buffers.c

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

/*
 * Mesa 3-D graphics library
 * Version:  7.1
 *
 * Copyright (C) 1999-2007  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.
 */


/**
 * \file buffers.c
 * General framebuffer-related functions, like glClear, glScissor, etc.
 */



#include "glheader.h"
#include "buffers.h"
#include "colormac.h"
#include "context.h"
#include "enums.h"
#include "fbobject.h"
#include "state.h"


#define BAD_MASK ~0u


#if _HAVE_FULL_GL
void GLAPIENTRY
_mesa_ClearIndex( GLfloat c )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (ctx->Color.ClearIndex == (GLuint) c)
      return;

   FLUSH_VERTICES(ctx, _NEW_COLOR);
   ctx->Color.ClearIndex = (GLuint) c;

   if (!ctx->Visual.rgbMode && ctx->Driver.ClearIndex) {
      /* it's OK to call glClearIndex in RGBA mode but it should be a NOP */
      (*ctx->Driver.ClearIndex)( ctx, ctx->Color.ClearIndex );
   }
}
#endif


/**
 * Specify the clear values for the color buffers.
 *
 * \param red red color component.
 * \param green green color component.
 * \param blue blue color component.
 * \param alpha alpha component.
 *
 * \sa glClearColor().
 *
 * Clamps the parameters and updates gl_colorbuffer_attrib::ClearColor.  On a
 * change, flushes the vertices and notifies the driver via the
 * dd_function_table::ClearColor callback.
 */
void GLAPIENTRY
_mesa_ClearColor( GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha )
{
   GLfloat tmp[4];
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   tmp[0] = CLAMP(red,   0.0F, 1.0F);
   tmp[1] = CLAMP(green, 0.0F, 1.0F);
   tmp[2] = CLAMP(blue,  0.0F, 1.0F);
   tmp[3] = CLAMP(alpha, 0.0F, 1.0F);

   if (TEST_EQ_4V(tmp, ctx->Color.ClearColor))
      return; /* no change */

   FLUSH_VERTICES(ctx, _NEW_COLOR);
   COPY_4V(ctx->Color.ClearColor, tmp);

   if (ctx->Visual.rgbMode && ctx->Driver.ClearColor) {
      /* it's OK to call glClearColor in CI mode but it should be a NOP */
      (*ctx->Driver.ClearColor)(ctx, ctx->Color.ClearColor);
   }
}


/**
 * Clear buffers.
 * 
 * \param mask bit-mask indicating the buffers to be cleared.
 *
 * Flushes the vertices and verifies the parameter. If __GLcontextRec::NewState
 * is set then calls _mesa_update_state() to update gl_frame_buffer::_Xmin,
 * etc. If the rasterization mode is set to GL_RENDER then requests the driver
 * to clear the buffers, via the dd_function_table::Clear callback.
 */ 
void GLAPIENTRY
_mesa_Clear( GLbitfield mask )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glClear 0x%x\n", mask);

   if (mask & ~(GL_COLOR_BUFFER_BIT |
                GL_DEPTH_BUFFER_BIT |
                GL_STENCIL_BUFFER_BIT |
                GL_ACCUM_BUFFER_BIT)) {
      /* invalid bit set */
      _mesa_error( ctx, GL_INVALID_VALUE, "glClear(0x%x)", mask);
      return;
   }

   if (ctx->NewState) {
      _mesa_update_state( ctx );	/* update _Xmin, etc */
   }

   if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                  "glClear(incomplete framebuffer)");
      return;
   }

   if (ctx->DrawBuffer->Width == 0 || ctx->DrawBuffer->Height == 0 ||
       ctx->DrawBuffer->_Xmin >= ctx->DrawBuffer->_Xmax ||
       ctx->DrawBuffer->_Ymin >= ctx->DrawBuffer->_Ymax)
      return;

   if (ctx->RenderMode == GL_RENDER) {
      GLbitfield bufferMask;

      /* don't clear depth buffer if depth writing disabled */
      if (!ctx->Depth.Mask)
         mask &= ~GL_DEPTH_BUFFER_BIT;

      /* 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 BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
       * BUFFER_BIT_COLORn flags.
       */
      bufferMask = 0;
      if (mask & GL_COLOR_BUFFER_BIT) {
         GLuint i;
         for (i = 0; i < ctx->DrawBuffer->_NumColorDrawBuffers; i++) {
            bufferMask |= (1 << ctx->DrawBuffer->_ColorDrawBufferIndexes[i]);
         }
      }

      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, bufferMask);
   }
}



/**
 * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
 * available to the rendering context (for drawing or reading).
 * This depends on the type of framebuffer.  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.
 * \param fb  the framebuffer to draw to, or read from
 * \return  bitmask of BUFFER_BIT_* flags
 */
static GLbitfield
supported_buffer_bitmask(const GLcontext *ctx, const struct gl_framebuffer *fb)
{
   GLbitfield mask = 0x0;

   if (fb->Name > 0) {
      /* A user-created renderbuffer */
      GLuint i;
      ASSERT(ctx->Extensions.EXT_framebuffer_object);
      for (i = 0; i < ctx->Const.MaxColorAttachments; i++) {
         mask |= (BUFFER_BIT_COLOR0 << i);
      }
   }
   else {
      /* A window system framebuffer */
      GLint i;
      mask = BUFFER_BIT_FRONT_LEFT; /* always have this */
      if (fb->Visual.stereoMode) {
         mask |= BUFFER_BIT_FRONT_RIGHT;
         if (fb->Visual.doubleBufferMode) {
            mask |= BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
         }
      }
      else if (fb->Visual.doubleBufferMode) {
         mask |= BUFFER_BIT_BACK_LEFT;
      }

      for (i = 0; i < fb->Visual.numAuxBuffers; i++) {
         mask |= (BUFFER_BIT_AUX0 << i);
      }
   }

   return mask;
}


/**
 * Helper routine used by glDrawBuffer and glDrawBuffersARB.
 * Given a GLenum naming one or more color buffers (such as
 * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
 */
static GLbitfield
draw_buffer_enum_to_bitmask(GLenum buffer)
{
   switch (buffer) {
      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 BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
      case GL_FRONT_RIGHT:
         return BUFFER_BIT_FRONT_RIGHT;
      case GL_BACK_RIGHT:
         return BUFFER_BIT_BACK_RIGHT;
      case GL_BACK_LEFT:
         return BUFFER_BIT_BACK_LEFT;
      case GL_FRONT_AND_BACK:
         return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT
              | BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
      case GL_LEFT:
         return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT;
      case GL_FRONT_LEFT:
         return BUFFER_BIT_FRONT_LEFT;
      case GL_AUX0:
         return BUFFER_BIT_AUX0;
      case GL_AUX1:
         return BUFFER_BIT_AUX1;
      case GL_AUX2:
         return BUFFER_BIT_AUX2;
      case GL_AUX3:
         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;
      case GL_COLOR_ATTACHMENT4_EXT:
         return BUFFER_BIT_COLOR4;
      case GL_COLOR_ATTACHMENT5_EXT:
         return BUFFER_BIT_COLOR5;
      case GL_COLOR_ATTACHMENT6_EXT:
         return BUFFER_BIT_COLOR6;
      case GL_COLOR_ATTACHMENT7_EXT:
         return BUFFER_BIT_COLOR7;
      default:
         /* error */
         return BAD_MASK;
   }
}


/**
 * Helper routine used by glReadBuffer.
 * Given a GLenum naming a color buffer, return the index of the corresponding
 * renderbuffer (a BUFFER_* value).
 * return -1 for an invalid buffer.
 */
static GLint
read_buffer_enum_to_index(GLenum buffer)
{
   switch (buffer) {
      case GL_FRONT:
         return BUFFER_FRONT_LEFT;
      case GL_BACK:
         return BUFFER_BACK_LEFT;
      case GL_RIGHT:
         return BUFFER_FRONT_RIGHT;
      case GL_FRONT_RIGHT:
         return BUFFER_FRONT_RIGHT;
      case GL_BACK_RIGHT:
         return BUFFER_BACK_RIGHT;
      case GL_BACK_LEFT:
         return BUFFER_BACK_LEFT;
      case GL_LEFT:
         return BUFFER_FRONT_LEFT;
      case GL_FRONT_LEFT:
         return BUFFER_FRONT_LEFT;
      case GL_AUX0:
         return BUFFER_AUX0;
      case GL_AUX1:
         return BUFFER_AUX1;
      case GL_AUX2:
         return BUFFER_AUX2;
      case GL_AUX3:
         return BUFFER_AUX3;
      case GL_COLOR_ATTACHMENT0_EXT:
         return BUFFER_COLOR0;
      case GL_COLOR_ATTACHMENT1_EXT:
         return BUFFER_COLOR1;
      case GL_COLOR_ATTACHMENT2_EXT:
         return BUFFER_COLOR2;
      case GL_COLOR_ATTACHMENT3_EXT:
         return BUFFER_COLOR3;
      case GL_COLOR_ATTACHMENT4_EXT:
         return BUFFER_COLOR4;
      case GL_COLOR_ATTACHMENT5_EXT:
         return BUFFER_COLOR5;
      case GL_COLOR_ATTACHMENT6_EXT:
         return BUFFER_COLOR6;
      case GL_COLOR_ATTACHMENT7_EXT:
         return BUFFER_COLOR7;
      default:
         /* error */
         return -1;
   }
}


/**
 * Called by glDrawBuffer().
 * Specify which renderbuffer(s) to draw into for the first color output.
 * <buffer> can name zero, one, two or four renderbuffers!
 * \sa _mesa_DrawBuffersARB
 *
 * \param buffer  buffer token such as GL_LEFT or GL_FRONT_AND_BACK, etc.
 *
 * Note that the behaviour of this function depends on whether the
 * current ctx->DrawBuffer is a window-system framebuffer (Name=0) or
 * a user-created framebuffer object (Name!=0).
 *   In the former case, we update the per-context ctx->Color.DrawBuffer
 *   state var _and_ the FB's ColorDrawBuffer state.
 *   In the later case, we update the FB's ColorDrawBuffer state only.
 *
 * Furthermore, upon a MakeCurrent() or BindFramebuffer() call, if the
 * new FB is a window system FB, we need to re-update the FB's
 * ColorDrawBuffer state to match the context.  This is handled in
 * _mesa_update_framebuffer().
 *
 * See the GL_EXT_framebuffer_object spec for more info.
 */
void GLAPIENTRY
_mesa_DrawBuffer(GLenum buffer)
{
   GLbitfield 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(buffer));
   }

   if (buffer == GL_NONE) {
      destMask = 0x0;
   }
   else {
      const GLbitfield supportedMask
         = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
      destMask = draw_buffer_enum_to_bitmask(buffer);
      if (destMask == BAD_MASK) {
         /* totally bogus buffer */
         _mesa_error(ctx, GL_INVALID_ENUM, "glDrawBuffer(buffer)");
         return;
      }
      destMask &= supportedMask;
      if (destMask == 0x0) {
         /* none of the named color buffers exist! */
         _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawBuffer(buffer)");
         return;
      }
   }

   /* if we get here, there's no error so set new state */
   _mesa_drawbuffers(ctx, 1, &buffer, &destMask);

   /*
    * Call device driver function.
    */
   if (ctx->Driver.DrawBuffers)
      ctx->Driver.DrawBuffers(ctx, 1, &buffer);
   else if (ctx->Driver.DrawBuffer)
      ctx->Driver.DrawBuffer(ctx, buffer);
}


/**
 * Called by glDrawBuffersARB; specifies the destination color renderbuffers
 * for N fragment program color outputs.