Primitives added in 4.0.6.3

<#5935#><#5935#>: <#1612#>cblob<#1612#> <#1613#>thresh st r<#1613#> #math150##tex2html_wrap_inline5937# <#1615#>sutface<#1615#> [<#1616#>st r<#1616#> #math151##tex2html_wrap_inline5939# <#1618#>surface<#1618#> ...]
Creates a multicolored blob. The syntax is the same as for a blob, with an additional surface definition for each metaball.

The <#526#>cblob<#526#> primitive was provided by George McGregor
<#527#>;SPMlt;mcgregor@ncifcrf.gov;SPMgt;<#527#>

<#5940#><#5940#>: <#1621#>flame<#1621#> <#1622#>size<#1622#> #math152##tex2html_wrap_inline5942# <#1624#>lightswitch speed<#1624#>
Creates a flame at the given position of the given size. The <#533#>lightswitch<#533#> option allows light sources to automatically be placed inside the flame (1) or no lights for faster runs (0). The <#534#>speed<#534#> setting is used for animation and controlls how fast the flame appears to ``move'' upward. A value of 0.5 is suggested as a starting point.

The <#536#>flame<#536#> primitive was provided by Reto Mani <#537#>;SPMlt;mani@iam.unibe.ch;SPMgt;<#537#>

<#5943#><#5943#>: <#1627#>fracland<#1627#> <#1628#>seed subdiv<#1628#>
This primitive creates a fractal surface centered at x = 0.5, y = 0.5 and ranging from x = 0.0, y = 0.0 to x = 1.0, y = 1.0. It is actually a heightfield primitive that is generated within rayshade rather than being read in from a file.

The <#542#>seed<#542#> value is the seed for the random number function. The seed value specifies the shape of the surface -- changing the seed value will randomly change the surface shape.

The <#543#>subdiv<#543#> value is the number of subdivisions for the surface -- #math153##tex2html_wrap_inline5951# = 0 will produce a flat square, #math154#subdiv ;SPMgt; 0 will produce a square with an ever more detailed surface. So far, rayshade seems to have trouble with subdivisions greater than eight (if anyone finds otherwise please tell me!!) and produces surfaces with ;SPMquot;holes;SPMquot; in it for values greater than this.

The number of points in the surface follows the following formulas, where <#545#>Size<#545#> is the total points per side of the object:

#math155#

Size = (2^subdiv) + 1

#math156#

TotalPoints = Size²

The four corner points will always have an altitude of zero, the maximum altitude should never be never be more 1.0 and the min should never be less than -1.0.

The <#546#>fracland<#546#> primitive was provided by Larry Coffin
<#547#>;SPMlt;lcoffin@clciris.chem.umr.edu;SPMgt;<#547#>

<#5955#><#5955#>: <#1631#>rotspline<#1631#> #math157##tex2html_wrap_inline5957# #math158##tex2html_wrap_inline5959# <#1634#>coeffs<#1634#> c₃ c₂ c₁ c₀
Creates a solid of revolution. This primitive can be defined in two ways.

<#5964#><#5964#>: <#1637#>rotspline<#1637#> #math159##tex2html_wrap_inline5966# r_base g_base #math160##tex2html_wrap_inline5970# r_apex g_apex

The curve that is rotated is of the form

#math161#

r² = c₃x³ + c₂x² + c₁x + c₀

#math162##tex2html_wrap_inline5975# is the position of the center of one end and #math163##tex2html_wrap_inline5977# is the center of the other. The word <#565#>coeffs<#565#> must be included in the first method. r_base and r_apex are the radii of the base and apex, and g_base and g_apex are the gradients.

The <#570#>rotspline<#570#> primitive was provided by Gerald Iles
<#571#>;SPMlt;ilesg@p4.cs.man.ac.uk;SPMgt;<#571#>

<#5982#><#5982#>: <#1646#>sweptsph<#1646#> <#1647#>bezier<#1647#> #math164##tex2html_wrap_inline5984# #math165##tex2html_wrap_inline5986# #math166##tex2html_wrap_inline5988# #math167##tex2html_wrap_inline5990# r₀ r₁ r₂ r₃
This primitive is defined as a sphere of varying radius swept, or extruded along a path in space. The path is defined in one of several ways. The path can either be defined as four points which define a bezier path, where the path passes through the first and last endpoints with the second and third points defining the slope or tangent line for the curve at the first and last points.

<#5995#><#5995#>

<#1654#>sweptsph<#1654#> <#1655#>coeffs<#1655#> x₀ x₁ x₂ x₃ y₀ y₁ y₂ y₃ z₀ z₁ z₂ z₃ r₀ r₁ r₂ r₃
A second way to define the curve is to specify the coeffecients for the parametric equations that define the curve. This is specified as ``<#583#>coeffs<#583#> f_x f_y f_z'' where each f_n is a third order equation, c₀ c₁ c₂ c₃, where

#math168#

f_n = c₀ + c₁x + c₂x² + c₃x³

<#6021#><#6021#>: <#1658#>sweptsph<#1658#> [<#1659#>nbezier<#1659#> n₀ n₁ n₂ n₃] [<#1660#>ncoeffs<#1660#> cn₀ cn₁ cn₂ cn₃]
A third way is to use any combination of parametric bezier curves or function coeffs. These are specified as <#589#>nbezier<#589#> or <#590#>ncoeffs<#590#> where n is x, y, or z. These are followed by four numbers that are interpreted as the coeffecients for the parametric variable x, y, or z in the case of <#591#>ncoeffs<#591#> or as the bezier curve where the first number is the starting value, the last value is the ending value, and the second and third values define the ``speed'' at which the curve leaves the endpoints.

Hopefilly the following examples make this clearer:

verbatim51#

There are a few known bugs:

Often there is a ``shadow'' ring around the diameter of the primitive where the functions are evaluated at t = 0.5. Presumably this is due to roundoff error possibly in the root finding algorithms, perhaps elsewhere.
Some configurations using the <#596#>bezier<#596#> specification result in garbage. Usually this can be avoided by changing the defining point's values slightly without affecting the curve noticeably. Examples are
<#597#>bezier -10 0 0 -10 0 0 10 0 0 10 0 0<#597#>
and <#598#>bezier -10 0 0 10 0 10 -10 0 10 10 0 0<#598#>.