[PD] still struggling with basic understanding of Gem dataflow

[marius schebella]

hi john,
I just looked at your patches, here's what I think:
1) pix_buffer_write seems to copy and clear the pix buffer. so if your
pix_video is connected to pix_buffer_write it is gone and you don't
see it anymore (rectangle stays white). I am not sure if this is a
bug, it seems strange to me, too. but as soon as you disconnect the
pix_buffer_write the image will be shown on the rotated rectangle.
2) the rotateXYZ does not rotate the pixels, but only the geometry
that this texture is mapped to (the rectangle). so in your left
example you go from gemhead through buffer_read, texture to the
rectangle. in that line no rotationXYZ is applied to the rectangle.
marius.

2009/3/24 John Harrison <john.harrison at alum.mit.edu>:
> Attached is a small example patch of how I just don't get Gem...still...
>
> [pix_rtx] has a steady wave that normally flows from left to right.
>
> I would have thought that the attached patch shows me rotating the image
> first, then applying [pix_rtx]. So it would stand to reason in my mind I
> would see a rotated image with [pix_rtx] flowing from left to right.
>
> But that isn't the result I see. The patch has [pix_rtx] flowing from right
> to left now. It is as if [pix_rtx] is applied *before* the rotation instead
> of *after* as I would have expected.
>
> Grasping at straws, I have tried [pix_separator] between just about every
> object, but that makes no difference.
>
> What am I misunderstanding that makes the behavior of the patch make sense?
> And...how would I get [pix_rtx] to flow from left to right on a mirrored
> image?
>
> -John
>
> P.S. Are questions like this better on the Gem-dev list? That's a developer
> list but at the same time I feel a bit awkward putting too many Gem
> questions on a Pd list
>
>
> #N canvas 962 171 305 227 10;
> #X obj 29 -58 gemhead;
> #X obj 29 -35 pix_video;
> #X obj 29 44 pix_texture;
> #X obj 28 72 rectangle 4 3;
> #X obj 159 9 gemwin;
> #X msg 136 -34 create \, 1;
> #X msg 214 -33 destroy;
> #X obj 135 -57 loadbang;
> #X obj 29 17 pix_rtx;
> #X obj 29 -10 rotateXYZ 0 180 0;
> #X connect 0 0 1 0;
> #X connect 1 0 9 0;
> #X connect 2 0 3 0;
> #X connect 5 0 4 0;
> #X connect 6 0 4 0;
> #X connect 7 0 5 0;
> #X connect 8 0 2 0;
> #X connect 9 0 8 0;
>
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