I am using a pre-made vector shape (below), and I would like to fill all of the triangular paths it contains with a certain colour. I am not sure how to do this. Any advice would be much appreciated.
Just put a solid color object behind the black compound shape. But before you bother with that …
Please redraw that poor envelope so the pixels aren’t such a mess!
Here’s one I did recently to solve the same problem. All vector. We needed a specific size and scaling down a pixel icon is rarely successful (even if it starts as vectors).
Once you drop below a 60px square, things get tricky. A little pixel alignment goes a long way. Rather than just scaling a vector shape and saving for web, you have to work very carefully.
Draw your shape so that it hits the pixel grid correctly
Do it the old fashioned way with squares and rectangles blocked out like pixels
A little bit of points 1 and 2
The envelope example I included is something that is most often done in Photoshop: I worked entirely with squares and rectangles, like painting with pixels. No simple rounded rectangle would give me what I wanted for the outer shape and diagonals are even more bothersome at this size. Since all my other assets (including the color palette) were in Illustrator, I just did it there.