fglColorPointer(3G) OpenGL Reference 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.
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fglColorPointer(3G) OpenGL Reference fglColorPointer(3G)
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];}
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fglColorPointer(3G) OpenGL Reference fglColorPointer(3G)
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
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