Framsticks

Creature body

The two basic symbols are:

• X – stick,
• () – branch.

The body structure is built like a tree: new sticks are attached to the ends of the previous ones.

• X(X,X) means two sticks from a one-stick root,
• X(X,X,X) means three sticks from a one-stick root,
• X(X,X,) is also possible, as well as
• X(,X,,,X,,X,,)

Inside parentheses, the full angle is divided into as many parts as there are commas+2. Each stick in such a 'junction', when controlled by a bending muscle, has the freedom of the full angle divided by the number of branches.

Modifiers (special characters) can be placed before X's and ('s. They affect the following X and, with a progressively lesser effect, subsequent X's. Modifiers modify stick position and features. Uppercase and lowercase letters can be used; uppercase letters increase the given property while lowercase ones decrease it.

Modifiers: Rr, Qq, Cc, Ll, Ww, Ff, Aa, Ss, Mm, Ii, Ee.

Modifiers affecting color (only visuals, no other function) of Parts: Dd (red), Gg (green), Bb (blue).

The order of the modifier symbols is important (i.e., Ccc is different from cCc and ccC). The later characters in a sequence have higher influence. See the following example of the g,G genes (coding the green color). The target value of the green color is from 0.0 to 1.0:

$ ./geneprops_test G 3 | sort -n -k 2

ggg     0.0625
gg      0.125
Ggg     0.1875
g       0.25
gGg     0.3125
Gg      0.375
GGg     0.4375
-       0.5
ggG     0.5625
gG      0.625
GgG     0.6875
G       0.75
gGG     0.8125
GG      0.875
GGG     0.9375

$ ./geneprops_test F 3 | sort -n -k 2

fff     0.05
ff      0.1
f       0.2
-       0.4
Fff     0.55
fFf     1.05
Ff      1.1
FFf     1.55
ffF     2.05
fF      2.1
F       2.2
FfF     2.55
fFF     3.05
FF      3.1
FFF     3.55

Technical details of modifiers

We start with the current (default) value of a given property (e.g., 0.4 for friction). A lowercase letter (f) moves the value to the midpoint between the current value and the lower boundary of the allowed range (0.0). An uppercase letter (F) behaves analogously, but for the upper boundary (4.0). Once one modifier character is interpreted, the current value is updated, and the next character (if present) is analyzed. In this approach, there is no need to know upfront how many modifier characters a sequence holds.

Note that depending on how far the lower and the upper limits are from the current value, lowercase and uppercase modifiers may have weaker or stronger influence on the current value. When you compare the G and F examples above, you will notice that the lowercase-uppercase-lowercase sequence decreases the value from the default for green, but increases the value from the default for friction.

Also note that in some cases, different sequences may result in the same value – e.g., for weight with the allowed range of [0.5, 2.0] and the current value of 1.0, the Ww sequence becomes neutral and yields the same current value. The list below is sorted highest to lowest to match the picture:

$ ./geneprops_test W 3 | sort -n -k 2 -r

WWW     1.875
WW      1.75
wWW     1.6875
WwW     1.5
W       1.5
wW      1.375
wwW     1.3125
WWw     1.125
Ww      1
-       1
wWw     0.9375
Www     0.75
w       0.75
ww      0.625
www     0.5625

Examples

XXX(XX,X)
X(X,RRX(X,X))
XlCXlCXlCX

Some more samples of possible structures:

Creature brain

Neurons are placed in [], after X's. The following information can be supplied inside square brackets:

• neuron type
• properties (parameters) of the neuron
• inputs of the neuron (if it can have inputs)

The syntax is:

Neuron inputs can be taken from different signal sources: other neurons' outputs or receptors. A neuron input can also have a constant value. If a neuron is a muscle, it can control its stick's bend or rotation.

A useful tool for adding/removing neurons from an f1 genotype while preserving relative references (links) between neurons is here.

See also: the brain simulation page.

Examples

Enter these genotypes into Framsticks GUI to see the corresponding neural networks.

• X[N]
• X[@]
• X[@][N]
• X[@, 1:1.0][N]
• X[1:1.0][-1:2.0]
• X[G][-1:-3.5, -1:-0.5, 0:0.1]
• X[N, fo:1, si:-4]
• X[Sin, f0:0.1, t:0.5]