I have an STL previewer which can preview the file with mime type "application/sla" in alfresco. So I want to render the file with the mime type "application/ply" as "application/sla". For this, I have created a rule on a folder with the following script
var renderingEngineName = 'reformat';
var renditionDefinitionName = 'cm:stl';
var renditionDef = renditionService.createRenditionDefinition(renditionDefinitionName, renderingEngineName);
renditionDef.parameters['mime-type'] = 'application/sla';
renditionService.render(document, renditionDef);
And I am also able to see rendition child in node browser as given in a below image

But still, I am not able to get a preview of the files with mime type "application/pla".
I would be great if anyone can help me with this.