fglTexCoordPointerEXT(3G) OpenGL Reference fglTexCoordPointerEXT(3G)NAME
fglTexCoordPointerEXT - define an array of texture coordinates
FORTRAN SPECIFICATION
SUBROUTINE fglTexCoordPointerEXT( INTEGER*4 size,
INTEGER*4 type,
INTEGER*4 stride,
INTEGER*4 count,
CHARACTER*8 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
fglTexCoordPointerEXT 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 fglEnable and
fglDisable with the argument GL_TEXTURE_COORD_ARRAY_EXT. If enabled, the
texture coordinate array is used when fglDrawArraysEXT or
fglArrayElementEXT is called.
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fglTexCoordPointerEXT(3G) OpenGL Reference fglTexCoordPointerEXT(3G)
Use fglDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
fglArrayElementEXT to specify primitives by indexing vertices and vertex
attributes.
NOTES
Non-static array elements are not accessed until fglArrayElementEXT or
fglDrawArraysEXT is executed.
By default the texture coordinate array is disabled and it won't be
accessed when fglArrayElementEXT or fglDrawArraysEXT is called.
Although it is not an error to call fglTexCoordPointerEXT between the
execution of fglBegin and the corresponding execution of fglEnd, the
results are undefined.
fglTexCoordPointerEXT 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 fglPushAttrib and fglPopAttrib.
fglTexCoordPointerEXT commands are not entered into display lists.
fglTexCoordPointerEXT 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 fglGetString, 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
fglIsEnabled with argument GL_TEXTURE_COORD_ARRAY_EXT
fglGet with argument GL_TEXTURE_COORD_ARRAY_SIZE_EXT
fglGet with argument GL_TEXTURE_COORD_ARRAY_TYPE_EXT
fglGet with argument GL_TEXTURE_COORD_ARRAY_STRIDE_EXT
fglGet with argument GL_TEXTURE_COORD_ARRAY_COUNT_EXT
fglGetPointervEXT with argument GL_TEXTURE_COORD_ARRAY_POINTER_EXT
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fglTexCoordPointerEXT(3G) OpenGL Reference fglTexCoordPointerEXT(3G)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.
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fglTexCoordPointerEXT(3G) OpenGL Reference fglTexCoordPointerEXT(3G)SEE ALSO
fglArrayElementEXT, fglColorPointerEXT, fglDrawArraysEXT,
fglEdgeFlagPointerEXT, fglEnable, fglGetPointervEXT, fglIndexPointerEXT,
fglNormalPointerEXT, fglVertexPointerEXT
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