Skinned Decals Manual

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MANUAL
Version 1.0

(18.11.2018)

Contact: info@ironsight.fi

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Table of Contents
................................................................................................................................................................ 1
SKINNED DECALS – MANUAL .................................................................................................................. 1
OVERVIEW............................................................................................................................................... 3
FEATURES ............................................................................................................................................ 3
COMPATIBILITY ................................................................................................................................... 3
GUIDE ...................................................................................................................................................... 4
How to setup Skinned Decal System................................................................................................... 4
How to add decals in script ................................................................................................................. 4
Projecting from a transform ............................................................................................................... 4
Projecting from a camera ................................................................................................................... 5
How to create a new decal type ......................................................................................................... 5
How to add decals in editor ................................................................................................................ 5
How to save decal mesh to the project .............................................................................................. 5
SHADERS ................................................................................................................................................. 7
Texture ................................................................................................................................................ 7
Specular............................................................................................................................................... 7
Parallax ................................................................................................................................................ 7
Tessellated Parallax............................................................................................................................. 7
Atlas .................................................................................................................................................... 8
Packed Parallax ................................................................................................................................... 8
Packed Atlas ........................................................................................................................................ 8
COMPONENT OVERVIEW ...................................................................................................................... 10
Skinned Decal System (SkinnedDecalSystem.cs) .............................................................................. 10
Skinned Decal (SkinnedDecal.cs) ...................................................................................................... 11
Skinned Decal Builder (SkinnedDecalBuilder.cs) .............................................................................. 11
Skinned Decal Mesh (SkinnedDecalMesh.cs) ................................................................................... 11

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OVERVIEW
You need a way to show effects on your character model such as damage, bullet holes, scratches,
stains, dirt and more. Skinned Decals will allow you to add impressive decals to your characters during
gameplay (and editor) with ease, just one line of code.
The system does not require the skinned mesh to have any colliders, the decals are placed according
the mesh data.
The mesh based solution allows flexibility in shaders, for example it is possible to use Tesselation to
enhance the depth of the effects. Skinned decals will also perfectly follow the animation of your
model.
Sample character, bullet hole decals and shaders are included!

FEATURES







Run-time generation (with optional multithreading)
Does not require collider
One line of code to add decal
Supports characters composed of many skinned meshes
Atlasing, draw many decal types with one draw call.
Option to add decals to character in the editor and save mesh for later use.

COMPATIBILITY





Works with GPU skinning
Combatible with UMA
Doesn’t support Blendshape-animation.
Doesn’t support cloth and dynamic meshes that are animated by something else than bones.

3

GUIDE
How to setup Skinned Decal System
1. Add SkinnedDecalSystem-component to your character
gameobject.
2. Now you can add decals to this character in Editor and
during run-time using CreateDecal-function.

By default “Find all child skinned meshes”-box is
checked and the system will find all skinned meshes
under its hierarchy.

How to add decals in script
1. Call CreateDecal() function of SkinnedDecalSystem.cs

2. This function takes in:
a. SkinnedDecal-object, that defines the decal material and properties,
b. origin-vector (where the decal is projected from)
c. direction-vector (direction from origin where the decal is projected to).
d. Optionally an up-vector for orientation.

Projecting from a transform
1. Call CreateDecal() with the transforms position as the origin, and forward as direction.

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Projecting from a camera
1. Create a ray from mouse position using Camera.ScreenPointToRay().
2. Call CreateDeca() with the resulting rays origin and direction, and additionally the camera
transform up.

How to create a new decal type
1. In

the

Project-window

press

“Create”

button

and

find

SkinnedDecal.

2. This will create a new SkinnedDecal -scriptable object that you can use to define a decal type.
3. Create a new Material with your textures and shader (you can find our included shaders under
“SkinnedDecals” in the shader dropdown view) and drag it in to the material slot.
4. Set size and other settings to your liking.

How to add decals in editor
1. In SkinnedDecalSystem-inspector find Decal-field under Editor:

2. Drag a SkinnedDecal -scriptable object to this slot
3. ALT - left click on the character in Scene-view to add decals.

How to save decal mesh to the project
1. When you have placed decals on the model and want to save it for later use:
2. Find the SkinnedDecalMesh-component with your decals in the hierarchy under you
SkinnedDecalSystem.
3. In the SkinnedDecalMesh-inspector, press “Save to Assets…” button and select the location
where you want the mesh to be saved.
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4. Keep the generated SkinnedMeshRenderer in the character hierarchy.
5. Use by enabling the renderer when the effect is needed.

6

SHADERS
Following shaders are included in the package.

Texture
Minimal shader with just color texture.
Textures:


Albedo map

Specular
Basic shader for specular workflow.
Textures:




Albedo map (alpha = opacity)
Normal map
Specular map (alpha = smoothness)

Parameters:



Specular color
Shininess

Parallax
Shader with parallax mapping.
Textures:





Albedo map (alpha = opacity)
Normal map
Specular map (alpha = smoothness)
Height map

Parameters:


Parallax amount

Tessellated Parallax
Shader with parallax and tessellation.
Textures:




Albedo map (alpha = opacity)
Normal map
Specular map (alpha = smoothness)
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

Height map

Parameters:




Parallax amount
Tessellation amount
Displacement amount

NOTE about Tessellation shaders:
Tessellation shaders supplied by this package only displace mesh to the direction of mesh normal with values
that are above 0.5(50% grey to white) in the height map. Parallax effect is applied only to values below 0.5
(50% grey to black) to create illusion of depth. This method makes sure that there won’t be any clipping
geometry. It is extremely important that your height maps have their middle ground at 0.5 (50% grey) value.

Atlas
Shader that supports atlas textures.
Textures:




Albedo map (alpha = opacity)
Normal map
Specular map (alpha = smoothness)

Parameters:



Atlas width
Atlas height

Packed Parallax
Same as Parallax, but with height, normal and smoothness packed to a single texture.
Textures:



Albedo map (alpha = opacity)
Packed normal (r = height, g = normal up, b = smoothness, a = normal right)

Packed Atlas
Same as Atlas, but with height, normal and smoothness packed to a single texture.
Textures:




Albedo map (alpha = opacity)
Packed normal (r = height, g = normal up, b = smoothness, a = normal right)
Normal map

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How to assemble Packed Normals texture:

Important about texture import settings:



Height maps
o sRGB(Color Texture) = False
Packed Normals
o sRGB(Color Texture) = False

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COMPONENT OVERVIEW
Skinned Decal System (SkinnedDecalSystem.cs)
Provides the interface to add decal using script and defines which Skinned Mesh Renderers are
affected. Creates Skinned Decal Builders for each child Skinned Mesh Renderer.
OPTIONS
Skinned meshes
o

o

Find all child skinned meshes
o If enabled, the system will use GetComponentsInChildren() to find all Skinned Mesh
Renderers under it.
Specific skinned meshes
o If “find all child skinned meshes” is disabled, this list determines which Skinned Mesh
Renderers are used.

Combining
o

Combine meshes of same decal type
o If enabled, the system will produce one decal mesh for each decal type across all
skinned meshes. This means that if the system has for example 10 Skinned Mesh
Renderers, the decal geometry from all these will be combined to a single mesh.
o If disabled, each skinned mesh renderer will produce its own mesh for each decal
type.

Settings
o
o

Update when offscreen
o Enables “update when offscreen” on each generated decal mesh.
Allow over 65k vertices
o If enabled, the system will continue to add vertices to decal mesh even after this limit.
NOTE: make sure your Unity version supports this.
o If disabled a new mesh is generated after previous exceeds this limit.

Editor
o

Decal
o Decal type that is used when adding decals in the Editor (using ALT-left click).

Splitting
o

Split vertex limit
o A vertex count that causes the decal mesh to be started over. The old mesh will remain
but all new decal geometry will be added to the new one (until it reaches vertex limit
again).

Scripting interface for creating decals:
public void CreateDecal(SkinnedDecal decalType, Vector3 origin, Vector3 direction)

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public void CreateDecal(SkinnedDecal decalType, Vector3 origin, Vector3 direction,
Vector3 up)

Scripting interface for adding / removing Skinned Mesh Renderers:
public void AddSkinnedMesh(SkinnedMeshRenderer smr)
public void RemoveSkinnedMesh(SkinnedMeshRenderer smr)

Skinned Decal (SkinnedDecal.cs)
A Scriptable Object that holds data related to specific decal type. These are created by the user in
Editor and need to be supplied when calling CreateDecal() on the Skinned Decal System.
SETTINGS
o
o
o
o
o

o

Material
Size
Size randomization
Rotation randomization
Normal clipping
o This normal clip is tested as a dot product between the decal projection direction
(supplied to CreateDecal) and the skinned mesh normal, when selecting vertices for
the decal mesh.
Atlasing
o Atlasing provides a way to include many decals in a single material, texture and
therefore decal type. This allows many different decals to be rendered with a single
draw call.
o User can specify a specific item from the atlas using “selected item”, or enable “select
random item” which selects item randomly each time.
o NOTE: Atlasing works by encoding the item index in to the vertex color buffer or the
generated decal mesh and therefore requires a shader that can calculate the correct
UV from it (atlas shader provided).

Skinned Decal Builder (SkinnedDecalBuilder.cs)
These are added by the decal system to each Skinned Mesh Renderer. This component holds data
related to the Skinned Mesh Renderer it manages and this is where the mesh operations are
performed.
Handled by Skinned Decal System and has no functions for the user.

Skinned Decal Mesh (SkinnedDecalMesh.cs)
Holds the generated mesh data.
OPTIONS
o

Save to assets
o Saves the current decal mesh to user defined location in the project.
o NOTE: The mesh is only usable if the skinned mesh using it remains in the character
hierarchy.
o NOTE: Can only be used in the editor
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