What's the difference between move.direction and move.angle?

[htopia]

Hi there,
I've been trying to make a rain effect and I keep getting the particles to go in different directions instead of the same direction.
I tried setting the angle in both the direction and angle properties of the move property but it keeps changing it randomly somehow.

Here's the pen where you can see the issue: https://codepen.io/htopia/pen/dyzRWxK

Any idea why this happens?

Thanks in advance.

[matteobruni]

Hi @htopia,

angle sets the spread angle of the movement for the randomization. If you have particles going down like in the sample, a smaller angle spread them less then a wider one.

direction is the direction of the particles, which can be a defined angle (numeric) or a general direction (top, left, etc.).

The particles movement has two other properties: random and straight. The first one multiplies the movement speed with a random factor, the second one interact with angle, adding to the direction angle a random value between angle min and angle max.

I'll explain straight better, it's a bit complicated:

• Set to true, the particle will follow the exact direction set in the config, for example if it's set to left, the particle will go horizontally left. If set to any number the particle will follow the exact direction set.
• Set to false (default), the particle will have a general direction read from the config, with a 90° spread (default). If you reduce angle values, the particles will have a smaller angle for spread. If you set the value to 0 it's the same as straight: true. The spread is calculated starting from the direction angle, which is the center of the spread angle, and a random value between the spread angle will be used.

[htopia]

hi @matteobruni, thanks for the great explanation!

So according to what you say, if I set straight: true if I want my rain particles to fall in a 45° angle direction, it should be just a matter of setting direction to 45 right?

I've updated my pen with these values, I also set random: false just in case and angle to 0 since I just want them all to fall exactly with a 45° angle, but they keep falling down straight without any angle.

Am I missing something? Is the numeric value in the direction property working as expected?

[matteobruni]

Yes, if you set straight: true they should follow your direction. You can also set "bottom-left" or "bottom-right" for 45° down-left or down-right.

direction numeric values replaces the "bottom" value, so you have to calculate the angle from an imaginary horizontal middle-right line which is 0°.

[htopia]

Ooh, I just noticed that I had another direction property on the emitters object which was set to bottom, I set the angle there and now it worked.
I thought that setting the direction on the move object would override the one in the emitters object.