On Wed, Jun 12, 2013 at 8:29 AM, Sletta Gunnar <gunnar.sle...@digia.com> wrote: >> > This graph concept might be a good usecase for a more complex example down >> > the line though.. I'll keep it in mind and maybe it will be included in Qt >> > in the future :) >> >> Oh... that sucks. > > I think so too, so I spent some time yesterday evening to put it together: > https://codereview.qt-project.org/#change,58589 > > It does the background, grid, line and dropshadow as 4 separate geometry > nodes and shows several new sides of the scene graph API. > > The line stroking is a bit crude as it doesn't account for the line angle so > steep slopes will come out thinner, but it should be a good starting point.
Oh wow! You're trying to do everything i tried in just a couple of hours where i would spend several nights and not even get close to what you just made. Thank you very much for this! > > cheers, > Gunnar > >> Well, i guess i'm just gonna have to play with this >> and see how it turns out. If (assuming i can figure it out) i get it >> working i will certainly share my code in here or on this list. > >> >>> >>>> - for the dropshadow, do exactly the same as for the line, except you can >>>> use the custom vertex shader to expand it a little bit more and change the >>>> opacity to make it a more blurry. >>> Here i really do wonder if it isn't easier to just make a simple line >>> component and use QtGraphicalEffects for the shadowing... I guess >>> experimenting with both will tell which option works best. >>> >>> >>>> - for the gradient under the line, create a trianglestrip and colorize it >>>> according based on the y position in the fragment shader. >>> Yeah, figured it would be something like that. Will do. >>>> >>>>> >>>>> 2. Another way i see is taking the OpenGL direct approach following >>>>> the "OpenGLunderQML example [1]. I can probably work of that example, >>>>> but i really try to stay away from doing direct opengl interaction.. >>>> >>>> Raw OpenGL has its benefits, which is why the example and the feature is >>>> there, but I've been thinking that the primary usecase for OpenGLUnderQML >>>> is when you have a game/cad app running and QML is just the HUD controls. >>>> Using raw opengl for UI elements has the downside that you don't get any >>>> inherited clipping, transformation, nor opacity so things might be quite a >>>> bit more complicated to manage inside your UI. >>> Exactly my opinion as well. I try to stay away from raw opengl calls. >>>> >>>>> >>>>> 3. A third possible way that i can think of is by throwing everything >>>>> out and starting over in a very abstract manner. Making a bunch of >>>>> small components (in C++) like: >>>>> (note: this is still for the charting stuff [0]) >>>>> - 1 component to draw the background with a little more power then a >>>>> Rectangle. However, if i choose this route i might as well use the >>>>> QtGraphicalEffects for the added power (gradients) since that provides >>>>> it. >>>>> - 1 component for drawing a grid on top of the gradient. >>>>> - 1 component for drawing a line where i probably only provide the >>>>> data indicating where the line should be. Again i can use >>>>> QtGraphicalEffects on top of this to add additional shadow. However, i >>>>> find the default OpenGL line drawing stuff (even with multisampling) >>>>> of a very very very poor rendering quality. I'm really thinking of >>>>> using the "vase renderer" for drawing a way sharper line [2] Another >>>>> note, this might also be very interesting for you to draw way sharper >>>>> "scene graph fonts" which at the moment still look quite blurry at >>>>> it's best under desktop environments. >>>> >>>> The distancefield fonts are unhinted and this is why they look more blurry >>>> than native fonts (at least on windows and potentially linux). You can >>>> enable native rendering by sacrificing font scalability: >>>> http://blog.qt.digia.com/blog/2012/08/08/native-looking-text-in-qml-2/ >>>> >>>>> - I'm stuck at how to animate the line as more data flows in.. >>>>> >>>>> I hope you can advice me here in picking an option to go for. It's all >>>>> quite a bit of work and all likely has the same end result. Right now >>>>> i'm leaning towards option 3 where i was trying to go for option 1 >>>>> till this very moment. >>>>> >>>>> >>>>> [0] http://i.stack.imgur.com/Zk2RG.png -- i try to make it look as >>>>> crisp as this one >>>> >>>> >>>>> [1] >>>>> https://qt.gitorious.org/qt/qtdeclarative/trees/stable/examples/quick/scenegraph/openglunderqml >>>>> [2] >>>>> http://www.codeproject.com/Articles/226569/Drawing-polylines-by-tessellation >>>>> >>>>> >>>>> On Mon, Jun 10, 2013 at 10:07 AM, Sletta Gunnar <gunnar.sle...@digia.com> >>>>> wrote: >>>>>> >>>>>> On Jun 8, 2013, at 11:33 PM, Mark <mark...@gmail.com> wrote: >>>>>> >>>>>>> Hi, >>>>>>> >>>>>>> Back when the graphical effects where first showcased in a blog i was >>>>>>> already kinda scared that there would be no C++ interface to use them >>>>>>> from the C++ side. Now i find myself in the position where i want to >>>>>>> use the DropShadow element from that very same module in custom QML >>>>>>> Scene Graph module and give a line a shadow. >>>>>>> >>>>>>> I kinda - very much - dislike copying the relavant parts of the >>>>>>> DropShadow code and re-create that in C++.. >>>>>>> >>>>>>> Is there a way that i can use DropShadow from the C++ side? >>>>>> >>>>>> There is no way to do this using pure C++ API. You could construct it >>>>>> from c++ using QQmlComponent and set the source property by passing it >>>>>> the item that creates the geometry node. >>>>>> >>>>>> cheers, >>>>>> Gunnar >>>>>> >>>>>>> >>>>>>> Regards, >>>>>>> Mark >>>>>>> _______________________________________________ >>>>>>> Interest mailing list >>>>>>> Interest@qt-project.org >>>>>>> http://lists.qt-project.org/mailman/listinfo/interest >>>>>> >>>> >> _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
