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Particles, LUT Color Grading, Camera and other questons

13 July 2018 18:25
Hi!

So I'm making this martian landscape scene and there's a few things that I either can't find how to achieve, or it doesn't seem to be working.

1. Does blend4web support LUT based color grading? Or any other more advanced settings than just the standard Brightness/Contrast/Saturation settings? A LUT texture is pretty much essential for me.

2. I'm using the particle system to generate A LOT of rocks and they seem to be instanced, and work fast and flawless, but what I need to do is to map a generated gradient to each rock so it has reddish dust reaching up from the surface, and to blend the rock with the ground - and that's working perfectly in Cycles but when I export it the rocks seem to be batched somehow? and take the gradient as if they where a single object…

3. Random color for particles seem to be made for grass and leaves, is it still possible if I don't want to enable dynamic grass for rocks?

4. Can particles be made to use the ground vertex colour somewhere in their material?

5. Camera control - can I have both the orbiting and "eye" cameras in scene, and switch to each one by clicking on a hotspot (preferably using the nodes and not that much coding)

6. Is there any tutorial on custom loading screen/bars?


Thanks for any help in advance!
You guys are the best! :)
16 July 2018 15:31
1. Does blend4web support LUT based color grading? Or any other more advanced settings than just the standard Brightness/Contrast/Saturation settings? A LUT texture is pretty much essential for me.
The available color correction options are described here. Brightness/Contrast/Saturation are included.



2. I'm using the particle system to generate A LOT of rocks and they seem to be instanced, and work fast and flawless, but what I need to do is to map a generated gradient to each rock so it has reddish dust reaching up from the surface, and to blend the rock with the ground - and that's working perfectly in Cycles but when I export it the rocks seem to be batched somehow? and take the gradient as if they where a single object…
Yeah. by default the batching is enabled and this is why you have fast performance. Disabeling batching will have impact on the performance. Try to detect what parameters are broken after exporting. Try to use different outputs of Geometry or Particle info node.


5. Camera control - can I have both the orbiting and "eye" cameras in scene, and switch to each one by clicking on a hotspot (preferably using the nodes and not that much coding)
Try this node: https://www.blend4web.com/doc/en/logic_editor.html#set-camera-move-style



6. Is there any tutorial on custom loading screen/bars?
https://www.blend4web.com/en/community/article/258/


On 3 and 4 will answer later
Alexander (Blend4Web Team)
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17 July 2018 14:57
3. Random color for particles seem to be made for grass and leaves, is it still possible if I don't want to enable dynamic grass for rocks?
It should work. Have you tried this?


4. Can particles be made to use the ground vertex colour somewhere in their material?
You can inherit vertex colors from the ground and use them for the particles. See the corresponding tutoial: https://www.blend4web.com/en/community/article/28/
Alexander (Blend4Web Team)
twitter
17 July 2018 17:38
Thanks for the exhaustive response!

I'll try everything out in order, right now I'm fiddling with the cameras,
this is my nth iteration of it: https://i.imgur.com/emZHFuF.png and it's working perfectly.

Now, no matter what I do I can't get camera limits to work correctly here, even when I try and use the camera limits node, the ending limits do not correspond to what I would set up in the camera in Blender - in fact it seems totally broken.

Further more, if I do set them up sorta okayish, the camera starts acting weird, pointing upwards, or ends up on the opposite side of the object.

I'm probably doing something wrong here?
On the camera limits node I set up (as I would in the camera properties) the min to something like 2.5, Max to 12, and Vertical to -15 and max to 70. The final effect is completely different than the camera limits gizmos show.
If I try and reset it by putting in the limits node with nothing checked, the eye camera ends up flipped after doing MoveCamera.
18 July 2018 13:07
1. Does blend4web support LUT based color grading? Or any other more advanced settings than just the standard Brightness/Contrast/Saturation settings? A LUT texture is pretty much essential for me.
The available color correction options are described here. Brightness/Contrast/Saturation are included.

Do you guys maybe plan on adding LUT colour grading? Coming from a gamedev environment it's a feature I really miss to have a scene come together - you can import a screenshot from your game into Gimp or PS, add your filters and do colour grading, apply that same set of filters to a LUT texture and use that in the engine for an exact parity.

The regular HSL/Brightness/Contrast/Exposure settings just don't cut in comparison.

https://gamedev.stackexchange.com/questions/96048/how-to-use-a-buffer-in-glsl-to-do-a-lut-lookup
https://en.wikipedia.org/wiki/3D_lookup_table

I'm attaching a few LUT textures from Unity for comparison.
20 July 2018 14:22
Thanks for the suggestion! We will review this.
Alexander (Blend4Web Team)
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