src/mesa/swrast/s_accum.c

   1 /* $Id: s_accum.c,v 1.11 2001/04/20 19:21:41 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.5
   6  *
   7  * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included
  17  * in all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  23  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27
  28 #include "glheader.h"
  29 #include "context.h"
  30 #include "macros.h"
  31 #include "mmath.h"
  32 #include "mem.h"
  33
  34 #include "s_accum.h"
  35 #include "s_alphabuf.h"
  36 #include "s_context.h"
  37 #include "s_masking.h"
  38 #include "s_span.h"
  39
  40
  41 /*
  42  * Accumulation buffer notes
  43  *
  44  * Normally, accumulation buffer values are GLshorts with values in
  45  * [-32767, 32767] which represent floating point colors in [-1, 1],
  46  * as suggested by the OpenGL specification.
  47  *
  48  * We optimize for the common case used for full-scene antialiasing:
  49  *    // start with accum buffer cleared to zero
  50  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  51  *    glAccum(GL_ACCUM, w);
  52  *    ...
  53  *    glAccum(GL_ACCUM, w);
  54  *    glAccum(GL_RETURN, 1.0);
  55  * That is, we start with an empty accumulation buffer and accumulate
  56  * n images, each with weight w = 1/n.
  57  * In this scenario, we can simply store unscaled integer values in
  58  * the accum buffer instead of scaled integers.  We'll also keep track
  59  * of the w value so when we do GL_RETURN we simply divide the accumulated
  60  * values by n (=1/w).
  61  * This lets us avoid _many_ int->float->int conversions.
  62  */
  63
  64
  65 #if CHAN_BITS == 8
  66 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  67 #endif
  68
  69
  70
  71 void
  72 _mesa_alloc_accum_buffer( GLcontext *ctx )
  73 {
  74    SWcontext *swrast = SWRAST_CONTEXT(ctx);
  75    GLint n;
  76
  77    if (ctx->DrawBuffer->Accum) {
  78       FREE( ctx->DrawBuffer->Accum );
  79       ctx->DrawBuffer->Accum = NULL;
  80    }
  81
  82    /* allocate accumulation buffer if not already present */
  83    n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4 * sizeof(GLaccum);
  84    ctx->DrawBuffer->Accum = (GLaccum *) MALLOC( n );
  85    if (!ctx->DrawBuffer->Accum) {
  86       /* unable to setup accumulation buffer */
  87       _mesa_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  88    }
  89 #ifdef USE_OPTIMIZED_ACCUM
  90    swrast->_IntegerAccumMode = GL_TRUE;
  91 #else
  92    swrast->_IntegerAccumMode = GL_FALSE;
  93 #endif
  94    swrast->_IntegerAccumScaler = 0.0;
  95 }
  96
  97
  98
  99
 100
 101
 102 /*
 103  * This is called when we fall out of optimized/unscaled accum buffer mode.
 104  * That is, we convert each unscaled accum buffer value into a scaled value
 105  * representing the range[-1, 1].
 106  */
 107 static void rescale_accum( GLcontext *ctx )
 108 {
 109    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 110    const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
 111    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 112    const GLfloat s = swrast->_IntegerAccumScaler * (32767.0 / fChanMax);
 113    GLaccum *accum = ctx->DrawBuffer->Accum;
 114    GLuint i;
 115
 116    assert(swrast->_IntegerAccumMode);
 117    assert(accum);
 118
 119    for (i = 0; i < n; i++) {
 120       accum[i] = (GLaccum) (accum[i] * s);
 121    }
 122
 123    swrast->_IntegerAccumMode = GL_FALSE;
 124 }
 125
 126
 127
 128
 129
 130
 131 /*
 132  * Clear the accumulation Buffer.
 133  */
 134 void
 135 _mesa_clear_accum_buffer( GLcontext *ctx )
 136 {
 137    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 138    GLuint buffersize;
 139    GLfloat acc_scale;
 140
 141    if (ctx->Visual.accumRedBits==0) {
 142       /* No accumulation buffer! */
 143       return;
 144    }
 145
 146    if (sizeof(GLaccum)==1) {
 147       acc_scale = 127.0;
 148    }
 149    else if (sizeof(GLaccum)==2) {
 150       acc_scale = 32767.0;
 151    }
 152    else {
 153       /* sizeof(GLaccum) > 2 (Cray) */
 154       acc_scale = (float) SHRT_MAX;
 155    }
 156
 157    /* number of pixels */
 158    buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;
 159
 160    if (!ctx->DrawBuffer->Accum) {
 161       /* try to alloc accumulation buffer */
 162       ctx->DrawBuffer->Accum = (GLaccum *)
 163                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 164    }
 165
 166    if (ctx->DrawBuffer->Accum) {
 167       if (ctx->Scissor.Enabled) {
 168          /* Limit clear to scissor box */
 169          GLaccum r, g, b, a;
 170          GLint i, j;
 171          GLint width, height;
 172          GLaccum *row;
 173          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 174          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 175          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 176          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 177          /* size of region to clear */
 178          width = 4 * (ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin);
 179          height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
 180          /* ptr to first element to clear */
 181          row = ctx->DrawBuffer->Accum
 182                + 4 * (ctx->DrawBuffer->_Ymin * ctx->DrawBuffer->Width
 183                       + ctx->DrawBuffer->_Xmin);
 184          for (j=0;j<height;j++) {
 185             for (i=0;i<width;i+=4) {
 186                row[i+0] = r;
 187                row[i+1] = g;
 188                row[i+2] = b;
 189                row[i+3] = a;
 190             }
 191             row += 4 * ctx->DrawBuffer->Width;
 192          }
 193       }
 194       else {
 195          /* clear whole buffer */
 196          if (ctx->Accum.ClearColor[0]==0.0 &&
 197              ctx->Accum.ClearColor[1]==0.0 &&
 198              ctx->Accum.ClearColor[2]==0.0 &&
 199              ctx->Accum.ClearColor[3]==0.0) {
 200             /* Black */
 201             BZERO( ctx->DrawBuffer->Accum, buffersize * 4 * sizeof(GLaccum) );
 202          }
 203          else {
 204             /* Not black */
 205             GLaccum *acc, r, g, b, a;
 206             GLuint i;
 207
 208             acc = ctx->DrawBuffer->Accum;
 209             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 210             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 211             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 212             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 213             for (i=0;i<buffersize;i++) {
 214                *acc++ = r;
 215                *acc++ = g;
 216                *acc++ = b;
 217                *acc++ = a;
 218             }
 219          }
 220       }
 221
 222       /* update optimized accum state vars */
 223       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 224           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 225 #ifdef USE_OPTIMIZED_ACCUM
 226          swrast->_IntegerAccumMode = GL_TRUE;
 227 #else
 228          swrast->_IntegerAccumMode = GL_FALSE;
 229 #endif
 230          swrast->_IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 231       }
 232       else {
 233          swrast->_IntegerAccumMode = GL_FALSE;
 234       }
 235    }
 236 }
 237
 238
 239 void
 240 _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
 241                GLint xpos, GLint ypos,
 242                GLint width, GLint height )
 243
 244 {
 245    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 246    GLuint width4;
 247    GLfloat acc_scale;
 248    GLchan rgba[MAX_WIDTH][4];
 249    const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);
 250    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 251    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 252
 253
 254    if (SWRAST_CONTEXT(ctx)->NewState)
 255       _swrast_validate_derived( ctx );
 256
 257    if (!ctx->DrawBuffer->Accum) {
 258       _mesa_warning(ctx,
 259                     "Calling glAccum() without an accumulation "
 260                     "buffer (low memory?)");
 261       return;
 262    }
 263
 264    if (sizeof(GLaccum)==1) {
 265       acc_scale = 127.0;
 266    }
 267    else if (sizeof(GLaccum)==2) {
 268       acc_scale = 32767.0;
 269    }
 270    else {
 271       /* sizeof(GLaccum) > 2 (Cray) */
 272       acc_scale = (float) SHRT_MAX;
 273    }
 274
 275    width4 = 4 * width;
 276
 277    switch (op) {
 278       case GL_ADD:
 279          if (value != 0.0F) {
 280             const GLaccum intVal = (GLaccum) (value * acc_scale);
 281             GLint j;
 282             /* Leave optimized accum buffer mode */
 283             if (swrast->_IntegerAccumMode)
 284                rescale_accum(ctx);
 285             for (j = 0; j < height; j++) {
 286                GLaccum * acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 287                GLuint i;
 288                for (i = 0; i < width4; i++) {
 289                   acc[i] += intVal;
 290                }
 291                ypos++;
 292             }
 293          }
 294          break;
 295
 296       case GL_MULT:
 297          if (value != 1.0F) {
 298             GLint j;
 299             /* Leave optimized accum buffer mode */
 300             if (swrast->_IntegerAccumMode)
 301                rescale_accum(ctx);
 302             for (j = 0; j < height; j++) {
 303                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 304                GLuint i;
 305                for (i = 0; i < width4; i++) {
 306                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 307                }
 308                ypos++;
 309             }
 310          }
 311          break;
 312
 313       case GL_ACCUM:
 314          if (value == 0.0F)
 315             return;
 316
 317          (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 318                                           ctx->Pixel.DriverReadBuffer );
 319
 320          /* May have to leave optimized accum buffer mode */
 321          if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 322             swrast->_IntegerAccumScaler = value;
 323          if (swrast->_IntegerAccumMode && value != swrast->_IntegerAccumScaler)
 324             rescale_accum(ctx);
 325
 326          RENDER_START(swrast,ctx);
 327
 328          if (swrast->_IntegerAccumMode) {
 329             /* simply add integer color values into accum buffer */
 330             GLint j;
 331             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 332             assert(swrast->_IntegerAccumScaler > 0.0);
 333             assert(swrast->_IntegerAccumScaler <= 1.0);
 334             for (j = 0; j < height; j++) {
 335
 336                GLint i, i4;
 337                _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 338                for (i = i4 = 0; i < width; i++, i4+=4) {
 339                   acc[i4+0] += rgba[i][RCOMP];
 340                   acc[i4+1] += rgba[i][GCOMP];
 341                   acc[i4+2] += rgba[i][BCOMP];
 342                   acc[i4+3] += rgba[i][ACOMP];
 343                }
 344                acc += width4;
 345                ypos++;
 346             }
 347          }
 348          else {
 349             /* scaled integer accum buffer */
 350             const GLfloat rscale = value * acc_scale / fChanMax;
 351             const GLfloat gscale = value * acc_scale / fChanMax;
 352             const GLfloat bscale = value * acc_scale / fChanMax;
 353             const GLfloat ascale = value * acc_scale / fChanMax;
 354             GLint j;
 355             for (j=0;j<height;j++) {
 356                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 357                GLint i;
 358                _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 359                for (i=0;i<width;i++) {
 360                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 361                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 362                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 363                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 364                }
 365                ypos++;
 366             }
 367          }
 368          /* restore read buffer = draw buffer (the default) */
 369          (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 370                                           ctx->Color.DriverDrawBuffer );
 371          RENDER_FINISH(swrast,ctx);
 372          break;
 373
 374       case GL_LOAD:
 375          (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 376                                           ctx->Pixel.DriverReadBuffer );
 377
 378          /* This is a change to go into optimized accum buffer mode */
 379          if (value > 0.0 && value <= 1.0) {
 380 #ifdef USE_OPTIMIZED_ACCUM
 381             swrast->_IntegerAccumMode = GL_TRUE;
 382 #else
 383             swrast->_IntegerAccumMode = GL_FALSE;
 384 #endif
 385             swrast->_IntegerAccumScaler = value;
 386          }
 387          else {
 388             swrast->_IntegerAccumMode = GL_FALSE;
 389             swrast->_IntegerAccumScaler = 0.0;
 390          }
 391
 392          RENDER_START(swrast,ctx);
 393          if (swrast->_IntegerAccumMode) {
 394             /* just copy values into accum buffer */
 395             GLint j;
 396             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 397             assert(swrast->_IntegerAccumScaler > 0.0);
 398             assert(swrast->_IntegerAccumScaler <= 1.0);
 399             for (j = 0; j < height; j++) {
 400                GLint i, i4;
 401                _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 402                for (i = i4 = 0; i < width; i++, i4 += 4) {
 403                   acc[i4+0] = rgba[i][RCOMP];
 404                   acc[i4+1] = rgba[i][GCOMP];
 405                   acc[i4+2] = rgba[i][BCOMP];
 406                   acc[i4+3] = rgba[i][ACOMP];
 407                }
 408                acc += width4;
 409                ypos++;
 410             }
 411          }
 412          else {
 413             /* scaled integer accum buffer */
 414             const GLfloat rscale = value * acc_scale / fChanMax;
 415             const GLfloat gscale = value * acc_scale / fChanMax;
 416             const GLfloat bscale = value * acc_scale / fChanMax;
 417             const GLfloat ascale = value * acc_scale / fChanMax;
 418             const GLfloat d = 3.0 / acc_scale;
 419             GLint i, j;
 420             for (j = 0; j < height; j++) {
 421                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 422                _mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 423                for (i=0;i<width;i++) {
 424                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 425                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 426                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 427                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 428                }
 429                ypos++;
 430             }
 431          }
 432
 433          /* restore read buffer = draw buffer (the default) */
 434          (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 435                                        ctx->Color.DriverDrawBuffer );
 436          RENDER_FINISH(swrast,ctx);
 437          break;
 438
 439       case GL_RETURN:
 440          /* May have to leave optimized accum buffer mode */
 441          if (swrast->_IntegerAccumMode && value != 1.0)
 442             rescale_accum(ctx);
 443
 444          RENDER_START(swrast,ctx);
 445          if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {
 446             /* build lookup table to avoid many floating point multiplies */
 447             static GLchan multTable[32768];
 448             static GLfloat prevMult = 0.0;
 449             const GLfloat mult = swrast->_IntegerAccumScaler;
 450             const GLint max = MIN2((GLint) (256 / mult), 32767);
 451             GLint j;
 452             if (mult != prevMult) {
 453                for (j = 0; j < max; j++)
 454                   multTable[j] = IROUND((GLfloat) j * mult);
 455                prevMult = mult;
 456             }
 457
 458             assert(swrast->_IntegerAccumScaler > 0.0);
 459             assert(swrast->_IntegerAccumScaler <= 1.0);
 460             for (j = 0; j < height; j++) {
 461                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 462                GLint i, i4;
 463                for (i = i4 = 0; i < width; i++, i4 += 4) {
 464                   ASSERT(acc[i4+0] < max);
 465                   ASSERT(acc[i4+1] < max);
 466                   ASSERT(acc[i4+2] < max);
 467                   ASSERT(acc[i4+3] < max);
 468                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 469                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 470                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 471                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 472                }
 473                if (colorMask != 0xffffffff) {
 474                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 475                }
 476                (*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 477                                              (const GLchan (*)[4])rgba, NULL );
 478                if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
 479                    && ctx->Color.ColorMask[ACOMP]) {
 480                   _mesa_write_alpha_span(ctx, width, xpos, ypos,
 481                                          (CONST GLchan (*)[4]) rgba, NULL);
 482                }
 483                ypos++;
 484             }
 485          }
 486          else {
 487             const GLfloat rscale = value / acc_scale * fChanMax;
 488             const GLfloat gscale = value / acc_scale * fChanMax;
 489             const GLfloat bscale = value / acc_scale * fChanMax;
 490             const GLfloat ascale = value / acc_scale * fChanMax;
 491             GLint i, j;
 492             for (j=0;j<height;j++) {
 493                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 494                for (i=0;i<width;i++) {
 495                   GLint r = IROUND( (GLfloat) (acc[0]) * rscale );
 496                   GLint g = IROUND( (GLfloat) (acc[1]) * gscale );
 497                   GLint b = IROUND( (GLfloat) (acc[2]) * bscale );
 498                   GLint a = IROUND( (GLfloat) (acc[3]) * ascale );
 499                   acc += 4;
 500                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 501                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 502                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 503                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 504                }
 505                if (colorMask != 0xffffffff) {
 506                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 507                }
 508                (*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 509                                              (const GLchan (*)[4])rgba, NULL );
 510                if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
 511                    && ctx->Color.ColorMask[ACOMP]) {
 512                   _mesa_write_alpha_span(ctx, width, xpos, ypos,
 513                                          (CONST GLchan (*)[4]) rgba, NULL);
 514                }
 515                ypos++;
 516             }
 517          }
 518          RENDER_FINISH(swrast,ctx);
 519          break;
 520
 521       default:
 522          _mesa_error( ctx, GL_INVALID_ENUM, "glAccum" );
 523    }
 524 }