OpengGL Vertex Buffer Objects

**technomage** · 19-08-2007, 12:36 PM

Hi

Any ideas on converting this macro to a Delphi function, it's used to specific offsets when using vertex buffer objects which are Interleaved, or serialized under opengl

Code:

#define BUFFER_OFFSET&#40;i&#41; &#40;&#40;char*&#41;NULL + &#40;i&#41;&#41;

my first attempt is

[pascal]
function BUFFER_OFFSET(i: Integer): Pointer;
begin
Pointer(Longint(Pointer(nil))+i);
end;
[/pascal]

comments?

**JSoftware** · 19-08-2007, 02:34 PM

Originally Posted by technomage

Hi

Any ideas on converting this macro to a Delphi function, it's used to specific offsets when using vertex buffer objects which are Interleaved, or serialized under opengl

Code:

#define BUFFER_OFFSET&#40;i&#41; &#40;&#40;char*&#41;NULL + &#40;i&#41;&#41;

my first attempt is

[pascal]
function BUFFER_OFFSET(i: Integer): Pointer;
begin
Pointer(Longint(Pointer(nil))+i);
end;
[/pascal]

comments?

[pascal]
function BUFFER_OFFSET(i: Integer): Pointer;
begin
result := Pointer(Longint(Pointer(nil))+i);
end;
[/pascal]?

**JernejL** · 19-08-2007, 02:43 PM

Code:

function BUFFER_OFFSET&#40;i&#58; longword&#41;&#58; Pointer;
var
ptr&#58; pointer absolute i;
begin
  result &#58;= ptr;
end;

**technomage** · 19-08-2007, 06:17 PM

That looks OK, but it's the

Code:

&#40;char *&#41;null

bit that gets me.

**technomage** · 19-08-2007, 09:19 PM

Well my version does not work...

Delfi - you version appears to do the Job

nice work , thank you

.

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