» VL.Skia
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VL.Skia

Skia is a modern and fast 2d rendering library. As usual, we stand upon the shoulders of giants when making this functionality available to you: the core Skia technology and the .Net binding "SkiaSharp". The VL.Skia package aims to make all of this functionality available within VL in an easy-to-use high-level node set.

You now can have the first glimpse on it. From the start, it comes with a nice stack of tutorials and example patches. This package is done for vvvvbeta37.

Here is a rough overview of what the key concepts are:


Layers and Renderers

Just like known from vvvv the main idea is that layers can be grouped and can be connected to a renderer to draw them. Most Layers come with a Bounds input OR Position and Size and Anchor.

We offer different renderers:

  • Renderer: this one comes with a window
  • Renderer (OffScreen): outputs an image that can be drawn with DrawImage or converted to an IImage via ToImage. Here is what you can do with an IImage.
  • SVGWriter, PDFWriter: they take a Layer and write an SVG or PDF file to disk
A Layer connected to a Renderer

Paint

Every layer comes with a Paint input. It describes how to draw the layer. This is very comparable to the render states in DX9/DX11.

You can stack the Paint-modifying nodes. Nodes like SetColor would take everything from the incoming paint and only adjust the color.

Stroke sets up some paint properties

Shaders, Filters, and PathEffects are all properties of Paint. 1000 words wouldn't be enough to describe what you can do with them. You probably just need to play with them a bit.

What can I say

Text

Text nodes are also just Layers. You can think of them as text boxes.

Within that rectangular region you now can adjust horizontal and vertical alignment. This is done via properties of Paint. The FontAndParagraph node allows to conveniently adjust several text related paint properties in one go.

You can visualize the text box with the Show Helpers pin of FontAndParagraph.

(See the examples\3_Text for how to do word wrapping etc.)


Transforms

Layers can be transformed. This allows you to patch a Camera. You would then connect your scene to the Camera and the camera to the renderer.

Transforms are not that important as in 3D rendering frameworks as all Layers already can be placed.
Scaling a Layer influences the stroke width. If this is unwanted specify the Size on the layer itself and not via transform node.
Everything scales. Also the stroke

Spaces

We designed the library in a way that it works for different scenarios. Sometimes you would like to think in a normalized space, like known from DX9/DX11. In other scenarios, you want to think pixel- or device-independent-pixel-based.
You can choose the space on the renderer. But you can also combine spaces: With the WithinCommonSpace node you can adjust the space for everything upstream. By that, you could have a game that adjusts its content depending on the size of the renderer and still draw some text top-left with a constant text size no matter how big the renderer is. (See examples\1_Basics\08_Spaces-Overview for more details)

Top Left - Device Independent Pixels

Interaction

Layers in Skia can be interactive. The main idea here is: "What you see is what you want to interact with". So if the layer is interactive, connecting it to the renderer in one way or the other means that it will be drawn AND that you can interact with it. (See examples\5_Interaction)

This part is under construction still.
Button is just a experimental proof of concept node

How to install

In order to use this library with VL, you have to install the NuGet that is available via nuget.org. For information on how to use NuGets with VL, see Managing NuGets in the VL documentation. In short, navigate via document menu to Dependencies -> Manage NuGets -> Commandline and then type:

nuget install VL.Skia -prerelease -Source nuget.org

As long as we don't have an example browser here is how to get them via windows explorer:

VVVVDir\lib\packs\VL.Skia...\examples

Drag & drop an example patch onto vvvv or VL. For closing the example use the X on the renderer or hit Ctrl-F4 on the VL patch.

Happy exploring!

Yours,
Devvvvs

gregsn, Saturday, Jul 28th 2018 Digg | Tweet | Delicious 17 comments  
u7angel 29/07/2018 - 22:56

impressive

milo 30/07/2018 - 09:43

wow. This thing opens a new universe for creating UI within v4.
big Up guys!

u7angel 30/07/2018 - 12:45

minor thing, the renderer flickers sometimes here. but i guess this is already on the issue list

gregsn 30/07/2018 - 16:16

@u7angel: you mean when changing the patch? That's probably a hotswap issue. This one is on the list. Yes. Thank you!

dominikKoller 01/08/2018 - 13:45

Nice! Looking forward to trying it!

As for interaction, are there plans yet what happens when there are multiple renderers attached? Big topic and under construction, I know

gregsn 01/08/2018 - 17:54

@dominikKoller: attaching an interactive layer to several renderers just works - it gets drawn and is interactive.

gegenlicht 03/08/2018 - 12:18

Ive tried the Girlpower patches and really like the look! It looks really close to how Flash Rendered games look like. Very Crisp and Smooth 2d :) Is there a way to Check Performance FPS on the renderer?

soriak 03/08/2018 - 12:22

is the harfbuzz integration also on the list? (to implement it in the vl wrapper)

what rendering method are you using? (hw accelerated yet?)

joreg 03/08/2018 - 17:03

@gegenlicht there is no perfmeter yet but check VL.Skia\examples\6_Demos\Skia-Spray.vl for how it could be done

@soriak yes, the renderer is hw accelerated (opengl under the hood) and harfbuzz is not exactly on our list but should be simple to integrate

sebescudie 05/08/2018 - 18:13

I can see some awesome potential for GUIs, once again : big up !

io 08/08/2018 - 01:54

How would you create a linear fader and rotary pot (interactive) ?

velcrome 17/08/2018 - 11:42

At LINK you (the devs) showed to a select few how to register a skia control to a datatype for in-patch use. Some kind of Make-Your-Own-IOBox if I understood correctly.

Is there any online ressource on how to do that?

joreg 17/08/2018 - 11:54

@velcrome i'm afraid this is not yet released, still needs some work..

gregsn 20/08/2018 - 17:43

@io: this is still under construction, but if you navigate into Button, ButtonBehavior and ButtonRendering you can already inspect the general idea of how this may work in the future.

Another idea, for now, is to use the Console node which may serve as a glue:

  • it, for now, outputs Keyboard and Mouse devices, that can be consumed by several nodes including MouseState and KeyboardState.
  • connect it to a group node. That way you have one layer input free to connect your rendering layers.
  • when working with MouseState consider using the first output "Position in World", giving you a position that plays well together with the transform nodes.

There will be some proper documentation when this part is more polished.

jerry 01/10/2018 - 03:02

Suggestions to improve the article as those parts were unclear to me:

> For information on how to use NuGets with VL, see Managing NuGets in the VL documentation.

A link to the respective paragraph in the documentation would be helpful.

> In short, navigate via document menu to Dependencies -> Manage NuGets -> Commandline and then type:

Specify what document menu this is referring to. I initially couldn't figure it out (vvvv, some other development environment, ...). After looking around for a bit I figured it's the document menu of VL.

> Drag & drop an example patch onto vvvv

This doesn't work for me. vvvv only creates an IOBox with the path to the example. UPDATE: This works with the latest version of vvvv beta37.

yar 14/10/2018 - 20:59

Hi! Sorry, does it support features like boolean operations on paths?

joreg 14/10/2018 - 23:40

@yar absolutely, see: lib\packs\VL.Skia...\examples\4_Path\03_Path-Operations.vl

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