The calculation requires LibGandalf. You might need to specify additional include and library paths in the makefile. Build the program with the target QT_TEXT ("make QT_TEXT").
Load a 3D model you want to texture map. Press the "Mapping" button on the icon bar at the right end. A new window opens. Load a jpg image file. Select four corresponding points in the 3D data and the image data (see the first image below). Be aware of the order of the points! Corresponding points have the same color. All four points in the 3D model must lie on the same (VRML) shape. The texture coordinates will be only calculated for the shape with the four selected points. Pressing the calculation button should calculate the texture coordinates for the 3D model and map the image on the 3D data (see the second image below). Finally, save the 3D model with the new texture map as a VRML2 model.
You may want to use it first with this example model. The model consists of three planes. The three planes are already segmented into three VRML shapes (try "Display/Shape Colors" to see the shapes).