I'm making a simcity-style game. I use one big RenderTexture for the terrain and one big RenderTexture for all the roads, so I don't have to iterate through all the tiles every frame. So for the terrain and the roads I only have two sprites and two draw-calls. If the player builds a road, the corresponding sprite (I use an atlas with all possible roadtypes, e.g. horizontal, vertical, corners, crossing, etc.) is drawn on the roads-rendertexture. This works fine.
The problem is when I remove a road, I want to clear that part of the rendertexture with transparant pixels. But since the rendertexture is never 'cleared', how can I do this? I tried drawing a transparant rectangleshape on the rendertexture, but (of course) this draws on top of the current pixels, so nothing happens. How can I 'replace' the pixels on the rendertexture with transparant ones?
