The most typical semantic role of the direct object (Od) is that of the affected participant (animate or inanimate). The object participant does not cause the event denoted by the verb, instead, it is directly involved in the event and is affected in some way. For instance, the Od is affected in the sense that it is changed in its location and its owner.
1a.春风吹绿了草原。
Chūnfēng chuī lǜ le cǎoyuán.
(The spring breeze has turned the prairie into green.)
1b. 他烧了那封信。
Tā shāo le nà fēngxìn.
(He burnt the letter.)
In (1a) the object NP 草原‘cǎoyuán’ (grassland) is affected by the spring breeze in such a way that it has been changed into green, in (1b) the object 那封信‘nà fēngxìn’ (that letter) was so affected that it changed its form. Therefore both the object NPs have the semantic role of ‘affected’ or Patient.
[1] Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.