## reb Class REB_TrapShapeAtzemaSpiral

```Object
common:Generic
common:TrapShape
reb:REB_TrapShapeAtzemaSpiral
```

`class TrapShape:REB_TrapShapeAtzemaSpiral`

This shape uses the Atzema spiral function.

This variant of the function has a signed and absolute value version of the distance. The function also has a complex conjugate variant. The transformed value is the complex return value of the function.

Ultra Fractal Source
``` class REB_TrapShapeAtzemaSpiral(common.ulb:TrapShape) {
; This shape uses the Atzema spiral function.<br>
; <p>
; This variant of the function has a signed and absolute value
; version of the distance. The function also has a complex conjugate variant.
; The transformed value is the complex return value of the function.
public:
import "common.ulb"

; Constructor
func REB_TrapShapeAtzemaSpiral(Generic pparent)
TrapShape.TrapShape(pparent)
endfunc

; Call this for each iteration being trapped.
float func Iterate(complex pz)
TrapShape.Iterate(pz)
int sgn = 1
if @sgn
sgn = -1
endif
float theta = 0
float d =  0
theta = atan2(pz)

float af1 = 0.5*@a*(sin(theta)/theta-2*cos(theta)-theta*sin(theta))
float af2 = 0.05*@b*(cos(theta)/theta-2*sin(theta)+theta*cos(theta))
complex as = (af1 + sgn*flip(af2))
IF @absval
d = abs(cabs(pz) -  cabs(as))
ELSE
d = cabs(pz -  as)
ENDIF
m_LastZ = as
return d
endfunc

default:
title = "Atzema Spiral"
int param v_trapshapeatzemaspiral
caption = "Version (Trap Shape Atzema Spiral)"
default = 101
hint = "This version parameter is used to detect when a change has been made to the formula that is incompatible with the previous version. When that happens, this field will reflect the old version number to alert you to the fact that an alternate rendering is being used."
visible = @v_trapshapeatzemaspiral < 101
endparam

float param a
caption = "Polar parameter"
default = 0.2
hint = "Affects spread and scale of trap"
endparam

float param b
caption = "2nd Polar parameter"
default = 1.0
hint = "Affects spread and scale of trap"
endparam
bool param sgn
caption = "Conjugate transform"
default = false
endparam

param absval
caption = "Absolute Value"
default = false
endparam
}
```

Constructor Summary
`REB_TrapShapeAtzemaSpiral()`

`REB_TrapShapeAtzemaSpiral(Generic pparent)`
Constructor

Method Summary
` float` `Iterate(complex pz)`
Call this for each iteration being trapped.

Methods inherited from class common:TrapShape
`GetColorChannel, GetTextureValue, GetTransformedPoint, Init, IterateSilent, SetThreshold`

Methods inherited from class common:Generic
`GetParent`

Methods inherited from class Object

Constructor Detail

### REB_TrapShapeAtzemaSpiral

`public REB_TrapShapeAtzemaSpiral(Generic pparent)`
Constructor

### REB_TrapShapeAtzemaSpiral

`public REB_TrapShapeAtzemaSpiral()`
Method Detail

### Iterate

`public float Iterate(complex pz)`
Call this for each iteration being trapped.

Overrides:
`Iterate` in class `TrapShape`