pyjbt

Python extension module for the jbt library. The only extension provided for in this module is for the jbt_build class. So with this module you can generate a BlobTree data structure. These data structures can be passed to pyrtl objects or to pybv through their infrastructure.

Module Functions

BlobTree()

Builds a pyjbt object. This object encapsulates the functionality of the jbt_build class. Use the pyjbt members to build a BlobTree data structure.

Geoff()

Constructs a Geoff field function. This is the standard field function. The return of this function is suitable for passing to the field method.

BiCubic([<bound=0.5:float>])

Constructs a bi-cubic field function with the given bound. The return of this function is suitable for passing to the field method. bound should be greater than 0 and less than 1.

ArcTan([<bound=50:float>])

Constructs an arctan field function with the given stiffness. The return of this function is suitable for passing to the field method.

Blinn([<a=-2:float>])

Constructs an Blinn exponential field function with the given exponent argument. The return of this function is suitable for passing to the field method.

InversePower([<n=2:float>])

Constructs an inverse power field function with the given exponent argument. The return of this function is suitable for passing to the field method.

Blanc([<a=0:float>])

Constructs an Blanc field function with the given hardness argument. The return of this function is suitable for passing to the field method.

Euclidean([(<kx=1:float>,<ky=1:float>,<kz=1:float>)])

Constructs a Euclidean distance metric . This is the standard distance metric. The return of this function is suitable for passing to the distance method.

LMetric([<l=2:float>,(<kx=1:float>,<ky=1:float>,<kz=1:float>)])

Constructs an l-metric distance metric. An l-metric is a generalization of the Euclidean metric, l==2 is the same as the l-metric. The return of this function is suitable for passing to the distance method.

SuperQuadric([<ew=1:float>,<ns=1:float>,(<kx=1:float>,<ky=1:float>,<kz=1:float>)])

Constructs a super-quadric distance metric. This metric is somewhat due to Barr, it is a generalization of the l-metric. When ew=1 and ns=1 we have squared Euclidean distance. The return of this function is suitable for passing to the distance method.

AnisotropicLMetric((<x:float>,<y:float>,<z:float>),<p0:float>,<p1:float>,[<a:float=0>,<b:float=1>,(<kx:float>,<ky:float>,<kz:float>)])

Constructs an anisotropic L_p distance metric. Given a direction and two p parameters it cubic interpolates between the two p parameters based on the dot product of the displacement vector and the given direction vector. The last parameter is the scaling parameter for the metric.

AnisotropicSuperQuadric((<ew0:float>,<ns0:float>),(ew1:float>,<ns1:float>),[<a:float=0>,<b:float=1>,<axis:int=2>,(<x:float>,<y:float>,<z:float>)])

Constructs an anisotropic SuperQuadric distance metric. Given a direction and two ew,ns parameter sets it cubic interpolates between the two parameter sets based on the dot product of the displacement vector and the given direction vector.

pyjbt Member Functions

push()

Pushes the attributes of the jbt object onto a stack. All attributes including attributes and transformations are pushed.

pop()

Pops the stack

translate(<x:float>,<y:float>,<z:float>)

Multiplies the current transformation matrix by the given translation.

scale(<x:float>,<y:float>,<z:float>)

Multiplies the current transformation matrix by the given scale.

rotate(<axis:int>,<angle:float>)

Multiplies the current transformation matrix by the given rotation. The axis is specified as 0|1|2 for x|y|z and the angle is given in degrees.

textranslate(<x:float>,<y:float>)

Multiplies the current texture space transfomation matrix by the given translation.

texscale(<x:float>,<y:float>)

Multiplies the current texture space transformation matrix by the given scale.

texrotate(<angle:float>)

Multiplies the current texture space transformation matrix by the given rotation.

colour((<red:float>,<green:float>,<blue::float>))

Sets the diffuse attribute for primitive objects in the BlobTree.

specular((<red:float>,<green:float>,<blue::float>))

Sets the specular attribute for primitive objects in the BlobTree.

specularexp(<e:float>)

Sets the specular exponent for primitive objects in the BlobTree.

specularcoeff(<e:float>)

Sets the specular coefficient for primitive objects in the BlobTree.

coefficient(<t:float>)

Sets the coefficient of the field value for the primitive objects in the BlobTree.

texturemap(<file:string>,[(<ssa:float=-1>,<ssb:float=-1>),<mode:int=0>])

Sets the texture map attribute for the primitive objects in the BlobTree. The first parameter specifies the raw ppm (P6) file to use for the texture map. The last two parameters specify how the texture map should be incorporated with the colour attribute of the primitives. The tuple gives the two parameters in 0..1 for the smoothstep function (a cubic interpolation producing range 0..1 over the domain ssa..ssb), the input to smoothstep is the y channel of the texture map, the output is used to weight between the texture map and the primitives colour. The mode parameter specifies if this blending should be done 1, or should not be done 0. You probably want to use values (0,0.1),1 if you want to use blending of the texture map and the primitive colour.

checkermap([(<red:float=0>,<green:float=0>,<blue::float=0>),(<width:int=300>,<height:int=300>),(<ssa:float=-1>,<ssb:float=-1>),<mode:int=0>])

Sets the texture map attribute for the primitive objects in the BlobTree to a checker board texture. The checkers are coloured with the given colour and its inverse. The pair of integers sets the width and height for the image. For an explanation of the rest of the parameters see the documentation to texturemap.

blend([<se-n=1:float>])

Begins the definition of a blending node of a BlobTree. The parameter specifies the super-elliptic blending parameter. If you want the children to be combined with the standard summation of their fields then just neglect passing this parameter. The range of the se-n parameter should be 1..inf. All types of interior nodes contribute to the geometry of the blend. To end a composite node call one of blend, union, intersection ... etc. See the following documentation. Of course the se-n parameter is ignored if the composite node is a csg operator. To add children to this interior node, simply call some of the primitive functions, or insert other composite interior nodes before the terminating call of this node.

union()

Begins the union of the children objects specified for a composite interior node.

intersection()

Begins the intersection of the children objects specified for a composite interior node.

difference()

Begins the difference of the first child and the union of the remaining children specified for a composite interior node.

twist([<angle:float=0>,<ymin:float=-bnd>,<ymax:float=bnd>])

Begins twist of the blended children specified for a composite interior node. Parameters are the angle in degrees to twist by .

taper([<x:float=1>,<z:int=1>,<ymin:float=-bnd>,<ymax:float=bnd>])

Tapers the children specified for this composite interior node. Parameters are the degree by which to taper along x and z respectively, and the y values through which to perform the taper (the default is through the bounds of the object)

bend([<angle:float=0>,<min:float=-1>,<max:float=1>,<mid:float=0>])

A linear bend combination of the children specified for this composite interior node. The parameters are the angle between the two non-bent regions of space, the range of the curvature, and the center of the curvature. The last three parameters specify together the radius of the curvature of the bend. The bend is along the y-axis and bending towards positive z.

extrude([(<axis=0:int>,<sign=1,int>)),<l=1:float>,(<kx=1:float>,<ky=1:float>,<kz=1:float>))

Extrudes a field along a vector. Parameters are the axis and direction

parameterize([<support:int=0>,<axis:int=1>])

Combine the children for this interior composite node and compute texturing mapping for their blend. The first parameter is the geometry of the support surface, 0 for cylindrical, 1 for spherical.

bumpmap(<map:string>[,<scale:float=1>])

Combine the children for this interior composite node and compute bump mapping for their blend. The first parameter is the filename of the bump map. It should be in raw (P6) ppm . The scale parameter is provided to exert control over the amount of perturbation.

cblend(<blends:(int,int)*>)

Controlled blending is not yet implemented in jbt.

end()

Terminates the current composite object.

object(<obj:pyjbt>)

Insert the given child into the current level of the BlobTree.

point([<radius:float=1>])

Insert a point primitive with the given radius into the current level of the BlobTree.

triangle((<x0:float>,<y0:float>,<z0:float>),(<x1:float>,<y1:float>,<z1:float>),(<x2:float>,<y2:float>,<z2:float>))

Triangles are not yet implemented in jbt. Insert a triangle primitive into the current level of the BlobTree.

line([<length:float=1>,<radius:float=1>])

Insert a line primitive into the current level of the BlobTree.

vrline([<length:float=1.0>,<top-radius:float=0.5>,<base-radius:float=0.5])

Variable radius lines are not yet implemented in jbt.

plane([<R:float=1>])

Inserts a plane primitive, this type is meant to be used as a cutting plane for CSG. R is the radius of the field.

circle([<radius-a=1:float>,<radius-b=0.5:float>])

Insert a torus lieing in the xz plane. The radius of the swept circle of the torus is radius-a

disk([<radius-a:float=1>,<radius-b:float=1>])

Insert a disk lieing in the xz plane. The radius of the disk is radius-a, the radius of the field is radius-b.

square([<x-radius:float=1>,<y-radius:float=1>,<radius-b:float=1>])

Insert a square lieing in the xz plane. The square can be a rectangle by changing the x-radius, y-radius.

polyline([(<x:float>,<y:float>,<z:float>)*],<pr:radius>,[<r:float=1>])

A poly-line primitive. This creates a set of connected line segments, each pair of contiguous segments is connected by a continuous arc of radius pr.

bound()

Returns a 2-tuple of 3-tuples. The two 3-tuples are the minimum and maximum corners of the bounds of the object.

field(<f:pyjbtfield>)

Allows the setting of the function to use for field evaluations. The argument must be the return of one of the module functions which returns a field function.

distance(<f:pyjbtdistance>)

Allows the setting of the function to use for distance evaluations. The argument must be the return of one of the module functions which returns a distance metric.