The voicings possible for piano chords are not always easy to play on guitar. Sometimes they may not be possible at all. There is a simple reason for this. Piano chords are easy to play when the notes are close together, and become somewhat harder as the notes are further apart. Guitar chords, on the other hand, become harder to play, as the notes become closer together. It is easy to see why this is the case: notes with adjacent pitches are on adjacent keys on the piano; notes on adjacent strings which are also on the same fret are (mostly) a fourth apart on guitar, as the strings are (mostly) tuned in fourths. The example below shows this in practice. The chord shown is very easy to play on the piano; although possible, it is difficult to play on the guitar, as you have to really stretch (remember, guitar sounds an octave lower than written…):
However, there is some "middle-ground". Arguably the easiest chords to play on piano, major and minor triads in close position, are also easy to play on the guitar. The example below shows a C Major and C Minor triad written for both piano and guitar. On guitar this chord shape can be transposed to the required key by simply shifting the chord shape up and down the neck; from this point of view it is actually easier to do than on piano (where different combinations of black and white keys must be learned for triads in different keys).
However, beyond this simple example, chord voicings tend to be different on piano than on guitar, for the reasons given above. Let's take an extended chord as an example. The example below shows a dominant 13th chord written: as it is constructed in theory, by stacking thirds; as a close voicing that would be really easy on piano (it misses out the 11th…); as a voicing that would work well on guitar (this misses out the 5th and 11th…):
Of course, there are many other possible voicings for this chord, using the range of both hands on the piano (arguably many better ones!); and there are many other voicings possible for G13 on guitar, too.
You can, of course, combine knowledge of notes on the fretboard, with knowledge of the notes required to produce required chords, to create your own shapes for guitar chords. However, the approach to doing this is different on guitar, to on piano. Whereas on piano you may tend to play the required notes closer together, on guitar you will tend to play the required notes in a voicing that allows them to be evenly spaced, approximately a fourth apart (so, mainly using 3rds, 4ths and 5ths). Below is an example that, I'm sure, many guitar teachers have shown to their pupils, to illustrate that complexity of chord is not necessarily related to complexity of guitar chord shape (or difficulty of execution):
(It's a pretty unsophisticated guitar chord to use, but hopefully it makes my point!)
Finally, it should be noted, that this approach isn't necessarily how guitarists learn chords. While it may make sense to learn piano chords by adding in the required notes, guitarists are far more likely to think in terms of learning shapes for chords. This is understandable; a pianist can see all the notes laid out side-by-side, "ready" to be selected for whichever chord (or set of pitches, if you like) is required. Because of the tuning in (mostly) fourths, a guitarist cannot do this as easily.
In reality, I would imagine that most pianists start with triads and add extensions, as they learn chords; they then think about changing the octave of required pitches to give more sophisticated voicings. In contrast guitarists are likely to learn a variety of shapes using some open strings, for basic major and minor chords (for example, C A G E D and Am Dm Em), before then moving onto: more complex chord types, but still using some open strings (eg. C7 B7 A7 G7 E7 D7 Asus4 Dsus4 Esus4 etc.); movable shapes for major and minor chords (these have no open strings and are often, but not always, barre chords); movable shapes for more complex chord types.
Finally, after already learning a wide variety of chord shapes, a guitarist would be likely to use his knowledge of the required notes in a chord to "make-up" his own chord voicings. There is no reason why a guitarist can't always create chord shapes from a purely theoretical starting point, by thinking within scales and arpeggios (as I'm guessing your question hints at), to find the necessary notes. But, from experience, this doesn't seem to be the way most guitarists start learning chords.
To start with, we guitarists learn shapes.