Hi everyone, as of the steam release all official vehicles now have 3d windshield cracks - and new mods such as the Honda CRX del Sol are starting to incorporate the feature - so here's a quick guide on how to create them in Blender. The process takes about an hour from scratch, but once you've done it once you can skip the most time-consuming part when adapting it for another vehicle. To begin, I'll assume you have your complete car model, and also a cracks texture on the windshield. In Blender you can enable textured view and go to top view (num pad 7). Next, create a plane above the windshield and delete all 4 vertices. You can now add your own vertices using Ctrl+left click to extrude along the crack lines. Continue this process of extruding lines to trace the cracks in the texture. It isn't necessary to be 100% accurate, but try to keep the pattern similar. Try to extend any cracks near the edges so they go to the boundary of the windshield. When you've finished tracing all the cracks you should have 1000-1500 vertices. This is the most time-consuming phase done. Next, select the windshield mesh and extend the edges a little. This will serve as a surface to project the cracks onto. To do this you need to use Blender's 'shrinkwrap' modifier on the cracks mesh, and set the windshield mesh as the target. You can see all the correct settings below: Apply the modifier. With the cracks now in the correct shape of the windshield, it's time to extrude them inward to give them some thickness. 3mm is a good amount since it is equal to the thickness of one of the two laminated glass panels in a typical windshield. You may want to assign either the inner or outer vertices to a group, so they are easier to select later on (see panel on right). Now, to add some random variation to the crack thickness, select random (25% or so) of the vertices, deselect the original (not extruded) vertices and move them outwards or inwards. This will make the cracks appear less artificial and more random. Finally, select all the edges at the ends of cracks and scale them down to zero, so the cracks fade out. Now that the windshield cracks are finished, you can add them to the vehicle. Check out the official vehicles for examples of how to set up the materials and deformGroups, so the cracks appear when the windshield breaks. Hope to see this in more mods soon!
