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int teximport(string map, string attribute, <type>&value)
Reads a single value. Returns 1 on success or 0 on failure.
int teximport(string map, string token, int|string&values[])
Returns the number of strings in the array.
Note that if the values cannot be imported, values will not be written to and may remain uninitialized.
This function queries metadata stored in an image file, and works with most texture formats.
You can choose what properties are stored using the vm_saveoptions
Houdini property on a camera or light
(image:saveoptions in IFD).
However, the defaults probably contain all the information you'd want.
See rendering properties.
Queryable attributes
There are several generic attributes you can always query:
int texture:xres
X resolution of the texture map.
int texture:yres
Y resolution of the texture map.
int texture:channels
Number of channels in the texture map.
vector texture:resolution
Resolution of the texture as the vector (xres, yres, channels).
matrix texture:worldtoview
The transform matrix that will take world space points into the camera space used to generate the image.
matrix texture:projection
The transform matrix representing the projection matrix of the camera used to generate the image.
matrix texture:worldtondc
The transform matrix that will transform world spaced points into the NDC space of the camera used to make the image. The points are generated in homogeneous coordinates. That is, to get the values in the range 0 to 1:
matrix ndc; if (teximport(map, "texture:worldtoNDC", ndc)) { vector P_ndc = pos * ndc; // If the camera is a perspective camera, // dehomogenize the point if (getcomp(ndc, 2, 3) != 0) { P_ndc.x = P_ndc.x / P_ndc.z; P_ndc.y = P_ndc.y / P_ndc.z; } // Finally, scale and offset XY // from [-1,1] to [0,1] P_ndc *= {.5, .5, 1}; P_ndc += {.5, .5, 0}; }
string texture:tokens
A space separated list of all attribute names you can query.
The string &values[] version can query the following
texture:channelnames
List of all the raster plane channel names.
texture:channelsize
This returns an array of the number of floats in each image channel.
texture:channelstorage
This returns an array with a string for the underlying storage type for each channel (i.e. "uint8" or "real16").
texture:tokens
List of all the built-in tokens understood by teximport().
Examples
cvex test(string map="Mandril.rat") { for (string token : { "texture:xres", "texture:yres", "texture:channels", "texture:resolution", "texture:tokens", "image:pixelaspect", "space:world" }) { float fval; vector vval; matrix mval; printf("----------------- %s ---------------------\n", token); if (teximport(map, token, fval)) printf("'%s' = %g\n", token, fval); else if (teximport(map, token, vval)) printf("'%s' = %g\n", token, vval); else if (teximport(map, token, mval)) printf("'%s' = %g\n", token, mval); } }
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