Mental Ray rendering multicolored sprites as one color! Why?

# 1 20-08-2012 , 06:20 AM

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Mental Ray rendering multicolored sprites as one color! Why?

Hi folks.

So I'm trying to get mental ray to render a bunch of STATIC particles that are no longer dynamic. I have assigned a lambert shader to them, with a sequence of seven images, generated randomly at creation via a SpriteNumPP expression. They are shown correctly in the viewport (see first image). These colors are assigned from an image sequence - NOT from rgbPP, and that's how this has to remain.

Now, when I do a Hardware render, the colors are correct, but when I do a Mental Ray render, the colors are all the same (see second image). The color that they will have seems be the current image sequence color, which is not what I want...I want the sprites to keep their various colorations that they show in the viewport. My guess is that MR is reassigning the current frame's image file (see third image) to ALL of the sprites, but I don't know why...

Anyone have an idea about this? user added image

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# 2 20-08-2012 , 07:40 AM

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What happens if you render another frame?

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# 3 20-08-2012 , 05:30 PM

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They will all look the same in the viewport (multiple colors) regardless of the frame number, because their dynamics have been turned off. Static field of particles.

But if I render a different frame with MR, they will all be colored the same - directly related to the lambert assigned to them, and the image sequence they are based on. In that example, they are all a yellow color, because that particular image in the sequence is the yellow one. If I scrub one more frame and do another MR render, the color will change because the image sequence will cycle to the next in line.

I want the MR render to look like the first attached image.

Last edited by scentmental; 20-08-2012 at 05:42 PM.

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# 4 20-08-2012 , 09:21 PM

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Not sure if this link is any use..............dave

https://forums.cgsociety.org/archive/.../t-606259.html

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# 5 20-08-2012 , 10:31 PM

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Not sure if this link is any use..............dave

https://forums.cgsociety.org/archive/.../t-606259.html

Originally Posted by daverave

Thanks for the reply, dave.

That's the exact technique I've been using. I got it from a gnomon pixie dust sprites tutorial. It works well...just not when using mental ray to render. Mental ray seems to ignore the colors of the sprites, and just assign the current frame's image to all of them.

I'd use hardware rendering, but I also need to use depth of field, and HR doesn't support DOF. I can't use software render because it won't see sprites.

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# 6 20-08-2012 , 10:47 PM

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The only reason I asked what happens on another frame is to see if your image sequence was working.
Without posting the scene it might be hard to figure out what's wrong.

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# 7 20-08-2012 , 11:26 PM

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@ honestdom:

Appreciated! The image sequence is working from what I can tell. I'm attaching my .ma file with a sequence of three images. This is a stripped down scene, with only the elements needed to troubleshoot this problem. If you could, please load it up, scrub a few frames to generate particles, and see what happens when you try to render with Mental Ray.

I'm using Maya 2013 by the way.

Thanks!

edit: Just realized that the attachment didn't go through...here it is

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spriteColorProblem.zip (581.3 KB, 230 views)

Last edited by scentmental; 21-08-2012 at 03:29 AM.

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# 8 21-08-2012 , 06:54 PM

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Checking in. I haven't figured this out yet - mental ray still renders all sprites as the same color instead of a mix of the three colors supplied by the image sequence.

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# 9 21-08-2012 , 07:03 PM

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Mental Ray doesn't support spriteNumPP, even as late as version 2013, just a heads up.

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# 10 21-08-2012 , 07:56 PM

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Mental Ray doesn't support spriteNumPP, even as late as version 2013, just a heads up.

Originally Posted by GecT

Well that's a disappointment. Thanks for clearing this up for me. I guess I'll have to figure out another way to get the effect I want.

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# 11 21-08-2012 , 09:08 PM

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Try another way using instances, I have managed to get some thing to work in mental ray see link, this is using 1 emiter and the colour in is black and white................dave

https://forums.creativecow.net/thread/61/856294

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