The task for the second week is to start visiting the particle system and start some preview videos.

Auto update]: When we change the value of a node in Houdini, it will automatically (and very quickly) update the effect on the screen.

[On mouse up]: When we change the value of a node in Houdini, it will only update when we click on the window with the mouse.

[Manual]: Manual update. This can be interpreted as an independent update of the window effect when we change the value of the node. (This mode is very convenient. I have been using this mode for my last homework.)

[Null] Node: This node has no effect. But it is easier to create a [Null] node in the panel to observe the process. (Maybe because the shape of this node is too unusual. Most of the other nodes are rectangular, and the [Null] node is a shape similar to X).

Vop and Vex

First create a box, select the node and press I to enter
Create an attribute wrangle node and connect it to the box node
Select the attribute wrangle node, press P to open the parameter panel, and enter the vex code in the vexpression
Click on vexpression and press Alt + E to open the vex code editor

[Gravity] is something common to all solvers.

Put [gravity] under [popsolver]. At this point, we can see that the particles on the [testgeometry_crag] model have a downward trend.

There are different types of wind in [popnet]

Increase the value of [Wind Velocity] in [popwind], the particles will change the direction of movement.

[Rendering animation book]

Render Houdini files.

Create a [popforce] node. Changing the value of [Amplitude] in [popforce] can be similar to [noise wind] and can affect the direction of particle movement.