Level Of Detail

Light-weight or heavy-duty? How about both!

Level of Detail

Setup your character once with all bells-and-whistles, and interactively pick which level of detail to use for your simulation in a given situation.

Usecases

1. Body at Level 0, fingers at Level 1
2. Props at Level 1, muscles at Level 2
3. Major masses at Level 0, extremities at Level 1 and Level 2

For example, here's a Wasp character with 3 levels of increasing detail.

As you'd expect, it'll record only the currently active markers.

Workflow

Here's how it works.

1. Give each marker a "level", such as 1
2. Tell solver which "level" to solve at, such as 1

And that's it! Any marker with a matching level is simulated and recorded.

Operators

What does each level mean? The answer lies in the "operator".

Operator	Description
Less Than	If the Marker Level is less than (or equal) to the Solver Level, simulate it.
Greater Than	If the Marker Level is greater than (or equal) to the Solver Level, simulate it.
Equal	If the Marker Level is equal to the Solver Level, simulate it.
NotEqual	If the Marker Level is not equal to the Solver Level, simulate it.

With these, you can use each level for..

1. An increasing amount of detail
2. An increasing amount of reduction
3. Something completely custom

With Equal and NotEqual operators, you can have some markers appear or disappear on particular levels, enabling endless combinations.

Roadmap

This should cover a majority of cases, but there are things you cannot yet do, but will be able to in the future.

1. Capsule on one level, Mesh on another. For higher-resolution contacts.
2. Dense hierarchy of controls at one level, sparse at another. For e.g. twist joints versus a simple 2-joint chain, or a densely packed spine versus just hip and torso controls.

Algorithm

For the geeks out there, here's what the underlying algorithm looks like in Python.

# Membership types
Minimum = 1  # Present at this level and higher
Maximum = 3  # Present at this level and lower
Only = 4     # Only present at this level
Not = 5      # Present at all levels *except* this one

markers = [
    {"name": "hip", "level": 0, "membership": Minimum},
    {"name": "spine", "level": 0, "membership": Minimum},
    {"name": "neck", "level": 0, "membership": Minimum},
    {"name": "head", "level": 0, "membership": Minimum},
    {"name": "L_upper_leg", "level": 0, "membership": Minimum},
    {"name": "L_lower_leg", "level": 0, "membership": Minimum},
    {"name": "R_hand", "level": 1, "membership": Minimum},
    {"name": "L_foot_box", "level": 1, "membership": Maximum},
    {"name": "L_foot_convex", "level": 2, "membership": Minimum},
    {"name": "R_toe_capsule", "level": 2, "membership": Not},
    {"name": "R_toe_convex", "level": 2, "membership": Only},
]

def resolve(level):
    print("Level %d" % level)
    for marker in markers:
        if marker["membership"] == Minimum and marker["level"] <= level:
            print(" - {name} ({level})".format(**marker))

        if marker["membership"] == Maximum and marker["level"] >= level:
            print(" - {name} ({level})".format(**marker))

        if marker["membership"] == Only and marker["level"] == level:
            print(" - {name} ({level})".format(**marker))

        if marker["membership"] == Not and marker["level"] != level:
            print(" - {name} ({level})".format(**marker))

resolve(0)
resolve(1)
resolve(2)

Run this, and this is what you'll find.

Level 0
 - hip (0)
 - spine (0)
 - neck (0)
 - head (0)
 - L_upper_leg (0)
 - L_lower_leg (0)
 - L_foot_box (1)
 - R_toe_capsule (2)
Level 1
 - hip (0)
 - spine (0)
 - neck (0)
 - head (0)
 - L_upper_leg (0)
 - L_lower_leg (0)
 - R_hand (1)
 - L_foot_box (1)
 - R_toe_capsule (2)
Level 2
 - hip (0)
 - spine (0)
 - neck (0)
 - head (0)
 - L_upper_leg (0)
 - L_lower_leg (0)
 - R_hand (1)
 - L_foot_convex (2)
 - R_toe_convex (2)