The PRD entry for environment states:
Transparent Floor: Transparent floors, made of reinforced glass or magic materials (even a wall of force) [...]
The PRD entry for Wall of Force states:
The caster can form the wall into a flat, vertical plane whose area is up to one 10-foot square per level. The wall must be continuous and unbroken when formed. If its surface is broken by any object or creature, the spell fails.
If interpreting RAW for the entire ruleset, is there any way a can PC caster create bridges/umbrellas/ramps using this spell? Or is there a different spell for planes of force at other angles?