Grass growing over text - Gradient growth?

Question

I made this simple render with some grass growing on some text. I would however like to make the growth start at one side and then spread, preferably with some sort of gradient. As it is now it grows everywhere at the same time.

https://drive.google.com/file/d/13VuFb1lYPRAhrykHtWadldaN3yHeX1OU/view?usp=sharing

So far it is just a scatter of objects that has a size value increase. Can anyone point me in the right direction on how to achieve this effect?

Is it possible to make the size value of the grass increase by the proximity of another hidden object? Or is it possible with Geometry Nodes, with which I have no experience...

Answer 1

You can solve this as follows:

Here the node Gradient Texture is used as a base for creating the gradual gradient.

1. First create your letters (however you want to do it) and distribute the points for the instantiation of the objects on them with Distribute Points on Faces.
2. Then grab the X-positions of the points and scale these values. The node Gradient Texture creates a gradient between $0$ and $1$, and thus you fit the values into this range. Depending on how smooth you want the transition to be, you can make different calculations here.
3. Then use the current frame and a value for the velocity to create a vector for the node Gradient Texture.
4. After that you have to use Map Range to bring the obtained values into a range that serves as scaling. Here you can also try different values for To Min and To Max, because this also produces a nice result.
5. Finally you use Instance on Points, take the Rotation from your previously created points and finally apply the scaling.

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Another possibility would be to use an Empty or other object with which you control the scaling of the points:

Here I use the node Geometry Proximity to evaluate the distance to the points.

_{(Blender 3.1+)}