Major check-in of changes for GL_EXT_framebuffer_object extension.

Main driver impacts:
- new code for creating the Mesa GLframebuffer
- new span/pixel read/write code
Some drivers not yet updated/tested.

1 files changed, 273 insertions, 275 deletions

diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index 41a1fdb7cca..12f58ff6621 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -29,16 +29,15 @@
 
 
 #include "glheader.h"
-#include "imports.h"
 #include "buffers.h"
 #include "colormac.h"
 #include "context.h"
-#include "depth.h"
 #include "enums.h"
 #include "fbobject.h"
-#include "stencil.h"
 #include "state.h"
-#include "mtypes.h"
+
+
+#define BAD_MASK ~0u
 
 
 #if _HAVE_FULL_GL
@@ -133,12 +132,12 @@ _mesa_Clear( GLbitfield mask )
       _mesa_update_state( ctx );	/* update _Xmin, etc */
    }
 
-   if (ctx->RenderMode==GL_RENDER) {
+   if (ctx->RenderMode == GL_RENDER) {
       const GLint x = ctx->DrawBuffer->_Xmin;
       const GLint y = ctx->DrawBuffer->_Ymin;
       const GLint height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
       const GLint width  = ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
-      GLbitfield ddMask;
+      GLbitfield bufferMask;
 
       /* don't clear depth buffer if depth writing disabled */
       if (!ctx->Depth.Mask)
@@ -146,20 +145,31 @@ _mesa_Clear( GLbitfield mask )
 
       /* Build the bitmask to send to device driver's Clear function.
        * Note that the GL_COLOR_BUFFER_BIT flag will expand to 0, 1, 2 or 4
-       * of the FRONT/BACK_LEFT/RIGHT_BIT flags.
+       * of the BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
+       * BUFFER_BIT_COLORn flags.
        */
-      ddMask = 0;
-      if (mask & GL_COLOR_BUFFER_BIT)
-         ddMask |= ctx->Color._DrawDestMask[0];
-      if ((mask & GL_DEPTH_BUFFER_BIT) && ctx->Visual.depthBits > 0)
-         ddMask |= GL_DEPTH_BUFFER_BIT;
-      if ((mask & GL_STENCIL_BUFFER_BIT) && ctx->Visual.stencilBits > 0)
-         ddMask |= GL_STENCIL_BUFFER_BIT;
-      if ((mask & GL_ACCUM_BUFFER_BIT) && ctx->Visual.accumRedBits > 0)
-         ddMask |= GL_ACCUM_BUFFER_BIT;
+      bufferMask = 0;
+      if (mask & GL_COLOR_BUFFER_BIT) {
+         bufferMask |= ctx->DrawBuffer->_ColorDrawBufferMask[0];
+      }
+
+      if ((mask & GL_DEPTH_BUFFER_BIT)
+          && ctx->DrawBuffer->Visual.haveDepthBuffer) {
+         bufferMask |= BUFFER_BIT_DEPTH;
+      }
+
+      if ((mask & GL_STENCIL_BUFFER_BIT)
+          && ctx->DrawBuffer->Visual.haveStencilBuffer) {
+         bufferMask |= BUFFER_BIT_STENCIL;
+      }
+
+      if ((mask & GL_ACCUM_BUFFER_BIT)
+          && ctx->DrawBuffer->Visual.haveAccumBuffer) {
+         bufferMask |= BUFFER_BIT_ACCUM;
+      }
 
       ASSERT(ctx->Driver.Clear);
-      ctx->Driver.Clear( ctx, ddMask, (GLboolean) !ctx->Scissor.Enabled,
+      ctx->Driver.Clear( ctx, bufferMask, (GLboolean) !ctx->Scissor.Enabled,
 			 x, y, width, height );
    }
 }
@@ -167,27 +177,41 @@ _mesa_Clear( GLbitfield mask )
 
 
 /**
- * Return bitmask of DD_* flags indicating which color buffers are
- * available to the rendering context;
+ * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
+ * available to the rendering context.
+ * This depends on the framebuffer we're writing to.  For window system
+ * framebuffers we look at the framebuffer's visual.  But for user-
+ * create framebuffers we look at the number of supported color attachments.
  */
 static GLuint
-supported_buffer_bitmask(const GLcontext *ctx)
+supported_buffer_bitmask(const GLcontext *ctx, GLuint framebufferID)
 {
-   GLuint mask = DD_FRONT_LEFT_BIT; /* always have this */
+   GLuint mask = 0x0;
    GLint i;
 
-   if (ctx->Visual.stereoMode) {
-      mask |= DD_FRONT_RIGHT_BIT;
-      if (ctx->Visual.doubleBufferMode) {
-         mask |= DD_BACK_LEFT_BIT | DD_BACK_RIGHT_BIT;
+   if (framebufferID > 0) {
+      /* A user-created renderbuffer */
+      ASSERT(ctx->Extensions.EXT_framebuffer_object);
+      for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
+         mask |= (BUFFER_BIT_COLOR0 << i);
       }
    }
-   else if (ctx->Visual.doubleBufferMode) {
-      mask |= DD_BACK_LEFT_BIT;
-   }
+   else {
+      /* A window system renderbuffer */
+      mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
+      if (ctx->Visual.stereoMode) {
+         mask |= BUFFER_BIT_FRONT_RIGHT;
+         if (ctx->Visual.doubleBufferMode) {
+            mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
+         }
+      }
+      else if (ctx->Visual.doubleBufferMode) {
+         mask |= BUFFER_BIT_BACK_LEFT;
+      }
 
-   for (i = 0; i < ctx->Visual.numAuxBuffers; i++) {
-      mask |= (DD_AUX0_BIT << i);
+      for (i = 0; i < ctx->Visual.numAuxBuffers; i++) {
+         mask |= (BUFFER_BIT_AUX0 << i);
+      }
    }
 
    return mask;
@@ -196,45 +220,53 @@ supported_buffer_bitmask(const GLcontext *ctx)
 
 /**
  * Helper routine used by glDrawBuffer and glDrawBuffersARB.
- * Given a GLenum naming (a) color buffer(s), return the corresponding
- * bitmask of DD_* flags.
+ * Given a GLenum naming one or more color buffers (such as
+ * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
  */
 static GLuint
 draw_buffer_enum_to_bitmask(GLenum buffer)
 {
    switch (buffer) {
-      case GL_FRONT:
-         return DD_FRONT_LEFT_BIT | DD_FRONT_RIGHT_BIT;
-      case GL_BACK:
-         return DD_BACK_LEFT_BIT | DD_BACK_RIGHT_BIT;
       case GL_NONE:
          return 0;
+      case GL_FRONT:
+         return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
+      case GL_BACK:
+         return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
       case GL_RIGHT:
-         return DD_FRONT_RIGHT_BIT | DD_BACK_RIGHT_BIT;
+         return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
       case GL_FRONT_RIGHT:
-         return DD_FRONT_RIGHT_BIT;
+         return BUFFER_BIT_FRONT_RIGHT;
       case GL_BACK_RIGHT:
-         return DD_BACK_RIGHT_BIT;
+         return BUFFER_BIT_BACK_RIGHT;
       case GL_BACK_LEFT:
-         return DD_BACK_LEFT_BIT;
+         return BUFFER_BIT_BACK_LEFT;
       case GL_FRONT_AND_BACK:
-         return DD_FRONT_LEFT_BIT | DD_BACK_LEFT_BIT
-              | DD_FRONT_RIGHT_BIT | DD_BACK_RIGHT_BIT;
+         return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
+              | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
       case GL_LEFT:
-         return DD_FRONT_LEFT_BIT | DD_BACK_LEFT_BIT;
+         return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
       case GL_FRONT_LEFT:
-         return DD_FRONT_LEFT_BIT;
+         return BUFFER_BIT_FRONT_LEFT;
       case GL_AUX0:
-         return DD_AUX0_BIT;
+         return BUFFER_BIT_AUX0;
       case GL_AUX1:
-         return DD_AUX1_BIT;
+         return BUFFER_BIT_AUX1;
       case GL_AUX2:
-         return DD_AUX2_BIT;
+         return BUFFER_BIT_AUX2;
       case GL_AUX3:
-         return DD_AUX3_BIT;
+         return BUFFER_BIT_AUX3;
+      case GL_COLOR_ATTACHMENT0_EXT:
+         return BUFFER_BIT_COLOR0;
+      case GL_COLOR_ATTACHMENT1_EXT:
+         return BUFFER_BIT_COLOR1;
+      case GL_COLOR_ATTACHMENT2_EXT:
+         return BUFFER_BIT_COLOR2;
+      case GL_COLOR_ATTACHMENT3_EXT:
+         return BUFFER_BIT_COLOR3;
       default:
          /* error */
-         return ~0;
+         return BAD_MASK;
    }
 }
 
@@ -249,43 +281,48 @@ read_buffer_enum_to_bitmask(GLenum buffer)
 {
    switch (buffer) {
       case GL_FRONT:
-         return DD_FRONT_LEFT_BIT;
+         return BUFFER_BIT_FRONT_LEFT;
       case GL_BACK:
-         return DD_BACK_LEFT_BIT;
+         return BUFFER_BIT_BACK_LEFT;
       case GL_RIGHT:
-         return DD_FRONT_RIGHT_BIT;
+         return BUFFER_BIT_FRONT_RIGHT;
       case GL_FRONT_RIGHT:
-         return DD_FRONT_RIGHT_BIT;
+         return BUFFER_BIT_FRONT_RIGHT;
       case GL_BACK_RIGHT:
-         return DD_BACK_RIGHT_BIT;
+         return BUFFER_BIT_BACK_RIGHT;
       case GL_BACK_LEFT:
-         return DD_BACK_LEFT_BIT;
+         return BUFFER_BIT_BACK_LEFT;
       case GL_LEFT:
-         return DD_FRONT_LEFT_BIT;
+         return BUFFER_BIT_FRONT_LEFT;
       case GL_FRONT_LEFT:
-         return DD_FRONT_LEFT_BIT;
+         return BUFFER_BIT_FRONT_LEFT;
       case GL_AUX0:
-         return DD_AUX0_BIT;
+         return BUFFER_BIT_AUX0;
       case GL_AUX1:
-         return DD_AUX1_BIT;
+         return BUFFER_BIT_AUX1;
       case GL_AUX2:
-         return DD_AUX2_BIT;
+         return BUFFER_BIT_AUX2;
       case GL_AUX3:
-         return DD_AUX3_BIT;
+         return BUFFER_BIT_AUX3;
+      case GL_COLOR_ATTACHMENT0_EXT:
+         return BUFFER_BIT_COLOR0;
+      case GL_COLOR_ATTACHMENT1_EXT:
+         return BUFFER_BIT_COLOR1;
+      case GL_COLOR_ATTACHMENT2_EXT:
+         return BUFFER_BIT_COLOR2;
+      case GL_COLOR_ATTACHMENT3_EXT:
+         return BUFFER_BIT_COLOR3;
       default:
          /* error */
-         return ~0;
+         return BAD_MASK;
    }
 }
 
 
-
 /**
  * Specify which color buffers to draw into.
  *
- * \param mode color buffer combination.
- *
- * \sa glDrawBuffer().
+ * \param buffer  color buffer, such as GL_LEFT or GL_FRONT_AND_BACK.
  *
  * Flushes the vertices and verifies the parameter and updates the
  * gl_colorbuffer_attrib::_DrawDestMask bitfield. Marks new color state in
@@ -293,160 +330,180 @@ read_buffer_enum_to_bitmask(GLenum buffer)
  * dd_function_table::DrawBuffer callback.
  */
 void GLAPIENTRY
-_mesa_DrawBuffer( GLenum mode )
+_mesa_DrawBuffer(GLenum buffer)
 {
+   GLuint bufferID;
+   GLuint destMask;
    GET_CURRENT_CONTEXT(ctx);
    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx); /* too complex... */
 
-   if (MESA_VERBOSE & VERBOSE_API)
-      _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(mode));
+   if (MESA_VERBOSE & VERBOSE_API) {
+      _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
+   }
 
-   if (ctx->Extensions.EXT_framebuffer_object && ctx->CurrentFramebuffer) {
-      /* Set drawbuffer for a framebuffer object */
-      if (mode == GL_NONE) {
-         ctx->CurrentFramebuffer->DrawBuffer[0] = mode;
-      }
-      else {
-         const GLint k = mode - GL_COLOR_ATTACHMENT0_EXT;
-         if (k >= 0 && k < ctx->Const.MaxColorAttachments) {
-            /* XXX check that the attachment point's Type != GL_NONE */
-            ctx->CurrentFramebuffer->DrawBuffer[0] = mode;
-         }
-         else {
-            _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(mode)");
-            return;
-         }
-      }
+   bufferID = ctx->DrawBuffer->Name;
+
+   if (buffer == GL_NONE) {
+      destMask = 0x0;
    }
    else {
-      /* conventional behaviour */
-      /* Do error checking and compute the _DrawDestMask bitfield. */
-      GLenum destMask, supportedMask;
-
-      destMask = draw_buffer_enum_to_bitmask(mode);
-      if (destMask == ~0u) {
-         _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(mode)");
+      const GLuint supportedMask = supported_buffer_bitmask(ctx, bufferID);
+      destMask = draw_buffer_enum_to_bitmask(buffer);
+      if (destMask == BAD_MASK) {
+         /* totally bogus buffer */
+         _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer)");
          return;
       }
-
-      supportedMask = supported_buffer_bitmask(ctx);
       destMask &= supportedMask;
-
-      if (destMask == 0) {
-         _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffer(mode)");
+      if (destMask == 0x0) {
+         /* none of the named color buffers exist! */
+         _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffer(buffer)");
          return;
       }
-
-      ctx->Color.DrawBuffer[0] = mode;
-      ctx->Color._DrawDestMask[0] = destMask;
-      ctx->NewState |= _NEW_COLOR;
    }
 
-   /*
-    * Call device driver function.
-    */
-   if (ctx->Driver.DrawBuffer)
-      (*ctx->Driver.DrawBuffer)(ctx, mode);
+   /* if we get here, there's no error so set new state */
+   _mesa_drawbuffers(ctx, 1, &buffer, &destMask);
 }
 
 
 /**
  * Called by glDrawBuffersARB; specifies the destination color buffers
  * for N fragment program color outputs.
+ *
+ * XXX This function is called by _mesa_PopAttrib() and we need to do
+ * some more work to deal with the current framebuffer binding state!
  */
 void GLAPIENTRY
 _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
 {
+   GLint output;
+   GLuint usedBufferMask, supportedMask;
+   GLuint bufferID;
+   GLuint destMask[MAX_DRAW_BUFFERS];
    GET_CURRENT_CONTEXT(ctx);
    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 
+   if (!ctx->Extensions.ARB_draw_buffers) {
+      _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffersARB");
+      return;
+   }
    if (n < 1 || n > (GLsizei) ctx->Const.MaxDrawBuffers) {
-      _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)" );
+      _mesa_error(ctx, GL_INVALID_VALUE, "glDrawBuffersARB(n)");
       return;
    }
 
-   if (ctx->Extensions.EXT_framebuffer_object && ctx->CurrentFramebuffer) {
-      /* Set drawbuffers for a framebuffer object */
-      GLint i;
-      GLuint usedAttachments = 0x0;
-      for (i = 0; i < n; i++) {
-         if (buffers[i] == GL_NONE) {
-            /* OK */
-            ctx->CurrentFramebuffer->DrawBuffer[i] = GL_NONE;
-         }
-         else {
-            const GLint k = buffers[i] - GL_COLOR_ATTACHMENT0_EXT;
-            if (k >= 0 && k < ctx->Const.MaxColorAttachments) {
-               /* XXX check that the attachment point's Type != GL_NONE */
-               if ((1 << k) & usedAttachments) {
-                  _mesa_error(ctx, GL_INVALID_OPERATION,
-                              "glDrawBuffersARB(duplicated attachment)");
-                  return;
-               }
-               usedAttachments |= (1 << k);
-               ctx->CurrentFramebuffer->DrawBuffer[i] = buffers[i];
-            }
-            else {
-               _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(mode)");
-               return;
-            }
-         }
-      }
+   bufferID = ctx->DrawBuffer->Name;
+
+   supportedMask = supported_buffer_bitmask(ctx, bufferID);
+   usedBufferMask = 0x0;
 
-      /* set remaining color outputs to NONE */
-      for (i = n; i < ctx->Const.MaxDrawBuffers; i++) {
-         ctx->CurrentFramebuffer->DrawBuffer[i] = GL_NONE;
+   /* complicated error checking... */
+   for (output = 0; output < n; output++) {
+      if (buffers[output] == GL_NONE) {
+         destMask[output] = 0x0;
       }
-   }
-   else {
-      /* Conventional operation */
-      GLint i;
-      GLuint usedBufferMask, supportedMask;
-
-      supportedMask = supported_buffer_bitmask(ctx);
-      usedBufferMask = 0;
-      for (i = 0; i < n; i++) {
-         GLuint destMask = draw_buffer_enum_to_bitmask(buffers[i]);
-         if (destMask == ~0u ) {
+      else {
+         destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
+         if (destMask[output] == BAD_MASK
+             || _mesa_bitcount(destMask[output]) > 1) {
             _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffersARB(buffer)");
             return;
          }         
-         destMask &= supportedMask;
-         if (destMask == 0) {
+         destMask[output] &= supportedMask;
+         if (destMask[output] == 0) {
             _mesa_error(ctx, GL_INVALID_OPERATION,
                         "glDrawBuffersARB(unsupported buffer)");
             return;
          }
-         if (destMask & usedBufferMask) {
+         if (destMask[output] & usedBufferMask) {
             /* can't specify a dest buffer more than once! */
             _mesa_error(ctx, GL_INVALID_OPERATION,
                         "glDrawBuffersARB(duplicated buffer)");
             return;
          }
+
          /* update bitmask */
-         usedBufferMask |= destMask;
-         /* save state */
-         ctx->Color.DrawBuffer[i] = buffers[i];
-         ctx->Color._DrawDestMask[i] = destMask;
+         usedBufferMask |= destMask[output];
       }
+   }
+
+   /* OK, if we get here, there were no errors so set the new state */
+   _mesa_drawbuffers(ctx, n, buffers, destMask);
+}
+
 
-      /* set remaining color outputs to NONE */
-      for (i = n; i < ctx->Const.MaxDrawBuffers; i++) {
-         ctx->Color.DrawBuffer[i] = GL_NONE;
-         ctx->Color._DrawDestMask[i] = 0;
+/**
+ * Set color output state.  Traditionally, there was only one color
+ * output, but fragment programs can now have several distinct color
+ * outputs (see GL_ARB_draw_buffers).  This function sets the state
+ * for one such color output.
+ */
+static void
+set_color_output(GLcontext *ctx, GLuint output, GLenum buffer, GLuint destMask)
+{
+   struct gl_framebuffer *fb = ctx->DrawBuffer;
+
+   ASSERT(output < ctx->Const.MaxDrawBuffers);
+
+   fb->ColorDrawBuffer[output] = buffer;
+   fb->_ColorDrawBufferMask[output] = destMask;
+
+   if (fb->Name == 0) {
+      /* Set traditional state var */
+      ctx->Color.DrawBuffer[output] = buffer;
+   }
+
+   /* not really needed, will be set later */
+   fb->_NumColorDrawBuffers[output] = 0;
+}
+
+
+/**
+ * Helper routine used by _mesa_DrawBuffer, _mesa_DrawBuffersARB and
+ * _mesa_PopAttrib to set drawbuffer state.
+ */
+void
+_mesa_drawbuffers(GLcontext *ctx, GLsizei n, const GLenum *buffers,
+                  const GLuint *destMask)
+{
+   GLuint mask[MAX_DRAW_BUFFERS];
+   GLint output;
+
+   if (!destMask) {
+      /* compute destMask values now */
+      const GLuint bufferID = ctx->DrawBuffer->Name;
+      const GLuint supportedMask = supported_buffer_bitmask(ctx, bufferID);
+      for (output = 0; output < n; output++) {
+         mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
+         ASSERT(mask[output] != BAD_MASK);
+         mask[output] &= supportedMask;
       }
+      destMask = mask;
+   }
+
+   for (output = 0; output < n; output++) {
+      set_color_output(ctx, output, buffers[output], destMask[output]);
+   }
 
-      ctx->NewState |= _NEW_COLOR;
+   /* set remaining color outputs to NONE */
+   for (output = n; output < ctx->Const.MaxDrawBuffers; output++) {
+      set_color_output(ctx, output, GL_NONE, 0x0);
    }
 
+   ctx->NewState |= _NEW_COLOR;
+
    /*
     * Call device driver function.
     */
    if (ctx->Driver.DrawBuffers)
-      (*ctx->Driver.DrawBuffers)(ctx, n, buffers);
+      ctx->Driver.DrawBuffers(ctx, n, buffers);
+   else if (ctx->Driver.DrawBuffer)
+      ctx->Driver.DrawBuffer(ctx, buffers[0]);
 }
 
 
+
 /**
  * Set the color buffer source for reading pixels.
  *
@@ -454,60 +511,53 @@ _mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
  *
  * \sa glReadBuffer().
  *
- * Verifies the parameter and updates gl_pixel_attrib::_ReadSrcMask.  Marks
- * new pixel state in __GLcontextRec::NewState and notifies the driver via
- * dd_function_table::ReadBuffer.
  */
 void GLAPIENTRY
-_mesa_ReadBuffer( GLenum mode )
+_mesa_ReadBuffer(GLenum buffer)
 {
+   struct gl_framebuffer *fb;
+   GLuint srcMask, supportedMask;
+   GLuint bufferID;
    GET_CURRENT_CONTEXT(ctx);
    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
 
+   fb = ctx->ReadBuffer;
+   bufferID = fb->Name;
+
    if (MESA_VERBOSE & VERBOSE_API)
-      _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(mode));
+      _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 
-   if (ctx->Extensions.EXT_framebuffer_object && ctx->CurrentFramebuffer) {
-      /* Set readbuffer for a framebuffer object */
-      if (mode == GL_NONE) {
-         ctx->CurrentFramebuffer->ReadBuffer = mode;
-      }
-      else {
-         const GLint k = mode - GL_COLOR_ATTACHMENT0_EXT;
-         if (k >= 0 && k < ctx->Const.MaxColorAttachments) {
-            /* XXX check that the attachment point's Type != GL_NONE */
-            ctx->CurrentFramebuffer->ReadBuffer = mode;
-         }
-         else {
-            _mesa_error(ctx, GL_INVALID_ENUM, "glReadBuffer(mode)");
-            return;
-         }
-      }
+   if (bufferID > 0 && buffer == GL_NONE) {
+      /* legal! */
+      srcMask = 0x0;
    }
    else {
-      /* conventional operation */
-      GLuint srcMask, supportedMask;
-
-      srcMask = read_buffer_enum_to_bitmask(mode);
-      if (srcMask == ~0u) {
-         _mesa_error(ctx, GL_INVALID_ENUM, "glReadBuffer(mode)");
+      /* general case */
+      srcMask = read_buffer_enum_to_bitmask(buffer);
+      if (srcMask == BAD_MASK) {
+         _mesa_error(ctx, GL_INVALID_ENUM, "glReadBuffer(buffer)");
          return;
       }
-      supportedMask = supported_buffer_bitmask(ctx);
+      supportedMask = supported_buffer_bitmask(ctx, bufferID);
       if ((srcMask & supportedMask) == 0) {
-         _mesa_error(ctx, GL_INVALID_OPERATION, "glReadBuffer(mode)");
+         _mesa_error(ctx, GL_INVALID_OPERATION, "glReadBuffer(buffer)");
          return;
       }
-      ctx->Pixel._ReadSrcMask = srcMask;
-      ctx->Pixel.ReadBuffer = mode;
-      ctx->NewState |= _NEW_PIXEL;
    }
 
+   if (bufferID == 0) {
+      ctx->Pixel.ReadBuffer = buffer;
+   }
+   fb->ColorReadBuffer = buffer;
+   fb->_ColorReadBufferMask = srcMask;
+
+   ctx->NewState |= _NEW_PIXEL;
+
    /*
     * Call device driver function.
     */
    if (ctx->Driver.ReadBuffer)
-      (*ctx->Driver.ReadBuffer)(ctx, mode);
+      (*ctx->Driver.ReadBuffer)(ctx, buffer);
 }
 
 
@@ -524,53 +574,51 @@ _mesa_ReadBuffer( GLenum mode )
  * \note This function may be called from within Mesa or called by the
  * user directly (see the GL_MESA_resize_buffers extension).
  */
+#if OLD_RENDERBUFFER
+/* THIS FUNCTION IS OBSOLETE!!!
+ * See _mesa_resize_framebuffer
+ */
+#endif
 void GLAPIENTRY
 _mesa_ResizeBuffersMESA( void )
 {
    GET_CURRENT_CONTEXT(ctx);
 
+   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
+
    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glResizeBuffersMESA\n");
 
-   if (ctx) {
-      ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
-
-      if (ctx->DrawBuffer) {
-         GLuint buf_width, buf_height;
-         GLframebuffer *buffer = ctx->DrawBuffer;
-
-         /* ask device driver for size of output buffer */
-         (*ctx->Driver.GetBufferSize)( buffer, &buf_width, &buf_height );
+   if (ctx->DrawBuffer && ctx->DrawBuffer->Name == 0) {
+      GLuint newWidth, newHeight;
+      GLframebuffer *buffer = ctx->DrawBuffer;
 
-         /* see if size of device driver's color buffer (window) has changed */
-         if (buffer->Width == buf_width && buffer->Height == buf_height)
-            return; /* size is as expected */
+      /* ask device driver for size of output buffer */
+      ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 
-         buffer->Width = buf_width;
-         buffer->Height = buf_height;
-
-         ctx->Driver.ResizeBuffers( buffer );
+      /* see if size of device driver's color buffer (window) has changed */
+      if (buffer->Width != newWidth || buffer->Height != newHeight) {
+         if (ctx->Driver.ResizeBuffers)
+            ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
       }
+   }
 
-      if (ctx->ReadBuffer && ctx->ReadBuffer != ctx->DrawBuffer) {
-         GLuint buf_width, buf_height;
-         GLframebuffer *buffer = ctx->ReadBuffer;
-
-         /* ask device driver for size of read buffer */
-         (*ctx->Driver.GetBufferSize)( buffer, &buf_width, &buf_height );
-
-         /* see if size of device driver's color buffer (window) has changed */
-         if (buffer->Width == buf_width && buffer->Height == buf_height)
-            return; /* size is as expected */
+   if (ctx->ReadBuffer && ctx->ReadBuffer != ctx->DrawBuffer
+       && ctx->ReadBuffer->Name == 0) {
+      GLuint newWidth, newHeight;
+      GLframebuffer *buffer = ctx->ReadBuffer;
 
-         buffer->Width = buf_width;
-         buffer->Height = buf_height;
+      /* ask device driver for size of read buffer */
+      ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );
 
-         ctx->Driver.ResizeBuffers( buffer );
+      /* see if size of device driver's color buffer (window) has changed */
+      if (buffer->Width != newWidth || buffer->Height != newHeight) {
+         if (ctx->Driver.ResizeBuffers)
+            ctx->Driver.ResizeBuffers(ctx, buffer, newWidth, newHeight );
       }
-
-      ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
    }
+
+   ctx->NewState |= _NEW_BUFFERS;  /* to update scissor / window bounds */
 }
 
 
@@ -642,56 +690,6 @@ _mesa_Scissor( GLint x, GLint y, GLsizei width, GLsizei height )
 
 
 /**********************************************************************/
-/** \name State management */
-/*@{*/
-
-
-/**
- * Update the context's current drawing buffer's Xmin, Xmax, Ymin, Ymax fields.
- * These values are computed from the buffer's width and height and
- * the scissor box, if it's enabled.
- * \param ctx  the GL context.
- */
-void
-_mesa_update_draw_buffer_bounds(GLcontext *ctx)
-{
-   GLframebuffer *buffer = ctx->DrawBuffer;
-
-   buffer->_Xmin = 0;
-   buffer->_Ymin = 0;
-   buffer->_Xmax = buffer->Width;
-   buffer->_Ymax = buffer->Height;
-
-   if (ctx->Scissor.Enabled) {
-      if (ctx->Scissor.X > buffer->_Xmin) {
-	 buffer->_Xmin = ctx->Scissor.X;
-      }
-      if (ctx->Scissor.Y > buffer->_Ymin) {
-	 buffer->_Ymin = ctx->Scissor.Y;
-      }
-      if (ctx->Scissor.X + ctx->Scissor.Width < buffer->_Xmax) {
-	 buffer->_Xmax = ctx->Scissor.X + ctx->Scissor.Width;
-      }
-      if (ctx->Scissor.Y + ctx->Scissor.Height < buffer->_Ymax) {
-	 buffer->_Ymax = ctx->Scissor.Y + ctx->Scissor.Height;
-      }
-      /* finally, check for empty region */
-      if (buffer->_Xmin > buffer->_Xmax) {
-         buffer->_Xmin = buffer->_Xmax;
-      }
-      if (buffer->_Ymin > buffer->_Ymax) {
-         buffer->_Ymin = buffer->_Ymax;
-      }
-   }
-
-   ASSERT(buffer->_Xmin <= buffer->_Xmax);
-   ASSERT(buffer->_Ymin <= buffer->_Ymax);
-}
-
-/*@}*/
-
-
-/**********************************************************************/
 /** \name Initialization */
 /*@{*/