我用openGL绘制纹理（视频图像）。图像是在地图上绘制的，因此在大多数情况下绘制的图像是梯形的。仅当我使用“透视正确纹理”时，图像在地图上看起来才不错。 我的问题是如何捕获绘制的纹理并将其存储到文件中。 我只想保存绘制的纹理，而不是屏幕截图或此函数中未绘制的任何其他内容（公共覆盖 void OnRender()）。 我还在地图上渲染其他东西，所以截图不是解决方案。那么如何绘制一些帧缓冲区以在屏幕上使用它并将其保存到文件中。
使用 openTK nuGet v1.1.1589.5942 (v4.0.6)
using GMap.NET.OpenGL;
using OpenTK;
using OpenTK.Graphics.OpenGL;
public GMapControl() : base(new OpenTK.Graphics.GraphicsMode(32, 24, 8, 4))
{
Paint += glControl_Paint;
}
void glControl_Paint(object sender, PaintEventArgs e)
{
if (!loaded)
return;
if (makeControlContext)
{
//VideoForm
controlContext = new GraphicsContext(GraphicsMode, WindowInfo);
makeControlContext = false;
}
if (controlContext != null)
controlContext.MakeCurrent(WindowInfo);
else
MakeCurrent();
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
GL.MatrixMode(MatrixMode.Modelview);
GL.BlendFunc(BlendingFactorSrc.SrcAlpha, BlendingFactorDest.OneMinusSrcAlpha);
GL.Enable(EnableCap.Blend);
GL.Enable(EnableCap.LineSmooth);
GL.Hint(HintTarget.LineSmoothHint, HintMode.Nicest);
DrawMap();
textureLoader();
if (OnPaint != null)
{
GL.DepthMask(false);
GL.LoadIdentity();
OnPaint(sender, e);
if (useViewPortFix)
setupViewport();
}
GL.Disable(EnableCap.Blend);
GL.Flush();
SwapBuffers();
}
void DrawMap()
{
try
{
}
finally
{
if (themeFont != null)
OnPaintOverlays();
GL.PopMatrix();
}
}
protected virtual void OnPaintOverlays()
{
GL.LoadIdentity();
GL.Translate(Core.renderOffset.X, Core.renderOffset.Y, 0);
try
{
foreach (GMapOverlay o in Overlays)
{
if (o.IsVisibile)
{
o.OnRender();
}
}
}
catch { }
}
public override void OnRender()
{
GL.Color4(backgroundColor.Value);
lock (bitmapSync)
{
if (bitmap != null)
createTexture();
}
GL.Enable(EnableCap.Texture2D);
GL.BindTexture(TextureTarget.Texture2D, texture);
//Do the magick for "Perspective correct texturing"
// center point
GPoint localTargetPosition = MainForm.instance.gMapControl.FromLatLngToLocalWithOffset(targetPosition);
// determines distances to center for all vertexes
double dUL = Common.distance(new double[] { LocalPoints[0].X, LocalPoints[0].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dUR = Common.distance(new double[] { LocalPoints[1].X, LocalPoints[1].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLR = Common.distance(new double[] { LocalPoints[2].X, LocalPoints[2].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLL = Common.distance(new double[] { LocalPoints[3].X, LocalPoints[3].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
var texCoords = new[]
{
new Vector4(0, 0, 1, 1),
new Vector4(1, 0, 1, 1),
new Vector4(1, 1, 1, 1),
new Vector4(0, 1, 1, 1)
};
texCoords[0] *= (float)((dUL + dLR) / dLR);
texCoords[1] *= (float)((dUR + dLL) / dLL);
texCoords[2] *= (float)((dLR + dUL) / dUL);
texCoords[3] *= (float)((dLL + dUR) / dUR);
GL.Begin(PrimitiveType.Quads);
{
GL.TexCoord4(texCoords[0]); GL.Vertex4(LocalPoints[0].X, LocalPoints[0].Y, 1, 1); //UL LocalPoints[0] gimbalUL
GL.TexCoord4(texCoords[1]); GL.Vertex4(LocalPoints[1].X, LocalPoints[1].Y, 1, 1); //UR LocalPoints[1] gimbalUR
GL.TexCoord4(texCoords[2]); GL.Vertex4(LocalPoints[2].X, LocalPoints[2].Y, 1, 1); //LR LocalPoints[2] gimbalLR
GL.TexCoord4(texCoords[3]); GL.Vertex4(LocalPoints[3].X, LocalPoints[3].Y, 1, 1); //LL LocalPoints[3] gimbalLL
}
GL.End();
GL.Disable(EnableCap.Texture2D);
//TODO store drawn texture/image to file (only the drawn texture not screenshot or anything else which is not drawn here)
}
我尝试使用 Framebuffer 执行此操作，但没有成功。绘制到帧缓冲区，然后从中读取像素，输出是空图像。
int FramebufferName = -1;
int depthrenderbuffer;
int fbo_width = 1280;
int fbo_height = 720;
public override void OnRender()
{
if (!targetPosition.IsEmpty)
{
if (FramebufferName == -1)
{
//Create new Framebuffer only once
GL.GenFramebuffers(1, out FramebufferName);
GL.BindFramebuffer(FramebufferTarget.Framebuffer, FramebufferName);
//create texture from bitmap 1280x720
lock (bitmapSync)
{
if (bitmap != null)
{
fbo_width = bitmap.Width;
fbo_height = bitmap.Height;
int t = GL.GenTexture();
GL.BindTexture(TextureTarget.Texture2D, t);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToEdge);
GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToEdge);
GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, bitmap.Width, bitmap.Height, 0, OpenTK.Graphics.OpenGL.PixelFormat.Rgba, PixelType.UnsignedByte, IntPtr.Zero);
Rectangle rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
System.Drawing.Imaging.BitmapData data = bitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
GL.BindTexture(TextureTarget.Texture2D, t);
GL.TexSubImage2D(TextureTarget.Texture2D, 0, rect.X, rect.Y, rect.Width, rect.Height, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0);
bitmap.UnlockBits(data);
bitmap.Dispose();
bitmap = null;
if (renderedTexture > 0)
GL.DeleteTexture(renderedTexture);
renderedTexture = t;
GL.FramebufferTexture2D(FramebufferTarget.DrawFramebuffer, FramebufferAttachment.ColorAttachment0, TextureTarget.Texture2D, renderedTexture, 0); //original texture 1280x720
}
}
/* Storage must be one of: */
/* GL_RGBA4, GL_RGB565, GL_RGB5_A1, GL_DEPTH_COMPONENT16, GL_STENCIL_INDEX8. */
//GL.RenderbufferStorage(RenderbufferTarget.Renderbuffer, RenderbufferStorage.DepthComponent16, fbo_width, fbo_height);
//GL.FramebufferRenderbuffer(FramebufferTarget.Framebuffer, FramebufferAttachment.ColorAttachment0, RenderbufferTarget.Renderbuffer, renderedTexture);
/* Depth renderbuffer. */
GL.GenRenderbuffers(1, out depthrenderbuffer);
GL.BindRenderbuffer(RenderbufferTarget.Renderbuffer, depthrenderbuffer);
GL.RenderbufferStorage(RenderbufferTarget.Renderbuffer, RenderbufferStorage.DepthComponent24, fbo_width, fbo_height);
GL.FramebufferRenderbuffer(FramebufferTarget.DrawFramebuffer, FramebufferAttachment.DepthAttachment, RenderbufferTarget.Renderbuffer, depthrenderbuffer);
//GL.ReadBuffer(ReadBufferMode.ColorAttachment0);
//DrawBuffersEnum[] drawBuffersEnum = new DrawBuffersEnum[] { DrawBuffersEnum.ColorAttachment0 };
//GL.DrawBuffers(1, drawBuffersEnum);
if (GL.CheckFramebufferStatus(FramebufferTarget.Framebuffer) != FramebufferErrorCode.FramebufferComplete)
{
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0); //would draw to the default framebuffer again, basically finishing the drawing to the other framebuffer(the backbuffer which will be brought to front by SwapBuffers)
GL.DeleteFramebuffers(1, ref FramebufferName);
GL.DeleteFramebuffers(1, ref depthrenderbuffer);
return;
}
checkGlError();
}
//drawInFramebuffer
//GL.BindTexture(TextureTarget.Texture2D, 0);
//GL.Enable(EnableCap.Texture2D);
GL.BindFramebuffer(FramebufferTarget.Framebuffer, FramebufferName);
//GL.Viewport(0, 0, fbo_width, fbo_height);
checkGlError();
//clear all
GL.ClearColor(1, 1, 1, 0);
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
//GL.MatrixMode(MatrixMode.Projection);
//GL.LoadIdentity();
checkGlError();
//bind texture to framebuffer
GL.Enable(EnableCap.Texture2D);
checkGlError();
GL.ActiveTexture(TextureUnit.Texture0);
checkGlError();
GL.BindTexture(TextureTarget.Texture2D, renderedTexture);
checkGlError();
//GL.BindRenderbuffer(RenderbufferTarget.Renderbuffer, renderedTexture);
//checkGlError();
//draw in framebuffer
//Do the magick for "Perspective correct texturing"
// center point
GPoint localTargetPosition = MainForm.instance.gMapControl.FromLatLngToLocalWithOffset(targetPosition);
// determines distances to center for all vertexes
double dUL = Common.distance(new double[] { LocalPoints[0].X, LocalPoints[0].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dUR = Common.distance(new double[] { LocalPoints[1].X, LocalPoints[1].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLR = Common.distance(new double[] { LocalPoints[2].X, LocalPoints[2].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
double dLL = Common.distance(new double[] { LocalPoints[3].X, LocalPoints[3].Y }, new double[] { localTargetPosition.X, localTargetPosition.Y });
var texCoords = new[]
{
new Vector4(0, 0, 1, 1),
new Vector4(1, 0, 1, 1),
new Vector4(1, 1, 1, 1),
new Vector4(0, 1, 1, 1)
};
texCoords[0] *= (float)((dUL + dLR) / dLR);
texCoords[1] *= (float)((dUR + dLL) / dLL);
texCoords[2] *= (float)((dLR + dUL) / dUL);
texCoords[3] *= (float)((dLL + dUR) / dUR);
GL.Begin(PrimitiveType.Quads);
{
GL.TexCoord4(texCoords[0]); GL.Vertex4(LocalPoints[0].X, LocalPoints[0].Y, 1, 1); //UL LocalPoints[0] gimbalUL
GL.TexCoord4(texCoords[1]); GL.Vertex4(LocalPoints[1].X, LocalPoints[1].Y, 1, 1); //UR LocalPoints[1] gimbalUR
GL.TexCoord4(texCoords[2]); GL.Vertex4(LocalPoints[2].X, LocalPoints[2].Y, 1, 1); //LR LocalPoints[2] gimbalLR
GL.TexCoord4(texCoords[3]); GL.Vertex4(LocalPoints[3].X, LocalPoints[3].Y, 1, 1); //LL LocalPoints[3] gimbalLL
}
GL.End();
GL.Disable(EnableCap.Texture2D);
checkGlError();
//TODO, get size an location where image is in framebuffer
fbo_width = 1280;
fbo_height = 720;
long minX = 0;
long maxY = 0;
#endregion
using (Bitmap bitmap = new Bitmap(fbo_width, fbo_height))
{
BitmapData bits = bitmap.LockBits(new Rectangle(0, 0, fbo_width, fbo_height), ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
GL.ReadPixels((int)minX, (int)maxY, fbo_width, fbo_height, OpenTK.Graphics.OpenGL.PixelFormat.Bgra, PixelType.UnsignedByte, bits.Scan0);
bitmap.UnlockBits(bits);
bitmap.RotateFlip(RotateFlipType.Rotate180FlipX);
bitmap.Save(@"c:\Downloads\aaa\ReadPixels_" + now.ToString("HHmmss_fff") + ".png", ImageFormat.Png); //getting empty image, alpha = 0
}
checkGlError();
GL.BindFramebuffer(FramebufferTarget.Framebuffer, 0); //would draw to the default framebuffer again, basically finishing the drawing to the other framebuffer(the backbuffer which will be brought to front by SwapBuffers)
//TODO draw framebuffer on screen. HOW???
/*
GL.Enable(EnableCap.Texture2D);
GL.BindTexture(TextureTarget.Texture2D, renderedTexture);
GL.BlitFramebuffer(0, 0, fbo_width, fbo_height, 0, 0, fbo_width, fbo_height, ClearBufferMask.ColorBufferBit, BlitFramebufferFilter.Nearest);
*/
}
else
{
base.OnRender();
}
}
private void checkGlError()
{
ErrorCode errorCode = GL.GetError();
if (errorCode != ErrorCode.NoError)
{
Console.WriteLine("ERROR: " + errorCode);
}
}
GL.ReadPixelsBitmap bmp = new Bitmap(width, height);
System.Drawing.Imaging.BitmapData data =
bmp.LockBits(this.ClientRectangle, System.Drawing.Imaging.ImageLockMode.WriteOnly,
System.Drawing.Imaging.PixelFormat.Format24bppRgb);
GL.ReadPixels(x, y, width, height, PixelFormat.Bgr, PixelType.UnsignedByte, data.Scan0);
bmp.UnlockBits(data);
GL.GetTexImageGL.BindTexture(TextureTarget.Texture2D, texture);
GL.GetTexImage(TextureTarget.Texture2D, 0, PixelFormat.Bgr, PixelType.UnsignedByte, target);
在 OpenGL ES 中，您需要将纹理附加到帧缓冲区。请参阅 opengl es 2.0 android c++ glGetTexImage 替代品。
问题解决了吗？
谢谢。