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NAME

       SoCalculator -

       General purpose calculator for floats and 3D float vectors.

       The SoCalculator uses the values from the input fields (which are either single floating
       point values or vectors) as variables in the free-form engine expressions and places the
       results on the output fields.

SYNOPSIS

       #include <Inventor/engines/SoCalculator.h>

       Inherits SoEngine.

   Public Member Functions
       virtual SoType getTypeId (void) const
           Returns the type identification of an object derived from a class inheriting SoBase.
           This is used for run-time type checking and 'downward' casting.
       virtual const SoFieldData * getFieldData (void) const
       virtual const SoEngineOutputData * getOutputData (void) const
       SoCalculator (void)

   Static Public Member Functions
       static SoType getClassTypeId (void)
       static void * createInstance (void)
       static void initClass (void)

   Public Attributes
       SoMFFloat a
       SoMFFloat b
       SoMFFloat c
       SoMFFloat d
       SoMFFloat e
       SoMFFloat f
       SoMFFloat g
       SoMFFloat h
       SoMFVec3f A
       SoMFVec3f B
       SoMFVec3f C
       SoMFVec3f D
       SoMFVec3f E
       SoMFVec3f F
       SoMFVec3f G
       SoMFVec3f H
       SoMFString expression
       SoEngineOutput oa
       SoEngineOutput ob
       SoEngineOutput oc
       SoEngineOutput od
       SoEngineOutput oA
       SoEngineOutput oB
       SoEngineOutput oC
       SoEngineOutput oD

   Protected Member Functions
       virtual ~SoCalculator (void)
       virtual void inputChanged (SoField *which)

   Static Protected Member Functions
       static const SoFieldData ** getInputDataPtr (void)
       static const SoEngineOutputData ** getOutputDataPtr (void)

   Additional Inherited Members

Detailed Description

       General purpose calculator for floats and 3D float vectors.

       The SoCalculator uses the values from the input fields (which are either single floating
       point values or vectors) as variables in the free-form engine expressions and places the
       results on the output fields.

       The engine has sixteen input fields; eight scalar inputs (a, b, c, d, e, f g, and h), and
       eight vector inputs (A, B, C, D, E, F, G, and H).

       There are eight output fields; four scalar outputs (oa, ob, oc, and od), and four vector
       outputs (oA, oB, oC, and oD).

       The expression syntax is quite similar to C/C++, with a very limited set of keywords and
       functions.

       An example:

       oa = a * (0.5 + b) / c

       Will multiply the value in a with the value in b plus 0.5, divide that result with c, and
       place the result in oa. Since this is an engine, the expression will only be evaluated
       when someone attempts to read the value in oa, not every time an input in changed.

       All inputs are multi-fields, and if there are several values in an input, the expression
       will be evaluated once for every input field value, and the output will create as many
       values as there are input field values.

       If there is more than one input field, and the input fields do not have the same number of
       values, the engine will create as many output values as the input field with the biggest
       number of values. When the index get out of bounds for some other input field, the last
       field value will be used.

       Vector expressions are similar to scalar expression. An example:

       oA = A + vec3f(1.0, 0.0, 0.0) * B

       Will take the vector in A, add the value in B multiplied with (1,0,0), and place the
       result in oA.

       In addition to regular arithmetics, the SoCalculator syntax also includes some functions.

       Scalar functions:

       · cos(x) - cosine function (x in radians)
       · sin(x) - sinus function
       · tan(x) - tangent function
       · acos(x) - arc cosine function
       · asin(x) - arc sinus function
       · atan(x) - arc tangent function
       · atan2(y, x) - arc tangent function of two variables (y, x).
       · cosh(x) - hyperbolic cosine function
       · sinh(x) - hyperbolic sinus function
       · tanh(x) - hyperbolic tangent function
       · sqrt(x) - square root function
       · pow(x,y) - x raised to the power of y
       · exp(x) - e to the power of x
       · log(x) - natural logarithm of x
       · log10() - base-10 logarithm of x
       · ceil(x) - rounds x upwards to the nearest integer
       · floor(x) - rounds x downwards to the nearest integer
       · fabs(x) - absolute value
       · fmod(x, y) - remainder of dividing x by y
       · rand(x) - pseudo-random value between 0 and 1
       Vector functions:
       · cross(x, y) - cross product of x and y
       · dot(x,y) - dot product of x and y (returns scalar value)
       · length(x) - length of x (returns scalar value)
       · normalize(x) - returns normalized version of x
       · x[y] - access components in x (y should be a scalar value in the range [0,2])
       There are also some named constants that can be used:
       · MAXFLOAT
       · MINFLOAT
       · M_E
       · M_LOG2E
       · M_LOG10E
       · M_LN2
       · M_PI
       · M_SQRT2 - sqrt(2)
       · M_SQRT1_2 - sqrt(1/2)
       The only control flow available is the ? operator. An example:
       oa = (a > b) ? (a * 0.5) : (b * c)
       (The parentheses are not necessary, they're there just to make the example easier to read)
       In addition to the standard comparators (<, >, <=, >=, ==, !=), you can also use && (AND)
       and || (OR) to combine expression, and the unary ! (NOT) operator.
       One final thing worth mentioning is the temporary variables. There exists sixteen
       temporary variables that can be used in expressions. ta, tb, tc, td, te, tf, tg, and th
       are scalar variables, and tA, tB, tC, tD, tE, tF, tG, and tH are vector variables. They
       are usually used when you have more than one expression that should be evaluated in order.
       An example with three expressions:
       ta = a * b; tb = c + d; tc = e - f
       tA = vec3f(ta, tb, tc) + A
       oA = tA * B
       The example just shows how temporary variables can be used to make your expressions easier
       to read. Please note that it's possible to have several statements in one expression. You
       just separate them with semicolons.
       Here is a simple example of how an SoCalculator engine may be used in an .iv file:
       DEF mycamera PerspectiveCamera {
         orientation 1 0 0 1.57
       }

       DEF headlight DirectionalLight {
         intensity 0.8
         direction 0 0 1
       }

       Separator {
         # Render a cube not affected by lighting
         LightModel { model BASE_COLOR }
         BaseColor { rgb = Calculator {
                             a = USE headlight . intensity
                             expression [ "oA = vec3f( a, a, a)" ]
                           } . oA }
         Cube {}
       }
       In the example, the color of the Cube is a function of the intensity of the
       DirectionalLight, even though the Cube is rendered without lighting because of the
       BASE_COLOR LightModel.

Constructor & Destructor Documentation

   SoCalculator::SoCalculator (void)
       Constructor.
   SoCalculator::~SoCalculator (void) [protected],  [virtual]
       Destructor.

Member Function Documentation

   SoType SoCalculator::getTypeId (void) const [virtual]
       Returns the type identification of an object derived from a class inheriting SoBase. This
       is used for run-time type checking and 'downward' casting. Usage example:
       void foo(SoNode * node)
       {
         if (node->getTypeId() == SoFile::getClassTypeId()) {
           SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
         }
       }
       For application programmers wanting to extend the library with new nodes, engines,
       nodekits, draggers or others: this method needs to be overridden in all subclasses. This
       is typically done as part of setting up the full type system for extension classes, which
       is usually accomplished by using the pre-defined macros available through for instance
       Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes),
       Inventor/engines/SoSubEngine.h (for engine classes) and so on.
       For more information on writing Coin extensions, see the class documentation of the
       toplevel superclasses for the various class groups.
       Implements SoBase.
   const SoFieldData * SoCalculator::getFieldData (void) const [virtual]
       Returns a pointer to the class-wide field data storage object for this instance. If no
       fields are present, returns NULL.
       Reimplemented from SoFieldContainer.
   const SoEngineOutputData * SoCalculator::getOutputData (void) const [virtual]
       This API member is considered internal to the library, as it is not likely to be of
       interest to the application programmer.
       Implements SoEngine.
   void SoCalculator::inputChanged (SoField *which) [protected],  [virtual]
       Called when an input is changed. The default method does nothing, but subclasses may
       override this method to do The Right Thing when a specific field is changed.
       Reimplemented from SoEngine.

Member Data Documentation

   SoMFFloat SoCalculator::a
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::b
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::c
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::d
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::e
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::f
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::g
       Input floating point value for the expressions.
   SoMFFloat SoCalculator::h
       Input floating point value for the expressions.
   SoMFVec3f SoCalculator::A
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::B
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::C
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::D
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::E
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::F
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::G
       Input vector with three floating point values for the expressions.
   SoMFVec3f SoCalculator::H
       Input vector with three floating point values for the expressions.
   SoMFString SoCalculator::expression
       Mathematical expressions for the calculator.
   SoEngineOutput SoCalculator::oa
       (SoMFFloat) Output value with result from the calculations.
   SoEngineOutput SoCalculator::ob
       (SoMFFloat) Output value with result from the calculations.
   SoEngineOutput SoCalculator::oc
       (SoMFFloat) Output value with result from the calculations.
   SoEngineOutput SoCalculator::od
       (SoMFFloat) Output value with result from the calculations.
   SoEngineOutput SoCalculator::oA
       (SoMFVec3f) Output value with result from the calculations.
   SoEngineOutput SoCalculator::oB
       (SoMFVec3f) Output value with result from the calculations.
   SoEngineOutput SoCalculator::oC
       (SoMFVec3f) Output value with result from the calculations.
   SoEngineOutput SoCalculator::oD
       (SoMFVec3f) Output value with result from the calculations.

Author

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