--- /dev/null
+Coding Rules {#dev_guides__coding_rules}
+======================================
+
+@tableofcontents
+
+@section OCCT_RULES_SECTION_1 Introduction
+
+The purpose of this document is to define and formalize one style of programming for developers working on Open CASCADE Technology.
+The establishment of a common style facilitates understanding and maintaining code developed by more than one programmer as well as making it easier for several people to co-operate in the development of the same framework.
+In addition, following a common programming style enables the construction of tools that incorporate knowledge of these standards to help in the programming task.
+Using a consistent coding style throughout a particular module, package, or project is important because it allows people other than the author, and the author himself, to easily understand and (hopefully) maintain the code.
+Most programming styles are somewhat arbitrary, and this one is no exception. Some guidelines have been excerpted from the public domain of widely accepted practices.
+This suggests that the guide will continue to evolve over time as new ideas and enhancements are added.
+
+@subsection OCCT_RULES_SECTION_1_1 Scope of the rules in this document
+
+Rules in this document was written for C++ code.
+However, with minor exceptions due to language restrictions, them should be applied to any sources in Open CASCADE Technology framework, including:
+- C/C++
+- GLSL programs
+- OpenCL kernels
+- TCL scripts and test cases
+
+@section OCCT_RULES_SECTION_2 Naming Conventions
+
+@subsection OCCT_RULES_SECTION_2_1 General naming rules
+
+The names considered in this section are mainly those which compound the interface to Open CASCADE Technology libraries as well as source code itself.
+
+### International language [MANDATORY]
+All names are composed of English words and their abbreviations.
+Open CASCADE Technology is an open source available for international community.
+
+### Suggestive names
+Names should be suggestive or, at least, contain a suggestive part.
+Currently, there is no exact rule that would define how to generate suggestive names. However, usually names given to toolkits, packages, classes and methods are suggestive. Here are several examples:
+- Packages containing words Geom or Geom2d in their names are related to geometrical data and operations.
+- Packages containing words TopoDS or BRep in their names are related to topological data and operations.
+- In OCAF, packages that define transient, persistent data classes and drivers to map between them, have similar names prefixed by 'T', 'P', and 'M' correspondingly (e.g. TDocStd, PDocStd, MDocStd).
+- Packages ending with ...Test define Draw Harness plugins.
+- Methods starting with Get... and Set... are usually responsible for (accordingly) retrieving/storing some data.
+
+### Related names
+Names that define logically connected functionality should have the same prefix (start with the same letters) or, at least, have any other common part in them.
+As an example the method GetCoord can be given. It returns a triple of real values and is defined for directions, vectors and points. The logical connection is obvious.
+
+### Camel Case style
+Camel Case style is preferred for names.
+For example:
+
+~~~~~{.cpp}
+Standard_Integer awidthofbox; // this is bad
+Standard_Integer width_of_box; // this is bad
+Standard_Integer aWidthOfBox; // this is OK
+~~~~~
+
+@subsection OCCT_RULES_SECTION_2_2 Names of development units
+Usually unit (e.g. package) is a set of classes, methods, enumerations or any other sources implementing certain common functionality which, to the certain extent, is self contained and independent from other parts of library.
+
+### Underscores in units names [MANDATORY]
+Names of units should not contain underscores, except cases where usage of underscores is allowed explicitly.
+Usually names of files consisting Open CASCADE Technology are constructed according to the rules defined in the appropriate sections of this document.
+
+### File names extensions [MANDATORY]
+The following extensions should be used for source files, depending on their type:
+
+ .cdl - CDL declaration files
+ .cxx - C++ source files
+ .hxx - C++ header files
+ .lxx - headers with definitions of inline methods (CDL packages)
+
+@subsection OCCT_RULES_SECTION_2_3 Names of toolkits
+
+The following rules are usually used in naming of toolkits:
+
+### Prefix for toolkits names [MANDATORY]
+Toolkits names are prefixed by TK, followed by suggestive part of name explaining the domain of functionality covered by the toolkit (e.g. TKOpenGl).
+
+### Names of classes
+Usually source files located in the unit have names that start from the name of the unit, separated from remaining part of file name (if any) by underscore "_".
+For instance, names of files containing sources of C++ classes are constructed according to the following template.
+
+### Naming of C++ class files
+The following template should be used for names of files containing sources of C++ classes:
+
+ <unit-name>_<class-name>.cxx (.hxx, .cdl etc.)
+
+Files that contain sources related to whole unit are called by the name of unit with appropriate extension.
+
+### Names of functions
+The term 'function' here is defined as:
+- Any class method
+- Any package method
+- Any non-member procedure or function
+
+It is preferred to name public methods from upper case, while protected and private methods from low case.
+
+~~~~~{.cpp}
+class MyPackage_MyClass
+{
+
+public:
+
+ Standard_Integer Value() const;
+ void SetValue (const Standard_Integer theValue);
+
+private:
+
+ void setIntegerValue (const Standard_Integer theValue);
+
+};
+~~~~~
+
+@subsection OCCT_RULES_SECTION_2_4 Names of variables
+There are several rules that describe currently accepted practice used for naming variables.
+
+### Naming of variables
+Name of variable should not conflict with the global names (packages, macros, functions, global variables etc.), either existing or possible.
+The name of variable should not start with underscore(s).
+
+See the following examples:
+
+~~~~~{.cpp}
+Standard_Integer Elapsed_Time = 0; // this is bad - possible class name
+Standard_Integer gp = 0; // this is bad - existing package name
+Standard_Integer aGp = 0; // this is OK
+Standard_Integer _KERNEL = 0; // this is bad
+Standard_Integer THE_KERNEL = 0; // this is OK
+~~~~~
+
+### Names of function parameters
+The name of a function (procedure, class method) parameter should start with 'the' followed by the rest of the name starting with capital letter.
+
+See the following examples:
+
+~~~~~{.cpp}
+void Package_MyClass::MyFunction (const gp_Pnt& p); // this is bad
+void Package_MyClass::MyFunction (const gp_Pnt& theP); // this is OK
+void Package_MyClass::MyFunction (const gp_Pnt& thePoint); // this is preferred
+~~~~~
+
+### Names of class member variables
+The name of a class member variable should start with 'my' followed by the rest of the name (rule for suggestive names applies) starting with capital letter.
+
+See the following examples:
+
+~~~~~{.cpp}
+Standard_Integer counter; // This is bad
+Standard_Integer myC; // This is OK
+Standard_Integer myCounter; // This is preferred
+~~~~~
+
+### Names of global variables
+It is strongly recommended to avoid defining any global variables.
+However, as soon as global variable is necessary, the following rule applies.
+Global variable name should be prefixed by the name of a class or a package where it is defined followed with '_my'.
+
+See the following examples:
+
+~~~~~{.cpp}
+Standard_Integer MyPackage_myGlobalVariable = 0;
+Standard_Integer MyPackage_MyClass_myGlobalVariable = 0;
+~~~~~
+
+Static constants within the file should be spelled upper-case and started with 'THE_' prefix:
+~~~~~{.cpp}
+namespace
+{
+ static const Standard_Real THE_CONSTANT_COEF = 3.14;
+};
+~~~~~
+
+### Names of local variables
+Local variable name should be constructed in such way that it can be distinguished from the name of a function parameter, a class member variable and a global variable.
+It is preferred to prefix local variable names with 'a' and 'an' (also 'is', 'to' and 'has' for Boolean variables).
+
+See the following examples:
+
+~~~~~{.cpp}
+Standard_Integer theI; // this is bad
+Standard_Integer i; // this is bad
+Standard_Integer index; // this is bad
+Standard_Integer anIndex; // this is OK
+~~~~~
+
+### Avoid dummy names
+Avoid dummy names like I, j, k. Such names are meaningless and easy to mix up.
+Code becomes more and more complicated when such dummy names used multiple times in code with different meaning, in cycles with different iteration ranges and so on.
+
+See the following examples for preferred style:
+
+~~~~~{.cpp}
+void Average (const Standard_Real** theArray,
+ Standard_Integer theRowsNb,
+ Standard_Integer theRowLen,
+ Standard_Real& theResult)
+{
+ theResult = 0.0;
+ for (Standard_Integer aRow = 0; aRow < aRowsNb; ++aRow)
+ {
+ for (Standard_Integer aCol = 0; aCol < aRowLen; ++aCol)
+ {
+ theResult += theArray[aRow][aCol];
+ }
+ theResult /= Standard_Real(aRowsNb * aRowLen);
+ }
+}
+~~~~~
+
+@section OCCT_RULES_SECTION_3 Formatting rules
+
+In order to improve the open source readability and, consequently, maintainability, the following set of rules is applied.
+
+### International language [MANDATORY]
+All comments in all sources must be in English.
+
+### Line length
+In all sources try not to exceed 120 characters limit of line length.
+
+### C++ style comments
+Prefer C++ style comments in C++ sources.
+
+### Commenting out unused code
+Delete unused code instead of commenting it or using #define.
+
+### Indentation in sources [MANDATORY]
+Indentation in all sources should be set to two space characters.
+Use of tabulation characters for indentation is disallowed.
+
+### Separating spaces
+Punctuation rules follow the rules of English.
+C/C++ reserved words, commas, colons and semicolons should be followed by a space character if they are not at the end of line.
+There should be no space characters after '(' and before ')'. Closing and opening brackets should be separated by a space character.
+For better readability it is also recommended to surround conventional operators by a space character. See the following examples:
+
+~~~~~{.cpp}
+while (true) // NOT: while( true ) ...
+{
+ DoSomething (theA, theB, theC, theD); // NOT: DoSomething(theA,theB,theC,theD);
+}
+for (anIter = 0; anIter < 10; ++anIter) // NOT: for (anIter=0;anIter<10;++anIter){
+{
+ theA = (theB + theC) * theD; // NOT: theA=(theB+theC)*theD
+}
+~~~~~
+
+### Separate logical blocks
+Separate logical blocks of code with one blank line and comments.
+See the following example:
+
+~~~~~{.cpp}
+// check arguments
+Standard_Integer anArgsNb = argCount();
+if (anArgsNb < 3 || isSmthInvalid)
+{
+ return THE_ARG_INVALID;
+}
+
+// read and check header
+...
+...
+
+// do our job
+...
+...
+~~~~~
+
+Notice that multiple blank lines should be avoided.
+
+### Separate function bodies [MANDATORY]
+Use function descriptive blocks to separate function bodies from each other.
+Each descriptive block should contain at least a function name and description of purpose.
+See the following example:
+
+~~~~~{.cpp}
+// ----------------------------------------------
+// function : TellMeSmthGood
+// purpose : Gives me good news
+// ----------------------------------------------
+void TellMeSmthGood()
+{
+ ...
+}
+
+// ----------------------------------------------
+// function : TellMeSmthBad
+// purpose : Gives me bad news
+// ----------------------------------------------
+void TellMeSmthBad()
+{
+ ...
+}
+~~~~~
+
+### Block layout [MANDATORY]
+Figure brackets '{', '}' and each operator (for, if, else, try, catch) should be on dedicated line.
+General block should have layout similarly to the following:
+
+~~~~~{.cpp}
+while (expression)
+{
+ ...
+}
+~~~~~
+
+Entering block increases and leaving block decreases indentation to one tabulation.
+
+### Single-line operators
+Single-line conditional operator (if, while, for etc.) can be written without brackets on the following line.
+
+~~~~~{.cpp}
+if (!myIsInit) return Standard_False; // bad
+
+if (thePtr == NULL) // OK
+ return Standard_False;
+
+if (!theAlgo.IsNull()) // preferred
+{
+ DoSomething();
+}
+~~~~~
+
+Code on the same line is less convenient for debugging.
+
+### Use alignment
+Use alignment wherever it enhances readability. See the following example:
+
+~~~~~{.cpp}
+MyPackage_MyClass anObject;
+Standard_Real aMinimum = 0.0;
+Standard_Integer aVal = theVal;
+switch (aVal)
+{
+ case 0: computeSomething(); break;
+ case 12: computeSomethingElse (aMinimum); break;
+ case 3:
+ default: computeSomethingElseYet(); break;
+}
+~~~~~
+
+### Indentation of comments
+Comments should be indented similar to the code which they refer to or can be on the same line if they are short.
+Text should be delimited with single space character from slash.
+See the following example:
+
+~~~~~{.cpp}
+while (expression) //bad comment
+{
+ // this is a long multi-line comment
+ // which is really required
+ DoSomething(); // maybe, enough
+ DoSomethingMore(); // again
+}
+~~~~~
+
+### Early return statement
+Prefer early return condition rather than collecting indentations.
+Better write like this:
+
+~~~~~{.cpp}
+Standard_Integer ComputeSumm (const Standard_Integer* theArray,
+ const Standard_Size theSize)
+{
+ Standard_Integer aSumm = 0;
+ if (theArray == NULL || theSize == 0)
+ {
+ return 0;
+ }
+
+ ... computing summ ...
+ return aSumm;
+}
+~~~~~
+
+rather than:
+
+~~~~~{.cpp}
+Standard_Integer ComputeSumm (const Standard_Integer* theArray,
+ const Standard_Size theSize)
+{
+ Standard_Integer aSumm = 0;
+ if (theArray != NULL && theSize != 0)
+ {
+ ... computing summ ...
+ }
+ return aSumm;
+}
+~~~~~
+
+to improve readability and reduce unnecessary indentation depth.
+
+### Trailing spaces
+Trailing spaces should be removed when possible.
+Spaces at end of line are useless and do not affect functionality.
+
+### Headers order
+Split into groups: system headers, per framework headers, project headers; sort includes list alphabetically.
+This rule can improve readability, allows detection of useless header's multiple inclusions and makes 3rd-party dependencies clearly visible.
+
+~~~~~{.cpp}
+// system headers
+#include <iostream>
+#include <windows.h>
+
+// Qt headers
+#include <QDataStream>
+#include <QString>
+
+// OCCT headers
+#include <gp_Pnt.hxx>
+#include <gp_Vec.hxx>
+#include <NCollection_List.hxx>
+~~~~~
+
+@section OCCT_RULES_SECTION_4 Documentation rules
+
+The source code is one of the most important references for documentation.
+The comments in the source code should be complete enough to allow understanding of that code, and to serve as basis for other documents.
+The main reasons why comments are regarded as documentation and should be maintained are:
+
+- The comments are easy to reach - they are always together with source code
+- It's easy to update description in the comment when source is modified
+- The source itself represents a good context to describe various details that would require much more explanations in separate document
+- As a summary, this is the most cost-effective documentation
+
+The comments should be compatible with Doxygen tool for automatic documentation generation (thus should use compatible tags).
+
+### Documenting classes [MANDATORY]
+Each class should be documented in its header file (.hxx or .cdl).
+The comment should give enough details for the reader to understand the purpose of the class and main way of work with it.
+
+### Documenting class methods [MANDATORY]
+Each class or package method should be documented in the header file (.hxx or .cdl).
+The comment should explain the purpose of the method, its parameters, and returned value(s).
+Accepted style is:
+
+@verbatim
+//! Method computes the square value.
+//! @param theValue the input value
+//! @return squared value
+Standard_Export Standard_Real Square (Standard_Real theValue);
+@endverbatim
+
+### Documenting C/C++ sources
+It is very desirable to put comments in the C/C++ sources of the package/class.
+They should be detailed enough to allow any person to understand what does each part of code, and get familiar with it.
+It is recommended to comment all static functions (like methods in headers), and at least each 10-100 lines of the function bodies.
+There are also some rules that define how comments should be formatted, see section "Formatting Rules".
+Following these rules is important for good comprehension of the comments;
+moreover it makes possible to automatically generate user-oriented documentation directly from commented sources.
+
+@section OCCT_RULES_SECTION_5 Application design
+
+The following set of rules defines the common style which should be applied by any developer contributing to the open source.
+
+### Allow for possible inheritance
+Try to design general classes (objects) keeping possible inheritance in mind.
+This rule means that making possible extensions of your class the user should not encounter with problems of private implementations.
+Try to use protected members and virtual methods wherever you expect extensions in the future.
+
+### Avoid friend declarations
+Avoid using 'friend' classes or functions except some specific cases (ex., iteration) 'Friend' declarations increase coupling.
+
+### Set/get methods
+Avoid providing set/get methods for all fields of the class.
+Intensive set/get functions break down encapsulation.
+
+### Hiding virtual functions [MANDATORY]
+Avoid hiding a base class virtual function by a redefined function with a different signature.
+Most of the compilers issue warning on this.
+
+### Avoid mixing error reporting strategies
+Try not to mix different error indication/handling strategies (exceptions or returned values) on the same level of an application.
+
+### Minimize compiler warnings [MANDATORY]
+When compiling the source pay attention to and try to minimize compiler warnings.
+
+### Avoid unnecessary inclusion
+Try to minimize compilation dependencies by removing unnecessary inclusion.
+
+@section OCCT_RULES_SECTION_6 General C/C++ rules
+
+This section defines rules for writing portable and maintainable C/C++ source code.
+
+### Wrapping of global variables [MANDATORY]
+Use package or class methods returning reference to wrap global variables to reduces possible name space conflicts.
+
+### Avoid private members
+Use 'protected' members instead of 'private' wherever reasonable to enable future extensions.
+Use 'private' fields if future extensions should be disabled.
+
+### Constants and inlines over defines [MANDATORY]
+Use constant variables (const) and inline functions instead of defines (#define).
+
+### Avoid explicit numerical values [MANDATORY]
+Avoid usage of explicit numeric values. Use named constants and enumerations instead.
+Magic numbers are badly to read and maintain.
+
+### Three mandatory methods
+A class with any of (destructor, assignment operator, copy constructor) usually needs all of them.
+
+### Virtual destructor
+A class with virtual function(s) ought to have a virtual destructor.
+
+### Default parameter value
+Do not redefine a default parameter value in an inherited function.
+
+### Use const modifier
+Use const modifier wherever possible (functions parameters, return values etc.)
+
+### Usage of goto [MANDATORY]
+Avoid goto statement except the cases where it is really needed.
+
+### Declaring variable in for() header
+Declaring cycle variable in the header of the for() statement if not used out of cycle.
+
+~~~~~{.cpp}
+Standard_Real aMinDist = Precision::Infinite();
+for (NCollection_Sequence<gp_Pnt>::Iterator aPntIter (theSequence);
+ aPntIter.More(); aPntIter.Next())
+{
+ aMinDist = Min (aMinDist, theOrigin.Distance (aPntIter.Value()));
+}
+~~~~~
+
+### Condition statements within zero
+Avoid usage of C-style comparison for non-boolean variables:
+
+~~~~~{.cpp}
+void Function (Standard_Integer theValue,
+ Standard_Real* thePointer)
+{
+ if (!theValue) // bad style - ambiguous logic
+ {
+ DoSome();
+ }
+
+ if (theValue == 0) // OK
+ {
+ DoSome();
+ }
+
+ if (thePointer != NULL) // OK, predefined NULL makes pointer comparison cleaner to reader
+ { // (nullptr should be used instead as soon as C++11 will be available)
+ DoSome2();
+ }
+}
+~~~~~
+
+@section OCCT_RULES_SECTION_7 Portability issues
+
+This chapter contains rules that are critical for cross-platform portability.
+
+### Ensure code portability [MANDATORY]
+It is required that source code must be portable to all platforms listed in the official 'Technical Requirements'.
+The term 'portable' here means 'able to be built from source'.
+
+The C++ source code should meet C++03 standard.
+Any usage of compiler-specific features or further language versions (C++11, until all major compliers on all supported platforms do not implement all it features)
+should be optional (escaped with appropriate preprocessor checks) and non-exclusive (alternative implementation should be provided, compatible with other compilers).
+
+### Avoid usage of global variables [MANDATORY]
+Avoid usage of global variables. Usage of global variables may cause problems of accessing them from another shared library.
+Instead of global variables, use global (package or class) functions that return reference to static variable local to this function.
+Another possible problem is the order of initialization of global variables defined in various libraries that may differ depending on platform, compiler and environment.
+
+### Avoid explicit basic types
+Avoid explicit usage of basic types (int, float, double etc.), use Open CASCADE Technology types (from package Standard - see Standard_Integer, Standard_Real, Standard_ShortReal, Standard_Boolean, Standard_CString and others) or specific typedef instead.
+
+### Use sizeof() to calculate sizes [MANDATORY]
+Do not assume sizes of types. Use sizeof() instead to calculate sizes.
+
+### Empty line at end of file [MANDATORY]
+In accordance with C++03 standard source files should be trailed by empty line.
+It is recommended to follow this rule for any plain text files for consistency and for correct work of git difference tools.
+
+@section OCCT_RULES_SECTION_8 Stability issues
+
+The rules listed in this chapter are important for stability of the programs that use Open CASCADE Technology libraries.
+
+### OSD::SetSignal() to catch exceptions
+When using Open CASCADE Technology in an application, make sure to call OSD::SetSignal() function when the application is initialized.
+This will install C handlers for run-time interrupt signals and exceptions,
+so that low-level exceptions (such as access violation, division by zero etc.) will be redirected to C++ exceptions
+(that use try {...} catch (Standard_Failure) {...} blocks).
+The above rule is especially important for robustness of modeling algorithms.
+
+### Cross-referenced handles
+Take care about cycling of handled references to avoid chains which will never be freed.
+For that purpose, use a pointer at one (subordinate) side. See the following example:
+
+In MyPackage.cdl:
+
+ class MyFirstHandle;
+ class MySecondHandle;
+ pointer MySecondPointer to MySecondHandle;
+ ...
+
+In MyPackage_MyFirstHandle.cdl:
+
+ class MyFirstHandle from MyPackage
+ ...
+ is
+ ...
+ SetSecondHandleA (me: mutable; theSecond: MySecondHandle from MyPackage);
+ SetSecondHandleB (me: mutable; theSecond: MySecondHandle from MyPackage);
+ ...
+ fields
+ ...
+ mySecondHandle : MySecondHandle from MyPackage;
+ mySecondPointer : MySecondPointer from MyPackage;
+ ...
+ end MyFirstHandle from MyPackage;
+
+In MyPackage_MySecondHandle.cdl:
+
+ class MySecondHandle from MyPackage
+ ...
+ is
+ ...
+ SetFirstHandle (me: mutable; theFirst: MyFirstHandle from MyPackage);
+ ...
+ fields
+ ...
+ myFirstHandle : MyFirstHandle from MyPackage;
+ ...
+ end MySecondHandle from MyPackage;
+
+In C++ code:
+
+~~~~~{.cpp}
+void MyFunction()
+{
+ Handle(MyPackage_MyFirstHandle) anObj1 = new MyPackage_MyFirstHandle();
+ Handle(MyPackage_MySecondHandle) anObj2 = new MyPackage_MySecondHandle();
+ Handle(MyPackage_MySecondHandle) anObj3 = new MyPackage_MySecondHandle();
+
+ anObj1->SetSecondHandleA(anObj2);
+ anObj1->SetSecondHandleB(anObj3);
+ anObj2->SetFirstHandle(anObj1);
+ anObj3->SetFirstHandle(anObj1);
+
+ // memory is not freed here !!!
+ anObj1.Nullify();
+ anObj2.Nullify();
+
+ // memory is freed here
+ anObj3.Nullify();
+}
+~~~~~
+
+### C++ memory allocation
+In C++ use new and delete operators instead of malloc() and free().
+Try not to mix different memory allocation techniques.
+
+### Match new and delete [MANDATORY]
+Use the same form of new and delete.
+
+~~~~~{.cpp}
+aPtr1 = new TypeA[n]; ... ; delete[] aPtr1;
+aPtr2 = new TypeB(); ... ; delete aPtr2;
+aPtr3 = Standard::Allocate (4096); ... ; Standard::Free (aPtr3);
+~~~~~
+
+### Methods managing dynamical allocation [MANDATORY]
+Define a destructor, a copy constructor and an assignment operator for classes with dynamically allocated memory.
+
+### Uninitialized variables [MANDATORY]
+Every variable should be initialized.
+
+~~~~~{.cpp}
+Standard_Integer aTmpVar1; // bad
+Standard_Integer aTmpVar2 = 0; // OK
+~~~~~
+
+Uninitialized variables might be kept only within performance-sensitive code blocks and only when their initialization is *guarantied* by following code.
+
+### Do not hide global new
+Avoid hiding the global new operator.
+
+### Assignment operator
+In operator=() assign to all data members and check for assignment to self.
+
+### Float comparison
+Don't check floats for equality or non-equality; check for GT, GE, LT or LE.
+
+~~~~~{.cpp}
+if (Abs (theFloat1 - theFloat2) < theTolerance)
+{
+ DoSome();
+}
+~~~~~
+
+Package 'Precision' provides standard values for SI units and widely adopted by existing modeling algorithms:
+- Precision::Confusion() for lengths in meters
+- Precision::Angular() for angles in radians
+
+as well as definition of infinity values within sanity range of double precision:
+- Precision::Infinite()
+- Precision::IsInfinite()
+- Precision::IsPositiveInfinite()
+- Precision::IsNegativeInfinite()
+
+### Non-indexed iteration
+Avoid usage of iteration over non-indexed collections of objects.
+If such iteration is used, make sure that the result of the algorithm does not depend on order.
+
+Since the order of iteration is unpredictable in this case, it frequently leads to different behavior of the application from one run to another,
+thus embarrassing the debugging process.
+It mostly concerns mapped objects for which pointers are involved in calculating the hash function.
+For example, the hash function of TopoDS_Shape involves the address of TopoDS_TShape object.
+Thus the order of the same shape in the TopTools_MapOfShape will vary in different sessions of the application.
+
+### Do not throw in destructors
+Do not throw from within destructor.
+
+### Assigning to reference [MANDATORY]
+Avoid possible assignments of the temporary object to a reference.
+Different behavior for different compiler of different platforms.
+
+@section OCCT_RULES_SECTION_9 Performance issues
+
+These rules define the ways of avoiding possible loss of performance caused by ineffective programming.
+
+### Class fields alignment
+In a class, declare its fields in the decreasing order of their size for better alignment.
+Generally, try to reduce misaligned accesses since they impact the performance (for example, on Intel machines).
+
+### Fields initialization order [MANDATORY]
+List class data members in the constructor's initialization list in the order they are declared.
+
+~~~~~{.cpp}
+class MyPackage_MyClass
+{
+
+public:
+
+ MyPackage_MyClass()
+ : myPropertyA (1),
+ myPropertyB (2) {}
+
+// NOT
+// : myPropertyB (2),
+// myPropertyA (1) {}
+
+private:
+
+ Standard_Integer myPropertyA;
+ Standard_Integer myPropertyB;
+
+};
+~~~~~
+
+### Initialization over assignment
+In class constructors prefer initialization over assignment.
+
+~~~~~{.cpp}
+MyPackage_MyClass()
+: myPropertyA (1) // preferred
+{
+ myPropertyB = 2; // not recommended
+}
+~~~~~
+
+### Optimize caching
+When programming procedures with extensive memory access, try to optimize them in terms of cache behavior.
+Here is an example of how cache behavior can be impact:
+On x86 this code
+
+~~~~~{.cpp}
+Standard_Real anArray[4096][2];
+for (Standard_Integer anIter = 0; anIter < 4096; ++anIter)
+{
+ anArray[anIter][0] = anArray[anIter][1];
+}
+~~~~~
+
+is more efficient than
+
+~~~~~{.cpp}
+Standard_Real anArray[2][4096];
+for (Standard_Integer anIter = 0; anIter < 4096; ++anIter)
+{
+ anArray[0][anIter] = anArray[1][anIter];
+}
+~~~~~
+
+since linear access (above) does not invalidate cache too often.
+
+@section OCCT_RULES_SECTION_10 Examples
+
+Here is C++ source file sample:
+
+@verbatim
+//! Sample documented class
+class Package_Class
+{
+
+public: //! @name public methods
+
+ //! Method computes the square value.
+ //! @param theValue the input value
+ //! @return squared value
+ Standard_Export Standard_Real Square (const Standard_Real theValue);
+
+private: //! @name private methods
+
+ //! Auxiliary method
+ void increment();
+
+private: //! @name private fields
+
+ Standard_Integer myCounter; //!< usage counter
+
+};
+@endverbatim
+
+~~~~~{.cpp}
+#include <Package_Class.hxx>
+
+// ==========================================================
+// function : Square
+// purpose : Method computes the square value
+// ==========================================================
+Standard_Real Package_Class::Square (const Standard_Real theValue)
+{
+ increment();
+ return theValue * theValue;
+}
+
+// ==========================================================
+// function : increment
+// purpose :
+// ==========================================================
+void Package_Class::increment()
+{
+ ++myCounter;
+}
+~~~~~
+
+TCL script for Draw Harness:
+~~~~~{.tcl}
+# show fragments (solids) in shading with different colors
+proc DisplayColored {theShape} {
+ set aSolids [uplevel #0 explode $theShape so]
+ set aColorIter 0
+ set THE_COLORS {red green blue1 magenta1 yellow cyan1 brown}
+ foreach aSolIter $aSolids {
+ uplevel #0 vdisplay $aSolIter
+ uplevel #0 vsetcolor $aSolIter [lindex $THE_COLORS [expr [incr aColorIter] % [llength $THE_COLORS]]]
+ uplevel #0 vsetdispmode $aSolIter 1
+ uplevel #0 vsetmaterial $aSolIter plastic
+ uplevel #0 vsettransparency $aSolIter 0.5
+ }
+}
+
+# load modules
+pload MODELING VISUALIZATION
+
+# create boxes
+box bc 0 0 0 1 1 1
+box br 1 0 0 1 1 2
+compound bc br c
+
+# show fragments (solids) in shading with different colors
+vinit View1
+vclear
+vaxo
+vzbufftrihedron
+DisplayColored c
+vfit
+vdump $imagedir/${casename}.png 512 512
+~~~~~
+
+GLSL program:
+~~~~~{.fs}
+vec3 Ambient; //!< Ambient contribution of light sources
+vec3 Diffuse; //!< Diffuse contribution of light sources
+vec3 Specular; //!< Specular contribution of light sources
+
+//! Computes illumination from light sources
+vec4 ComputeLighting (in vec3 theNormal,
+ in vec3 theView,
+ in vec4 thePoint)
+{
+ // clear the light intensity accumulators
+ Ambient = occLightAmbient.rgb;
+ Diffuse = vec3 (0.0);
+ Specular = vec3 (0.0);
+ vec3 aPoint = thePoint.xyz / thePoint.w;
+ for (int anIndex = 0; anIndex < occLightSourcesCount; ++anIndex)
+ {
+ int aType = occLight_Type (anIndex);
+ if (aType == OccLightType_Direct)
+ {
+ directionalLight (anIndex, theNormal, theView);
+ }
+ else if (aType == OccLightType_Point)
+ {
+ pointLight (anIndex, theNormal, theView, aPoint);
+ }
+ }
+
+ return vec4 (Ambient, 1.0) * occFrontMaterial_Ambient()
+ + vec4 (Diffuse, 1.0) * occFrontMaterial_Diffuse()
+ + vec4 (Specular, 1.0) * occFrontMaterial_Specular();
+}
+
+//! Entry point to the Fragment Shader
+void main()
+{
+ gl_FragColor = computeLighting (normalize (Normal),
+ normalize (View),
+ Position);
+}
+~~~~~