Modelling Architectural Destruction

I don't have long before my Digital Tutors Account expires so I've been trying to work through any tutorials which look like they might be useful for my current project.  I want to get as much valuable information as I can, so I haven't bothered to complete the tutorial from the other day yet.

I like to have this information handy to look back on later so as I complete tutorials I'll be noting down useful tips and techniques here on my blog.

This tutorial takes you through the process of breaking down an existing model, which is provided.  It runs for 1hr55 across 12 lessons, but actually takes significantly longer to complete as there is a lot of 'Here's how you do one- you need 12 of these'.  I've got wire frame turned on in my screen grabs so you can easily see the changes in resolution (number of polygons).

The Original Model

The techniques used are again actually pretty simple, but there are definitely areas where I would have taken the long way without thinking of the simpler alternatives that this tutorial uses in places.

Isolate Select is something I had been wishing for in Maya but didn't even know it really did exist.  As the name suggests this allows you to hide all the unselected geometry in a scene and just work on one piece at a time.  Usually I've gone through and manually hidden each piece, which takes a long time, or just dealt with cluttered scenes.

It's found in the show menu (which I've hardly used before).

I can't believe I didn't know about this!

The majority of the tutorial is about isolating areas of the building, extracting them from the main geometry, and filling in the holes caused by this.  The mesh tools Fill Hole and Bridge are used in the tutorial, which are time savers if the initial model is good.

To add roughness to the destruction the model needs extra resolution, which can be added with the insert edge loop tool.

Jaggered cuts are made using the split polygon tool, however this tool has been removed from Maya 2015 so I've been using the Multicut tool for the same effect.  The thing to watch out for here is ngons (Polygons with more than 4 sides).

These can become a problem when texturing, especially if the geometry is being taken into another software such as Mudbox for texturing or sculpting.    

Destruction

In lesson 5 the tutor uses curves and surfaces to create pipes and wires.  I've used curves before for this but have always extruded polygons along them rather than surfaces.  I really don't know anything about surface modelling so I'm not sure how this works out in other stages of the pipeline.

Lesson 8 shows how to break apart the bricks, once again using the split polygon tool.  After a piece is extracted it needs volume added to it so that it is not just a shell.

It's important that if the brick is to fit back together after being cut up that the edges of the extracted pieces aren't moved.  To prevent the vertices from being moved the bridge tool is used, rather than merge vertices which pulls two vertices to the average point between them.

Tutorial Screenshot: Check out that old interface!

I didn't want to spend too much time breaking apart a brick I wouldn't use so here's a screen shot of a completed one from the tutorial.

Broken Brick

For low-res splintered wood things start out in the same way: adding more resolution using edge loops.  Vertices are then pushed around to make the edges jagged, and different faces are extruded out.

Splintered wood

Dynamics are used to assist with the placement of the rubble.  The rubble is selected and turned into a Active Rigid Body.  This means that they can be affected by various forces in the scene and can react against other objects.  The objects that the Active Rigids will interact with need to be turned into Passive Rigid Bodies.

FYI:
Active rigid bodies: move around and react with forces (in this case gravity has been added to the scene)
Passive Rigid Bodies: do not move or react to the forces but will collide with Active Rigid Bodies.   

This is definitely a shortcut compared with manually placing each individual piece of rubble.  
One the rubble is placed the rubble can be selected and the rigid body removed to stop the simulation.

Destruction!

Finally the tutorial talks about adding extra detail to the model.  This is important for areas where the camera will be getting closer to the model.  They use Zbrush for this but I use Mudbox for sculpting and the same techniques can be applied there.  I didn't bother actually completing this part of the tutorial myself but watched the lessons to see how it was approached. 

• They start off by increasing the resolution of the model so it can be sculpted.  The edges are sharpened using a basic brush.  
• 'Alphas' are used to add texture to the model.  These seem similar to the 'Stamps' in Mudbox.  A noise brush is also used.
• More variation to the shape is created by sculpting with a normal brush. 

Tutorial Screen Grab

For the wood a very basic low-res model is used, and subdivisions are added slowly with sculpting happening between each step up.

This tutorial has been useful, but is more about creating destruction for how something would look after the event than during it.  If I wanted to add dynamics and simulate the destruction as it happens I could apply some of these techniques, but I would need to put more thought into how the destruction pieces fit together to create the undamaged building.  This was touched upon in lesson 8- which broke apart the brick.