The Ruinator's Purpose

The Ruinator allows 3D artists to quickly turn structures into partial ruins by non-destructively hiding parts of a mesh and filling it with damaged beams, girders, walls, floors, and debris.

The Ruinator Documentation for version 08

1. The Ruinator assumes you have intermediate experience with Blender and have a basic understanding of Blender's workflow and user interface.
2. Get started by importing the The Ruinator asset: The Ruinator is not an addon, so don't try to add the .zip file as such. Unzip the product file first. The zip files contains an example blend file and a blend file with the Ruinator nodetree. You'll append that into your project. In your project, append the following Nodetree from the blend file in the zipped folder: ruinator_v08.blend > NodeTree > ruinator.v08.
   
3. THE IMPORTANCE OF SCALE: The structure you plan to ruin should be close to real-life scale in Blender - so a 40 meter building should be around 40 meters in your Blender scene. (You can see the scale of an object in the 3D viewport in the N-Panel under the section labeled 'Dimensions'.) Be sure to Apply All Transforms (CTRL-A) on the structure you plan to ruin. Also, set the structure's origin to its geometry - this helps with the debris scattering (Object > Set Origin > Origin to Geometry). Warning, initiating The Ruinator on a very large huge structure (> 80 meters) may result in Blender crashing as the modifier fills whatever space is available with increasing levels of beams, pipes, and debris. 
   
   
4. If your structure is low-poly, you may need to subdivide it: Do this in edit mode—not with a subdivision modifier. Use either subdivide or loop cuts. The subdivision allows a more natural border between the ruined part of the structure and the original. Less subdivision will result in a border that follows the contours of the polygons - which in some cases might actually seem more realistic. So, play around with what level of subdivision works best for your project. A uniform topographic flow is preferred but not required. Subdivision does not affect the default density of this modifier—only the scale of the structure controls that.
   
   
   
5. Select the part of the mesh you would like to ruin: In edit mode, select a portion of the structure you would like to ruin and create a vertex group from it. You must name the vertex group 'ruined'.
   
   
   
6. Add the Ruinator modifier: In the modifiers tab, add a new geometry nodes modifier. Click the Browse Nodetree button and select 'ruinator.v05'. Alternatively, from the Assets browser panel, you should see a Ruinator thumbnail. You can drag that to the structure you plan to ruin. The modifier should now be adding debris to the section of your structure you specified as a vertex group called 'ruined'.
   
   
   
7. Cut out the façade: Set your 3D viewport shading to either Material Preview or Rendered. If your ruined structure doesn't have a material, create one. If it does, go into the shader node editor and add the nodegroup called 'Ruinator Alpha Generator'. Then drag the output labeled 'ruined alpha' to the alpha input of your shader. You should now have a hole in your structure revealing multiple levels of debris. (You will only see the alpha channel cutting the hole in the façade if your viewport is in Material Preview or Rendered modes. You won't see it in Solid Mode.) You should now see the ruins inside the structure. Depending on the size of the object, you may need to make adjustments to the debris density and debris scale settings (detailed below). For better lighting, switch the 3D viewport to the Rendered mode and (if using Eevee) turn on Raytracing for more accurate lighting.
   
   
8. Paint on more ruins: With your ruined structure selected, and your viewport in either Material Preview or Rendered mode, select Weight Paint mode. Your structure should turn blue for Weight Painting mode, but this actually interferes with what we see as we paint, so turn off Overlays in the 3D viewport (Shift-Alt-Z). Now you can freely paint on more ruins. Switch the brush to Subtract and you will unpaint the ruins. 
   
   

Ruinator Limitations

• Very large buildings should be avoided on weaker computers as the Ruinator bases mesh size on structure size. Experiment with small structures first. The Ruinator needs a computer of average or better power for most projects. Very limited systems may not have a enough video RAM or processing power to use it effectively.
• The Ruinator was built and tested on Blender 4.3.2. Older versions of Blender may have issues.
• The Ruinator hides the surface of the structure with an alpha mask. This can make the facade appear paper-thin from some angles and is not ideal. Future version hope to address this issue.
• As of the time of this writing, only one Ruinator modifier vertex group per Blender object is allowed. However, that vertex group does not need to be contiguous, so many parts of the same structure can be ruined with one Ruinator modifier. If you need to have multiple parts of the same object ruined but with different Ruinator settings, either separate the object into multiple objects (preferred option), or Apply the Ruinator modifier and add a new one (this may cause the default alpha generator to malfunction).
• The Ruinator uses a convex hull generator to create an interior mesh in your structure. If you only set a flat plane as your vertex group, the Ruinator will only render the beams and girders of that façade without rendering the floors and debris behind it. So, make sure your vertex group traverses corners or goes through the structure so an interior mesh will form. Conversely, if your structure has large gaps in it (a torus for example), and the vertex group traverses this gap, the Ruinator will attempt to draw debris unnecessarily between those two sections. The easiest way to remedy this is to apply the Ruinator modifier after you are happy with the settings and delete the unwanted mesh manually in edit mode. These  issues should be remediated in future versions. 

Published Ruinator Modifier Parameters:

• complexity: basically a mesh subdivision. Be carefull about setting this too high.
• destruct amount: distorts the ruined mesh via a noise texture
• destruct scale: changes the distortion noise scale - allows for more wavy or jittery destruction 
• delete geometry during destruct: increasingly deletes the ruins as the destruction increases
• taper delete: deletes the geometry on a gradient based on proximity from structure
• beam radius: the radius of the beams and girders
• beam decay: randomly hides the beams with a noise texture in the truss shader material
• floor spacing: changes the distance between floors
• random beam size: randomly selects beams and allows their scale to be adjusted to create variety
• debris edge proximity: depending on the size the ruins, affects the distance of the debris from the ruin boundary
• debris 1: size of random debris planes
• debris 2: size of random debris cubes
• debris 3: size of random debris icospheres
• pipe density: how many random pipes and tubes are drawn throughout the ruin
• pipe seed: random direction and location of drawn pipes
• pipe radius: radius of randomly drawn pipes
• beam on / off: hide the beams
• triangulate beams: whether to draw the beams as a grid or as a triangle grid

Future Development:

• Convex hull interior simulation has limitations on flat surfaces, so a version raymarching may be employed in future versions
• Create a ribar simulation
• Publish options in the modifier for changing debris options and materials
• Add random light sources through distruction
• Create a rotation option for the floor generator
• Add spark generators
• Publish Debris objects in modifier to allow easier customization
• Provide more options for easier material customization

License:

CC BY-SA 

This license enables reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. If you remix, adapt, or build upon the material, you must license the modified material under identical terms. CC BY-SA includes the following elements:

 BY: credit must be given to the creator.

 SA: Adaptations must be shared under the same terms.

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