【转帖】exture Coordinates
 

texture coordinates
texture coordinates
hello there !
could someone just tell where i can find information on the texture coordinate system in dd ? it seems to me that i'm supposed to use the "xdata" stuff... but how am i supposed to extract this information i want and how can i use it ? (ie: is there a way to assign those uv coords to each vertex when using the vectorization framework for example ?)
thanks for your help !
manu.
xdata for uv coords (in fact uvw matrix transformation ?)
hello again !
i tryed to use odreadex sample to check some xdata, and the only thing i found is something like:
xdata:
1011. . . . . . . . . . . . . . [43.2 510.0 3.0]
1011. . . . . . . . . . . . . . [44.2 510.0 3.0]
1011. . . . . . . . . . . . . . [43.2 511.0 3.0]
1011. . . . . . . . . . . . . . [43.2 510.0 4.0]
does this represent the uvw coord system i'm looking for ?? in this case, am i right tu assume that i will always have 4 values in this order : the origin, the x axis, the y axis and the z axis ?...
and if this is the only way to represent the uv coords, it means that autocad is limited to one simple matrix transform to apply those coords... (which could be easily linking to texture matrices in opengl for example i guess...) ? this means that those coords cann't be assigned per face inside a given entity, am i wrong ?
manu.
where are 2 kinds of materials used by autocad: avematerials (used up to ac2006) and dbmaterials (used sinse autocad 2007)
ave materials and related data were stored as xdata of ave_* application (ave_finish, ave_render, ave_entity_material etc.)
new material-related stuff is represented by new classes of database objects: acdbmaterial etc.
autocad 2007 which started using new materials simply ignores old (ave) data. autocad 2008 started to perform convertion between old and new representations (it's not always possible without some loss of information).
current dwgdirect does not perform convertion between old and new representation of materials.
materials from new drawings can be accessed via oddbmaterial, oddbmaterialmapping etc. classes.
materials from old drawings (ave) can be accessed via helper classes which parse the xdata. see headers from /include/ve folder and odaveex sample from /examples/odaveex.
uv mapping is stored in ave_entity_material xdata which represents mapping (the name is confusing).
sergey slezkin