Add pixel buffers to the USE_SHADERS codepath. Turn on USE_SHADERS.

git-svn-id: svn+ssh://truffle/home/andrew/repo/memview@63 6d4121a9-3ab8-48c6-8db9-97dca464e206

GLImage.h

@@ -6,25 +6,52 @@ class GLImage {
     GLImage()
 	: myData(0)
 	, myWidth(0)
-	, myHeight(0) {}
+	, myHeight(0)
+	, myOwnData(false) {}
+    ~GLImage()
+    {
+	if (myOwnData)
+	    delete [] myData;
+    }
 
     void resize(int width, int height)
     {
 	if (myWidth != width ||
 	    myHeight != height)
 	{
-	    delete [] myData;
-	    myData = 0;
+	    if (myOwnData)
+	    {
+		delete [] myData;
+		myData = 0;
+	    }
+
 	    myWidth = width;
 	    myHeight = height;
+
+	    if (myWidth && myHeight)
+	    {
+		myData = new uint32[myWidth*myHeight];
+		myOwnData = true;
+	    }
 	}
+    }
 
-	if (!myData)
-	    myData = new uint32[myWidth*myHeight];
+    // Interface to allow external ownership
+    void setSize(int width, int height)
+    {
+	myWidth = width;
+	myHeight = height;
+	myOwnData = false;
+    }
+    void setData(uint32 *data)
+    {
+	myData = data;
+	myOwnData = false;
     }
 
     int width() const	{ return myWidth; }
     int height() const	{ return myHeight; }
+    size_t  bytes() const   { return myWidth*myHeight*sizeof(uint32); }
     const uint32 *data() const	{ return myData; }
 
     void fill(uint32 val)
@@ -46,6 +73,7 @@ class GLImage {
     uint32	*myData;
     int		 myWidth;
     int		 myHeight;
+    bool	 myOwnData;
 };
 
 #endif

Window.C

@@ -1,6 +1,13 @@
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+
 #include "Window.h"
 #include "MemoryState.h"
 
+// This define causes rendering to use textures, PBOs, and to render a
+// full-screen quad.  When disabled, glDrawPixels is used.
+#define USE_SHADERS
+
 static const QSize	theDefaultSize(800, 600);
 
 Window::Window(int argc, char *argv[])
@@ -61,6 +68,7 @@ MemViewWidget::MemViewWidget(int argc, char *argv[],
     , myHScrollBar(hscrollbar)
     , myTexture(0)
     , myList(0)
+    , myPixelBuffer(0)
     , myStopWatch(false)
     , myDragging(false)
 {
@@ -109,6 +117,8 @@ MemViewWidget::initializeGL()
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
+    glGenBuffers(1, &myPixelBuffer);
+
     myList = glGenLists(1);
     glNewList(myList, GL_COMPILE);
 
@@ -163,6 +173,16 @@ MemViewWidget::resizeGL(int width, int height)
 
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
+
+#if defined(USE_SHADERS)
+    myImage.setSize(width, height);
+
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, myPixelBuffer);
+    glBufferData(GL_PIXEL_UNPACK_BUFFER, myImage.bytes(), 0, GL_STREAM_DRAW);
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+#else
+    myImage.resize(width, height);
+#endif
 }
 
 void
@@ -175,15 +195,22 @@ MemViewWidget::paintGL()
 	myAnchor.myAbsoluteOffset;
     myAnchor.myColumn += myHScrollBar->value() - myAnchor.myColumn;
 
+#if !defined(USE_SHADERS)
     myState->fillImage(myImage, myAnchor);
 
-#if !defined(USE_SHADERS)
     glDrawPixels(myImage.width(), myImage.height(), GL_BGRA,
 	    GL_UNSIGNED_BYTE, myImage.data());
 #else
-    glTexImage2D(GL_TEXTURE_2D, 0, 3,
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, myPixelBuffer);
+
+    myImage.setData((uint32 *)
+	    glMapBufferARB(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY));
+    myState->fillImage(myImage, myAnchor);
+    glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8,
 	    myImage.width(), myImage.height(), 0, GL_BGRA,
-	    GL_UNSIGNED_BYTE, myImage.data());
+	    GL_UNSIGNED_BYTE, 0);
 
     glCallList(myList);
 #endif
@@ -207,10 +234,9 @@ MemViewWidget::resizeEvent(QResizeEvent *event)
 
 	myVScrollBar->setPageStep(h);
 	myHScrollBar->setPageStep(w);
-	myImage.resize(w, h);
-	update();
 
 	QGLWidget::resizeEvent(event);
+	update();
     }
 }
 

Window.h

@@ -81,6 +81,7 @@ private slots:
     QGLShaderProgram	*myProgram;
     GLuint		 myTexture;
     GLuint		 myList;
+    GLuint		 myPixelBuffer;
 
     MemoryState::AnchorInfo  myAnchor;
     MemoryState		    *myState;