Ramp depending on object space


#1

Hey guys,

I have a situation where I just can’t find a solution and hope to find a hint. I am not asking you for doing the work for me, just point me in the right direction so I have a chance to get the information I need to solve my problem. After hours of trying and “googling” I am just :cry:

The setup and target:
I have a sphere with a VRay Material on it and a VRay Environment Fog. The material is fully transparent, so only the fog gets render. So far it works great. The surface and the volume shader are applied to a sphere. I need to control the color and the density of the fog dependent on the distance from the sphere center point. So basically I need a controlable ramp from the center to the surface of the sphere.

The problem:
In 3DS Max the solution would be very easy: Take a gradient ramp and set it to “object space” and have fun. But I can’t find something like this in Maya. There is only a regular ramp (2D). I thought about taking object x, y, z from samplerInfo Node but can’t figure out a way how to apply those. The reason why I need the ramp is so the color and density can be fine controlled on the outer parts. I need several layers without using multiple spheres with multiple environment fogs.

Thank you very much in advance!


#2

not sure it’s wat you mean but wouldn’t it be the classic samplerInfo.facingratio to a Vrampcoord of the ramp? so samplerInfo.facingRatio -> ramp.vcoord

try that and tell us if that it’s what you’re looking for.


#3

Thank you for your reply! But the facingRatio is not what I am looking for. The facingRatio is there to mimic fresnel-like shading.

I try to make a better understandable explanation:
What I need is the possiblity to change values from the center (the middle of the inside of the sphere) of a sphere to the surface – not from the center of the surface to the side of the surface.

This is not the effect I try to achieve, this image just should explain the kind of ramp that I need. I need this kind of ramp on a volume because I want change properties of a environment fog throughout it’s spread. So let’s say it begins with a red color in the center, goes through white and fades to blue on the surface. And also the density.

I hope this was a bit better to follow what I am talking about. Otherwise I will look for some more pictures, which make it more obvious.

Thanks again!


#4

Hi, did you ever find an answer to your question? I’m looking for a solution to the same problem… I’m following the Mastering V-Ray course, and I need to be able to control environment fog’s density (contained in a mesh) using a ramp. In the course the tutor shows how to do it using the Object XYZ in 3D Max (as you described), but I can’t seem to find a way to do it in Maya!

Any help would be greatly appreciated!


#5

why don’t you simply show us how you do it in 3dsmax? It would be much easier and clearer to understand rather than guessing.


#6

I’m afraid I don’t have a copy of 3DSMax to be able to show you…

The closest I can get in Maya is by using a Ramp (Projection) node instead of a Ramp (Texture) node, this then creates a 3D texture node for the ramp. Although when I try to join up a noise texture node to the ramp’s colours, the results are really different to what is achieved in 3DMax.