L-Py Helpcard

L-Py is based on the specification of Lstudio/cpfg-lpfg defined by P. Prusinkiewicz et al. (http://algorithmicbotany.org/lstudio).

Predefined Symbols

Here is a recap of the predefined symbol used in L-Py with their turtle interpretation:

None

None Module.

Structure

[	SB	Push the state in the stack.
]	EB	Pop last state from turtle stack and make it the its current state.

Rotation

Pinpoint		Orient turtle toward (x,y,z) . Params : ‘x, y, z’ or ‘v’ (optionals, default = 0).
PinpointRel		Orient turtle toward pos+(x,y,z) . Params : ‘x, y, z’ or ‘v’ (optionals, default = 0).
@R	SetHead	Set the turtle Heading and Up vector. Params: ‘hx, hy, hz, ux, uy, uz’ or ‘h,v’ (optionals, default=0,0,1, 1,0,0).
EulerAngles		Set the orientation of the turtle from the absolute euler angles. Params: ‘azimuth, elevation, roll’ (optionals, default=180,90,0).
	Left	Turn left around Up vector. Params : ‘angle’ (optional, in degrees).
	Right	Turn right around Up vector. Params : ‘angle’ (optional, in degrees).
^	Up	Pitch up around Left vector. Params : ‘angle’ (optional, in degrees).
&	Down	Pitch down around Left vector. Params : ‘angle’ (optional, in degrees).
/	RollL	Roll left around Heading vector. Params : ‘angle’ (optional, in degrees).
	RollR	Roll right around Heading vector. Params : ‘angle’ (optional, in degrees).
iRollL		Roll left intrinsically around Heading vector. Params : ‘angle’ (optional, in degrees).
iRollR		Roll right intrinsically around Heading vector. Params : ‘angle’ (optional, in degrees).
	TurnAround	Turn around 180deg the Up vector.
@v	RollToVert	Roll to Vertical : Roll the turtle around the H axis so that H and U lie in a common vertical plane with U closest to up
@h	RollToHorizontal	Roll to Horizontal : Roll the turtle so that H lie in the horizontal plane
LeftReflection		The turtle change the left vector to have a symmetric behavior.
UpReflection		The turtle change the up vector to have a symmetric behavior.
HeadingReflection		The turtle change the heading vector to have a symmetric behavior.

Position

@M	MoveTo	Set the turtle position. Params : ‘x, y, z’ or ‘v’ (optionals, default = None for not changing specific coordinates).
MoveRel		Move relatively from current the turtle position. Params : ‘x, y, z’ or ‘v’(optionals, default = 0).
@2D	StartScreenProjection	The turtle will create geometry in the screen coordinates system.
@3D	EndScreenProjection	The turtle will create geometry in the world system (default behaviour).

Scale

@Dd	DivScale	Divides the current turtle scale by a scale factor, Params : ‘scale_factor’ (optional, default = 1.0).
@Di	MultScale	Multiplies the current turtle scale by a scale factor, Params : ‘scale_factor’ (optional, default = 1.0).
@D	SetScale	Set the current turtle scale, Params : ‘scale’ (optional, default = 1.0).

Primitive

F		Move forward and draw. Params: ‘length , topradius’.
f		Move forward and without draw. Params: ‘length’.
nF		Produce a n steps path of a given length and varying radius. Params : ‘length, dlength [, radius = 1, radiusvariation = None]’.
@Gc	StartGC	Start a new generalized cylinder.
@Ge	EndGC	Pop generalized cylinder from the stack and render it.
{	BP	Start a new polygon.
}	EP	Pop a polygon from the stack and render it. Params : concavetest (default=False).
.	PP	Add a point for polygon.
LineTo		Trace line to (x,y,z) without changing the orientation. Params : ‘x, y, z, topdiameter’ or ‘v, topdiameter’ (optionals, default = 0).
OLineTo		Trace line toward (x,y,z) and change the orientation. Params : ‘x, y, z, topdiameter’ or ‘v, topdiameter’ (optionals, default = 0).
LineRel		Trace line to pos+(x,y,z) without changing the orientation. Params : ‘x, y, z, topdiameter’ or ‘v, topdiameter’(optionals, default = 0).
OLineRel		Trace line toward pos+(x,y,z) and change the orientation. Params : ‘x, y, z, topdiameter’ or ‘v, topdiameter’ (optionals, default = 0).
@O	Sphere	Draw a sphere. Params : ‘radius’ (optional, should be positive, default = line width).
@B	Box	Draw a box. Params : ‘length’,’topradius’.
@b	Quad	Draw a quad. Params : ‘length’,’topradius’.
@o	Circle	Draw a circle. Params : ‘radius’ (optional, should be positive, default = line width).
@L	Label	Draw a text label. Params : ‘text’,’size’.
surface		Draw the predefined surface at the turtle’s current location and orientation. Params : ‘surface_name’ (by default, ‘l’ exists), ‘scale_factor’ (optional, default= 1.0, should be positive).
~		Draw the predefined surface at the turtle’s current location and orientation. Params : ‘surface_name’ (by default, ‘l’ exists), ‘scale_factor’ (optional, default= 1.0, should be positive).
@g	PglShape	Draw a geometry at the turtle’s current location and orientation. Params : ‘geometric_model’, ‘scale_factor’ (optional, should be positive) or ‘shape’ or ‘scene’ or ‘material’.
Frame		Draw the current turtle frame as 3 arrows (red=heading,blue=up,green=left). Params : ‘size’ (should be positive), ‘cap_heigth_ratio’ (in [0,1]), ‘cap_radius_ratio’ (should be positive).
Arrow		Draw an arrow. Params : ‘size’ (should be positive), ‘cap_heigth_ratio’ (in [0,1]), ‘cap_radius_ratio’ (should be positive).
SetContour		Set Cross Section of Generalized Cylinder. Params : ‘Curve2D [, ccw]’.
SectionResolution		Set Resolution of Section of Cylinder. Params : ‘resolution’ (int).
SetGuide		Set Guide for turtle tracing. Params : ‘Curve[2D|3D], length [,yorientation, ccw]’.
EndGuide		End Guide for turtle tracing.
Sweep		Produce a sweep surface. Params : ‘path, section, length, dlength [, radius = 1, radiusvariation = None]’.
PositionOnGuide		Set position on Guide for turtle tracing.

Width

_	IncWidth	Increase the current line width or set it if a parameter is given. Params : ‘width’ (optional).
!	DecWidth	Decrease the current line width or set it if a parameter is given. Params : ‘width’ (optional).
SetWidth		Set current line width. Params : ‘width’.

Color

;	IncColor	Increase the current material index or set it if a parameter is given. Params : ‘index’ (optional, positive int).
,	DecColor	Decrease the current material index or set it if a parameter is given. Params : ‘index’ (optional, positive int).
SetColor		Set the current material. Params : ‘index’ (positive int) or ‘r,g,b[,a]’ or ‘material’.
InterpolateColors		Set the current material. Params : ‘index1’, ‘index2’, ‘alpha’ .

Tropism

@Ts	Elasticity	Set Branch Elasticity. Params : ‘elasticity’ (optional, default= 0.0, should be between [0,1]).
@Tp	Tropism	Set Tropism. Params : ‘tropism’ (optional, Vector3, default= (1,0,0)).

Request

?P	GetPos	Request position vector information. Params : ‘x,y,z’ or ‘v’ (optional, default=Vector3, filled by Turtle).
?H	GetHead	Request heading vector information. Params : ‘x,y,z’ or ‘v’ (optional, default=Vector3, filled by Turtle).
?U	GetUp	Request up vector information. Params : ‘x,y,z’ or ‘v’ (optional, default=Vector3, filled by Turtle).
?L	GetLeft	Request left vector information. Params : ‘x,y,z’ or ‘v’ (optional, default=Vector3, filled by Turtle).
?R	GetRight	Request right vector information. Params : ‘x,y,z’ or ‘v’ (optional, default=Vector3, filled by Turtle).
?F	GetFrame	Request turtle frame information. Params : ‘p,h,u,l’ (optional, filled by Turtle).

Texture

TextureBaseColor		Set the base color of the texture. Params : ‘index’ (positive int) or ‘r,g,b[,a]’ or ‘material’.
InterpolateTextureBaseColors		Set the base color of the texture from interpolation of 2 predefined material. Params : ‘index1’, ‘index2’, ‘alpha’ .
TextureScale		Set the scale coefficient for texture application. Params : ‘uscale, vscale’ (default = 1,1) or ‘scale’.
TextureUScale		Set the u-scale coefficient for texture application. Params : ‘uscale’ (default = 1).
TextureVScale	TextureVCoeff	Set the v-scale coefficient for texture application. Params : ‘vscale’ (default = 1).
TextureTranslation		Set the translation for texture application. Params : ‘utranslation, vtranslation’ (default = 0,0) or ‘translation’.
TextureRotation		Set the rotation for texture application. Params : ‘angle, urotcenter, vrotcenter’ (default = 0,0.5,0.5) or ‘angle, rotcenter’.
TextureTransformation		Set the transformation for texture application. Params : ‘uscale, vscale, utranslation, vtranslation, angle, urotcenter, vrotcenter’ (default = 1,1,0,0,0,0.5,0.5) or ‘scale, translation, angle, rotcenter’.

String Manipulation

X	MouseIns	Module inserted just before module selected by user in visualisation.
%	Cut	Cut the remainder of the current branch in the string.
new	newmodule	Create a new module whose name is given by first argument.

Pattern Matching

=]		Match exactly a closing bracket
	any	Used to match any module in rules predecessor. First argument will become name of the module.
x	repexp, all	Used to specify matching of a repetition of modules.
or	||	Used to specify an alternative matching of modules.
?I	GetIterator	Request an iterator over the current Lstring.
$	GetModule	Request a module of the current Lstring.

Predefined commands

Here comes the python commands that control the simulation.

The following commands can be redefined to initialize simulation state:

def Start([lstring])	is called at the beginning of the simulation. One argument can be optionally defined to receive the input lstring. A modified lstring can be returned by the function to modify the axiom of the simulation.
def End([lstring,geometries])	is called at the end of the simulation. One or two arguments can be optionally defined to receive the final lstring and its geometric interpretation. A modified lstring or scene can be returned by the function to change output of the simulation.
def StartEach([lstring])	is called before each derivation step. One argument can be optionally defined to receive the input lstring. A modified lstring can be returned by the function to modify input lstring of the current iteration.
def EndEach([lstring,geometries])	is called after each derivation step. One or two arguments can be optionally defined to receive the current lstring and its geometric interpretation. Returning an lstring or (lstring, geometries) will be used for next iterations and display. If frameDisplayed() is False, geometries is None.
def StartInterpretation()	is called at the beginning of the interpretation. Interpretable modules can be produced to generate extra graphical elements.
def EndInterpretation()	is called at the end of the interpretation. Interpretable modules can be produced to generate extra graphical elements.
def PostDraw()	is called after drawing the representation of a new lstring.

Python commands that control the rule application:

Stop()	Stop simlation at the end of this iteration.
forward()	Next iteration will be done in forward direction.
backward()	Next iteration will be done in backward direction.
isForward()	Test whether direction is forward.
getIterationNb()	Return the id of the current iteration.
useGroup(int)	Next iteration will use rules of given group and default group 0.
getGroup()	Gives which group will be used.
frameDisplay(bool)	Set whether a frame will be displayed at the end of the iteration. default is True in animation and False except for last iteration in run mode.
isFrameDisplayed()	Tell whether a frame will be displayed at the end of the iteration.
isAnimationEnabled()	Return the current simulation is in an animation.
requestSelection(caption)	Wait selection in the viewer before next iteration. Set frameDisplay to True.

Lpy specific declaration:

module name	Declaration of module name.
consider: name	Symbol to consider.
ignore: name	Symbol to ignore.
group id:	Following rules will be associated to group id.
Axiom: Lstring	Declaration of the axiom of the Lsystem.
produce Lstring	Produce an Lstring and return.
nproduce Lstring	Produce an Lstring whithout returning.
nsproduce(LstringStruct)	Produce a given Lstring data structure whithout returning.
makestring(Lstring)	Create an LstringStruct from Lstring.
InLeftContext(pattern, argdict)	Test a left context. argdict contains value of all parameter of the pattern.
InRightContext(pattern, argdict)	Test a right context. argdict contains value of all parameter of the pattern.
derivation length: value	Number of derivation to do (default=1).
initial_view=*value*	Number of derivation for bounding box evaluation (default=derivation length).
production:	Start of the production rules declaration.
homomorphism:	Start of the interpretation rules declaration.
interpretation:	Start of the interpretation rules declaration.
decomposition:	Start of the decomposition rules declaration.
maximum depth:	Number of decomposition or interpretation recursive call to do (default=1).
endgroup	Reactivate default group 0.
endlsystem	End of lsystem rules declaration.

These commands have been added to the original cpfg-lpfg specification:

context()

Get context of execution of the L-system. To use with care.

The following objects and commands are also accessible from within the lpy shell:

lstring	Contains the last computed lsystem string of the current simulation.
lsystem	Reference to the internal lsystem object representing the current simulation.
window	Reference to lpy widget object.
clear()	To clear the shell.

All these functions are imported from openalea.lpy module. Other data structures and functionnalities are available in the module. You can check them with help(openalea.lpy)

References

For More details, see:

• 6. Boudon, T. Cokelaer, C. Pradal and C. Godin, L-Py, an open L-systems framework in Python, FSPM 2010.

• 16. Prusinkiewicz et al., 89, The algorithmic Beauty of Plants, Springer-Verlag.

• 16. Prusinkiewicz. Graphical applications of L-systems. Proceedings of Graphics Interface ‘86, pp. 247-253.

• 16. Prusinkiewicz, R. Karwowski, and B. Lane. The L+C plant modelling language. In Functional-Structural Plant Modelling in Crop Production, J. Vos et al. (eds.), Springer, 2007.