SET_RAY_ITEM_BUFFER(3G)

NAME

set_ray_item_buffer, inq_ray_item_buffer − set/inquire the item buffer mode for ray tracing (HP-SBRR versions 1.0 - 1.1 only)

SYNOPSIS

C Syntax:

void set_ray_item_buffer(fildes,scene_id,item_buffer_mode);
int fildes,scene_id,item_buffer_mode;

void inq_ray_item_buffer(fildes,scene_id,item_buffer_mode);
int fildes,scene_id,*item_buffer_mode;

FORTRAN77 Syntax:

subroutine set_ray_item_buffer(fildes,scene_id,item_buffer_mode)
integer*4 fildes,scene_id,item_buffer_mode

subroutine inq_ray_item_buffer(fildes,scene_id,item_buffer_mode)
integer*4 fildes,scene_id,*item_buffer_mode

Pascal Syntax:

procedure set_ray_item_buffer(fildes,scene_id,item_buffer_mode:
integer);

procedure inq_ray_item_buffer(fildes,scene_id:integer;
var item_buffer_mode:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor returned by gopen when an I/O path to a graphics device is opened.

scene_id Scene identifier; as returned by create_scene.

Input/Output Parameters

item_buffer_mode
Item buffer mode setting for the given scene. May have the value NO_ITEM_BUFFER or SCREEN_ITEM_BUFFER.

Discussion

NOTE: Set_ray_item_buffer and has no effect on the rendering process in HP-SBRR versions 2.0 and higher. Support for this command has been dropped in favor of internal optimization to the ray tracer. Although calls to set_ray_item_buffer will not cause errors in post-v1.1 applications, use of this command should be discontinued. Inq_ray_item buffer, if called in these versions, will always return NO_ITEM_BUFFER

Set_ray_item_buffer defines whether an item buffer accelerator is created for subsequent ray tracings of scene_id.

NO_ITEM_BUFFER means that an item buffer is not created for subsequent ray trace computes. Ray trace computes will run slower without an item buffer, but will not tie up the graphics screen during computations. NO_ITEM_BUFFER is the default value for this command.

SCREEN_ITEM_BUFFER means that the graphics screen is used to create the item buffer, and that the item buffer is left on the screen for the duration of the ray trace computation. This mode is the fastest, and uses the least amount of system memory. If the ray output is directed to the screen, the output will gradually overwrite the item buffer as the ray trace progresses.

Note that because the item buffer uses the graphics screen, the screen_on parameter to set_ray_output must also be set TRUE in order for an item buffer to be created. If screen_on is set FALSE, no item buffer will be created, regardless of the status of this command.

NOTES

The item buffer should not be used in applications that are to run under the X Window System.

Ray tracing parameters do not affect radiosity renderings of scene_id.

This command cannot be stored in a segment.

ERRORS

Invalid file descriptor.
Invalid scene_id.
Invalid item_buffer_mode.

DEFAULTS

The default item_buffer_mode for any scene is NO_ITEM_BUFFER.

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