Transparency with GL tools grid renderer

Blunder82's picture

Hi Guys,

I made this composition together with my good friend Søren. It's made of a lot of different composition we found around the net incl. here (thanks to all off you!). The composition is to be used with a show control program called Qlab which basically lets you render your image thru one composition. It is also able to play a number of different video files and control some published inputs in the composer file. And this is where the plot thickens: What I'm trying to make is a warped output universe on a TH2G using, Image crop, the Gl tools grid generator and the grid renderer. This works somewhat really close to what we want to do, but there is one set back which we can't workaround. When I fade the top layer picture to black I want to see the underlying Image. But this doesn't seem to work. I want the top layer to become more and more transparent, but i just keeps getting more and more black until it disappear. Is this possible at all? Hope you understand the question. To help the attached file is what we've been working on.

I'm not a total noob at QC, but I'm not that great either. So please reply in very easy to understand language.

Best regards, Rasmus

Grid_Warp_13.qtz292.66 KB

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gtoledo3's picture
Re: Transparency with GL tools grid renderer

When you fade to "black", instead of fading to values RGBA=0,0,0,1, fade to 0,0,0,0. Does that make sense? You can achieve that color value with the RGB color generator patch, as well as other patches.

Then, you want to set your "blend mode" to Over.

So, if I had a Sprite with and RGB color generator attached, and the sprite in over blend mode, with R/G/B at 0/0/0, and then hooked an interpolate to the A (alpha) input on the RGB color generator, with a start value of 1, and an end value of 0, in repeat mode of none, I would expect an image to fade from pure "black" to "smoky translucent" to finally, "invisible".

If your actual "artwork" has alpha black value (0,0,0,0) then placing a render patch in "over" will make the black areas render translucently.

I haven't looked at the actual attachment.

Blunder82's picture
Re: Transparency with GL tools grid renderer

Hi gtoledo3,

Thanks a bunch and for the very good talk thru . This and removing a clear patch solved the problem! There is still a clear patch in the first render in image!

Best, Rasmus

wbdreynolds's picture
Re: Transparency with GL tools grid renderer

hi there did you ever get this working? i'm trying to do basically the same things (with out splitting up the image for a triple head) but am having problems with the 'over' blend mode - it doesn't ever seem to get to full opacity (it fades out fine to nothing when i adjust the alpha channel in the colour setting of the image but will not go fully 'solid' when i bring the alpha back up to full.) no opacity problems if i set blend mode to replace but i'm also using Qlab and doing that means it fades to black when i fade out the image in qlab rather than fading by alpha. testing your file from your first post gives the same problem. my patch is attached - any help from anyone would be much appreciated. will

grid warp from file.qtz265.65 KB