Abstract: In one embodiment, a method includes by a computing device, displaying a user interface for designing augmented-reality effects. The method includes receiving user input through the user interface. The method includes displaying a graph generated based on the user input. The graph may include multiple nodes and one or more edges. The nodes may include a detector node and a filter node connected by one or more edges. The method includes detecting, in accordance with an object type specified by the detector node, one or more object instances of the object type appearing in a scene. The method includes selecting, in accordance with at least one criterion specified by the filter node, at least one of the one or more detected object instances that satisfies the criterion. The method includes rendering an augmented-reality effect based on at least the selected object instance.