glPixelMapfv,
glPixelMapuiv, glPixelMapusv
[New
- Windows 95, OEM Service Release 2]
These functions
set up pixel transfer maps.
void glPixelMapfv(
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GLenum map, |
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GLint mapsize, |
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const GLfloat *values |
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); |
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void glPixelMapuiv(
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GLenum map, |
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GLint mapsize, |
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const GLuint *values |
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); |
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void glPixelMapusv(
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GLenum map, |
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GLint mapsize, |
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const GLushort *values |
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); |
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Parameters
map
A symbolic
map name. The ten maps are as follows:
GL_PIXEL_MAP_I_TO_I
Maps color
indexes to color indexes.
GL_PIXEL_MAP_S_TO_S
Maps stencil
indexes to stencil indexes.
GL_PIXEL_MAP_I_TO_R
Maps color
indexes to red components.
GL_PIXEL_MAP_I_TO_G
Maps color
indexes to green components.
GL_PIXEL_MAP_I_TO_B
Maps color
indexes to blue components.
GL_PIXEL_MAP_I_TO_A
Maps color
indexes to alpha components.
GL_PIXEL_MAP_R_TO_R
Maps red
components to red components.
GL_PIXEL_MAP_G_TO_G
Maps green
components to green components.
GL_PIXEL_MAP_B_TO_B
Maps blue
components to blue components.
GL_PIXEL_MAP_A_TO_A
Maps alpha
components to alpha components.
mapsize
The size of
the map being defined.
values
An array of mapsize
values.
Remarks
The
glPixelMap function sets up translation tables, or maps, used by glDrawPixels, glReadPixels, glCopyPixels, glTexImage1D, and glTexImage2D. Use of these maps is
described completely in the glPixelTransfer topic, and partly in the topics for the pixel
and texture image commands. Only the specification of the maps is described in
this topic.
The map
parameter is a symbolic map name, indicating one of ten maps to set. The mapsize
parameter specifies the number of entries in the map, and values is a
pointer to an array of mapsize map values.
The entries
in a map can be specified as single-precision floating-point numbers, unsigned
short integers, or unsigned long integers. Maps that store color component
values (all but GL_PIXEL_MAP_I_TO_I and GL_PIXEL_MAP_S_TO_S) retain their
values in floating-point format, with unspecified mantissa and exponent sizes.
Floating-point values specified by glPixelMapfv are converted directly
to the internal floating-point format of these maps, and then clamped to the
range [0,1]. Unsigned integer values specified by glPixelMapusv and glPixelMapuiv
are converted linearly such that the largest representable integer maps to 1.0,
and zero maps to 0.0.
Maps that
store indexes, GL_PIXEL_MAP_I_TO_I and GL_PIXEL_MAP_S_TO_S, retain their values
in fixed-point format, with an unspecified number of bits to the right of the
binary point. Floating-point values specified by glPixelMapfv are
converted directly to the internal fixed-point format of these maps. Unsigned
integer values specified by glPixelMapusv and glPixelMapuiv
specify integer values, with all zeros to the right of the binary point.
The following
table shows the initial sizes and values for each of the maps. Maps that are
indexed by either color or stencil indexes must have mapsize = 2^n
for some n or results are undefined. The maximum allowable size for each
map depends on the implementation and can be determined by calling glGet
with argument GL_MAX_PIXEL_MAP_TABLE. The single maximum applies to all maps,
and it is at least 32.
GL_PIXEL_MAP_I_TO_I
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Lookup
Index: |
color index |
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Lookup
Value: |
color index |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_S_TO_S
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Lookup
Index: |
stencil
index |
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Lookup
Value: |
stencil
index |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_I_TO_R
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Lookup
Index: |
color index |
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Lookup
Value: |
R |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_I_TO_G
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Lookup
Index: |
color index |
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Lookup
Value: |
G |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_I_TO_B
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Lookup
Index: |
color index |
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Lookup
Value: |
B |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_I_TO_A
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Lookup
Index: |
color index |
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Lookup
Value: |
A |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_R_TO_R
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Lookup Index: |
R |
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Lookup
Value: |
R |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_G_TO_G
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Lookup
Index: |
G |
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Lookup
Value: |
G |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_B_TO_B
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Lookup
Index: |
B |
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Lookup
Value: |
B |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
GL_PIXEL_MAP_A_TO_A
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Lookup
Index: |
A |
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Lookup
Value: |
A |
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Initial
Size: |
1 |
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Initial
Value: |
0.0 |
The following
functions retrieve information related to glPixelMap:
glGet
with argument GL_PIXEL_MAP_I_TO_I_SIZE
glGet with
argument GL_PIXEL_MAP_S_TO_S_SIZE
glGet with
argument GL_PIXEL_MAP_I_TO_R_SIZE
glGet with
argument GL_PIXEL_MAP_I_TO_G_SIZE
glGet with
argument GL_PIXEL_MAP_I_TO_B_SIZE
glGet with
argument GL_PIXEL_MAP_I_TO_A_SIZE
glGet with
argument GL_PIXEL_MAP_R_TO_R_SIZE
glGet with
argument GL_PIXEL_MAP_G_TO_G_SIZE
glGet with
argument GL_PIXEL_MAP_B_TO_B_SIZE
glGet with
argument GL_PIXEL_MAP_A_TO_A_SIZE
glGet with
argument GL_MAX_PIXEL_MAP_TABLE
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_ENUM
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map was not an accepted value. |
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GL_INVALID_VALUE
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mapsize was negative or larger than GL_MAX_PIXEL_MAP_TABLE. |
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GL_INVALID_VALUE
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map was GL_PIXEL_MAP_I_TO_I, GL_PIXEL_MAP_S_TO_S,
GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, or GL_PIXEL_MAP_I_TO_A,
and mapsize was not a power of two. |
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GL_INVALID_OPERATION
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glPixelMap was called between a call to glBegin and the
corresponding call to glEnd. |
See Also