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/* $Id: s_accum.c,v 1.1 2003-02-28 11:49:40 pj Exp $ */

/*

 * Mesa 3-D graphics library

 * Version:  4.1

 *

 * Copyright (C) 1999-2002  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.

 */

#include "glheader.h"

#include "context.h"

#include "macros.h"

#include "mmath.h"

#include "imports.h"

#include "s_accum.h"

#include "s_alphabuf.h"

#include "s_context.h"

#include "s_masking.h"

#include "s_span.h"

/*

 * Accumulation buffer notes

 *

 * Normally, accumulation buffer values are GLshorts with values in

 * [-32767, 32767] which represent floating point colors in [-1, 1],

 * as suggested by the OpenGL specification.

 *

 * We optimize for the common case used for full-scene antialiasing:

 *    // start with accum buffer cleared to zero

 *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image

 *    glAccum(GL_ACCUM, w);

 *    ...

 *    glAccum(GL_ACCUM, w);

 *    glAccum(GL_RETURN, 1.0);

 * That is, we start with an empty accumulation buffer and accumulate

 * n images, each with weight w = 1/n.

 * In this scenario, we can simply store unscaled integer values in

 * the accum buffer instead of scaled integers.  We'll also keep track

 * of the w value so when we do GL_RETURN we simply divide the accumulated

 * values by n (=1/w).

 * This lets us avoid _many_ int->float->int conversions.

 */

#if CHAN_BITS == 8 && ACCUM_BITS < 32

#define USE_OPTIMIZED_ACCUM   /* enable the optimization */

#endif

void

_mesa_alloc_accum_buffer( GLframebuffer *buffer )

{

   GET_CURRENT_CONTEXT(ctx);

   GLint n;

   if (buffer->Accum) {

      MESA_PBUFFER_FREE( buffer->Accum );

      buffer->Accum = NULL;

   }

   /* allocate accumulation buffer if not already present */

   n = buffer->Width * buffer->Height * 4 * sizeof(GLaccum);

   buffer->Accum = (GLaccum *) MESA_PBUFFER_ALLOC( n );

   if (!buffer->Accum) {

      /* unable to setup accumulation buffer */

      _mesa_error( NULL, GL_OUT_OF_MEMORY, "glAccum" );

   }

   if (ctx) {

      SWcontext *swrast = SWRAST_CONTEXT(ctx);

      /* XXX these fields should probably be in the GLframebuffer */

#ifdef USE_OPTIMIZED_ACCUM

      swrast->_IntegerAccumMode = GL_TRUE;

#else

      swrast->_IntegerAccumMode = GL_FALSE;

#endif

      swrast->_IntegerAccumScaler = 0.0;

   }

}

/*

 * This is called when we fall out of optimized/unscaled accum buffer mode.

 * That is, we convert each unscaled accum buffer value into a scaled value

 * representing the range[-1, 1].

 */

static void rescale_accum( GLcontext *ctx )

{

   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;

   const GLfloat s = swrast->_IntegerAccumScaler * (32767.0F / CHAN_MAXF);

   GLaccum *accum = ctx->DrawBuffer->Accum;

   GLuint i;

   assert(swrast->_IntegerAccumMode);

   assert(accum);

   for (i = 0; i < n; i++) {

      accum[i] = (GLaccum) (accum[i] * s);

   }

   swrast->_IntegerAccumMode = GL_FALSE;

}

/*

 * Clear the accumulation Buffer.

 */

void

_mesa_clear_accum_buffer( GLcontext *ctx )

{

   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   GLuint buffersize;

   GLfloat acc_scale;

   if (ctx->Visual.accumRedBits==0) {

      /* No accumulation buffer! */

      return;

   }

   if (sizeof(GLaccum)==1) {

      acc_scale = 127.0;

   }

   else if (sizeof(GLaccum)==2) {

      acc_scale = 32767.0;

   }

   else {

      acc_scale = 1.0F;

   }

   /* number of pixels */

   buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;

   if (!ctx->DrawBuffer->Accum) {

      /* try to alloc accumulation buffer */

      ctx->DrawBuffer->Accum = (GLaccum *)

                           MALLOC( buffersize * 4 * sizeof(GLaccum) );

   }

   if (ctx->DrawBuffer->Accum) {

      if (ctx->Scissor.Enabled) {

         /* Limit clear to scissor box */

         const GLaccum r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);

         const GLaccum g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);

         const GLaccum b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);

         const GLaccum a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);

         GLint i, j;

         GLint width, height;

         GLaccum *row;

         /* size of region to clear */

         width = 4 * (ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin);

         height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;

         /* ptr to first element to clear */

         row = ctx->DrawBuffer->Accum

               + 4 * (ctx->DrawBuffer->_Ymin * ctx->DrawBuffer->Width

                      + ctx->DrawBuffer->_Xmin);

         for (j=0;j<height;j++) {

            for (i=0;i<width;i+=4) {

               row[i+0] = r;

               row[i+1] = g;

               row[i+2] = b;

               row[i+3] = a;

            }

            row += 4 * ctx->DrawBuffer->Width;

         }

      }

      else {

         /* clear whole buffer */

         if (ctx->Accum.ClearColor[0]==0.0 &&

             ctx->Accum.ClearColor[1]==0.0 &&

             ctx->Accum.ClearColor[2]==0.0 &&

             ctx->Accum.ClearColor[3]==0.0) {

            /* Black */

            _mesa_bzero( ctx->DrawBuffer->Accum,

                         buffersize * 4 * sizeof(GLaccum) );

         }

         else {

            /* Not black */

            const GLaccum r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);

            const GLaccum g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);

            const GLaccum b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);

            const GLaccum a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);

            GLaccum *acc = ctx->DrawBuffer->Accum;

            GLuint i;

            for (i=0;i<buffersize;i++) {

               *acc++ = r;

               *acc++ = g;

               *acc++ = b;

               *acc++ = a;

            }

         }

      }

      /* update optimized accum state vars */

      if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&

          ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {

#ifdef USE_OPTIMIZED_ACCUM

         swrast->_IntegerAccumMode = GL_TRUE;

#else

         swrast->_IntegerAccumMode = GL_FALSE;

#endif

         swrast->_IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */

      }

      else {

         swrast->_IntegerAccumMode = GL_FALSE;

      }

   }

}

void

_swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,

               GLint xpos, GLint ypos,

               GLint width, GLint height )

{

   SWcontext *swrast = SWRAST_CONTEXT(ctx);

   GLuint width4;

   GLfloat acc_scale;

   GLchan rgba[MAX_WIDTH][4];

   const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);

   if (SWRAST_CONTEXT(ctx)->NewState)

      _swrast_validate_derived( ctx );

   if (!ctx->DrawBuffer->Accum) {

      _mesa_warning(ctx,

                    "Calling glAccum() without an accumulation "

                    "buffer (low memory?)");

      return;

   }

   if (sizeof(GLaccum)==1) {

      acc_scale = 127.0;

   }

   else if (sizeof(GLaccum)==2) {

      acc_scale = 32767.0;

   }

   else {

      acc_scale = 1.0F;

   }

   width4 = 4 * width;

   switch (op) {

      case GL_ADD:

         if (value != 0.0F) {

            const GLaccum val = (GLaccum) (value * acc_scale);

            GLint j;

            /* Leave optimized accum buffer mode */

            if (swrast->_IntegerAccumMode)

               rescale_accum(ctx);

            for (j = 0; j < height; j++) {

               GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4*xpos;

               GLuint i;

               for (i = 0; i < width4; i++) {

                  acc[i] += val;

               }

               ypos++;

            }

         }

         break;

      case GL_MULT:

         if (value != 1.0F) {

            GLint j;

            /* Leave optimized accum buffer mode */

            if (swrast->_IntegerAccumMode)

               rescale_accum(ctx);

            for (j = 0; j < height; j++) {

               GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;

               GLuint i;

               for (i = 0; i < width4; i++) {

                  acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );

               }

               ypos++;

            }

         }

         break;

      case GL_ACCUM:

         if (value == 0.0F)

            return;

         _swrast_use_read_buffer(ctx);

         /* May have to leave optimized accum buffer mode */

         if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)

            swrast->_IntegerAccumScaler = value;

         if (swrast->_IntegerAccumMode && value != swrast->_IntegerAccumScaler)

            rescale_accum(ctx);

         RENDER_START(swrast,ctx);

         if (swrast->_IntegerAccumMode) {

            /* simply add integer color values into accum buffer */

            GLint j;

            GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;

            assert(swrast->_IntegerAccumScaler > 0.0);

            assert(swrast->_IntegerAccumScaler <= 1.0);

            for (j = 0; j < height; j++) {

               GLint i, i4;

               _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);

               for (i = i4 = 0; i < width; i++, i4+=4) {

                  acc[i4+0] += rgba[i][RCOMP];

                  acc[i4+1] += rgba[i][GCOMP];

                  acc[i4+2] += rgba[i][BCOMP];

                  acc[i4+3] += rgba[i][ACOMP];

               }

               acc += width4;

               ypos++;

            }

         }

         else {

            /* scaled integer (or float) accum buffer */

            const GLfloat rscale = value * acc_scale / CHAN_MAXF;

            const GLfloat gscale = value * acc_scale / CHAN_MAXF;

            const GLfloat bscale = value * acc_scale / CHAN_MAXF;

            const GLfloat ascale = value * acc_scale / CHAN_MAXF;

            GLint j;

            for (j=0;j<height;j++) {

               GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;

               GLint i;

               _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);

               for (i=0;i<width;i++) {

                  acc[0] += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );

                  acc[1] += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );

                  acc[2] += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );

                  acc[3] += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );

                  acc += 4;

               }

               ypos++;

            }

         }

         /* restore read buffer = draw buffer (the default) */

         _swrast_use_draw_buffer(ctx);

         RENDER_FINISH(swrast,ctx);

         break;

      case GL_LOAD:

         _swrast_use_read_buffer(ctx);

         /* This is a change to go into optimized accum buffer mode */

         if (value > 0.0 && value <= 1.0) {

#ifdef USE_OPTIMIZED_ACCUM

            swrast->_IntegerAccumMode = GL_TRUE;

#else

            swrast->_IntegerAccumMode = GL_FALSE;

#endif

            swrast->_IntegerAccumScaler = value;

         }

         else {

            swrast->_IntegerAccumMode = GL_FALSE;

            swrast->_IntegerAccumScaler = 0.0;

         }

         RENDER_START(swrast,ctx);

         if (swrast->_IntegerAccumMode) {

            /* just copy values into accum buffer */

            GLint j;

            GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;

            assert(swrast->_IntegerAccumScaler > 0.0);

            assert(swrast->_IntegerAccumScaler <= 1.0);

            for (j = 0; j < height; j++) {

               GLint i, i4;

               _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);

               for (i = i4 = 0; i < width; i++, i4 += 4) {

                  acc[i4+0] = rgba[i][RCOMP];

                  acc[i4+1] = rgba[i][GCOMP];

                  acc[i4+2] = rgba[i][BCOMP];

                  acc[i4+3] = rgba[i][ACOMP];

               }

               acc += width4;

               ypos++;

            }

         }

         else {

            /* scaled integer (or float) accum buffer */

            const GLfloat rscale = value * acc_scale / CHAN_MAXF;

            const GLfloat gscale = value * acc_scale / CHAN_MAXF;

            const GLfloat bscale = value * acc_scale / CHAN_MAXF;

            const GLfloat ascale = value * acc_scale / CHAN_MAXF;

#if 0

            const GLfloat d = 3.0 / acc_scale;  /* XXX what's this? */

#endif

            GLint i, j;

            for (j = 0; j < height; j++) {

               GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;

               _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);

               for (i=0;i<width;i++) {

#if 0

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);

#else

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale);

                  *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale);

#endif

               }

               ypos++;

            }

         }

         /* restore read buffer = draw buffer (the default) */

         _swrast_use_draw_buffer(ctx);

         RENDER_FINISH(swrast,ctx);

         break;

      case GL_RETURN:

         /* May have to leave optimized accum buffer mode */

         if (swrast->_IntegerAccumMode && value != 1.0)

            rescale_accum(ctx);

         RENDER_START(swrast,ctx);

#ifdef USE_OPTIMIZED_ACCUM

         if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {

            /* build lookup table to avoid many floating point multiplies */

            static GLchan multTable[32768];

            static GLfloat prevMult = 0.0;

            const GLfloat mult = swrast->_IntegerAccumScaler;

            const GLint max = MIN2((GLint) (256 / mult), 32767);

            GLint j;

            if (mult != prevMult) {

               for (j = 0; j < max; j++)

                  multTable[j] = IROUND((GLfloat) j * mult);

               prevMult = mult;

            }

            assert(swrast->_IntegerAccumScaler > 0.0);

            assert(swrast->_IntegerAccumScaler <= 1.0);

            for (j = 0; j < height; j++) {

               const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;

               GLint i, i4;

               for (i = i4 = 0; i < width; i++, i4 += 4) {

                  ASSERT(acc[i4+0] < max);

                  ASSERT(acc[i4+1] < max);

                  ASSERT(acc[i4+2] < max);

                  ASSERT(acc[i4+3] < max);

                  rgba[i][RCOMP] = multTable[acc[i4+0]];

                  rgba[i][GCOMP] = multTable[acc[i4+1]];

                  rgba[i][BCOMP] = multTable[acc[i4+2]];

                  rgba[i][ACOMP] = multTable[acc[i4+3]];

               }

               if (colorMask != 0xffffffff) {

                  _mesa_mask_rgba_array( ctx, width, xpos, ypos, rgba );

               }

               (*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,

                                             (const GLchan (*)[4])rgba, NULL );

               if (ctx->DrawBuffer->UseSoftwareAlphaBuffers

                   && ctx->Color.ColorMask[ACOMP]) {

                  _mesa_write_alpha_span(ctx, width, xpos, ypos,

                                         (CONST GLchan (*)[4]) rgba, NULL);

               }

               ypos++;

            }

         }

         else

#endif /* USE_OPTIMIZED_ACCUM */

         {

            /* scaled integer (or float) accum buffer */

            const GLfloat rscale = value / acc_scale * CHAN_MAXF;

            const GLfloat gscale = value / acc_scale * CHAN_MAXF;

            const GLfloat bscale = value / acc_scale * CHAN_MAXF;

            const GLfloat ascale = value / acc_scale * CHAN_MAXF;

            GLint i, j;

            for (j=0;j<height;j++) {

               const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;

               for (i=0;i<width;i++) {

                  GLint r = IROUND( (GLfloat) (acc[0]) * rscale );

                  GLint g = IROUND( (GLfloat) (acc[1]) * gscale );

                  GLint b = IROUND( (GLfloat) (acc[2]) * bscale );

                  GLint a = IROUND( (GLfloat) (acc[3]) * ascale );

                  acc += 4;

                  rgba[i][RCOMP] = CLAMP( r, 0, CHAN_MAX );

                  rgba[i][GCOMP] = CLAMP( g, 0, CHAN_MAX );

                  rgba[i][BCOMP] = CLAMP( b, 0, CHAN_MAX );

                  rgba[i][ACOMP] = CLAMP( a, 0, CHAN_MAX );

               }

               if (colorMask != 0xffffffff) {

                  _mesa_mask_rgba_array( ctx, width, xpos, ypos, rgba );

               }

               (*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,

                                             (const GLchan (*)[4])rgba, NULL );

               if (ctx->DrawBuffer->UseSoftwareAlphaBuffers

                   && ctx->Color.ColorMask[ACOMP]) {

                  _mesa_write_alpha_span(ctx, width, xpos, ypos,

                                         (CONST GLchan (*)[4]) rgba, NULL);

               }

               ypos++;

            }

         }

         RENDER_FINISH(swrast,ctx);

         break;

      default:

         _mesa_error( ctx, GL_INVALID_ENUM, "glAccum" );

   }

}