Category Archives: Compositing

Sprut – 2d Fluid solver for Nuke.

Posted on by

Here’s something I’m hoping to release for free once it’s all packaged up.

Sprut – A fast 2d fluid solver for Nuke.

* Based on Jos Stam’s 1999 Paper “Stable Fluids”
* Written as 2d gizmos; making it really easy to implement new ideas
* Fast and stable
* Creates and saves Uv’s and velocities to do post-sim manipulation
* Density and velocity manipulation during sim (viscocity and density diffusion, as well as rate flow control)
* Super Fun yo !

Next to do on my list is finishing the emitter and collision tools and package the whole thing up for a smooth release.

-theo

Early bridge to Mantra.

Posted on by

Mantra for Nuke.

MantraBridge – Aka Mantra for Nuke.

* Point, Area and Environment light support
* Basic shader support (brdf, matte/shadow, occlusion/bent normal)
* Raytrace, Micropoly and Physically Based rendering engines available.
* Animation support for parameters. (lights, cameras, objects)
* Delayed_load object support. (with basic translation controls)
* Pixel and raytracing sampling controls (pr object and light)

Very handy if you want to render excessive amounts of Stanford Dragons in comp.

Shadows in Nuke

Posted on by

Self-shadowing in Nuke.

So here’s a little trick to get some dodgy hacky shadows in Nuke , by comparing projected and “rendered” pWorld passes we can derive the difference easily and use that as a shadow matte. Still aliasing and various issues, but works fairly well. Node requires geo, camera, bg and lights. Supports all regular nuke geo.

*Nuke script with gizmo/group , Geo needs reloading.

http://www.euqahuba.com/tools/nuke_shadows.rar

*Just the group in a txt file

http://www.euqahuba.com/tools/shadows.txt

Now, to trace the rays…Zomg!

-theo

Fusion:Creating a custom displacement tool

Posted on by

Creating a custom displacement tool

The custom tool in fusion is very versatile, you can use it to do expressions on a channel or per pixel level.In this case we’ll grab the pixel values of one image and use it to displace another one.

Step 1. Load a source image that you want to displace, and then load the image you want to use as the displacement.

Step 2. Create a Custom Tool and connect the first image to the background and the second image to the foreground. The resolution doesn’t have to be the same, as the custom tool will stretch the second image to the dimensions of the first.

The flow

Step 3. We’re going to grab the luminance of the second image, and use that to drive the position of each pixel on the first image. On the intermediate1 slot, write the following expression x-(getr2b(x,y))*n1 .

This tells fusion to substract the current pixels X position based on the second image (x-). It gets the values from the second image by grabbing it by the bounds of the red channel (getr2b= get (R)RED from image (2)2 by the (B)Bounds). And then multiply it with a arbitrary number (*n1) so you can control the amount of displacement with the first slider in the controls tab.

Do the same for Intermediate2, but replace the x- with y- and *n1 with *n2. (y-(getr2b(x,y))*n2)

Step 4. You’ve now done all the pixel calculations and need to feed it back to the image. Go to the channels tab and and in the Red expressions tab write getr1b(i1, i2) . This tells fusion to set the values in the first image’s red channel by the bounds (getR1B) based on the new X,Y positions from the intermediate tab (i1,i2).

Repeat for green,blue and alpha. But change the syntax from getR1b to getG1b, getB1b, getA1b.

Step 5. Switch to the controls tab and play with the two first sliders (n1 and n2) to displace both directions separately.


Remember to set the displacement image to float, otherwise you’ll encounter aliasing issues.

If you want to use something other then the red channel to displace, you can change the initial intermediate expression from getR1b to getB1b to blue. Or you could average the channels together ((r+g+b/3) to use the actual luminance.