Creating cracks in a model

Support Modeling
1

Can anybody help me with creating such cracks in the surface of a model

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I tried searching the web for solutions but all of them used noise texture which generated random results and were part of the texture only. But I want to create the same cracks as in the picture deforming the mesh as well.

2

That looks like a distorted voronoi texture to me, Use a voronoi texture node and drive its scale input by another texture, say, a noise and a gradient to achieve a similar effect. Switch Cycles’ featureset to “experimental”, add a subsurf modifier to the model and check “adaptive”. In the material settings switch displacement to “true” or “both” to get real displacement in your renders. However this still is a texture driven rendertime-only effect.

To actually break the mesh, well, use Houdini and drop in a EdgeFracture node, then a PolyExtrude, Reverse, and Subdiv. :slight_smile:

1 Like
3

The voronoi texture method disn’t quite work well. I might have screwed something but since you have mentioned that it is only a render-time effect, I didn’t go too far.
I am also not familiar with Houdini. I would love to try out Houdini but I also want to sort the problem in blender.

4

I can think of two ways:

  1. Model the cracks as a separate mesh. Then use the “shrink wrap” modifier to put the cracks on top of the desired mesh. Finally, use the “boolean” modifier with mode set to “difference” to carve out the cracks.
  2. Use the knife tool to carve the cracks on top of the mesh (as a bunch of edges with no thickness). Then select the crack edges and give them thickness using the bevel tool. Now extrude the cracks.

Btw, the method mentioned by @Helmut_S would change the mesh, not only the normals (unlike bump mapping).

5

There’s another method, maybe the simplest of all: why go procedural, just handpaint a displacement map and use true displacement as I described in my first response here.

I somehow thought you wanted to have the cracks “in” the model, but well, why should you, at least if you don’t want to add dynamics and actually shatter the model? This kind of effect is typically achieved by using textures, its just that somehow micropoly displacement still seems to be considered as some esoteric feature by most of the Blender community … but it isnt. Use it, fellows, it is around for some time now. :wink:

6

Sorry but I am new to such things. Do you mean to use program such as photoshop to paint the texture or to texture paint in blender when you say “handpaint a displacement map”?

7

There’s some good stuff on cracks in here: