Original subtitles

To blend the moss into the wall, let's add some greenish tint to the wall around the moss,

as if there is some algae growth or something, due to the extra moisture the moss holds.

Over here we have a mask of the moss. This mask is completely sharp,

and represents exactly where our moss is. But now, we want a soft mask that

is a bit bigger than this one, so that we can have a soft fade away from the moss.

For this, we can add a Math node, and plug in the moss depth texture.

And then plug in the wall depth texture, and set it to subtract.

Now, wherever the moss depth is greater than the wall depth, we get a positive

value, and wherever the wall depth is greater, we get a negative value. This means that at the

boundary of the moss, the value is zero, as it crosses from positive to negative.

If we compare this with the sharp mask, we see that indeed the shape is the same,

and the only difference is that this subtraction not only tells us where the moss is,

but also how far from the wall surface it is at any point.

To make absolutely sure that this is indeed equivalent to the sharp mask,

we can add a Greater Than after the subtraction and set it to zero. This confirms that the

positive values do indeed represent the moss, as this mask is identical to the other mask.

But now that we have this extra surface distance information, we can make soft masks as well. If

we add a Map Range onto this output value, we can control where our soft mask starts and ends.

We want it to have full intensity at the boundary,

so let's set the max input to zero, which as we covered, represents the boundary.

Then we can lower the min input, and going farther into the negative direction,

it expands outwards from the moss. This mask is looking pretty good for the color bleed,

so let's make some space here, for another Color Mix node.

And let's plug the new soft mask in there.

It's working, but we need to tweak the color a bit.

Let's copy the moss color as a starting point.

And let's look at the shader output to see it in context.

It's a bit too bright and saturated, so let's adjust it.

Now we can also lower the maximum output of the mask, so that it doesn't go fully green,

but always preserves some of the wall color underneath. And

we can tweak that input range a bit more as well.

Now, if we set the output to zero, to compare it with and without the green tint,

we see how this helps to integrate the moss and ground it onto the wall.

And it's always fun to take a look in Cycles as well.

Then it's just a matter of framing these nodes, naming it, and copying the node color.

And as always, let's organize the rest of the tree a bit.