I’m using tree sprites for terrain scenery and I would like to be able to collide with them. However, I want to be able to walk through the leaves, and collide only with the trunk. My workaround is to just have an invisible quad in the same spot as the trunk for collision. If my scene were to have hundreds/thousands of trees, would this negatively influence performance to have an extra quad per tree?
Separating visual model and physical model is a good idea. For example, you can have elements that render the tree trunk and others the leaves, then have a collider on the same element as the trunk just for collisions. You don’t even need the invisible quad part, just the collider.
As for performance impact, yes, everything has a performance impact, but if you want to be able to collide with an object, you will need a collider. It is another question that you can disable objects that are not visible or not relevant to the current situation, improving performance.