How to select a rectangle area with mouse dragging on GLSceneViewer?

[lees-avg]

Morning everyone,
i’m Delphi-rookie and have been using GLScene for only 2 weeks, rite now i got several questions about GLScene.

My project seems not so difficult for the first 3 Steps:
1). Load a *.stl file (ASCII format) with OpenDialog and then draw it on the GLSceneViewer.
2). Use Trackbars to control the Scale and Rotations.
3). Use Mouse-Dragging (onMouseDown, onMouseMove, onMouseUp) to select a rectangle area on the 3D-Modell within GLSceneViewer.
*. on next step i will use a function to detect the bulge on the surface of loaded 3D-Model WITHIN this selected rectangle area for further robot-deburring (KUKA-Robot).


Questions:

Task 1) and 2) i have finished,

but for 3), i don’t know which commands i should use in GLScene to make a rectangle select-area with mouse-dragging (GLScene is so powerful, but the help-docu is not so good i think L ) over the 3D-Object / GLSceneViewer, because there is no command like this: "GLSceneViewer1.Canvas.Rectangle(x1,y1,x2,y2);"
Please help me!




Thanks for the reply!

Best regards
Lee