Hello Mike, One pitfall when deleting nodes is that the inherent node numbering changes. E.g. If you had nodes 1, 2, 3, 4 and delete note 2, you are left with 1, 2, 3. If you are looping through your nodes with a for...next loop, you can either change your node count every time you delete a node or (the trick I use) process your nodes backwards.
As for multi-part objects and node counting, the ObjectInfo() function is your best friend. ObjectInfo(YourObj, OBJ_INFO_NPOLYGONS) gives you the number of polygons in a region, or the number of sections in a polyline. ObjectInfo(YourObj, OBJ_INFO_NPOLYGONS+i) gives you the number of nodes in polygon/section number "i". Use the above to construct your outer loop (for polygons and sections) and inner loop (for nodes), then use: ObjectNodeX(YourObj, i, j,) to get the X/longitude for polygon/section I, node j ObjectNodeY(YourObj, i, j) to get the Y/latitude Make sure you coordsys is set (explicitly or from a table) so that the coordinates coming out of these functions are what you expect. Delete your nodes with: Alter Object YourObj node remove position i, j When you're done changing YourObj, make sure you write it back to a table using a SQL "update". Since you only want to change the row where the object came from you should keep track of the .rowid and update "where rowid = YourRowId". Hope that helps. Node strip away... Regards, Warren Vick Europa Technologies Ltd. http://www.europa-tech.com -----Original Message----- From: Cummings, Mike [mailto:[EMAIL PROTECTED] Sent: 09 April 2004 01:43 To: [EMAIL PROTECTED] Subject: MI-L Problems with nodes in mapbasic I've been trying to write code to delete nodes basic on certain criteria. I can't get the "alter object" code to work. None of the nodes are deleted, even when I remove the criteria and I loop through all the nodes. I'm clearly missing something. (Because I can't get the alter table command to work either.-halt with an error message about having to save the file.) Also, if you have a multi-region object: I know you can determine the number of polygons and the number of nodes for the object. How do you determine what nodes are with what polygons? I've been looking for a reference that explains nodes and the related mapbasic codes and haven't been too successful. Does anyone have a good reference? --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 11345 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 11351
