Path Traversal

Published grammar

This page uses the same scene-first presentation as the gallery viewer while also showing the source grammar text.

//------------------------------------------------
// Progen3D grammar: stochastic path traversal
// Using shinymetal material
//------------------------------------------------

Start ->
[
    T(0 0 0)
    Path(0 0 0 22)
]

//------------------------------------------------
// Path traversal
//------------------------------------------------

Path(x z dir steps) ->
    ?(steps > 0)
        StepTile(x z)
        FeatureAt(x z)
        NextPath(x z dir steps)
    :
        EndCap(x z)

//------------------------------------------------
// Random direction control
//------------------------------------------------

NextPath(x z dir steps) ->
    R r(0 1)
    ?(r < 0.2)
        TurnLeft(x z dir steps)
    :
        ?(r < 0.4)
            TurnRight(x z dir steps)
        :
            GoStraight(x z dir steps)

//------------------------------------------------
// Movement rules
//------------------------------------------------

GoStraight(x z dir steps) ->
    ?(dir==0) Path(x+1 z   0 steps-1) :
    ?(dir==1) Path(x   z+1 1 steps-1) :
    ?(dir==2) Path(x-1 z   2 steps-1) :
               Path(x   z-1 3 steps-1)

TurnRight(x z dir steps) ->
    ?(dir==0) Path(x   z+1 1 steps-1) :
    ?(dir==1) Path(x-1 z   2 steps-1) :
    ?(dir==2) Path(x   z-1 3 steps-1) :
               Path(x+1 z   0 steps-1)

TurnLeft(x z dir steps) ->
    ?(dir==0) Path(x   z-1 3 steps-1) :
    ?(dir==1) Path(x+1 z   0 steps-1) :
    ?(dir==2) Path(x   z+1 1 steps-1) :
               Path(x-1 z   2 steps-1)

//------------------------------------------------
// Main path tile (metal surface)
//------------------------------------------------

StepTile(x z) ->
[
    T(x 0 z)
    S(0.9 0.08 0.9)
    I(Cube shinymetal 0)
]

//------------------------------------------------
// Random feature placement (metal variations)
//------------------------------------------------

FeatureAt(x z) ->
    R f(0 1)
    ?(f < 0.15)
        Marker(x z)
    :
        ?(f < 0.25)
            Pillar(x z)
        :
            ?(f < 0.30)
                WideTile(x z)
            :
                Empty

//------------------------------------------------
// Feature definitions
//------------------------------------------------

Marker(x z) ->
[
    T(x 0.2 z)
    S(0.3 0.25 0.3)
    I(Cube shinymetal 0)
]

Pillar(x z) ->
[
    T(x 0.5 z)
    S(0.2 1.0 0.2)
    I(Cube shinymetal 0)
]

// Wider reflective plate
WideTile(x z) ->
[
    T(x 0 z)
    S(1.2 0.08 1.2)
    I(Cube shinymetal 0)
]

//------------------------------------------------
// End cap
//------------------------------------------------

EndCap(x z) ->
[
    T(x 0.12 z)
    S(1.1 0.2 1.1)
    I(Cube shinymetal 0)
]

Empty ->
End ->

Viewer notes