src/mesa/swrast/s_accum.c

   1 /* $Id: s_accum.c,v 1.4 2001/01/23 23:39:37 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 "context.h"
  29 #include "macros.h"
  30 #include "mem.h"
  31
  32 #include "s_accum.h"
  33 #include "s_alphabuf.h"
  34 #include "s_context.h"
  35 #include "s_masking.h"
  36 #include "s_span.h"
  37
  38
  39 /*
  40  * Accumulation buffer notes
  41  *
  42  * Normally, accumulation buffer values are GLshorts with values in
  43  * [-32767, 32767] which represent floating point colors in [-1, 1],
  44  * as suggested by the OpenGL specification.
  45  *
  46  * We optimize for the common case used for full-scene antialiasing:
  47  *    // start with accum buffer cleared to zero
  48  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  49  *    glAccum(GL_ACCUM, w);
  50  *    ...
  51  *    glAccum(GL_ACCUM, w);
  52  *    glAccum(GL_RETURN, 1.0);
  53  * That is, we start with an empty accumulation buffer and accumulate
  54  * n images, each with weight w = 1/n.
  55  * In this scenario, we can simply store unscaled integer values in
  56  * the accum buffer instead of scaled integers.  We'll also keep track
  57  * of the w value so when we do GL_RETURN we simply divide the accumulated
  58  * values by n (=1/w).
  59  * This lets us avoid _many_ int->float->int conversions.
  60  */
  61
  62
  63 #if CHAN_BITS == 8
  64 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  65 #endif
  66
  67
  68
  69 void
  70 _mesa_alloc_accum_buffer( GLcontext *ctx )
  71 {
  72    SWcontext *swrast = SWRAST_CONTEXT(ctx);
  73    GLint n;
  74
  75    if (ctx->DrawBuffer->Accum) {
  76       FREE( ctx->DrawBuffer->Accum );
  77       ctx->DrawBuffer->Accum = NULL;
  78    }
  79
  80    /* allocate accumulation buffer if not already present */
  81    n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4 * sizeof(GLaccum);
  82    ctx->DrawBuffer->Accum = (GLaccum *) MALLOC( n );
  83    if (!ctx->DrawBuffer->Accum) {
  84       /* unable to setup accumulation buffer */
  85       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  86    }
  87 #ifdef USE_OPTIMIZED_ACCUM
  88    swrast->_IntegerAccumMode = GL_TRUE;
  89 #else
  90    swrast->_IntegerAccumMode = GL_FALSE;
  91 #endif
  92    swrast->_IntegerAccumScaler = 0.0;
  93 }
  94
  95
  96
  97
  98
  99
 100 /*
 101  * This is called when we fall out of optimized/unscaled accum buffer mode.
 102  * That is, we convert each unscaled accum buffer value into a scaled value
 103  * representing the range[-1, 1].
 104  */
 105 static void rescale_accum( GLcontext *ctx )
 106 {
 107    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 108    const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
 109    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 110    const GLfloat s = swrast->_IntegerAccumScaler * (32767.0 / fChanMax);
 111    GLaccum *accum = ctx->DrawBuffer->Accum;
 112    GLuint i;
 113
 114    assert(swrast->_IntegerAccumMode);
 115    assert(accum);
 116
 117    for (i = 0; i < n; i++) {
 118       accum[i] = (GLaccum) (accum[i] * s);
 119    }
 120
 121    swrast->_IntegerAccumMode = GL_FALSE;
 122 }
 123
 124
 125
 126
 127
 128
 129 /*
 130  * Clear the accumulation Buffer.
 131  */
 132 void
 133 _mesa_clear_accum_buffer( GLcontext *ctx )
 134 {
 135    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 136    GLuint buffersize;
 137    GLfloat acc_scale;
 138
 139    if (ctx->Visual.accumRedBits==0) {
 140       /* No accumulation buffer! */
 141       return;
 142    }
 143
 144    if (sizeof(GLaccum)==1) {
 145       acc_scale = 127.0;
 146    }
 147    else if (sizeof(GLaccum)==2) {
 148       acc_scale = 32767.0;
 149    }
 150    else {
 151       /* sizeof(GLaccum) > 2 (Cray) */
 152       acc_scale = (float) SHRT_MAX;
 153    }
 154
 155    /* number of pixels */
 156    buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;
 157
 158    if (!ctx->DrawBuffer->Accum) {
 159       /* try to alloc accumulation buffer */
 160       ctx->DrawBuffer->Accum = (GLaccum *)
 161                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 162    }
 163
 164    if (ctx->DrawBuffer->Accum) {
 165       if (ctx->Scissor.Enabled) {
 166          /* Limit clear to scissor box */
 167          GLaccum r, g, b, a;
 168          GLint i, j;
 169          GLint width, height;
 170          GLaccum *row;
 171          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 172          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 173          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 174          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 175          /* size of region to clear */
 176          width = 4 * (ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin);
 177          height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
 178          /* ptr to first element to clear */
 179          row = ctx->DrawBuffer->Accum
 180                + 4 * (ctx->DrawBuffer->_Ymin * ctx->DrawBuffer->Width
 181                       + ctx->DrawBuffer->_Xmin);
 182          for (j=0;j<height;j++) {
 183             for (i=0;i<width;i+=4) {
 184                row[i+0] = r;
 185                row[i+1] = g;
 186                row[i+2] = b;
 187                row[i+3] = a;
 188             }
 189             row += 4 * ctx->DrawBuffer->Width;
 190          }
 191       }
 192       else {
 193          /* clear whole buffer */
 194          if (ctx->Accum.ClearColor[0]==0.0 &&
 195              ctx->Accum.ClearColor[1]==0.0 &&
 196              ctx->Accum.ClearColor[2]==0.0 &&
 197              ctx->Accum.ClearColor[3]==0.0) {
 198             /* Black */
 199             BZERO( ctx->DrawBuffer->Accum, buffersize * 4 * sizeof(GLaccum) );
 200          }
 201          else {
 202             /* Not black */
 203             GLaccum *acc, r, g, b, a;
 204             GLuint i;
 205
 206             acc = ctx->DrawBuffer->Accum;
 207             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 208             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 209             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 210             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 211             for (i=0;i<buffersize;i++) {
 212                *acc++ = r;
 213                *acc++ = g;
 214                *acc++ = b;
 215                *acc++ = a;
 216             }
 217          }
 218       }
 219
 220       /* update optimized accum state vars */
 221       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 222           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 223 #ifdef USE_OPTIMIZED_ACCUM
 224          swrast->_IntegerAccumMode = GL_TRUE;
 225 #else
 226          swrast->_IntegerAccumMode = GL_FALSE;
 227 #endif
 228          swrast->_IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 229       }
 230       else {
 231          swrast->_IntegerAccumMode = GL_FALSE;
 232       }
 233    }
 234 }
 235
 236
 237 void
 238 _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
 239                GLint xpos, GLint ypos,
 240                GLint width, GLint height )
 241
 242 {
 243    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 244    GLuint width4;
 245    GLfloat acc_scale;
 246    GLchan rgba[MAX_WIDTH][4];
 247    const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);
 248    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 249    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 250
 251
 252    if (SWRAST_CONTEXT(ctx)->NewState)
 253       _swrast_validate_derived( ctx );
 254
 255    if (!ctx->DrawBuffer->Accum) {
 256       _mesa_warning(ctx,
 257                     "Calling glAccum() without an accumulation "
 258                     "buffer (low memory?)");
 259       return;
 260    }
 261
 262    if (sizeof(GLaccum)==1) {
 263       acc_scale = 127.0;
 264    }
 265    else if (sizeof(GLaccum)==2) {
 266       acc_scale = 32767.0;
 267    }
 268    else {
 269       /* sizeof(GLaccum) > 2 (Cray) */
 270       acc_scale = (float) SHRT_MAX;
 271    }
 272
 273    width4 = 4 * width;
 274
 275    switch (op) {
 276       case GL_ADD:
 277          if (value != 0.0F) {
 278             const GLaccum intVal = (GLaccum) (value * acc_scale);
 279             GLuint j;
 280             /* Leave optimized accum buffer mode */
 281             if (swrast->_IntegerAccumMode)
 282                rescale_accum(ctx);
 283             for (j = 0; j < height; j++) {
 284                GLaccum * acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 285                GLuint i;
 286                for (i = 0; i < width4; i++) {
 287                   acc[i] += intVal;
 288                }
 289                ypos++;
 290             }
 291          }
 292          break;
 293
 294       case GL_MULT:
 295          if (value != 1.0F) {
 296             GLuint j;
 297             /* Leave optimized accum buffer mode */
 298             if (swrast->_IntegerAccumMode)
 299                rescale_accum(ctx);
 300             for (j = 0; j < height; j++) {
 301                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 302                GLuint i;
 303                for (i = 0; i < width4; i++) {
 304                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 305                }
 306                ypos++;
 307             }
 308          }
 309          break;
 310
 311       case GL_ACCUM:
 312          if (value == 0.0F)
 313             return;
 314
 315          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 316                                        ctx->Pixel.DriverReadBuffer );
 317
 318          /* May have to leave optimized accum buffer mode */
 319          if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 320             swrast->_IntegerAccumScaler = value;
 321          if (swrast->_IntegerAccumMode && value != swrast->_IntegerAccumScaler)
 322             rescale_accum(ctx);
 323
 324          RENDER_START(ctx);
 325
 326          if (swrast->_IntegerAccumMode) {
 327             /* simply add integer color values into accum buffer */
 328             GLuint j;
 329             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 330             assert(swrast->_IntegerAccumScaler > 0.0);
 331             assert(swrast->_IntegerAccumScaler <= 1.0);
 332             for (j = 0; j < height; j++) {
 333
 334                GLuint i, i4;
 335                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 336                for (i = i4 = 0; i < width; i++, i4+=4) {
 337                   acc[i4+0] += rgba[i][RCOMP];
 338                   acc[i4+1] += rgba[i][GCOMP];
 339                   acc[i4+2] += rgba[i][BCOMP];
 340                   acc[i4+3] += rgba[i][ACOMP];
 341                }
 342                acc += width4;
 343                ypos++;
 344             }
 345          }
 346          else {
 347             /* scaled integer accum buffer */
 348             const GLfloat rscale = value * acc_scale / fChanMax;
 349             const GLfloat gscale = value * acc_scale / fChanMax;
 350             const GLfloat bscale = value * acc_scale / fChanMax;
 351             const GLfloat ascale = value * acc_scale / fChanMax;
 352             GLuint j;
 353             for (j=0;j<height;j++) {
 354                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 355                GLuint i;
 356                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 357                for (i=0;i<width;i++) {
 358                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 359                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 360                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 361                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 362                }
 363                ypos++;
 364             }
 365          }
 366          /* restore read buffer = draw buffer (the default) */
 367          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 368                                        ctx->Color.DriverDrawBuffer );
 369          RENDER_FINISH(ctx);
 370          break;
 371
 372       case GL_LOAD:
 373          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 374                                        ctx->Pixel.DriverReadBuffer );
 375
 376          /* This is a change to go into optimized accum buffer mode */
 377          if (value > 0.0 && value <= 1.0) {
 378 #ifdef USE_OPTIMIZED_ACCUM
 379             swrast->_IntegerAccumMode = GL_TRUE;
 380 #else
 381             swrast->_IntegerAccumMode = GL_FALSE;
 382 #endif
 383             swrast->_IntegerAccumScaler = value;
 384          }
 385          else {
 386             swrast->_IntegerAccumMode = GL_FALSE;
 387             swrast->_IntegerAccumScaler = 0.0;
 388          }
 389
 390          RENDER_START(ctx);
 391          if (swrast->_IntegerAccumMode) {
 392             /* just copy values into accum buffer */
 393             GLuint j;
 394             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 395             assert(swrast->_IntegerAccumScaler > 0.0);
 396             assert(swrast->_IntegerAccumScaler <= 1.0);
 397             for (j = 0; j < height; j++) {
 398                GLuint i, i4;
 399                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 400                for (i = i4 = 0; i < width; i++, i4 += 4) {
 401                   acc[i4+0] = rgba[i][RCOMP];
 402                   acc[i4+1] = rgba[i][GCOMP];
 403                   acc[i4+2] = rgba[i][BCOMP];
 404                   acc[i4+3] = rgba[i][ACOMP];
 405                }
 406                acc += width4;
 407                ypos++;
 408             }
 409          }
 410          else {
 411             /* scaled integer accum buffer */
 412             const GLfloat rscale = value * acc_scale / fChanMax;
 413             const GLfloat gscale = value * acc_scale / fChanMax;
 414             const GLfloat bscale = value * acc_scale / fChanMax;
 415             const GLfloat ascale = value * acc_scale / fChanMax;
 416             const GLfloat d = 3.0 / acc_scale;
 417             GLuint i, j;
 418             for (j = 0; j < height; j++) {
 419                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 420                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 421                for (i=0;i<width;i++) {
 422                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 423                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 424                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 425                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 426                }
 427                ypos++;
 428             }
 429          }
 430
 431          /* restore read buffer = draw buffer (the default) */
 432          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 433                                        ctx->Color.DriverDrawBuffer );
 434          RENDER_FINISH(ctx);
 435          break;
 436
 437       case GL_RETURN:
 438          /* May have to leave optimized accum buffer mode */
 439          if (swrast->_IntegerAccumMode && value != 1.0)
 440             rescale_accum(ctx);
 441
 442          RENDER_START(ctx);
 443          if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {
 444             /* build lookup table to avoid many floating point multiplies */
 445             static GLchan multTable[32768];
 446             static GLfloat prevMult = 0.0;
 447             const GLfloat mult = swrast->_IntegerAccumScaler;
 448             const GLint max = MIN2((GLint) (256 / mult), 32767);
 449             GLuint j;
 450             if (mult != prevMult) {
 451                for (j = 0; j < max; j++)
 452                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 453                prevMult = mult;
 454             }
 455
 456             assert(swrast->_IntegerAccumScaler > 0.0);
 457             assert(swrast->_IntegerAccumScaler <= 1.0);
 458             for (j = 0; j < height; j++) {
 459                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 460                GLuint i, i4;
 461                for (i = i4 = 0; i < width; i++, i4 += 4) {
 462                   ASSERT(acc[i4+0] < max);
 463                   ASSERT(acc[i4+1] < max);
 464                   ASSERT(acc[i4+2] < max);
 465                   ASSERT(acc[i4+3] < max);
 466                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 467                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 468                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 469                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 470                }
 471                if (colorMask != 0xffffffff) {
 472                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 473                }
 474                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 475                                              (const GLchan (*)[4])rgba, NULL );
 476                if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
 477                    && ctx->Color.ColorMask[ACOMP]) {
 478                   _mesa_write_alpha_span(ctx, width, xpos, ypos,
 479                                          (CONST GLubyte (*)[4]) rgba, NULL);
 480                }
 481                ypos++;
 482             }
 483          }
 484          else {
 485             const GLfloat rscale = value / acc_scale * fChanMax;
 486             const GLfloat gscale = value / acc_scale * fChanMax;
 487             const GLfloat bscale = value / acc_scale * fChanMax;
 488             const GLfloat ascale = value / acc_scale * fChanMax;
 489             GLuint i, j;
 490             for (j=0;j<height;j++) {
 491                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 492                for (i=0;i<width;i++) {
 493                   GLint r, g, b, a;
 494                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 495                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 496                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 497                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 498                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 499                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 500                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 501                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 502                }
 503                if (colorMask != 0xffffffff) {
 504                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 505                }
 506                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 507                                              (const GLchan (*)[4])rgba, NULL );
 508                if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
 509                    && ctx->Color.ColorMask[ACOMP]) {
 510                   _mesa_write_alpha_span(ctx, width, xpos, ypos,
 511                                          (CONST GLubyte (*)[4]) rgba, NULL);
 512                }
 513                ypos++;
 514             }
 515          }
 516          RENDER_FINISH(ctx);
 517          break;
 518
 519       default:
 520          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 521    }
 522 }