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/*

 * 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

 * glReadBuffer, DrawBuffer functions.

 */

#include "glheader.h"

#include "buffers.h"

#include "colormac.h"

#include "context.h"

#include "enums.h"

#define BAD_MASK ~0u

/**

 * 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 struct gl_context *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:

      case GL_AUX2:

      case GL_AUX3:

         return 1 << BUFFER_COUNT; /* invalid, but not BAD_MASK */

      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:

      case GL_AUX2:

      case GL_AUX3:

         return BUFFER_COUNT; /* invalid, but not -1 */

      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.

 *  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=0x%x)", buffer);

         return;

      }

      destMask &= supportedMask;

      if (destMask == 0x0) {

         /* none of the named color buffers exist! */

         _mesa_error(ctx, GL_INVALID_OPERATION,

                     "glDrawBuffer(buffer=0x%x)", 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.

 * \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);

   /* Turns out n==0 is a valid input that should not produce an error.

    * The remaining code below correctly handles the n==0 case.

    */

   if (n < 0 || 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.  Note that n can be equal to 0,

    * in which case we don't want to reference buffers[0], which

    * may not be valid.

    */

   if (ctx->Driver.DrawBuffers)

      ctx->Driver.DrawBuffers(ctx, n, buffers);

   else if (ctx->Driver.DrawBuffer)

      ctx->Driver.DrawBuffer(ctx, n > 0 ? buffers[0] : GL_NONE);

}

/**

 * Helper function to set the GL_DRAW_BUFFER state in the context and

 * current FBO.  Called via glDrawBuffer(), glDrawBuffersARB()

 *

 * 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(struct gl_context *ctx, GLuint n, const GLenum *buffers,

                  const GLbitfield *destMask)

{

   struct gl_framebuffer *fb = ctx->DrawBuffer;

   GLbitfield mask[MAX_DRAW_BUFFERS];

   GLboolean newState = GL_FALSE;

   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, destMask[0] may have up to four bits set.

    * Otherwise, destMask[x] can only have one bit set.

    */

   if (n == 1) {

      GLuint count = 0, destMask0 = destMask[0];

      while (destMask0) {

         GLint bufIndex = _mesa_ffs(destMask0) - 1;

         if (fb->_ColorDrawBufferIndexes[count] != bufIndex) {

            fb->_ColorDrawBufferIndexes[count] = bufIndex;

            newState = GL_TRUE;

         }

         count++;

         destMask0 &= ~(1 << bufIndex);

      }

      fb->ColorDrawBuffer[0] = buffers[0];

      if (fb->_NumColorDrawBuffers != count) {

         fb->_NumColorDrawBuffers = count;

         newState = GL_TRUE;

      }

   }

   else {

      GLuint buf, count = 0;

      for (buf = 0; buf < n; buf++ ) {

         if (destMask[buf]) {

            GLint bufIndex = _mesa_ffs(destMask[buf]) - 1;

            /* only one bit should be set in the destMask[buf] field */

            ASSERT(_mesa_bitcount(destMask[buf]) == 1);

            if (fb->_ColorDrawBufferIndexes[buf] != bufIndex) {

               fb->_ColorDrawBufferIndexes[buf] = bufIndex;

               newState = GL_TRUE;

            }

            fb->ColorDrawBuffer[buf] = buffers[buf];

            count = buf + 1;

         }

         else {

            if (fb->_ColorDrawBufferIndexes[buf] != -1) {

               fb->_ColorDrawBufferIndexes[buf] = -1;

               newState = GL_TRUE;

            }

         }

      }

      /* set remaining outputs to -1 (GL_NONE) */

      while (buf < ctx->Const.MaxDrawBuffers) {

         if (fb->_ColorDrawBufferIndexes[buf] != -1) {

            fb->_ColorDrawBufferIndexes[buf] = -1;

            newState = GL_TRUE;

         }

         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++) {

         if (ctx->Color.DrawBuffer[buf] != fb->ColorDrawBuffer[buf]) {

            ctx->Color.DrawBuffer[buf] = fb->ColorDrawBuffer[buf];

            newState = GL_TRUE;

         }

      }

   }

   if (newState)

      FLUSH_VERTICES(ctx, _NEW_BUFFERS);

}

/**

 * 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(struct gl_context *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_BUFFERS;

}

/**

 * 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);

   ctx->NewState |= _NEW_BUFFERS;

   /*

    * Call device driver function.

    */

   if (ctx->Driver.ReadBuffer)

      (*ctx->Driver.ReadBuffer)(ctx, buffer);

}