This engine is a general-purpose calculator. The calculator operates on floating-point values and 3D floating-point vectors. The engine takes up to eight inputs of each type (OIV.Inventor.Fields.SoMFFloat and OIV.Inventor.Fields.SoMFVec3f), and produces up to four outputs of each type.

Each input field (OIV.Inventor.Engines.SoCalculator.a-OIV.Inventor.Engines.SoCalculator.h, OIV.Inventor.Engines.SoCalculator.A-OIV.Inventor.Engines.SoCalculator.H) can have multiple values, allowing the engine to evaluate the expression with different values in parallel. Some inputs may have more values than others. In such cases, the last value of the shorter inputs will be repeated as necessary.

The OIV.Inventor.Engines.SoCalculator.expression input string specifies the expression to be evaluated. An expression can consist of multiple subexpressions. Several subexpressions can be specified in one string, separated by semicolons (;). Alternatively, the subexpressions can be stored in separate strings in the multiple-valued input field.

Each subexpression is of the form:

   \<lhs\> = \<rhs\>

The <rhs> supports arithmetic, logical and conditional operators. They are:

   (unary) !, -
  (binary) +, -, *, /, \%, <, > <=, >=, ==, !=, &&, ||
  (ternary) ? :

Valid operands for the <rhs> include the inputs, outputs, temporary variables, and their components (e.g. oA[0]). Operands can also be numeric constants (e.g. 1.0), pre-defined named constants, or pre-defined functions.

The named constants are:

   MAXFLOAT
  MINFLOAT
  M_E
  M_LOG2E
  M_LOG10E
  M_LN2
  M_LN10
  M_PI
  M_SQRT2 = sqrt(2)
  M_SQRT1_2 = sqrt(1/2)

   cos, sin, tan,
  acos, asin, atan, atan2,
  cosh, sinh, tanh,
  sqrt, pow, exp, log, log10,
  ceil, floor, fabs, fmod.

   rand(f) - Random number generator
  cross(v1, v2) - Vector cross
 product
  dot(v1, v2) - Vector dot product
  length(v) - Vector length
  normalize(v) - Normalize vector
  vec3f(f1, f2, f3) - Generate a vector from 3 floats

Note, when the input has multiple values, all the subexpressions specified in the OIV.Inventor.Engines.SoCalculator.expression are applied to all the multiple input values. This is unlike the OIV.Inventor.Engines.SoBoolOperation engine, where each operation is applied only to the corresponding entries of the input data. Note also, that even though the inputs and outputs can have multiple values the [ ] operator is only for indexing into the values of a single vector. It does not index into the multiple values of a field. For example, if the floating-point input field OIV.Inventor.Engines.SoCalculator.a has two values: 1.0, and 2.0, then the expression

   "oA[0]=a; oA[1]=a; oA[2]=0.0"

Examples of expressions:

   "ta = oA[0]*floor(a)"
  "tb = (a+b)*sin(M_PI)"
  "oA = vec3f(ta, tb, ta+tb)"
  "oB = normalize(oA)"
  "ta = a; tb = sin(ta); oA = vec3f(ta, tb, 0)"

FILE FORMAT/DEFAULT

Calculator {

a	0
b	0
c	0
d	0
e	0
f	0
g	0
h	0
A	0 0 0
B	0 0 0
C	0 0 0
D	0 0 0
E	0 0 0
F	0 0 0
G	0 0 0
H	0 0 0
expression	""

}

Reference