This is a project i took through the entire pipeline from creating the mesh to setting everything up in Unreal Engine. I modeled the car using houdini, maya and substance painter, simulated crashes in houdini and baked them to blend shapes, Created wear masks for damage on the paint, added differenct particle systems for the car and set evereything up in Unreal Engine to be completly playable.
So when Houdini 17 got released they introduced bullet soft constraints. That basicly meant that you could do RBD simulations that bends before breaking, as metal. So i simulated car crashes from different directions and baked the result in a cloth deform to a non fractured mesh in Houdini.
So when i had the entire mesh wrecked i took it in to substance painter and baked a curvature map. With the curvature map i could use the mask generator “metal edge wear“ to get a mask that acctually takes in to account where the car paint would get damaged.
Blendshapes and Materials
The result was then put in to blend shapes for each individual deformation. Each part also got a collision capsule that when hit triggered a function that checks for the cars velocity at the impact and adds deformation to the corresponding blend shape. The masks for the material are blended/masked in using vertex colors for the different areas and a smoothstep to get different amounts of wear.
For the tire tracks i used render-targets that painted a tire pattern at each corresponding tire when the car slided. To get the right rotation of the pattern the brush looks at each tire bones Y rotation. The opacity of the tire track was also blended in and out to create a more smooth transition.
It was a really fun project and i think i learned alot doing it. Because of limited time and it was the first time i modeled a car i noticed one thing with the model later down the pipeline i would change if i did this again. The body of the car is one entire piece and that made it harder to get a realistic look to the car when it broke because real cars are obviously not one solid piece. With and interior, separate meshes for the hood and doors i think the result would be really cool.