--- name: "Get" section: "3" platform: "linux" package: "libvolpack1-dev" version: "1.0b3-10" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/Get" --- # Get(3) get the value of an option ## NAME vpGeti, vpGetd, vpGetp - get the value of an option ## SYNOPSIS \#include \ vpResult **vpGeti(***vpc, option, iptr***)** - vpContext \**vpc;* - int *option;* - int \**iptr;* vpResult **vpGetd(***vpc, option, dptr***)** - vpContext \**vpc;* - int *option;* - double \**dptr;* vpResult **vpGetp(***vpc, option, pptr***)** - vpContext \**vpc;* - int *option;* - void \**pptr;* ## ARGUMENTS - *vpc* VolPack context from **vpCreateContext.** - *option* Constant that specifies the option to be retrieved. - *iptr* Location to store an integer result. - *dptr* Location to store a double result. - *pptr* Location to store a pointer result. ## DESCRIPTION These functions are used the get the values of integer-, double- or pointer-valued state variables in a rendering context. The following list summarizes the integer-valued options that can be retrieved with **vpGeti**. The value of the option is stored in the location given by *iptr;* the return value of **vpGeti** is not the value of the option. Unless otherwise noted, the result is a single integer and *iptr* should point to a single integer location. - VP\_XLEN Get the length of the X dimension of the volume in voxels. - VP\_YLEN Get the length of the Y dimension of the volume in voxels. - VP\_ZLEN Get the length of the Y dimension of the volume in voxels. - VP\_BYTES\_PER\_VOXEL Get the size of a voxel in bytes. - VP\_VOXEL\_FIELD\_COUNT Get the number of fields in a voxel. - VP\_SHADE\_FIELD\_COUNT Get the number of fields in a voxel used as parameters for shading the voxel. - VP\_FIELD\_SIZES Get the size of each voxel field in bytes. *iptr* must point to an array of integers containing one entry for each voxel field (use VP\_VOXEL\_FIELD\_COUNT to determine the number of fields). - VP\_FIELD\_OFFSETS Get the byte offset from the beginning of a voxel for each voxel field. *iptr* must point to an array of integers containing one entry for each voxel field (use VP\_VOXEL\_FIELD\_COUNT to determine the number of fields). - VP\_FIELD\_MAXES Get the maximum value of the quantity stored in each voxel field. *iptr* must point to an array of integers containing one entry for each voxel field (use VP\_VOXEL\_FIELD\_COUNT to determine the number of fields). - VP\_VOXEL\_DATA\_SIZE Get the size (in bytes) of the 3D voxel array. - VP\_VOXEL\_XSTRIDE Get the stride (in bytes) for the X dimension of the 3D voxel array. - VP\_VOXEL\_YSTRIDE Get the stride (in bytes) for the Y dimension of the 3D voxel array. - VP\_VOXEL\_ZSTRIDE Get the stride (in bytes) for the Z dimension of the 3D voxel array. - VP\_CLASSIFY\_FIELD\_COUNT Get the number of fields in a voxel used as parameters for classifying the voxel (the number of arguments to the opacity transfer function). - VP\_CLASSIFY\_FIELDS Get the field numbers for the arguments to the opacity transfer function. *iptr* must point to an array of integers containing one entry for each argument (use VP\_CLASSIFY\_FIELD\_COUNT to determine the number of arguments). - VP\_CLASSIFY\_TABLE\_SIZES Get the size (in bytes) of each lookup table used for the opacity transfer function. *iptr* must point to an array of integers containing one entry for each lookup table (use VP\_CLASSIFY\_FIELD\_COUNT to determine the number of lookup tables, which equals the number of arguments to the opacity transfer function). - VP\_COLOR\_CHANNELS Get the number of color channels that the current shading lookup tables or shading callback function will produce. - VP\_SHADE\_COLOR\_SIZE Get the size of the shading lookup table for color values (see vpSetLookupShader(3)). - VP\_SHADE\_WEIGHT\_SIZE Get the size of the shading lookup table for weight values (see vpSetLookupShader(3)). - VP\_MATERIAL\_COUNT Get the number of material types used by the current lookup shader (see vpSetLookupShader(3)). - VP\_SHADE\_COLOR\_FIELD Get the field number used for indexing the shading lookup table for color values (see vpSetLookupShader(3)). - VP\_SHADE\_WEIGHT\_FIELD Get the field number used for indexing the shading lookup table for weight values (see vpSetLookupShader(3)). - VP\_LIGHT0 - VP\_LIGHT1 - VP\_LIGHT2 - VP\_LIGHT3 - VP\_LIGHT4 - VP\_LIGHT5 The retrieved value is nonzero if the corresponding light is enabled, or 0 if it is disabled. - VP\_LIGHT\_BOTH\_SIDES The retrieved value is nonzero if two-sided lighting is enabled (see vpSetLight(3)), or 0 if it is disabled. - VP\_REVERSE\_SURFACE\_SIDES The retrieved value is nonzero if the definitions of interior and exterior surfaces have been reversed (see vpSetMaterial(3)), or 0 if they have not. - VP\_DEPTH\_CUE The retrieved value is nonzero if depth cueing is enabled, or 0 if it is disabled. - VP\_DEPTH\_CUE\_TABLE\_SIZE Get the current number of entries in the depth cueing table (see vpSetDepthCueing(3)). - VP\_DEPTH\_CUE\_SIZE\_HINT Get the current hint for the number of entries in the depth cueing table (see vpSetDepthCueing(3)). - VP\_CURRENT\_MATRIX Get the identifier for the current transformation matrix (VP\_MODEL, VP\_VIEW or VP\_PROJECT). - VP\_CONCAT\_MODE Get the identifier for the current matrix concatenation mode (VP\_CONCAT\_LEFT or VP\_CONCAT\_RIGHT). - VP\_IMAGE\_WIDTH Get the width (in pixels) of the output image array. - VP\_IMAGE\_HEIGHT Get the height (in pixels) of the output image array. - VP\_IMAGE\_SCAN\_SIZE Get the number bytes per scanline in the output image array. - VP\_VIEW\_AXIS Get the identifier for the current major viewing axis in the object coordinate system (VP\_X\_AXIS, VP\_Y\_AXIS or VP\_Z\_AXIS). The axis depends on the viewing transformation. - VP\_INTERMEDIATE\_WIDTH Get the width (in pixels) of the intermediate image required to render the current volume with the current viewing transformation (see vpRenderRawVolume(3)). - VP\_INTERMEDIATE\_HEIGHT Get the height (in pixels) of the intermediate image required to render the current volume with the current viewing transformation (see vpRenderRawVolume(3)). - VP\_INTERMEDIATE\_COLOR Get the number of color channels in the intermediate image (see vpRenderRawVolume(3)). - VP\_INT\_WIDTH\_HINT Get the current hint for the width (in pixels) of the intermediate image (see vpRenderRawVolume(3)). - VP\_INT\_HEIGHT\_HINT Get the current hint for the height (in pixels) of the intermediate image (see vpRenderRawVolume(3)). - VP\_VIEW\_X\_AXIS - VP\_VIEW\_Y\_AXIS - VP\_VIEW\_Z\_AXIS The retrieved value is non-zero if computing a preclassified volume for the corresponding major viewing axis is enabled (see vpClassifyVolume(3)). - VP\_VIEW\_X\_SIZE - VP\_VIEW\_Y\_SIZE - VP\_VIEW\_Z\_SIZE Get the size (in bytes) of the preclassified volume for the corresponding major viewing axis. - VP\_MMOCTREE\_THRESHOLDS Get the current min-max octree range thresholds. *iptr* must point to an array of integers containing one entry for each threshold (use VP\_CLASSIFY\_FIELD\_COUNT to determine the number of thresholds, which equals the number of arguments to the opacity transfer function). - VP\_MMOCTREE\_SIZE Get the size (in bytes) of the min-max octree. - VP\_SHADOW The retrieved value is nonzero if shadows are enabled (see vpSetShadowLookupShader(3)). - VP\_SHADOW\_LIGHT Get the constant (e.g. VP\_LIGHT0) associated with the current shadow light (see vpSetShadowLookupShader(3)). - VP\_SHADOW\_WIDTH\_HINT Get the current hint for the width (in pixels) of the shadow buffer (see vpSetShadowLookupShader(3)). - VP\_SHADOW\_HEIGHT\_HINT Get the current hint for the height (in pixels) of the shadow buffer (see vpSetShadowLookupShader(3)). - VP\_SHADOW\_COLOR\_SIZE Get the size of the shading lookup table for shadowed color values (see vpSetShadowLookupShader(3)). - VP\_SHADOW\_BIAS Get the current shadow bias value (see vpSetShadowLookupShader(3)). - VP\_PIXEL\_TYPE Get the current image pixel type (see vpSetImage(3)). - VP\_CLAMP\_SHADE\_TABLE The retrieved value is nonzero if clamping is enabled for shade table entries, or 0 if it is disabled (see vpShadeTable(3)). - VP\_COMPOSITE\_ORDER This value is used for debugging only. It returns 1 if the current major viewing axis (VP\_VIEW\_AXIS) points in the same direction as the viewing direction, or -1 if they point in opposite directions. The following list summarizes the double-valued options that can be retrieved with **vpGetd**. The result is always a single double and *dptr* should point to a single double location. - VP\_MIN\_VOXEL\_OPACITY Get the minimum opacity threshold (see vpSeti(3)). - VP\_DEPTH\_CUE\_FRONT Get the front depth cueing factor (see vpSetDepthCueing(3)). - VP\_DEPTH\_CUE\_DENSITY Get the depth cueing density (see vpSetDepthCueing(3)). - VP\_DEPTH\_CUE\_QUANTIZATION Get the depth cueing quantization (see vpSetDepthCueing(3)). - VP\_MAX\_RAY\_OPACITY Get the maximum opacity threshold (see vpSeti(3)). The following list summarizes the pointer-valued options that can be retrieved with **vpGetp**. Unless otherwise noted, the result is a single pointer and *pptr* should point to a single pointer location. - VP\_VOXEL\_DATA Get a pointer to the 3D voxel array. - VP\_CLASSIFY\_TABLES Get pointers to each of the lookup tables for the opacity transfer function. *pptr* must point to an array of pointers containing one entry for each table (use VP\_CLASSIFY\_FIELD\_COUNT to determine the number of tables, which is equal to the number of arguments to the opacity transfer function). - VP\_SHADE\_FUNC Get the shading callback function (see vpSetLookupShader(3)). - VP\_SHADE\_COLOR\_TABLE Get a pointer to the shading lookup table for colors (see vpSetLookupShader(3)). - VP\_SHADE\_WEIGHT\_TABLE Get a pointer to the shading lookup table for weights (see vpSetLookupShader(3)). - VP\_IMAGE Get a pointer to the output image array (see vpSetImage(3)). - VP\_LOG\_ALLOC\_FUNC Get a pointer to the memory allocator logging function (see vpSetCallback(3)). - VP\_LOG\_FREE\_FUNC Get a pointer to the memory deallocator logging function (see vpSetCallback(3)). - VP\_STATUS\_FUNC Get a pointer to the status reporting function (see vpSetCallback(3)). - VP\_READ\_FUNC Get a pointer to the file I/O read function (see vpSetCallback(3)). - VP\_WRITE\_FUNC Get a pointer to the file I/O write function (see vpSetCallback(3)). - VP\_MMAP\_FUNC Get a pointer to the file I/O memory mapping function (see vpSetCallback(3)). - VP\_CLIENT\_DATA Get a pointer to the client data (see vpSetClientData(3)). - VP\_SHADOW\_COLOR\_TABLE Get a pointer to the shading lookup table for shadowed color values (see vpSetShadowLookupShader(3)). ## ERRORS The normal return value is VP\_OK. The following error return values are possible: - VPERROR\_BAD\_OPTION The *option* argument is invalid. - VPERROR\_SINGULAR One of the current view transformation matrices is singular. (Only possible for options that depend on the current view transformation). ## SEE ALSO [VolPack(3)](/VolPack/3.md), vpCreateContext(3), vpSeti(3)