raytracing - obfuscated C++ Translation: float&, two for loops -

-

i reading hacker news , this article came up. contains raytracer code written on of business card. decided academic challenge translate c++ python, there's few concepts i'm stuck on.

first, function comes up: i t(v o,v d,f& t,v& n){...} translated int tracer(vector o, vector d, float& t, vector& n){...} float& mean? know in other places & used == case here? can in c++?

second, noticed these 3 lines:

for(i k=19;k--;)  //for each columns of objects for(i j=9;j--;)   //for each line on columns if(g[j]&1<<k){

i know << bit shift, , assume & ==. loops 1 loop in other?

finally, line: v p(13,13,13); not quite sure does. create class labeled p extends v (vector) defaults of 13,13,13?

these dumb questions, want see if can understand , searching didn't come anything. thank in advance!

what float& mean?

here, & means "reference", argument passed reference.

i know in other places & used == case here?

& means various things in various contexts, never means ==. in case, it's not operator either; it's part of type specification, meaning it's reference type.

i know << bit shift, , assume & ==

no, it's bitwise and operator. result has bits set bit set in both operands. here, 1<<k 1 operand, result kth bit of g[j]; tests whether bit set.

are loops 1 loop in other?

yes. if don't use braces around for-loop's body, body single statement. in case, body of first loop second loop. make clear, recommend indenting body of loop, , using braces whether or not strictly necessary. of course, don't write (deliberately) obfuscated code.

finally, line: v p(13,13,13);

v class constructor taking 3 arguments. declares variable called p, of type v, initialised using constructor; i.e. 3 co-ordinates initialised 13.


Comments

Post a Comment

Popular posts from this blog

c# - How Configure Devart dotConnect for SQLite Code First? -

-
can configure following sample code ? when run following code, error : no entity framework provider found ado.net provider invariant name 'devart.data.sqlite' setting in machine.config <system.data> <dbproviderfactories> <add name="dotconnect sqlite" invariant="devart.data.sqlite" description="devart dotconnect sqlite" type="devart.data.sqlite.sqliteproviderfactory, devart.data.sqlite, version=4.6.287.0, culture=neutral, publickeytoken=09af7300eec23701" /> </dbproviderfactories> </system.data> after add below block code in app.config <?xml version="1.0"?> <configuration>   <configsections> <!-- more information on entity framework configuration, visit http://go.microsoft.com/fwlink/?linkid=237468 --> <section name="entityframework" type="system.data.entity.internal.configfile.entityframeworksection, entit...
Read more

java - Copying object fields -

-
what best way of copying classes when need have 2 independent variables? have simple class: public class myclass { boolean = false; string b= "not empty"; } do need make method : assign(myclass data ) { a= data.a; b= data.b; } is there automatic method copy (duplicate) objects in java? do need make method : pretty close. instead of making method, should make constructor. such constructors called copy constructor , , create them this: myclass(myclass data) { = data.a; b = data.b; } and create copy of instance, use constructor this: myclass obj1 = new myclass(); myclass obj2 = new myclass(obj1); copy constructor can tedious : using copy constructor create deep-copy can tedious, when class has mutable fields. in case, assignment create copy of reference, , not object itself. have create copy of fields (if want deep copy). can go recursive. a better way create deep copy serialize , deserialize object. why not use clone()? ...
Read more

c++ - Clear the memory after returning a vector in a function -

-
i have function processes , stores lot of data in , returns results vector of class. amount of data stored in function tremendous , want clear storage memory of function after finished job. necessary (does function automatically clear memory) or should clear memory function? update: vector<customers> process(char* const *filename, vector<int> id) { vector<customers> list_of_customers; (perform actions) return list_of_customers; } variables defined locally within function automatically released @ end of function scope. destructors objects called, should free memory allocated objects (if objects coded correctly). example of such object std::vector . anything you've allocated new must have corresponding delete release storage. try avoid doing own allocation , use raii instead, i.e. containers or smart pointers.
Read more