Face selection masking is available in the 3D header when in 'Vertex Paint' mode:
Because this works on faces you will only be able to paint vertices that make up a face, individual vertices or edges won't be filled.
Select the vertices you want to paint on in edit mode.
Change to 'Vertex Paint' mode.
Enable 'Face selection masking' in the 3D header. There ...
There are a good many ways of doing this, but here are a few:
In the UV image editor, set the mode to Mask and press New:
Press ⇧ ShiftA>Circle to add a circle mask, the position it with G:
Use the mask to control the alpha over factor in the compositor:
You could even feather or blur the mask to make the objects fade out instead of ...
This cannot be done in shader nodes, because to Dilate (paint) a point on surface one must know the color of surrounding area of that point. The node that samples Vertex Color does not allow for mapping vectors input to sample surrounding area:
That said, dilation/erosion on procedural or image textures would be possible using a dilation/erosion morphology ...
You can do this using the Object ID and a ID mask node.
Select the object you want to use as a mask, and under the object tab in the properties set the Pass Index unequal 0 (I used 1, but if you have more then one mask give each one a different number)
Now, head over to the RenderLayers tab and check the Object ID pass
Re-render your image and head over ...
There are a couple ways, but I would use masks:
With a strip selected, add a mask modifier in the properties region (N) by pressing Add strip modifier > Mask. I also like to set the alpha blending to alpha over:
You can either use another strip to control the selected strip's alpha channel. You could use a scene strip to generate such a map based on the ...
This one is driven by the knob rotation, so you animate the knob and the lights are good.
Let's assume you are looking at your knob from top view.
For convenience, you model a led and you parent led and knob to an empty. Knob must have first rotation applied and rotation mode must be set to xyz euler, if you set it in quaternion or axis angle it will lit ...
One way you can do this is with the mask modifier:
Add a vertex group of the vertices you want to paint on (or the area you don't want to paint on, whichever is easier)
Add a mask modifier and toggle the invert option if you selected the vertices you don't want to paint on.
Paint, then disable/delete the mask modifier when you are done.
The short answer is no.
While in edit mode you can hide individual vertices, which also remain hidden in sculpt mode. Dynamic topology respects these hidden vertices as it is working directly with the mesh you have partly hidden.
The multires modifier works differently as it creates new vertices that are stored within the modifier, it isn't changing the ...
Here is a solution to light up the individual LED's one at a time without any type of unwanted gradient effect.
The basis of the effect is based on 36 equally spaced LED rectangles created by extruding a 36 point circle, bevelling the edges and then deleting the separating faces.
The texture mask that turns on the LED shader is made up of a number of ...
In your first attempt you are replacing the original alpha with the mask, you need to combine the original alpha (the render) with the new alpha (the mask):
Which would result in:
Based on this render and mask:
That's essentially what you're doing in your solution that doesn't 'seem right'. This is just a slightly simpler way of doing that.
I think what you want is a holdout shader. A holdout shader is like a transparent emission shader: wherever it is, it writes transparency (alpha 0). It still gets occluded itself.
With the use of a holdout shader, you can then alpha layer your footage that describes both background and foreground objects.
Holdout shaders work both in Eevee and Cycles.
One way this can be done, is using the render layers mask layers. While this may not be as simple as Denis's answer, it's always good to know more than one way to do something, and it can be a bit more flexible because it works with both cycles and BI (and should work with basically any other rendering engine also).
Using Mask Layers
To create a mask layer, ...
Two independent node groups for creating a mask based on a color and a texture :
material setup :
the first node group outputs boolean 1/0 ( all comparisions are "less than "):
the second node group outputs grayscale :
adjust the sensitivity/clipping to get a good result "sensitivity is added to overcome errors due to rounding the numbers"
The first thing that you have to do is create a mask.
There are two places where you can do this:
In the Image Editor.
Or it can be created on the Movie Clip Editor
Go to the Motion Tracking Screen Layout and load in your movie. Select Mask in the bottom options panel where it probably currently says Tracking.
Click to add a new mask, or select ...
No, the MCE or UV/Image editor's masks will not translate upwards to the 3D view.
They occur in the post phase of Blenders sequence of operations. Also I am told that its to hard to make a rasteriser for arbitrary material parameters. I guess they would have to operate at screen space?
You can see a more thorough breakdown of this at my blog.
The work ...
I don't think it's possible to utilize material (or object) index behind a refractive material as it is.
Blender is correctly showing the mask of the object that form the camera point of view truly has the material assigned. The squared piece is made of glass, the fact that is somehow showing what's behind doesn't change the material which is made of.
Similar to @Carlo's answer you can set this up within a single blendfile (and within the same scene) by making use of the Render Layers 'material override' setting. Set up each object with a pass index relating to the type of material in use. For example, we could have :
0 = Black diffuse (obscures mask)
1 = Emissive (the thing we want the mask for)
2 = ...
Load the background image in the image editor
Set the editor in mask mode
On on the image click while pressing the Ctrl key and draw a mask for the area you want to use as foreground.
Then in the compositor use that mask to combine the foreground and background elements.
At last, a use for the Build modifier?
Create a fan-filled circle-mask with the same number of segments as you have LEDs, rotate in Z to the desired start-point. Give it a Build modifier, set to the appropriate frame start/end, and 'Reverse'.
Segments are made visible one at a time.
@blender breath Thanks for the comment.. 'mask' is a bit vague - it could ...
Those are correlated alphas.
That basically means that you're not putting layer B over Layer A, but putting layer B in a hole poked in Layer A.
The regular alpha over operation, however, will work only for uncorrelated alphas.
If you take a look at the math beneath the alpha-over operation, you'll see that the first part of it creates a "shadow" on the ...
There are a couple issues. My first question is why are you using two scenes? That will really complicate things. In this answer I have only addressed one as you can copy that information to the second one.
The first thing I noticed is you have your makes layers set, and although that could be handy in many instances, it really is not necessary in this case....
Edit: does not work in 2.8
I propose another approach which is not vertex colors based, mainly because vertex colors influence is limited by the inner geometry of the mesh.
Instead, we can use some kind of "cut mask", which allow to do the following:
It can be used also with more complex shapes, as soon as a boolean intersect (same as the operation in ...
You can use "texture coordinate" input node and a "color ramp".
The X output is between 0 and 1. So if we split the color ramp in three constant steps at 0, 0.3333 and 0.6666 we'll have the color we want for the good disk.
For the grey part, we just compare the input value (0, 0.1, 0.2, 0.3) to X clamped into 0 and 0.3.