[Steve Bentley]

Is your viewport open? (the 1 or 4 views where you see your scene). xpresso (and some 3rd party IPR render windows), can only update when the viewport is open and can update on screen.
So if you have opened the xpresso editor and it has covered your viewports or you have made it a tab and that tab now has focus, xpresso can’t update.

[Steve Bentley]

Hmm, works for me. See project.

It might be an ordering thing? You can also turn off the spec on all lights except that one (spec isn’t a real thing anyway). You can also turn off spec in all materials except that eye one and keep the spec on for all lights.

Eyes look better anyway where there’s a real reflection instead of a spec highlight. That way you get horizons, the bridge of the nose and little Frodo-esque eclipses.

spec-lights.c4d 194 KB Cinema 4D project files - Click to view

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[Steve Bentley]

Not sure if this helps but post R19 (and maybe R20) the reflection tab is used more closely with a PBR work flow (even in non PBR materials). So the idea is that you stack everything in there except Luma. When creating a material, in the reflection tab, just delete the default channels and then add in a lambertian for color, a beckman for reflection etc and leave the main color channel of the material off.

In the reflection tab you can add a specular channel if you like (for some unknown reason this is the default channel that appears there) but there really isn’t such a thing as specular in the new work flow or the real world – everything is a reflection on surfaces that are more or less smooth.

[Steve Bentley]

This could be a couple of things:

The usual suspect is that the viewport isn’t visible. I have my xpresso window tabbed up along with the viewport and picture viewer and the material nodes window and often I will pop in to the xpresso tab and wonder why it won’t update – because it’s taken over the entire screen with the viewport hidden in “behind”. The viewport MUST be visible for xpresso to update.

It could also be an ordering thing. The order stuff happens, both in the xpresso window (left to right) and the object manager (top to bottom) matters. If something has to be calculated first before doing something else, often it has to be left or below that second thing.

It could be that the data type is wrong. In the Spy or Result nodes make sure that the data type you are wanting to read is what that node is set to. And make sure that the data type is appropriate. This is often difficult as C4D seems to care sometimes (like Frames being Integers instead of Reals) and sometimes it doesn’t (Bools instead of 0’s or 1’s).

The final trick to try is to make sure you are really on frame zero and then stuff can calculate as it evolves. Just hitting rewind doesn’t always do it – often you have to hit rewind twice or, once at frame 0, advance to frame 1, then rewind again. C4D has a terrible habit of not clearing its own cache when a calculation needs to start again.

[Steve Bentley]

There was a shadow catcher plug in for users prior to R19. Let me see if I can find it for you.

[Steve Bentley]

You can use the transform tab in the cloner to do this.

[Steve Bentley]

XP is a big hammer for this but easy enough.

Make a poly selection of the end of joint, set XP emitter to object and insert the joint and the selection tag in the emissions tab object and selection slots. Set speed to 0 and emission type to shot and just emit on the first frame – you probably won’t need many particles. Set display tab to gradient by age. and throw a black to white gradient in there.

Add a cycles instance tag to the emitter and set the divisions to something low like 12 (you don’t need a lot for this) and set the percent size to however large you want each glowing ember to be.

In the cycles materials node pipe a particle info node (color or age will work) into a color ramp node and set the gradient there to something that has lots of reds and oranges on the left and fades to black on the right (ideally there would be many black nodes between the reds and oranges so you get ember flickering – or you could use a noise mixed with the color ramp and set to multiply). Pipe the color ramp into an emission node and pipe that into the output or pipe that shader in a mix node with your rolled paper shader.

You could also add a scale modifier so that the embers get larger when they glow. You could copy that gradient you made in the material node and use that to run the scaling function in the scale mod.

You could also use the same emitter to emit a smoke volume and use turbulence curl to make it wispy and use a cycles volume shader to make it a pale white.

[Steve Bentley]

The easiest way is to use a Link List node. When put this node in your tree, you can drag objects into the Link List’s attributes panel. Then you can use that set up you have already to iterate through the objects randomly.

You input your range mapped random number into the index port on the left of the Link List node and then, out of the “link” port on the right side of the Link List node, you hook that to an object node through the Object port. This number generating the index should be an integer – it doesn’t always matter but xpresso is old so it’s finicky and I’ve seen this one thing trip people up all the time. If you are getting a float out of your range mapper just use a Calculate/FloatFunc node and choose Ceil(ing) or Floor to chop off those decimals

You can have a different link list for each group of objects (so one for different glasses and one list for different shirts), and then an object node coming out of each of those link list nodes for each article. To get a bunch of objects into the links lists in one operation, select a bunch of objects in the objects manager and then click the link list and then drag all those objects at the same time to the list, because you have clicked somewhere else to select the link list node, the objects will stay selected in the object manager. (this is easier than locking the focus of the attributes window and having to open another one.)

You can also synchronize things. So lets say a certain pair of glasses needs the hats to sit a little higher. You can store position data in nulls that are positioned correctly and stand in for the different positions of the hats. Then when you iterate down through your glasses link list, you can also iterate simultaneously down through the position null link list and pipe the matching position data from the outputted null into the position data of the chosen hat. In other words you are using the same range mapped index value for both glasses and position null lists, while another random number picks the hat.

[Steve Bentley]

Ya I’ve been seeing things like this of late too in R25 (closer to your second image). I think its the GPU driver. I just take the window or the palette and drag it a little and then maximize again and it goes away. Haven’t found the sweet spot yet with Nvidia (RTX3090)

[Steve Bentley]

I’m not sure what you mean by a sharp angle. The sweep will take the profile of whatever spline you give it. Do you have a project to look at to see what the problem is?