On Monday 06 May 2013 06:39:06 Sletta Gunnar wrote: > On May 5, 2013, at 11:47 AM, Sean Harmer <sean.har...@kdab.com> wrote: > > On 04/05/2013 19:30, Preet wrote: > >> Hi, > > ... > > >> 2. > >> I'd like to use ShaderEffects to apply a somewhat trivial shader to most > >> of the images in my application. The images are black and white icons, > >> and I'd like to use shaders to change the black and white output > >> fragments to different colors (ie maybe blue and green, red and yellow, > >> etc). > >> > >> The shader itself is super simple and probably adds negligable cost to > >> the pipeline, but I'm concerned about how overall performance would be > >> affected compared to the default method QtQuick uses to render a bunch > >> of images. > >> > >> Would QtQuick still intelligently batch the images and draw them using > >> only a few calls? Or would it individually bind the same shader and > >> issue a separate draw call for each image?> > > Using a ShaderEffect item implies rendering the source to a texture via an > > FBO and then applying the effect's shaders to the resulting texture. > > Therefore using many ShaderEffects will produce a performance impact at > > some point. If you really have many of these items to show it would be > > better to implement a custom item using the scene graph api. Take the > > existing QSGSimpleTextureNode or image item as starting points and > > provide a custom material that renders using your colourisation shader. > > > > This way you avoid the FBO pass for each item. > > This is not quite correct :)
Oops yeah sorry. I was assuming more complex case but even then the FBO pass is only done when the input changes not every frame. Sean _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
