArrayElement to specify primitives by indexing vertices and vertex
     attributes and fglDrawElements to construct a sequence of primitives by
     indexing vertices and vertex attributes.

NOTES
     fglTexCoordPointer 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 fglArrayElement, fglDrawElements, fglDrawRangeElements, or
     fglDrawArrays is called.

     Execution of fglTexCoordPointer is not allowed between the execution of
     fglBegin and the corresponding execution of fglEnd, but an error may or
     may not be generated. If no error is generated, the operation is
     undefined.

     fglTexCoordPointer 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 fglPushAttrib and fglPopAttrib.  Use
     fglPushClientAttrib and fglPopClientAttrib instead.

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 is negative.

ASSOCIATED GETS
     fglIsEnabled with argument GL_TEXTURE_COORD_ARRAY
     fglGet with argument GL_TEXTURE_COORD_ARRAY_SIZE
     fglGet with argument GL_TEXTURE_COORD_ARRAY_TYPE
     fglGetPointerv with argument GL_TEXTURE_COORD_ARRAY_POINTER


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 fglNewList and the corresponding call to fglEndList.
     Instead, enable or disable before the call to fglNewList.

     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 fglTexGen 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
     fglArrayElement, fglColorPointer, fglDrawArrays, fglDrawElements,
     fglDrawRangeElements, fglEdgeFlagPointer, fglEnable, fglGetPointerv,
     fglIndexPointer, fglNormalPointer, fglPopClientAttrib,
     fglPushClientAttrib, fglTexCoord, fglVertexPointer