Convert from c++ to Pascal

[SesillaAndromeda]

Hi guys,

can you help me with this code?

in C++

struct Stream {
    float *vertices;
};

void addValue(float *vertices){

    Stream stream;
    stream.vertices  = vertices;
}

void myProcedure
{
    Array <vec3> vertices;

    for (uint i = 0; i < 10; i++)
       vertices.add(vec3(x, y, z);

    addValue((float *) vertices);
}

in Pascal

type
  PArraySingle = ^TArraySingle;
  TArraySingle = array of single;  

  Stream = record
    vertices: PArraySingle;
  end;

procedure addValue(vertices: PArraySingle);
var
   iStream: Stream;
begin
    iStream.vertices := vertices;
end;

procedure myProcedure;
var
   vertices: array of TVec3;
   i: integer;
begin
   setlength(vertices, 10);
   for i:=0 to 10-1 do
       vertices[i] := vec3(x, y, z);

    addValue((float *) vertices); <--- This?!!!! addValue procedure wait array of single. With this line i call addValue with array of vec3!!!
end;

Thanks in advance
Sesilla

[User137]

addValue(@vertices[0]);

should do it. I'm just not sure if the myProcedure disposes of the memory reservation after it ends. That might cause access violations later if so.

And i find addValue a little misleading name, when what it does would better be described as setValue. Whatever exists in the stream before "adding" will be replaced with new one.

edit: Fine, even the C++ code is just a dummy test code

[SesillaAndromeda]

Thanks User137, you are right! This is test code...i'll try your solution!

Thanks
Sesilla

[laggyluk]

procedure addValue(vertices: PArraySingle);
  var   iStream: Stream;
begin
    iStream.vertices := vertices;
end;

shouldn't iStream be created first? or passed as parameter

[SesillaAndromeda]

Hi,

iStream is a record type. I don't create it!

I have another c++ code!!!!!
Then...

C++

struct Stream {
    float *vertices;
    uint verticesCount;
};

Array <Stream> streams;

void flip(const int index, const uint c0, const uint c1){
    
    for (uint i = 0; i < streams[index].verticesCount; i++){
        float *src = streams[index].vertices + i * 2;

        float temp = src[c0];
        src[c0] = src[c1];
        src[c1] = temp;
    }
}

Pascal

  Stream = record
    vertices: array of single;
    verticesCount: longword;
  end;

  streams = array of Stream;

procedure flip(const index: integer; const c0, c1: longword);
var
  i: intger;
begin  
    for i := 0 to streams[index].verticesCount-1 do
    begin
        float *src = streams[index].vertices + i * 2; <-- from this

        float temp = src[c0];
        src[c0] = src[c1];
        src[c1] = temp;
    end;
end;

Thanks
Sesilla

[Dan]

var src: PFloatArray;
var temp: Single;
...
src := PFloatArray(@streams[index].vertices[i * 2]);
temp := src^[c0];
src^[c0] := src^[c1];
src^[c1] := temp;

[SesillaAndromeda]

addValue(@vertices[0]);

should do it. I'm just not sure if the myProcedure disposes of the memory reservation after it ends. That might cause access violations later if so.

And i find addValue a little misleading name, when what it does would better be described as setValue. Whatever exists in the stream before "adding" will be replaced with new one.

edit: Fine, even the C++ code is just a dummy test code

Is possible otherwise? If i have an array of single and i want an array of vec3, is possible without a for loop?

Sesilla

[User137]

Not sure if i understand the question, you could give a bit more details of what you want to do. Function only sends a pointer reference, not copying anything. You can typecast a pointer to anything you want; record or array is irrelevant.

TVec3Array = array[0..65535] of vec3;
PVec3Array = ^TVec3Array;

var arr: array[0..5] of single;
begin
  // Now you can write the same sentence 3 ways:
  arr[3]:=0.2;
  PVec3Array(@arr[0])^[1].x:=0.2;
  PSingleArray(@arr[0])^[3]:=0.2;
end;

[SesillaAndromeda]

Thanks User137,

this is the question:

C++

float *vertices; //My array
vec3 *vectors = (vec3 *) vertices;

Pascal

var
   vertices: array of single;
   vectors: array of TVec3;
begin
   ???????
end;

Sesilla

[User137]

float *vertices doesn't convert to array of single. That is 1 type of cast you can't do with dynamic array. The C++ code uses pointers, so more precise translation would be:

var
   vertices: PSingleArray;
   vectors: PVec3Array;
begin
   vectors:=PVec3Array(vertices);
end;