merging offscreen rendering from brnach

Graphics/PixelBuffer.h

+#ifndef _PIXEL_BUFFER_H_
+#define _PIXEL_BUFFER_H_
+/*
+ * Copyright (C) 1999-2006 Christophe Geuzaine <geuz@geuz.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of either:
+ *
+ * a) the GNU Library General Public License as published by the Free
+ * Software Foundation, either version 2 of the License, or (at your
+ * option) any later version; or
+ *
+ * b) the GL2PS License as published by Christophe Geuzaine, either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either
+ * the GNU Library General Public License or the GL2PS License for
+ * more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library in the file named "COPYING.LGPL";
+ * if not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+ * Cambridge, MA 02139, USA.
+ *
+ * You should have received a copy of the GL2PS License with this
+ * library in the file named "COPYING.GL2PS"; if not, I will be glad
+ * to provide one.
+ */
+
+#include "Gmsh.h"
+#include "GmshUI.h"
+#include "Draw.h"
+#include "Context.h"
+
+extern Context_T CTX;
+
+#if defined(HAVE_OSMESA)
+#include <GL/osmesa.h>
+#endif
+
+class PixelBuffer{
+ private:
+  int _width, _height, _numComp, _dataSize;
+  GLenum _format, _type;
+  void *_pixels;
+ public:
+  PixelBuffer(int width, int height, GLenum format, GLenum type)
+    : _width(width), _height(height), _format(format), _type(type)
+  {
+    if(format == GL_RGB){
+      _numComp = 3;
+    }
+    else if(format == GL_RGBA){
+      _numComp = 4;
+    }
+    else{
+      Msg(GERROR, "Unknown pixel format: assuming RGB");
+      _format = GL_RGB;
+      _numComp = 3;
+    }
+    
+    if(type == GL_UNSIGNED_BYTE){
+      _dataSize = sizeof(unsigned char);
+    }
+    else if(type == GL_FLOAT){
+      _dataSize = sizeof(float);
+    }
+    else{
+      Msg(GERROR, "Unknown pixel storage type: assuming unsigned byte");
+      _type = GL_UNSIGNED_BYTE;
+      _dataSize = sizeof(unsigned char);
+    }
+    _pixels = Calloc(_numComp * _width * _height, _dataSize);
+  }
+  ~PixelBuffer()
+  {
+    Free(_pixels);
+  }
+  int GetWidth(){ return _width; }
+  int GetHeight(){ return _height; }
+  int GetNumComp(){ return _numComp; }
+  int GetDataSize(){ return _dataSize; }
+  GLenum GetFormat(){ return _format; }
+  GLenum GetType(){ return _type; }
+  void *GetPixels(){ return _pixels; }
+  void Fill()
+  {
+    if(!CTX.batch){
+      SetOpenglContext();
+      ClearOpengl();
+      Draw3d();
+      Draw2d();
+      glFinish();
+      glPixelStorei(GL_PACK_ALIGNMENT, 1);
+      glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+      glReadPixels(0, 0, _width, _height, _format, _type, _pixels);
+    }
+    else{
+#if defined(HAVE_OSMESA)
+      if(_format != GL_RGB && _type != GL_UNSIGNED_BYTE){
+	Msg(GERROR, "Offscreen rendering only implemented for GL_RGB/GL_UNSIGNED_BYTE");
+	return;
+      }
+      OSMesaContext ctx = OSMesaCreateContextExt(OSMESA_RGB, 16, 0, 0, NULL);
+      if(!ctx){
+	Msg(GERROR, "OSMesaCreateContext failed");
+	return;
+      }
+      if(!OSMesaMakeCurrent(ctx, _pixels, GL_UNSIGNED_BYTE, _width, _height)){
+	Msg(GERROR, "OSMesaMakeCurrent failed");
+      }
+      ClearOpengl();
+      Draw3d();
+      //Draw2d();
+      glFinish();
+      //OSMesaDestroyContext(ctx);
+#else
+      Msg(WARNING, "Offscreen rendering not available in this version");
+#endif
+    }
+  }
+};
+
+#endif