I know that I can use the align and distribute functionality of libreoffice impress to align objects. However, when I want to align two objects, both of them move if I choose to align their centers. How can I use one of them as a reference point.
Inkscape, for example, has a "Relative to" option when aligning different objects. The "Relative to" can get values such as "First selected", "Last selected" etc. If "First selected" is chosen, the first object will be the reference point and it will not move.
Best Answer
You can protect an object position (i.e. your reference object).
Right click on the reference object, select Pozition and Size…. Check Position option under "protect" (see the screenshot below); then do the alignment.
PS: It seems LibreOffice takes the relative center of the whole two objects, i.e. the centerline of a surface covering two objects, and then move all of them so that their centers sit on that centerline.