Drop Shadow Actor?

[Salimelo]

Hello community,

I did a lot of research about finding a drop shadow actor in Isadora, but couldn't find anything! Does anybody have a suggestion?

THANK YOU :)

[jhoepffner]

@Salimelo

Hello, your question is about with kind of shadow? For text on background? For 3D light and object?

[Salimelo]

@jhoepffner: hi! In this case, I am dealing with round disks of the size of 60px. Statical content in the format of png containing alpha channel information, so they appear round and without square shaped background. They are appearing on top of another layer that serves as a background. I want to add a little drop shadow so the disks separate a bit better from the background. THX :)

[Juriaan]

Ehhh, does the shadow needs to fade-in and fade-out ? Because honestly if it was just static I would open it up in a graphic program, add the drop shadow and just drop it back in isadora. 

[jhoepffner]

@Salimelo

I made a try, using the same motif with alpha channel, transforming it to black (colorizer), blurring it (Gaussian Blur) and moving it with position (projector)

I tried to make a GLSL shader but, unfortunately, isadora shaders doesn't import alpha mask…

Capture d’écran 2017-08-20 à 10.53.54.png

alphaShadow.izz

[Salimelo]

@Juriaan. Thank you, very good point indeed. I have thought about it beforehand, I just wanted to have the freedom to adapt the shadows on the fly. Anyway, your proposal might become the method of choice since I obviously need to save GPU power!

[Salimelo]

@jhoepffner: Thank you very much for help and taking on the challenge! I am amazed by the fact that you can build GLSL shaders! I have tried to understand what an alpha mask is, but I still don’t. Would you mind giving a short try to explain? Thank you :)

[jhoepffner]

@Salimelo

2 different questions…

alpha mask, in image computing, color iis determined as RGBA, A is alpha channel determining the transparency of the pixel. Its necessary in compositing and many other uses. Some software directly output it, as 3D software, in other, as Photoshop, you can create it (Memorize selection). For film it's supported by Animation, HAP alpha and ProRes 4444, in still it's supported by PSD, PNG and TGA files.

GLSL shaders are another story, it's very powerful as a tool who do what you want with image, all computations made in the GPU. There is good tutorials, particularly Books of Shaders. The problem is to navigate between the different versions and implementations of glsl.

[Salimelo]

@jhoepffner: merci beaucoup. I knew what an alpha channel is, I dealt with it at many occasions making use of plenty of applications. I know about codecs and containers and I found that Isadora is a bit picky when it comes to mainly movie content containing alpha. Since it took me a lot of trying to find out, it might be worth noting here that also png is a codec for movie containers and that the alpha channel of png encoded material is accepted by Isadora! What I still don't understand though, is what an alpha mask is doing …