Provided by: libcoin80-doc_3.1.4~abc9f50-4ubuntu2_all 
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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