Converts point coordinates from destination coordinate system to source.
int
ade_projptbackward(
ads_point pt,
ads_point result);
Returns RTNORM or an error code.
| pt | Destination point to convert, a set of 2D or 3D coordinate values. If 3D, the Z value is ignored. |
| result | Corresponding source values. |
Before you can use ade_projptbackward to convert points, you must first identify the coordinate systems that you are converting between. Use ade_projsetsrc to set the source system and ade_projsetdest to set the destination system. The ade_projptbackward function assumes that the coordinate values you pass to it belong to the destination system, and it returns corresponding source values. The ade_projptforward function does the inverse.
The following example prompts the user for a destination point and returns the corresponding source coordinates through the result parameter.
ads_point pt1; ads_point result; ads_getpoint (NULL, "Pick a point", pt1); ade_projptbackward (pt1, result);
For more information, see Converting Coordinates.