src/mesa/swrast/s_accum.c

   1 /* $Id: s_accum.c,v 1.1 2000/10/31 18:00:04 keithw Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.5
   6  *
   7  * Copyright (C) 1999-2000  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_masking.h"
  34 #include "s_span.h"
  35
  36
  37 /*
  38  * Accumulation buffer notes
  39  *
  40  * Normally, accumulation buffer values are GLshorts with values in
  41  * [-32767, 32767] which represent floating point colors in [-1, 1],
  42  * as suggested by the OpenGL specification.
  43  *
  44  * We optimize for the common case used for full-scene antialiasing:
  45  *    // start with accum buffer cleared to zero
  46  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  47  *    glAccum(GL_ACCUM, w);
  48  *    ...
  49  *    glAccum(GL_ACCUM, w);
  50  *    glAccum(GL_RETURN, 1.0);
  51  * That is, we start with an empty accumulation buffer and accumulate
  52  * n images, each with weight w = 1/n.
  53  * In this scenario, we can simply store unscaled integer values in
  54  * the accum buffer instead of scaled integers.  We'll also keep track
  55  * of the w value so when we do GL_RETURN we simply divide the accumulated
  56  * values by n (=1/w).
  57  * This lets us avoid _many_ int->float->int conversions.
  58  */
  59
  60
  61 #if CHAN_BITS == 8
  62 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  63 #endif
  64
  65
  66
  67 void
  68 _mesa_alloc_accum_buffer( GLcontext *ctx )
  69 {
  70    GLint n;
  71
  72    if (ctx->DrawBuffer->Accum) {
  73       FREE( ctx->DrawBuffer->Accum );
  74       ctx->DrawBuffer->Accum = NULL;
  75    }
  76
  77    /* allocate accumulation buffer if not already present */
  78    n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4 * sizeof(GLaccum);
  79    ctx->DrawBuffer->Accum = (GLaccum *) MALLOC( n );
  80    if (!ctx->DrawBuffer->Accum) {
  81       /* unable to setup accumulation buffer */
  82       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  83    }
  84 #ifdef USE_OPTIMIZED_ACCUM
  85    ctx->IntegerAccumMode = GL_TRUE;
  86 #else
  87    ctx->IntegerAccumMode = GL_FALSE;
  88 #endif
  89    ctx->IntegerAccumScaler = 0.0;
  90 }
  91
  92
  93
  94
  95
  96
  97 /*
  98  * This is called when we fall out of optimized/unscaled accum buffer mode.
  99  * That is, we convert each unscaled accum buffer value into a scaled value
 100  * representing the range[-1, 1].
 101  */
 102 static void rescale_accum( GLcontext *ctx )
 103 {
 104    const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
 105    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 106    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / fChanMax);
 107    GLaccum *accum = ctx->DrawBuffer->Accum;
 108    GLuint i;
 109
 110    assert(ctx->IntegerAccumMode);
 111    assert(accum);
 112
 113    for (i = 0; i < n; i++) {
 114       accum[i] = (GLaccum) (accum[i] * s);
 115    }
 116
 117    ctx->IntegerAccumMode = GL_FALSE;
 118 }
 119
 120
 121
 122 void
 123 _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
 124                GLint xpos, GLint ypos,
 125                GLint width, GLint height )
 126
 127 {
 128    GLuint width4;
 129    GLfloat acc_scale;
 130    GLchan rgba[MAX_WIDTH][4];
 131    const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);
 132    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 133    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 134
 135
 136    if (!ctx->DrawBuffer->Accum) {
 137       _mesa_warning(ctx, "Calling glAccum() without an accumulation buffer (low memory?)");
 138       return;
 139    }
 140
 141    if (sizeof(GLaccum)==1) {
 142       acc_scale = 127.0;
 143    }
 144    else if (sizeof(GLaccum)==2) {
 145       acc_scale = 32767.0;
 146    }
 147    else {
 148       /* sizeof(GLaccum) > 2 (Cray) */
 149       acc_scale = (float) SHRT_MAX;
 150    }
 151
 152    width4 = 4 * width;
 153
 154    switch (op) {
 155       case GL_ADD:
 156          if (value != 0.0F) {
 157             const GLaccum intVal = (GLaccum) (value * acc_scale);
 158             GLuint j;
 159             /* Leave optimized accum buffer mode */
 160             if (ctx->IntegerAccumMode)
 161                rescale_accum(ctx);
 162             for (j = 0; j < height; j++) {
 163                GLaccum * acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 164                GLuint i;
 165                for (i = 0; i < width4; i++) {
 166                   acc[i] += intVal;
 167                }
 168                ypos++;
 169             }
 170          }
 171          break;
 172
 173       case GL_MULT:
 174          if (value != 1.0F) {
 175             GLuint j;
 176             /* Leave optimized accum buffer mode */
 177             if (ctx->IntegerAccumMode)
 178                rescale_accum(ctx);
 179             for (j = 0; j < height; j++) {
 180                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 181                GLuint i;
 182                for (i = 0; i < width4; i++) {
 183                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 184                }
 185                ypos++;
 186             }
 187          }
 188          break;
 189
 190       case GL_ACCUM:
 191          if (value == 0.0F)
 192             return;
 193
 194          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 195                                        ctx->Pixel.DriverReadBuffer );
 196
 197          /* May have to leave optimized accum buffer mode */
 198          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 199             ctx->IntegerAccumScaler = value;
 200          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 201             rescale_accum(ctx);
 202
 203          RENDER_START(ctx);
 204
 205          if (ctx->IntegerAccumMode) {
 206             /* simply add integer color values into accum buffer */
 207             GLuint j;
 208             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 209             assert(ctx->IntegerAccumScaler > 0.0);
 210             assert(ctx->IntegerAccumScaler <= 1.0);
 211             for (j = 0; j < height; j++) {
 212
 213                GLuint i, i4;
 214                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 215                for (i = i4 = 0; i < width; i++, i4+=4) {
 216                   acc[i4+0] += rgba[i][RCOMP];
 217                   acc[i4+1] += rgba[i][GCOMP];
 218                   acc[i4+2] += rgba[i][BCOMP];
 219                   acc[i4+3] += rgba[i][ACOMP];
 220                }
 221                acc += width4;
 222                ypos++;
 223             }
 224          }
 225          else {
 226             /* scaled integer accum buffer */
 227             const GLfloat rscale = value * acc_scale / fChanMax;
 228             const GLfloat gscale = value * acc_scale / fChanMax;
 229             const GLfloat bscale = value * acc_scale / fChanMax;
 230             const GLfloat ascale = value * acc_scale / fChanMax;
 231             GLuint j;
 232             for (j=0;j<height;j++) {
 233                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 234                GLuint i;
 235                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 236                for (i=0;i<width;i++) {
 237                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 238                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 239                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 240                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 241                }
 242                ypos++;
 243             }
 244          }
 245          /* restore read buffer = draw buffer (the default) */
 246          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 247                                        ctx->Color.DriverDrawBuffer );
 248          RENDER_FINISH(ctx);
 249          break;
 250
 251       case GL_LOAD:
 252          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 253                                        ctx->Pixel.DriverReadBuffer );
 254
 255          /* This is a change to go into optimized accum buffer mode */
 256          if (value > 0.0 && value <= 1.0) {
 257 #ifdef USE_OPTIMIZED_ACCUM
 258             ctx->IntegerAccumMode = GL_TRUE;
 259 #else
 260             ctx->IntegerAccumMode = GL_FALSE;
 261 #endif
 262             ctx->IntegerAccumScaler = value;
 263          }
 264          else {
 265             ctx->IntegerAccumMode = GL_FALSE;
 266             ctx->IntegerAccumScaler = 0.0;
 267          }
 268
 269          RENDER_START(ctx);
 270          if (ctx->IntegerAccumMode) {
 271             /* just copy values into accum buffer */
 272             GLuint j;
 273             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 274             assert(ctx->IntegerAccumScaler > 0.0);
 275             assert(ctx->IntegerAccumScaler <= 1.0);
 276             for (j = 0; j < height; j++) {
 277                GLuint i, i4;
 278                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 279                for (i = i4 = 0; i < width; i++, i4 += 4) {
 280                   acc[i4+0] = rgba[i][RCOMP];
 281                   acc[i4+1] = rgba[i][GCOMP];
 282                   acc[i4+2] = rgba[i][BCOMP];
 283                   acc[i4+3] = rgba[i][ACOMP];
 284                }
 285                acc += width4;
 286                ypos++;
 287             }
 288          }
 289          else {
 290             /* scaled integer accum buffer */
 291             const GLfloat rscale = value * acc_scale / fChanMax;
 292             const GLfloat gscale = value * acc_scale / fChanMax;
 293             const GLfloat bscale = value * acc_scale / fChanMax;
 294             const GLfloat ascale = value * acc_scale / fChanMax;
 295             const GLfloat d = 3.0 / acc_scale;
 296             GLuint i, j;
 297             for (j = 0; j < height; j++) {
 298                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 299                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 300                for (i=0;i<width;i++) {
 301                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 302                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 303                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 304                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 305                }
 306                ypos++;
 307             }
 308          }
 309
 310          /* restore read buffer = draw buffer (the default) */
 311          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 312                                        ctx->Color.DriverDrawBuffer );
 313          RENDER_FINISH(ctx);
 314          break;
 315
 316       case GL_RETURN:
 317          /* May have to leave optimized accum buffer mode */
 318          if (ctx->IntegerAccumMode && value != 1.0)
 319             rescale_accum(ctx);
 320
 321          RENDER_START(ctx);
 322          if (ctx->IntegerAccumMode && ctx->IntegerAccumScaler > 0) {
 323             /* build lookup table to avoid many floating point multiplies */
 324             static GLchan multTable[32768];
 325             static GLfloat prevMult = 0.0;
 326             const GLfloat mult = ctx->IntegerAccumScaler;
 327             const GLint max = MIN2((GLint) (256 / mult), 32767);
 328             GLuint j;
 329             if (mult != prevMult) {
 330                for (j = 0; j < max; j++)
 331                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 332                prevMult = mult;
 333             }
 334
 335             assert(ctx->IntegerAccumScaler > 0.0);
 336             assert(ctx->IntegerAccumScaler <= 1.0);
 337             for (j = 0; j < height; j++) {
 338                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 339                GLuint i, i4;
 340                for (i = i4 = 0; i < width; i++, i4 += 4) {
 341                   ASSERT(acc[i4+0] < max);
 342                   ASSERT(acc[i4+1] < max);
 343                   ASSERT(acc[i4+2] < max);
 344                   ASSERT(acc[i4+3] < max);
 345                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 346                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 347                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 348                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 349                }
 350                if (colorMask != 0xffffffff) {
 351                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 352                }
 353                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 354                                              (const GLchan (*)[4])rgba, NULL );
 355                ypos++;
 356             }
 357          }
 358          else {
 359             const GLfloat rscale = value / acc_scale * fChanMax;
 360             const GLfloat gscale = value / acc_scale * fChanMax;
 361             const GLfloat bscale = value / acc_scale * fChanMax;
 362             const GLfloat ascale = value / acc_scale * fChanMax;
 363             GLuint i, j;
 364             for (j=0;j<height;j++) {
 365                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 366                for (i=0;i<width;i++) {
 367                   GLint r, g, b, a;
 368                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 369                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 370                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 371                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 372                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 373                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 374                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 375                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 376                }
 377                if (colorMask != 0xffffffff) {
 378                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 379                }
 380                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 381                                              (const GLchan (*)[4])rgba, NULL );
 382                ypos++;
 383             }
 384          }
 385          RENDER_FINISH(ctx);
 386          break;
 387
 388       default:
 389          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 390    }
 391 }
 392
 393
 394
 395 /*
 396  * Clear the accumulation Buffer.
 397  */
 398 void
 399 _mesa_clear_accum_buffer( GLcontext *ctx )
 400 {
 401    GLuint buffersize;
 402    GLfloat acc_scale;
 403
 404    if (ctx->Visual.AccumRedBits==0) {
 405       /* No accumulation buffer! */
 406       return;
 407    }
 408
 409    if (sizeof(GLaccum)==1) {
 410       acc_scale = 127.0;
 411    }
 412    else if (sizeof(GLaccum)==2) {
 413       acc_scale = 32767.0;
 414    }
 415    else {
 416       /* sizeof(GLaccum) > 2 (Cray) */
 417       acc_scale = (float) SHRT_MAX;
 418    }
 419
 420    /* number of pixels */
 421    buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;
 422
 423    if (!ctx->DrawBuffer->Accum) {
 424       /* try to alloc accumulation buffer */
 425       ctx->DrawBuffer->Accum = (GLaccum *)
 426                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 427    }
 428
 429    if (ctx->DrawBuffer->Accum) {
 430       if (ctx->Scissor.Enabled) {
 431          /* Limit clear to scissor box */
 432          GLaccum r, g, b, a;
 433          GLint i, j;
 434          GLint width, height;
 435          GLaccum *row;
 436          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 437          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 438          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 439          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 440          /* size of region to clear */
 441          width = 4 * (ctx->DrawBuffer->Xmax - ctx->DrawBuffer->Xmin);
 442          height = ctx->DrawBuffer->Ymax - ctx->DrawBuffer->Ymin;
 443          /* ptr to first element to clear */
 444          row = ctx->DrawBuffer->Accum
 445                + 4 * (ctx->DrawBuffer->Ymin * ctx->DrawBuffer->Width
 446                       + ctx->DrawBuffer->Xmin);
 447          for (j=0;j<height;j++) {
 448             for (i=0;i<width;i+=4) {
 449                row[i+0] = r;
 450                row[i+1] = g;
 451                row[i+2] = b;
 452                row[i+3] = a;
 453             }
 454             row += 4 * ctx->DrawBuffer->Width;
 455          }
 456       }
 457       else {
 458          /* clear whole buffer */
 459          if (ctx->Accum.ClearColor[0]==0.0 &&
 460              ctx->Accum.ClearColor[1]==0.0 &&
 461              ctx->Accum.ClearColor[2]==0.0 &&
 462              ctx->Accum.ClearColor[3]==0.0) {
 463             /* Black */
 464             BZERO( ctx->DrawBuffer->Accum, buffersize * 4 * sizeof(GLaccum) );
 465          }
 466          else {
 467             /* Not black */
 468             GLaccum *acc, r, g, b, a;
 469             GLuint i;
 470
 471             acc = ctx->DrawBuffer->Accum;
 472             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 473             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 474             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 475             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 476             for (i=0;i<buffersize;i++) {
 477                *acc++ = r;
 478                *acc++ = g;
 479                *acc++ = b;
 480                *acc++ = a;
 481             }
 482          }
 483       }
 484
 485       /* update optimized accum state vars */
 486       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 487           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 488 #ifdef USE_OPTIMIZED_ACCUM
 489          ctx->IntegerAccumMode = GL_TRUE;
 490 #else
 491          ctx->IntegerAccumMode = GL_FALSE;
 492 #endif
 493          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 494       }
 495       else {
 496          ctx->IntegerAccumMode = GL_FALSE;
 497       }
 498    }
 499 }