Cycling 74 » Topic: jit.gl advice desperately needed http://cycling74.com/forums/topic/jit-gl-advice-desperately-needed/feed Wed, 19 Jun 2013 23:23:48 +0000 http://bbpress.org/?v=2.2.4 http://cycling74.com/forums/topic/jit-gl-advice-desperately-needed/#post-56449 <![CDATA[jit.gl advice desperately needed]]> http://cycling74.com/forums/topic/jit-gl-advice-desperately-needed/#post-56449 Wed, 20 Apr 2011 23:30:46 +0000 jeffburger Hi jit.gl heads,

I’d greatly appreciate some advise on a Jitter OpenGL project. (I’ve already achieved this in non-GL Jitter, but need to rebuild using OpenGL for speed.) I’ve experimented with the various jit.gl objects but can’t seem to combine them in a way that achieves the goal.

- A background canvas of arbitrary size/aspect. (I’m assuming this can be a jit.gl.videoplane for onscreen display, then dumped to a matrix for file storage.)
- Multiple layers of photos, each layer having:
— on-the-fly arbitrary layer scaling and cropping of the original photo, with the ability to either maintain aspect ratio or stretch to arbitrary size/ratio
— on-the-fly arbitrary layer rotation (tx.rota seems fine for this)
— multiple shaders per layer
— replication effects on each layer such as tx.rota (fold edges)and tx.kaleida shaders
— layer blend and opacity relative to other layers

Attempt #1. I’ve successfully layered multiple videoplanes in a rendering context, however there appears to be no way to selectively blend multiple videoplanes. (The bed of a layer still shows solid after reducing the opacity on a layer texture.) [I can post a patch of this attempt if it's the right direction. Omitted here for brevity.]

Attempt #2. Blending two different-sized input matrixes in jit.gl.slab alone (ala Jitter tutorial 42) seems to force everything to the shared aspect ratio specified in jit.gl.videoplane. (tx.rota shader only let’s me zoom to scale uniformly. And changing the rect values on the slabs lets me crop the texture… but I can’t change the aspect of the plane the texture sits on to match the texture crop… and scaling the texture smaller than the plane it’s on leaves an opaque area of the plane. [I can post a patch of this attempt if it's the right direction. Omitted here for brevity.]

Attempt #3. I’ve also tried to map the photos as textures onto jit.gl.gridshape planes for each layer to see if adding that to the chain of slabs leading to a single vidplane solves the problem, but I’m not having any luck using the texture method to bind individual textures to object surfaces in individual layers—or jit.gl.render for that matter. [Patch listed below on the possibility that this is the right direction. ;) ]

– Pasted Max Patch, click to expand. –

Using jit.gl.mesh instead of gridshape could theoretically give me interesting deformation options, so I’m open to that approach. jit.gl.sketch looks like it might accomplish some of my goals with a single object, but I still need to aply multiple shaders to each layer… and jit.gl.sketch seems daunting given that I’ve not had any luck on the above.

BTW, I’ve read some advise suggesting that operations like cropping are best done before texturing. Even so, I need to be able to set the plane that the texture sits on to the arbitrary aspect of the texture so the texture fills it completely so any sizing/scaling acts as one. And I’d like to be able to change the cropping quickly on the fly, so handling cropping in GL still seems desirable if I can get there.

I know that was a long post, but I truly don’t know what direction to take now amidst various attempts… or how to fix what I’m missing if I’m already close.

Thanks so much for your help!

]]> http://cycling74.com/forums/topic/jit-gl-advice-desperately-needed/#post-202423 <![CDATA[Re: jit.gl advice desperately needed]]> http://cycling74.com/forums/topic/jit-gl-advice-desperately-needed/#post-202423 Mon, 25 Apr 2011 20:30:21 +0000 cap10subtext Sorry I’m having trouble wrapping my head around this post. I could probably be more help if you could narrow this down to a specific question or list of questions, ie: How do I _______?

You look like you are making progress but you aren’t going to advance much further until you can start to be very clear in your order of operations. OpenGL only likes it when you draw things in the correct order, so I recommend modifying your trigger object working under a single metro. Your drawing commands, banging textures etc should all be done between the first “erase” message and the last “bang”.

This will clean up your patch as well as getting you running in the right directions (things may not appear if you are sending drawing them in the wrong order).

I’m also sorry if this isn’t what you were asking but if you want to do multiple jit.gl.slab transformations, you can daisy chain them together rendering them finally to your video plane.

Hope this helps at all.

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