Shared code snippets!

[chronozphere]

Yeah, in general the scoping of that snippet could result in different pieces of code on different compilers Razz

Looks like it's been converted directly from C code Smile

Can you elaborate a little more on this? Is it because i allready assigned a result before the last statement is executed?

This would probably be better:
[pascal]
function Angle(X,Y: single): single;
begin
if X = 0 then
begin
if Y > 0 then Result := 180
else Result := 0;
end else
Result := 180+RadToDeg(Arctan2(-X,Y));
end;
[/pascal]

[User137]

This is perfectly functional at least in Delphi7. Arctan2() is defined to handle the divide by zero case in itself. If you do it yourself it's double code (slower ofc).

[pascal]// Result = ]-180, 180]
const
ToRad = 0.0174532925199432; // PI / 180 = Deg to Rad
ToDeg = 57.295779513082320; // 180 / PI = Rad to Deg
function Angle(px1,py1,px2,py2: double): double;
begin
result:=ToDeg*arctan2(py2-py1,px2-px1);
// Add if result<0 then result:=result+360;
// if you want range to be [0..360[
end;[/pascal]

I also noticed that you negate X, which is false.

[JernejL]

Sometimes you need the angles to be represented only between 0..360, you probably seen functions like this one:

function OLDclamp360(angle: single): single;
begin
  Result := angle;

  while Result <0> 360 do
    Result &#58;= Result - 360;

end;

Not only it's a bad code with a lot of branching that gets slower the bigger / smaller the numbers are, but there is a better / proper way:

function clamp360(angle: single): single;
begin
  Result := angle;

  if result > 360 then result:= result - (round(result) div 360 * 360);
  if result < 0   then result&#58;= 360 + result - &#40;round&#40;result&#41; div 360 * 360&#41;;

end;

[JSoftware]

Yeah, in general the scoping of that snippet could result in different pieces of code on different compilers Razz

Looks like it's been converted directly from C code Smile

Can you elaborate a little more on this? Is it because i allready assigned a result before the last statement is executed?

[ code ]

Yes, that code is perfect. Indeed, your last assignment would override any previous assignment effectively making the first 3 lines do nothing.

The scoping would be a problem because the following piece of code would be syntactically identical as your initial piece of code
[pascal]
function Angle(X,Y: single): single;
begin
Result := 0;
if X = 0 then
begin
if Y > 0 then
Result := 180
end
else
Result := 0;
Result := 180+RadToDeg(Arctan2(-X,Y));
end;[/pascal]

[Brainer]

My snippet is helpful when formatting data sizes.
[pascal]
{ .: FormatSize :. }
function FormatSize(const Size: Integer): String;
const
KB = 1024;
MB = KB * KB;
GB = MB * KB;
begin
case Size of
0..KB -1: Result := IntToStr(Size) + ' B';
KB..MB -1: Result := Format('%.2f KB', [Size / KB]);
MB..GB -1: Result := Format('%.2f MB', [Size / MB]);
else
Result := Format('%.2f GB', [Size / GB]);
end;
end;
[/pascal]

[chronozphere]

Okay... let's keep this topic alive shall we.

I just baked this piece of code...

Use this routine to read a Null-Terminated String from a MemoryStream. The function reads MaxLength - 1 Characters from the stream and adds the null-Char at the end. If the function encounters a NullChar while reading, Buffer will only contain the characters precending the NullChar and the NullChar itsself. The routine returns the ammount of bytes read.

[pascal]
var
Stream: TMemoryStream; //Global stream

function ReadStr(Buffer: PChar; MaxLength: Integer): Integer;
type
TCharArray = array [0..MaxInt-1] of Char;
PCharArray = ^TCharArray;
var
I: Integer;
Chars: PCharArray;
begin
Result := 0;
if (Stream.Size - Stream.Position <= 0) then Exit;

Chars := Stream.Memory;
I := -1;
repeat
Inc(I);
if Chars[Stream.Position+I] = #0 then Break;
until (I = MaxLength -1);

Result := Stream.Read( Buffer^, I ) + 1;
Buffer[Result-1] := #0;
end;
[/pascal]

I have tested this code, and it's working correctly AFAIK.

Might become handy when you are trying to make a C compatible API wich relies on Null-Terminated strings.

[chronozphere]

Okay... Here is a similair routine, but now to write a string.

Writes MaxLength characters of a Null-Terminated String to a MemoryStream. The routine doesn't write the NullChar. If a NullChar is found in the string, Only the precending Chars are written. Returns the number of bytes written.

[pascal]
function WriteStr(Buffer: PChar; MaxLength: Integer): Integer;
type
TCharArray = array [0..MaxInt-1] of Char;
PCharArray = ^TCharArray;
var
I: Integer;
Chars: PCharArray;
begin
Chars := Pointer(Buffer);
for I:=0 to MaxLength-1 do
if Chars[I] = #0 then Break;

Result := Stream.Write( Buffer^, I );
end;
[/pascal]

[Brainer]

This piece of code converts seconds into "hours:minutes:seconds" format.
[pascal]
{ .: FormatTime :. }
function FormatTime(const TheTime: Integer): String;
var
Hours, Mins, Secs: Integer;
begin
if (TheTime > 0) then
begin
Mins := (TheTime div 60);
Secs := (TheTime mod 60);
Hours := (Mins div 60);
Mins := (Mins mod 60);
Result := Format('%.2d:%.2d:%.2d', [Hours, Mins, Secs]);
end else
Result := '00:00:00';
end;
[/pascal]

[chronozphere]

Hi guys, No more new snippets these days?

I've got a new one. This routine concatenates two paths. The first is the basePath and the second is a path relative to this basepath. It handles "../" to jump to the parent directory.
My string programming skills are not that great, so I guess there's room for improvement.

[pascal]
function ConcatenatePaths(aBasePath, aRelativePath: String): String;
const
SEPARATORS = ['\','/'];
SEPARATOR = '/';
var
Name: String;
I: Integer;
begin
//Trim redundant slashes
if aRelativePath[1] in SEPARATORS then
aRelativePath := RightStr(aRelativePath, Length(aRelativePath)-1 );
if aBasePath[Length(aBasePath)] in SEPARATORS then
aBasePath := LeftStr(aBasePath, Length(aBasePath)-1 );

while Length(aRelativePath) > 0 do
begin
Name := Copy(aRelativePath, 1, 3);
if (Name = '../') or (Name = '..\') then
begin
for I := Length(aBasePath) downto 1 do
if aBasePath[I] in SEPARATORS then
begin
aBasePath := Copy(aBasePath, 1, I-1);
Break;
end;
aRelativePath := Copy(aRelativePath, 4, Length(aRelativePath)-3);
end
else
Break;
end;

Result := aBasePath + SEPARATOR + aRelativePath;
end;
[/pascal]

For example:

E:\some\groovy\file\path\to\somewhere + '..\..\..\myfile.txt'

results in:

E:\some\groovy\file\myfile.txt'

Now it's your turn again.

[User137]

There's few in nxMath i could show up:

n is any floating point number. It gives a result that is always between 0 and 1, but most interesting thing happens when n is 0..1; it smoothens the pattern to match "top to low peak" of cosine wave.
[pascal]function Smoothen(n: single): single;
begin
if n<0 then n:=0
else if n>1 then n:=1;
Smoothen:=0.5-cos(n*pi)*0.5;
end;[/pascal]

Simply modulus, but this handles also negative numbers so that it remains continuous pattern at 0 point. 11 mod2 10 = 1 , -11 mod2 10 = -9
[pascal]function Mod2(a,b: integer): integer;
begin
if b=0 then result:=0
else begin
b:=abs(b);
result:=abs(a) mod b;
if (a<0) and (result>0) then result:=result-b;
end;
end;[/pascal]

And 1 more...
If you need to get power of 2 number that your current fits in, this is the function.
Giving n = 140 or 220 would result in 256.
[pascal]function Pow2fit(n: integer): integer;
var neg: boolean;
begin
if n<0 then begin
n:=-n; neg:=true;
end else neg:=false;
if n<3 then result:=n
else result:=round(intpower(2,ceil(log2(n))));
if neg then result:=-result;
end;[/pascal]
There's still Pow2near() which would give the nearest fit which would result in 128 in case of 140. These are all part of Next3D.