buffers.c

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

 * \sa _mesa_DrawBuffer
 * \param n  number of outputs
 * \param buffers  array [n] of renderbuffer names.  Unlike glDrawBuffer, the
 *                 names cannot specify more than one buffer.  For example,
 *                 GL_FRONT_AND_BACK is illegal.
 */
void GLAPIENTRY
_mesa_DrawBuffersARB(GLsizei n, const GLenum *buffers)
{
   GLint output;
   GLbitfield usedBufferMask, supportedMask;
   GLbitfield 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)");
      return;
   }

   supportedMask = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
   usedBufferMask = 0x0;

   /* complicated error checking... */
   for (output = 0; output < n; output++) {
      if (buffers[output] == GL_NONE) {
         destMask[output] = 0x0;
      }
      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[output] &= supportedMask;
         if (destMask[output] == 0) {
            _mesa_error(ctx, GL_INVALID_OPERATION,
                        "glDrawBuffersARB(unsupported buffer)");
            return;
         }
         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[output];
      }
   }

   /* OK, if we get here, there were no errors so set the new state */
   _mesa_drawbuffers(ctx, n, buffers, destMask);

   /*
    * Call device driver function.
    */
   if (ctx->Driver.DrawBuffers)
      ctx->Driver.DrawBuffers(ctx, n, buffers);
   else if (ctx->Driver.DrawBuffer)
      ctx->Driver.DrawBuffer(ctx, buffers[0]);
}


/**
 * Helper function to set the GL_DRAW_BUFFER state in the context and
 * current FBO.
 *
 * All error checking will have been done prior to calling this function
 * so nothing should go wrong at this point.
 *
 * \param ctx  current context
 * \param n    number of color outputs to set
 * \param buffers  array[n] of colorbuffer names, like GL_LEFT.
 * \param destMask  array[n] of BUFFER_BIT_* bitmasks which correspond to the
 *                  colorbuffer names.  (i.e. GL_FRONT_AND_BACK =>
 *                  BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
 */
void
_mesa_drawbuffers(GLcontext *ctx, GLuint n, const GLenum *buffers,
                  const GLbitfield *destMask)
{
   struct gl_framebuffer *fb = ctx->DrawBuffer;
   GLbitfield mask[MAX_DRAW_BUFFERS];

   if (!destMask) {
      /* compute destMask values now */
      const GLbitfield supportedMask = supported_buffer_bitmask(ctx, fb);
      GLuint output;
      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;
   }

   if (n == 1) {
      GLuint buf, count = 0;
      /* init to -1 to help catch errors */
      fb->_ColorDrawBufferIndexes[0] = -1;
      for (buf = 0; buf < BUFFER_COUNT; buf++) {
         if (destMask[0] & (1 << buf)) {
            fb->_ColorDrawBufferIndexes[count] = buf;
            count++;
         }
      }
      fb->ColorDrawBuffer[0] = buffers[0];
      fb->_NumColorDrawBuffers = count;
   }
   else {
      GLuint buf, count = 0;
      for (buf = 0; buf < n; buf++ ) {
         if (destMask[buf]) {
            fb->_ColorDrawBufferIndexes[buf] = _mesa_ffs(destMask[buf]) - 1;
            fb->ColorDrawBuffer[buf] = buffers[buf];
            count = buf + 1;
         }
         else {
            fb->_ColorDrawBufferIndexes[buf] = -1;
         }
      }
      /* set remaining outputs to -1 (GL_NONE) */
      while (buf < ctx->Const.MaxDrawBuffers) {
         fb->_ColorDrawBufferIndexes[buf] = -1;
         fb->ColorDrawBuffer[buf] = GL_NONE;
         buf++;
      }
      fb->_NumColorDrawBuffers = count;
   }

   if (fb->Name == 0) {
      /* also set context drawbuffer state */
      GLuint buf;
      for (buf = 0; buf < ctx->Const.MaxDrawBuffers; buf++) {
         ctx->Color.DrawBuffer[buf] = fb->ColorDrawBuffer[buf];
      }
   }

   ctx->NewState |= _NEW_COLOR;
}


/**
 * Like \sa _mesa_drawbuffers(), this is a helper function for setting
 * GL_READ_BUFFER state in the context and current FBO.
 * \param ctx  the rendering context
 * \param buffer  GL_FRONT, GL_BACK, GL_COLOR_ATTACHMENT0, etc.
 * \param bufferIndex  the numerical index corresponding to 'buffer'
 */
void
_mesa_readbuffer(GLcontext *ctx, GLenum buffer, GLint bufferIndex)
{
   struct gl_framebuffer *fb = ctx->ReadBuffer;

   if (fb->Name == 0) {
      /* Only update the per-context READ_BUFFER state if we're bound to
       * a window-system framebuffer.
       */
      ctx->Pixel.ReadBuffer = buffer;
   }

   fb->ColorReadBuffer = buffer;
   fb->_ColorReadBufferIndex = bufferIndex;

   ctx->NewState |= _NEW_PIXEL;
}



/**
 * Called by glReadBuffer to set the source renderbuffer for reading pixels.
 * \param mode color buffer such as GL_FRONT, GL_BACK, etc.
 */
void GLAPIENTRY
_mesa_ReadBuffer(GLenum buffer)
{
   struct gl_framebuffer *fb;
   GLbitfield supportedMask;
   GLint srcBuffer;
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));

   fb = ctx->ReadBuffer;

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));

   if (fb->Name > 0 && buffer == GL_NONE) {
      /* This is legal for user-created framebuffer objects */
      srcBuffer = -1;
   }
   else {
      /* general case / window-system framebuffer */
      srcBuffer = read_buffer_enum_to_index(buffer);
      if (srcBuffer == -1) {
         _mesa_error(ctx, GL_INVALID_ENUM,
                     "glReadBuffer(buffer=0x%x)", buffer);
         return;
      }
      supportedMask = supported_buffer_bitmask(ctx, fb);
      if (((1 << srcBuffer) & supportedMask) == 0) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glReadBuffer(buffer=0x%x)", buffer);
         return;
      }
   }

   /* OK, all error checking has been completed now */

   _mesa_readbuffer(ctx, buffer, srcBuffer);

   /*
    * Call device driver function.
    */
   if (ctx->Driver.ReadBuffer)
      (*ctx->Driver.ReadBuffer)(ctx, buffer);
}


#if _HAVE_FULL_GL

/**
 * XXX THIS IS OBSOLETE - drivers should take care of detecting window
 * size changes and act accordingly, likely calling _mesa_resize_framebuffer().
 *
 * GL_MESA_resize_buffers extension.
 *
 * When this function is called, we'll ask the window system how large
 * the current window is.  If it's a new size, we'll call the driver's
 * ResizeBuffers function.  The driver will then resize its color buffers
 * as needed, and maybe call the swrast's routine for reallocating
 * swrast-managed depth/stencil/accum/etc buffers.
 * \note This function should only be called through the GL API, not
 * from device drivers (as was done in the past).
 */

void _mesa_resizebuffers( GLcontext *ctx )
{
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glResizeBuffersMESA\n");

   if (!ctx->Driver.GetBufferSize) {
      return;
   }

   if (ctx->WinSysDrawBuffer) {
      GLuint newWidth, newHeight;
      GLframebuffer *buffer = ctx->WinSysDrawBuffer;

      assert(buffer->Name == 0);

      /* ask device driver for size of output buffer */
      ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );

      /* 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->WinSysReadBuffer
       && ctx->WinSysReadBuffer != ctx->WinSysDrawBuffer) {
      GLuint newWidth, newHeight;
      GLframebuffer *buffer = ctx->WinSysReadBuffer;

      assert(buffer->Name == 0);

      /* ask device driver for size of read buffer */
      ctx->Driver.GetBufferSize( buffer, &newWidth, &newHeight );

      /* 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 */
}


/*
 * XXX THIS IS OBSOLETE
 */
void GLAPIENTRY
_mesa_ResizeBuffersMESA( void )
{
   GET_CURRENT_CONTEXT(ctx);

   if (ctx->Extensions.MESA_resize_buffers)
      _mesa_resizebuffers( ctx );
}


/*
 * XXX move somewhere else someday?
 */
void GLAPIENTRY
_mesa_SampleCoverageARB(GLclampf value, GLboolean invert)
{
   GET_CURRENT_CONTEXT(ctx);

   if (!ctx->Extensions.ARB_multisample) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glSampleCoverageARB");
      return;
   }

   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH( ctx );
   ctx->Multisample.SampleCoverageValue = (GLfloat) CLAMP(value, 0.0, 1.0);
   ctx->Multisample.SampleCoverageInvert = invert;
   ctx->NewState |= _NEW_MULTISAMPLE;
}

#endif /* _HAVE_FULL_GL */



/**
 * Define the scissor box.
 *
 * \param x, y coordinates of the scissor box lower-left corner.
 * \param width width of the scissor box.
 * \param height height of the scissor box.
 *
 * \sa glScissor().
 *
 * Verifies the parameters and updates __GLcontextRec::Scissor. On a
 * change flushes the vertices and notifies the driver via
 * the dd_function_table::Scissor callback.
 */
void
_mesa_set_scissor(GLcontext *ctx, 
                  GLint x, GLint y, GLsizei width, GLsizei height)
{
   if (x == ctx->Scissor.X &&
       y == ctx->Scissor.Y &&
       width == ctx->Scissor.Width &&
       height == ctx->Scissor.Height)
      return;

   FLUSH_VERTICES(ctx, _NEW_SCISSOR);
   ctx->Scissor.X = x;
   ctx->Scissor.Y = y;
   ctx->Scissor.Width = width;
   ctx->Scissor.Height = height;

   if (ctx->Driver.Scissor)
      ctx->Driver.Scissor( ctx, x, y, width, height );
}


void GLAPIENTRY
_mesa_Scissor( GLint x, GLint y, GLsizei width, GLsizei height )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (width < 0 || height < 0) {
      _mesa_error( ctx, GL_INVALID_VALUE, "glScissor" );
      return;
   }

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glScissor %d %d %d %d\n", x, y, width, height);

   _mesa_set_scissor(ctx, x, y, width, height);
}



/**********************************************************************/
/** \name Initialization */
/*@{*/

/**
 * Initialize the context's scissor state.
 * \param ctx  the GL context.
 */
void
_mesa_init_scissor(GLcontext *ctx)
{
   /* Scissor group */
   ctx->Scissor.Enabled = GL_FALSE;
   ctx->Scissor.X = 0;
   ctx->Scissor.Y = 0;
   ctx->Scissor.Width = 0;
   ctx->Scissor.Height = 0;
}


/**
 * Initialize the context's multisample state.
 * \param ctx  the GL context.
 */
void
_mesa_init_multisample(GLcontext *ctx)
{
   ctx->Multisample.Enabled = GL_TRUE;
   ctx->Multisample.SampleAlphaToCoverage = GL_FALSE;
   ctx->Multisample.SampleAlphaToOne = GL_FALSE;
   ctx->Multisample.SampleCoverage = GL_FALSE;
   ctx->Multisample.SampleCoverageValue = 1.0;
   ctx->Multisample.SampleCoverageInvert = GL_FALSE;
}

/*@}*/