framebuffer.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/*
 * Mesa 3-D graphics library
 * Version:  7.2
 *
 * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


/**
 * Functions for allocating/managing framebuffers and renderbuffers.
 * Also, routines for reading/writing renderbuffer data as ubytes,
 * ushorts, uints, etc.
 */


#include "glheader.h"
#include "imports.h"
#include "buffers.h"
#include "context.h"
#include "depthstencil.h"
#include "mtypes.h"
#include "fbobject.h"
#include "framebuffer.h"
#include "renderbuffer.h"
#include "texobj.h"



/**
 * Compute/set the _DepthMax field for the given framebuffer.
 * This value depends on the Z buffer resolution.
 */
static void
compute_depth_max(struct gl_framebuffer *fb)
{
   if (fb->Visual.depthBits == 0) {
      /* Special case.  Even if we don't have a depth buffer we need
       * good values for DepthMax for Z vertex transformation purposes
       * and for per-fragment fog computation.
       */
      fb->_DepthMax = (1 << 16) - 1;
   }
   else if (fb->Visual.depthBits < 32) {
      fb->_DepthMax = (1 << fb->Visual.depthBits) - 1;
   }
   else {
      /* Special case since shift values greater than or equal to the
       * number of bits in the left hand expression's type are undefined.
       */
      fb->_DepthMax = 0xffffffff;
   }
   fb->_DepthMaxF = (GLfloat) fb->_DepthMax;

   /* Minimum resolvable depth value, for polygon offset */
   fb->_MRD = 1.0 / fb->_DepthMaxF;
}


/**
 * Create and initialize a gl_framebuffer object.
 * This is intended for creating _window_system_ framebuffers, not generic
 * framebuffer objects ala GL_EXT_framebuffer_object.
 *
 * \sa _mesa_new_framebuffer
 */
struct gl_framebuffer *
_mesa_create_framebuffer(const GLvisual *visual)
{
   struct gl_framebuffer *fb = CALLOC_STRUCT(gl_framebuffer);
   assert(visual);
   if (fb) {
      _mesa_initialize_framebuffer(fb, visual);
   }
   return fb;
}


/**
 * Allocate a new gl_framebuffer object.
 * This is the default function for ctx->Driver.NewFramebuffer().
 * This is for allocating user-created framebuffers, not window-system
 * framebuffers!
 * \sa _mesa_create_framebuffer
 */
struct gl_framebuffer *
_mesa_new_framebuffer(GLcontext *ctx, GLuint name)
{
   struct gl_framebuffer *fb;
   (void) ctx;
   assert(name != 0);
   fb = CALLOC_STRUCT(gl_framebuffer);
   if (fb) {
      fb->Name = name;
      fb->RefCount = 1;
      fb->_NumColorDrawBuffers = 1;
      fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
      fb->_ColorDrawBufferIndexes[0] = BUFFER_COLOR0;
      fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
      fb->_ColorReadBufferIndex = BUFFER_COLOR0;
      fb->Delete = _mesa_destroy_framebuffer;
   }
   return fb;
}


/**
 * Initialize a gl_framebuffer object.  Typically used to initialize
 * window system-created framebuffers, not user-created framebuffers.
 * \sa _mesa_create_framebuffer
 */
void
_mesa_initialize_framebuffer(struct gl_framebuffer *fb, const GLvisual *visual)
{
   assert(fb);
   assert(visual);

   _mesa_bzero(fb, sizeof(struct gl_framebuffer));

   _glthread_INIT_MUTEX(fb->Mutex);

   fb->RefCount = 1;

   /* save the visual */
   fb->Visual = *visual;

   /* Init read/draw renderbuffer state */
   if (visual->doubleBufferMode) {
      fb->_NumColorDrawBuffers = 1;
      fb->ColorDrawBuffer[0] = GL_BACK;
      fb->_ColorDrawBufferIndexes[0] = BUFFER_BACK_LEFT;
      fb->ColorReadBuffer = GL_BACK;
      fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
   }
   else {
      fb->_NumColorDrawBuffers = 1;
      fb->ColorDrawBuffer[0] = GL_FRONT;
      fb->_ColorDrawBufferIndexes[0] = BUFFER_FRONT_LEFT;
      fb->ColorReadBuffer = GL_FRONT;
      fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
   }

   fb->Delete = _mesa_destroy_framebuffer;
   fb->_Status = GL_FRAMEBUFFER_COMPLETE_EXT;

   compute_depth_max(fb);
}


/**
 * Deallocate buffer and everything attached to it.
 * Typically called via the gl_framebuffer->Delete() method.
 */
void
_mesa_destroy_framebuffer(struct gl_framebuffer *fb)
{
   if (fb) {
      _mesa_free_framebuffer_data(fb);
      _mesa_free(fb);
   }
}


/**
 * Free all the data hanging off the given gl_framebuffer, but don't free
 * the gl_framebuffer object itself.
 */
void
_mesa_free_framebuffer_data(struct gl_framebuffer *fb)
{
   GLuint i;

   assert(fb);
   assert(fb->RefCount == 0);

   _glthread_DESTROY_MUTEX(fb->Mutex);

   for (i = 0; i < BUFFER_COUNT; i++) {
      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
      if (att->Renderbuffer) {
         _mesa_reference_renderbuffer(&att->Renderbuffer, NULL);
      }
      if (att->Texture) {
         _mesa_reference_texobj(&att->Texture, NULL);
      }
      ASSERT(!att->Renderbuffer);
      ASSERT(!att->Texture);
      att->Type = GL_NONE;
   }

   /* unbind _Depth/_StencilBuffer to decr ref counts */
   _mesa_reference_renderbuffer(&fb->_DepthBuffer, NULL);
   _mesa_reference_renderbuffer(&fb->_StencilBuffer, NULL);
}


/**
 * Set *ptr to point to fb, with refcounting and locking.
 */
void
_mesa_reference_framebuffer(struct gl_framebuffer **ptr,
                            struct gl_framebuffer *fb)
{
   assert(ptr);
   if (*ptr == fb) {
      /* no change */
      return;
   }
   if (*ptr) {
      _mesa_unreference_framebuffer(ptr);
   }
   assert(!*ptr);
   assert(fb);
   _glthread_LOCK_MUTEX(fb->Mutex);
   fb->RefCount++;
   _glthread_UNLOCK_MUTEX(fb->Mutex);
   *ptr = fb;
}


/**
 * Undo/remove a reference to a framebuffer object.
 * Decrement the framebuffer object's reference count and delete it when
 * the refcount hits zero.
 * Note: we pass the address of a pointer and set it to NULL.
 */
void
_mesa_unreference_framebuffer(struct gl_framebuffer **fb)
{
   assert(fb);
   if (*fb) {
      GLboolean deleteFlag = GL_FALSE;

      _glthread_LOCK_MUTEX((*fb)->Mutex);
      ASSERT((*fb)->RefCount > 0);
      (*fb)->RefCount--;
      deleteFlag = ((*fb)->RefCount == 0);
      _glthread_UNLOCK_MUTEX((*fb)->Mutex);
      
      if (deleteFlag)
         (*fb)->Delete(*fb);

      *fb = NULL;
   }
}




/**
 * Resize the given framebuffer's renderbuffers to the new width and height.
 * This should only be used for window-system framebuffers, not
 * user-created renderbuffers (i.e. made with GL_EXT_framebuffer_object).
 * This will typically be called via ctx->Driver.ResizeBuffers() or directly
 * from a device driver.
 *
 * \note it's possible for ctx to be null since a window can be resized
 * without a currently bound rendering context.
 */
void
_mesa_resize_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb,
                         GLuint width, GLuint height)
{
   GLuint i;

   /* XXX I think we could check if the size is not changing
    * and return early.
    */

   /* For window system framebuffers, Name is zero */
   assert(fb->Name == 0);

   for (i = 0; i < BUFFER_COUNT; i++) {
      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
      if (att->Type == GL_RENDERBUFFER_EXT && att->Renderbuffer) {
         struct gl_renderbuffer *rb = att->Renderbuffer;
         /* only resize if size is changing */
         if (rb->Width != width || rb->Height != height) {
            /* could just as well pass rb->_ActualFormat here */
            if (rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
               ASSERT(rb->Width == width);
               ASSERT(rb->Height == height);
            }
            else {
               _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
               /* no return */
            }
         }
      }
   }

   if (fb->_DepthBuffer) {
      struct gl_renderbuffer *rb = fb->_DepthBuffer;
      if (rb->Width != width || rb->Height != height) {
         if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
         }
      }
   }

   if (fb->_StencilBuffer) {
      struct gl_renderbuffer *rb = fb->_StencilBuffer;
      if (rb->Width != width || rb->Height != height) {
         if (!rb->AllocStorage(ctx, rb, rb->InternalFormat, width, height)) {
            _mesa_error(ctx, GL_OUT_OF_MEMORY, "Resizing framebuffer");
         }
      }
   }

   fb->Width = width;
   fb->Height = height;

   if (ctx) {
      /* update scissor / window bounds */
      _mesa_update_draw_buffer_bounds(ctx);
      /* Signal new buffer state so that swrast will update its clipping
       * info (the CLIP_BIT flag).
       */
      ctx->NewState |= _NEW_BUFFERS;
   }
}


/**
 * Examine all the framebuffer's renderbuffers to update the Width/Height
 * fields of the framebuffer.  If we have renderbuffers with different
 * sizes, set the framebuffer's width and height to zero.
 * Note: this is only intended for user-created framebuffers, not
 * window-system framebuffes.
 */
static void
update_framebuffer_size(struct gl_framebuffer *fb)
{
   GLboolean haveSize = GL_FALSE;
   GLuint i;

   /* user-created framebuffers only */
   assert(fb->Name);

   for (i = 0; i < BUFFER_COUNT; i++) {
      struct gl_renderbuffer_attachment *att = &fb->Attachment[i];
      const struct gl_renderbuffer *rb = att->Renderbuffer;
      if (rb) {
         if (haveSize) {
            if (rb->Width != fb->Width && rb->Height != fb->Height) {
               /* size mismatch! */
               fb->Width = 0;
               fb->Height = 0;
               return;
            }
         }
         else {
            fb->Width = rb->Width;
            fb->Height = rb->Height;
            haveSize = GL_TRUE;
         }
      }
   }
}


/**
 * 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)
{
   struct gl_framebuffer *buffer = ctx->DrawBuffer;

   if (!buffer)
      return;

   if (buffer->Name) {
      /* user-created framebuffer size depends on the renderbuffers */
      update_framebuffer_size(buffer);
   }

   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);
}


/**
 * The glGet queries of the framebuffer red/green/blue size, stencil size,
 * etc. are satisfied by the fields of ctx->DrawBuffer->Visual.  These can
 * change depending on the renderbuffer bindings.  This function updates
 * the given framebuffer's Visual from the current renderbuffer bindings.
 *
 * This may apply to user-created framebuffers or window system framebuffers.
 *
 * Also note: ctx->DrawBuffer->Visual.depthBits might not equal
 * ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer.DepthBits.
 * The former one is used to convert floating point depth values into
 * integer Z values.
 */
void
_mesa_update_framebuffer_visual(struct gl_framebuffer *fb)
{
   GLuint i;