fglColorPointer(3G)

NAME
     fglColorPointer - define an array of colors


FORTRAN SPECIFICATION
     SUBROUTINE fglColorPointer( INTEGER*4 size,
                                 INTEGER*4 type,
                                 INTEGER*4 stride,
                                 CHARACTER*8 pointer )


PARAMETERS
     size     Specifies the number of components per color. Must be 3 or 4.
              The initial value is 4.

     type     Specifies the data type of each color component in the array.
              Symbolic constants GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,
              GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT, GL_FLOAT, and
              GL_DOUBLE are accepted. The initial value is GL_FLOAT.

     stride   Specifies the byte offset between consecutive colors.  If stride
              is 0 (the initial value), the colors are understood to be
              tightly packed in the array. The initial value is 0.

     pointer  Specifies a pointer to the first component of the first color
              element in the array.

DESCRIPTION
     fglColorPointer specifies the location and data format of an array of
     color components to use when rendering.  size specifies the number of
     components per color, and must be 3 or 4.  type specifies the data type
     of each color component, and stride specifies the byte stride from one
     color 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 color array is specified, size, type, stride, and pointer are
     saved as client-side state.

     To enable and disable the color array, call fglEnableClientState and
     fglDisableClientState with the argument GL_COLOR_ARRAY. If enabled, the
     color array is used when fglDrawArrays, fglDrawElements,
     fglDrawRangeElements, or fglArrayElement is called.

NOTES
     fglColorPointer is available only if the GL version is 1.1 or greater.

     The color array is initially disabled and isn't accessed when
     fglArrayElement, fglDrawArrays, fglDrawRangeElements, or fglDrawElements
     is called.

     Execution of fglColorPointer 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.

     fglColorPointer is typically implemented on the client side.

     Color 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 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_COLOR_ARRAY
     fglGet with argument GL_COLOR_ARRAY_SIZE
     fglGet with argument GL_COLOR_ARRAY_TYPE
     fglGet with argument GL_COLOR_ARRAY_STRIDE
     fglGetPointerv with argument GL_COLOR_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, fglDrawArrays, fglDrawElements, fglEdgeFlagPointer,
     fglEnable, fglGetPointerv, fglIndexPointer, fglInterleavedArrays,
     fglNormalPointer, fglPopClientAttrib, fglPushClientAttrib,
     fglTexCoordPointer, fglVertexPointer