我需要一些帮助,关于在Delphi XE2中将OpenGL的ViewPort的渲染内容保存为位图文件。OpenGL与德尔福:离线渲染图像到文件
基本上,我想要做的事情是在完成一些渲染之后,将FrameBuffer的内容转储为位图(全彩色格式)文件。这是应该完成这个的代码摘录。
procedure TForm1.saveBtnClick(Sender: TObject);
var
//TBitmap object holding the newly created Bitmap.
srcBitmap: TBitmap;
// the array to hold pixels value while reading from the FrameBuffer
pixels: Array of GLUbyte;
dimensions: Array [0 .. 3] of Integer;
//Stream between the memory location of pixels and my bitmap.
MS: TMemoryStream;
I: Integer;
begin
if SaveDialog1.Execute then
begin
//create the bitmap and set it to Full Color Format; Open the Memory Stream
srcBitmap := TBitmap.Create;
srcBitmap.PixelFormat:=pf24bit;
MS:= TMemoryStream.Create;
//get the dimensions info for the current ViewPort
glGetIntegerv(GL_VIEWPORT, @dimensions);
srcBitmap.Width := dimensions[2];
srcBitmap.Height :=dimensions[3];
//allocate enough memory for pixels;
SetLength(pixels, dimensions[2] * dimensions[3] * 3);
//this is the function that is supposed to read the contents from the Frame
// Buffer and write them to pixels
glReadPixels(0, 0, dimensions[2], dimensions[3], GL_RGB,
GL_UNSIGNED_BYTE, @pixels);
//Do something if an error occured
ErrorHandler;
// Below I attempt to create a bitmap file from the read in pixels
MS.Read(pixels,dimensions[2] * dimensions[3] * 3) ;
srcBitmap.LoadFromStream(MS);
Edit2.Text := SaveDialog1.FileName;
srcBitmap.SaveToFile(Edit2.Text);
MS.Free;
srcBitmap.Free;
end;
end;
我遇到的主要问题是:
1)如果视口大小太大堆栈溢出错误(我得到这么错误试图保存的图像大小为256 * 256)。我认为这可能是因为'glReadPixels'函数将帧缓冲区读取到PROCESSOR MEMORY(我假设这是L2 Cache),而不是主存储器,并且这个不能适合整个图像。是这样吗?如果是这样,你有什么想法,我怎么读FrameBuffer到主存储器上?
2)为了避免1)中的错误,在较小的视口(25x25)上进行测试时,给我一个访问冲突错误,当我尝试访问存储在“像素”数组中的任何值时。这意味着glReadPixels不能正确地从缓冲区中读取数据,我相信其原因与我传递给函数glReadPixels(0, 0, dimensions[2], dimensions[3], GL_RGB,GL_UNSIGNED_BYTE, @pixels)
的参数之间有些不一致。
你是如何创建OpenGL上下文的?隐藏的窗口+ FBO或PBuffer? – datenwolf
那么我做了默认的上下文初始化,使用 DC:= GetDC(panelHandle); RC:= CreateRenderingContext(DC,[opDoubleBuffered],32,24,0,0,0,0); ActivateRenderingContext(DC,RC) – kenny