Reducing vertex colors to half their intensity

[treefish]

Good day all!

I have a particular model format which can only handle 128 color vertex color when exported from Maya. However I'd like to do my modeling/texturing in full (0 to 255'ed, or normalized 0 to 1) color space, then take all vertice color & alpha info down by a factor when exporting.

How might I go about reducing a polygon model's vertex colors to half their intensity?

I've experimented a bit with polyColorPerVertex & can query the different channels via:

float $vertr[]= polyColorPerVertex -q -r;
float $vertg[]= polyColorPerVertex -q -g;
float $vertb[]= polyColorPerVertex -q -b;
float $verta[]= polyColorPerVertex -q -a;

However I'm not sure how I can divide these array contents by 2 & then reapply the results to the model.

Any help would be greatly appreciated!
Thanks for your time!

[chris-rogers]

assuming you have only 1 vertex selected just loop through all of them:

float $vertr[]= polyColorPerVertex -q -r;
$vertr[0] = $vertr[0] / 2;
polyColorPerVertex -r $vertr[0];

i guess this command will return an array of r values for each vertex selected ( in case you have more than 1 vertex selected) so you could loop there instead, which is probably faster.

chris

[joojaa]

2 separate problems:

Reduce colors into maya model but thenagain why the hell would you bother with this:

Err... okay, yes you could do this (especially if you push them to file and leave maya intact) but the way mel works it would be highly inefficient (again if you push into a file in ascii form then the disk access is so inneficient in gerenla that it doesnt really matter).  But it so happens maya knows how to do this, it even has a gui for it.

What you do is you use artisan to flood a black color (same for alpha aöltough what you consider full may abe either 1 or 0) with 0.5 opacity in the brush contribution. Now this is MUCH faster to do then looping in mel. And its artist freindly thinking since you have a gui that you can use to accomplish this. Better yet you can echo what artisan does and you can accoplish the same thing with script real easy because meye writes the code for you (= istant dev time).

So maybe this opens the horizons a bit. For more complex calculation operations use mayas baking routines which are also much faster than looping in mel and again easier for artists to set up.

export:

On the otherhand maya doesnt store values in 0-255 maya stores values as floating point so you would be casting this to integers anyway so why bother adjusting the intensity to half? Its not like your 128 represets 0.5? THis however MIGHT be that the exporter is allready there. who knows.

Anyway WHY would you divide the intensity to half? your going to do a (int)floor($value*128) operatin on it anway in yoru code, as opposed to (int)floor($value*0.5*256)

Possibly also better design to do this oustde of maya, and fix it in your outer toolchain. Why? Well its a normalisation issue so your inetremediary format may be better for doing the change. Say you export to collada. Then its BETTER from a dev point to have a normalisation tool for collada assets. Because your data may come form other sources at some point and then not needing to fire up maya may be a boon for your prductivity as now this step of your toolchain is data source insesnitive. Which would eb great for the company if they merge in new artists assets etc. Plus now merging you to theors is easier too.

Same would apply to renders etc..

[treefish]

Thanks for the replies, both of you!
I suppose I should have said up front I am on the Art/design side, not a programmer/dev & have only a basic grasp of mel & programming in general.

Chris Rogers: Yeah, that whole looping part is what I don't quite understand. Thanks for the suggestion though!

Joojaa: Sorry, I always have a hard time explaining what I mean for things like this.

I realize the whole reducing colors stuff is strange but its necessary for the other tools in the pipeline of this project.

So here's what I'm trying to do:
- Model & vertex color edit in Maya with full 0-1 colors. This makes it easier to see what colors I will be getting in the final product.
- Reduce all vertex colors & alpha in half and export it (it's not necessary to convert all the colors & alpha into 255 equivalent for export). This of course makes all the colors less bright & the whole model transparent even in areas which should be completely opaque but when imported into the other tools, the exported model will appear nearly the same as it did before the reduction of colors/alpha in Maya.

Weird & hard to explain, I know. Besides Maya, the tools used are archaic as the project has continued for well over many years, thus it can't handle the whole scale of colors Maya can.

I was hoping the Paint Vertex Color Tool (that's what you mean by artisan, right?) would do something like this but it only seems to remove/add colors from each channel linearly. Is there some option I'm missing to reduce everything by 2?

Thanks again to both of you for your time & consideration!

[joojaa]

seems to remove/add colors from each channel linearly. Is there some option I'm missing to reduce everything by 2?

how old is your maya? Anyway maya can do it in 2 different ways.

Well atleast my paint vertex color tool has a scale option, just set the rgba values to 0.5 0.5 0.5 0.5 mode to scale and flood. You can convert this to mel if you wish.

setToolTo artAttrColorPerVertexContext;
artAttrPaintVertexCtx -e
                      -sao "scale"
                      -paintRGBA 1
             -cl4 0.5 0.5 0.5 0.5
             -opacity 1
          "artAttrColorPerVertexContext";
artAttrPaintVertexCtx -e
                      -clear
          "artAttrColorPerVertexContext";

Even if it does not a alternate method is to set mode to replace blush opacity to 0.5 and rgba value to 0 0 0 0 and flood.

setToolTo artAttrColorPerVertexContext;
artAttrPaintVertexCtx -e 
                      -sao "absolute"
                      -paintRGBA 1
			 -colorAlphaValue 0
			 -cl3 0.0 0.0 0.0 
			 -opacity 0.5
          "artAttrColorPerVertexContext";
artAttrPaintVertexCtx -e 
                      -clear
          "artAttrColorPerVertexContext";

Weird & hard to explain, I know. Besides Maya, the tools used are archaic as the project has continued for well
over many years, thus it can't handle the whole scale of colors Maya can.

yes however thats why im proposing to make a additional module to your toolchain that works on a intermediary format, since its easier for you to use it over in batch and you dont need to bastardize the maya toolchain. Now all old and new files would work. No need to change maya other than automatically calling that external tool after a export if you wish. (alternate is to do it when you dump the data to the engine) Now it wouldnt matter if the data modern or not it would just work and be of no concern to maya users, and its easier to manage these modules when you nee dto repurpose things later (something which your toolchain currently neglects by the sound of it, but its never to late to start working better)

Change input. So prefeer not to change mayas colors at all!

[treefish]

Hi Joojaa,

I'm currently using Maya 8.5 which does not seem to have the scale function built into the visible UI options for the tool but the mel output you were nice enough to post works just the same for some reason so I won't complain!

An additional module would be nice but I'm unfortunately not qualified to make one & I doubt the programmers would be able to do anything about it (the code hasn't changed for a very long time so I don't think we even have programmers working much on this particular project).

Anyway, thanks again for your help!

[joojaa]

Well with the time and money they spent you asking for this means they could have done it cheaper. So that is money well spent.