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ikoon

Mantra Glowing points and fake DOF, fake Light emitting

Hello,
please, I would like to achieve this kind of effect in my production:
render glowing lines, points.png

I am a freelancer, I have Houdini Indie and four computers (one 6core and three 4core-i7). I do jingles for local event agency. The projects I do are quite low-budget and deadline is in a week or two usually. I had to do this in a week, so I have used my C4D https://vimeo.com/186295732

Now I am more and more using Houdini. Please, would you be so kind and direct me to a solution?


A] Mantra superfast shader (fake)
It doesnt have to be photorealistic - points do not emit light, but they reflect on surfaces.

Can I get under cca 2 seconds for such glowing line (A-reference), fullHD frame, on my local CPUs?

Should I "clone" points onto the line?
Can I set the blending mode of the points to be additive?
Can I set the fuzzines of a point by custom gradient (radial from center of the point)?
Btw can I set the alpha of a point with bitmap, for example small earths?


For further development, I want to go this way:

B] Mantra semi-physical shader
Is it possible to get under cca 10 sec render time, with this:
- fake depth of field (for example by setting the radius bigger and darker)
- fake interacting with volumes (bigger radius, darker)
- can I somehow fake, that points are emitting light?
Maybe by some proximity shader on the "rigid" objects or volumes?

This is beautiful:
https://www.instagram.com/rbrthrsk/


C) Gpu renderer?
Should I go for some GPU renderer? I like mantra very much.
This is done with the Redshift
https://www.artstation.com/artwork/XOKQn

 

Edited by ikoon
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I have found thread about the blending modes here: https://www.sidefx.com/forum/topic/30813 There is hip with a shader, who solves the additive blending. I have done some tests. Credit goes to Sadjad Rabiee from the mentioned thread.

Rendertime 1280x720 on one six core cpu:
- with DOF is 11 second
- without DOF is 10 seconds

Results and the project file are attached.

If anybody can give me some answers to my questions... I will be very thankful. I am still quite lost, as this is still not what I need.

additive mode.hiplc

dof.png

no-dof.png

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I have tried more settings, the files are attached. Now it is quite fast, just two seconds (pixel sample 1x1, but it looks quite ok). Problem is, that every single line is just flat. Please ... what about the hair shader ... is it possible to have the opacity fading out from the "core"? I dont mean phong or specular hair normal, but I want the line to be most opaque in the centre and fading out.

additive mode - settings.png

additive mode - settings.hiplc

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I have tried to make it more clear. Here is what I would like to accomplish. Please, is it possible? Maybe with hair shader? And is it going to be fast?

 

 

dream shaders - v0.png

Edited by ikoon

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it's just an idea, you could use the uv attributes of the curve to drive the shader.

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why not convert the curves to geo light and control the attenuation?

color and opacity along the line could be set on point attributes and adjusted in the shader.

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Thank you very much, Andrea. This is great! I have tried to add a ramp to make the ends "round" a bit. I will make more development, but everything seems possible :) it renders very fast. Thank yout! Tests are attached. As regards fake volume ... this is quite easy. But what about the proximity shader on the polygon mesh, have you seen anything like that? I would like to see the proximity of the curve on polygon. Something like a fake light emission from the curve onto polygon. I could use the attribute transfer SOP from curve to mesh, but that would need many points or remeshing. Do you understand what I mean? Is it possible with some shader on the polygon mesh?

EDIT: I also cannot make this "curve shader" to be seen in reflections :-/ am I doing something wrong, or is it not possible? It is probably due to the additive mode?

render.PNG

additive mode - shader Menoz - ramp along length.hiplc

Edited by ikoon

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This is brilliant! Thank you guys so much for this superfast additive render trick!

I was able to render my point-advected splines in seconds instead of hours...

GlowingLines.jpg

Cheers,

Tom

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I created a version of the shader from MENOZ for points that works exactly the same way as the one for lines but in a circular manner like in this combined image:

LinesAndDotsExample.jpg

Both versions are contained in this .gal file, they are called FastGlow and FastGlowPoint.

Additive.gal

For this trick to work, Mantra needs to have Stochastic Samples disabled and be in Raytracing Mode.

I hope it's useful.

Cheers,

Tom

 

 

Edited by Thomas Helzle
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I have made experiment to "fake volume glow" with pyro shader + vdb from points + cloud noise + volume booleans. My scene file is unfortunately untidy as I am tired and busy :) but if anybody is interested, I will clean it and upload. The idea is quite simple, and of course it will not look as good as real pbr. But render times are fast, probably the same as rendering classic pyro. Some extra time is needed for that vdb and cloud noise.

mantra.png

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<naive>Another fake that came to my mind: Convert the surface of the smoke to polygons (Convert VDB). Then evaluate Normals of the smoke surface (is it exposed to those "glowing" lines?) and then add more fake glow to the exposed areas of smoke.</naive>

EDIT: In the morning I realized that the surface poly method is naive, because it would flicker when animated.

Edited by ikoon

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(I have edited the previous post)
Now I have another question, please:

There is the VDB Occlusion Mask SOP, which is super super fast  and for this test video it generates the mask (shadows) realtime, cca 40fps. Please, I did not manage to convert the boolean VDB result to float VDB result :( We could use that superfast VDB Occlusion principle to drive the Temperature and Heat of the Pyro shader and make the volume glow nicely. Or not?

mask.PNG

vdb - v1.hiplc

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here is another way to fake the light.

you can sample your geometry color and based on the distance you can dim the intensity. You only have to remember to export the values you want from the "source" object and read it back in the shader. in the scene there's a quick example.

You could also do the same reading point clouds, it's probably cheaper and easier. 

hope it helps or gives some ideas.. 

sampleGather.hipnc

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Menoz thank you very much! That gather() function seems to be very powerful. Mantra is amazing, but it requires very deep and complex knowledge, which I dont have now. But I will still dig deeper.

Maybe somebody could optimize these fake shaders and techniques and make a packet (glow source, volume, surface material) and sell it on the asset store?

I have uploaded my latest scene here. I have also added sticky notes which should guide even novice users. Preview of renders is here.

 

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Hey guys, awesome thread. However I can't seem to get this additive point render method working in Houdini 16. Black screen. Tried in 15.5 and renders perfect.. any thoughts?

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Works the same for me (I use 16.0.583 if that should make a difference).

- To see the gallery materials I posted, you need to enable "All Materials" in the dropdown in the header of the Material Palette since by default H16 only shows the "mat" context materials.

- You still need to use Raytracing and disable Stochastic Transparency in the Mantra ROP.

- For the points, you need to have point rendering in the object -> geometry tab active.

Cheers,

Tom

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