how do I import new textures for the particle simulator effect in Hitfilm 4?
Take a look at this tutorial. It's fir HF2U, so the interface will be a little different, but, basically you import the image as a layer, or embedded composite shot. You can also use generated media as a texture (do that as an embedded composite shot) or an actual video clip. You can also import a 3D model as a texture source.
In the Appearance tab, open the texture source controls and select Layer, then choose the layer desired.
This tutorial covers setting up a video as the texture.
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