NAME

vpSetCallback - define a callback function

SYNOPSIS

#include <volpack.h>

vpResult

vpSetCallback(vpc, option, func)

: vpContext *vpc;
: int option;
: void (*func)();

ARGUMENTS

vpc: VolPack context from vpCreateContext.
option: A code specifying which callback function to set.
func: A pointer to the callback function.

DESCRIPTION

vpSetCallback is used to set a callback function. The following list gives the possible values for option:

VP_GRAY_SHADE_FUNC: The func argument is a shading callback function that produces a floating point grayscale pixel intensity. The function should be declared:

: void func(void *voxel_ptr, float *i_ptr,
void *client_data);
voxel_ptr: Pointer to the beginning of a voxel that must be shaded.
i_ptr: Location into which the function should store the grayscale intensity result. It should be a single-precision floating point in the range 0.0 (black) to 1.0 (white).
client_data: Pointer to the application-defined client data (see vpSetClientData(3)).

The callback can be used to implement custom shading routines that cannot be implemented with a lookup table. See vpSetLookupShader(3) for more information.

VP_RGB_SHADE_FUNC: The func argument is a shading callback function that produces a floating point RGB pixel intensity. The function should be declared:

: void func(void *voxel_ptr, float *r_ptr,
float *r_ptr, float *r_ptr,
void *client_data);
voxel_ptr: Pointer to the beginning of a voxel that must be shaded.
r_ptr, g_ptr, b_ptr: Location into which the function should store the RGB intensities of the result. Each intensity should be a single-precision floating point in the range 0.0 (no intensity) to 1.0 (full intensity).
client_data: Pointer to the application-defined client data (see vpSetClientData(3)).

The callback can be used to implement custom shading routines that cannot be implemented with a lookup table. See vpSetLookupShader(3) for more information.

VP_READ_FUNC: The func argument is a callback function that takes the same arguments and returns the same result as the read(2) system call. This function is used to read data from files (see vpLoadRawVolume(3)). By default, the read system call is used. The callback can be used to implement a custom I/O interface, for example a compression/decompression system.
VP_WRITE_FUNC: The func argument is a callback function that takes the same arguments and returns the same result as the write(2) system call. This function is used to write data to files (see vpStoreRawVolume(3)). By default, the write system call is used. The callback can be used to implement a custom I/O interface, for example a compression/decompression system.
VP_MMAP_FUNC: The func argument is a callback function that is called to memory map data from a file instead of copying the data into memory (see vpLoadRawVolume(3)). The function should be declared:

: void *func(int fd, unsigned offset,
void *client_data);
fd: File descriptor from open(2) open for reading.
offset: Byte offset in the file to the beginning of the memory to be mapped.
client_data: Pointer to the application-defined client data (see vpSetClientData(3)).

The function should map the entire file into memory and return a pointer to the memory location that corresponds to the file offset. By default, memory mapping is disabled.

VP_STATUS_FUNC: The func argument is a callback function that is called periodically during long-running operations such as during preprocessing of a volume. The function should be declared:

: void func(double frac, void *client_data);
frac: An estimate of the fraction of the current operation that is complete.
client_data: Pointer to the client data associated with the context.

The callback can be used to print a status report or to process time-critical events such as user input. However, the callback should not make any calls to VolPack functions since the internal VolPack state may be inconsistent.

VP_LOG_ALLOC_FUNC: The func argument is a callback function that is called whenever VolPack allocates memory. The function should be declared:

: void func(void *ptr, int size, char *use,
int line, char *file, void *client_data);
ptr: Address of the allocated memory.
size: Size (in bytes) of the allocated memory.
use: Short description of the use of the allocated memory.
line: Source code line number for the call to the memory allocator.
file: Source code file name for the call to the memory allocator.
client_data: Pointer to the client data associated with the context.

The callback can be used to track memory allocations (primarily for debugging memory leaks).

VP_LOG_FREE_FUNC: The func argument is a callback function that is called whenever VolPack deallocates memory. The function should be declared:

: void func(void *ptr, void *client_data)
ptr: Address of the deallocated memory.
client_data: Pointer to the client data associated with the context.

The callback can be used to track memory deallocations (primarily for debugging memory leaks).

If the func argument is NULL then the corresponding callback function is reset to the default behavior or disabled if there is no default behavior.

ERRORS

The normal return value is VP_OK. The following error return value is possible:

VPERROR_BAD_OPTION: The option argument is invalid.

NAME

SYNOPSIS

ARGUMENTS

DESCRIPTION

ERRORS

SEE ALSO