2.0 3.0 > comp > gb.opengl > gl > calllists
Previous  Next  Edit  Rename  Undo  Search  Administration
 Documentation
Gl.CallLists (gb.opengl)
Static Sub CallLists ( Lists As Integer[] )

Execute a list of display lists.

### Parameters

n

Specifies the number of display lists to be executed.

type

Specifies the type of values in lists. Symbolic constants Gl.BYTE, Gl.UNSIGNED_BYTE, Gl.SHORT, Gl.UNSIGNED_SHORT, Gl.INT, Gl.UNSIGNED_INT, Gl.FLOAT, Gl.2_BYTES, Gl.3_BYTES, and Gl.4_BYTES are accepted.

lists

Specifies the address of an array of name offsets in the display list. The pointer type is void because the offsets can be bytes, shorts, ints, or floats, depending on the value of type.

### Description

Gl.CallLists causes each display list in the list of names passed as lists to be executed. As a result, the commands saved in each display list are executed in order, just as if they were called without using a display list. Names of display lists that have not been defined are ignored.

Gl.CallLists provides an efficient means for executing more than one display list. type allows lists with various name formats to be accepted. The formats are as follows:

Gl.BYTE

lists is treated as an array of signed bytes, each in the range $-128$ through 127.

Gl.UNSIGNED_BYTE

lists is treated as an array of unsigned bytes, each in the range 0 through 255.

Gl.SHORT

lists is treated as an array of signed two-byte integers, each in the range $-32768$ through 32767.

Gl.UNSIGNED_SHORT

lists is treated as an array of unsigned two-byte integers, each in the range 0 through 65535.

Gl.INT

lists is treated as an array of signed four-byte integers.

Gl.UNSIGNED_INT

lists is treated as an array of unsigned four-byte integers.

Gl.FLOAT

lists is treated as an array of four-byte floating-point values.

Gl.2_BYTES

lists is treated as an array of unsigned bytes. Each pair of bytes specifies a single display-list name. The value of the pair is computed as 256 times the unsigned value of the first byte plus the unsigned value of the second byte.

Gl.3_BYTES

lists is treated as an array of unsigned bytes. Each triplet of bytes specifies a single display-list name. The value of the triplet is computed as 65536 times the unsigned value of the first byte, plus 256 times the unsigned value of the second byte, plus the unsigned value of the third byte.

Gl.4_BYTES

lists is treated as an array of unsigned bytes. Each quadruplet of bytes specifies a single display-list name. The value of the quadruplet is computed as 16777216 times the unsigned value of the first byte, plus 65536 times the unsigned value of the second byte, plus 256 times the unsigned value of the third byte, plus the unsigned value of the fourth byte.

The list of display-list names is not null-terminated. Rather, n specifies how many names are to be taken from lists.

An additional level of indirection is made available with the Gl.ListBase command, which specifies an unsigned offset that is added to each display-list name specified in lists before that display list is executed.

Gl.CallLists can appear inside a display list. To avoid the possibility of infinite recursion resulting from display lists calling one another, a limit is placed on the nesting level of display lists during display-list execution. This limit must be at least 64, and it depends on the implementation.

GL state is not saved and restored across a call to Gl.CallLists. Thus, changes made to GL state during the execution of the display lists remain after execution is completed. Use Gl.PushAttrib, Gl.PopAttrib, Gl.PushMatrix, and Gl.PopMatrix to preserve GL state across Gl.CallLists calls.

### Notes

Display lists can be executed between a call to Gl.Begin and the corresponding call to Gl.End, as long as the display list includes only commands that are allowed in this interval.

### Errors

Gl.INVALID_VALUE is generated if n is negative.

Gl.INVALID_ENUM is generated if type is not one of Gl.BYTE, Gl.UNSIGNED_BYTE, Gl.SHORT, Gl.UNSIGNED_SHORT, Gl.INT, Gl.UNSIGNED_INT, Gl.FLOAT, Gl.2_BYTES, Gl.3_BYTES, Gl.4_BYTES.

### Associated Gets

Gl.Get with argument Gl.LIST_BASE

Gl.Get with argument Gl.MAX_LIST_NESTING