src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.11 1999/11/11 01:22:25 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.1
   6  *
   7  * Copyright (C) 1999  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 #ifdef PC_HEADER
  29 #include "all.h"
  30 #else
  31 #include "glheader.h"
  32 #include "accum.h"
  33 #include "context.h"
  34 #include "mem.h"
  35 #include "masking.h"
  36 #include "span.h"
  37 #include "types.h"
  38 #endif
  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 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  66
  67
  68
  69 void gl_alloc_accum_buffer( GLcontext *ctx )
  70 {
  71    GLint n;
  72
  73    if (ctx->Buffer->Accum) {
  74       FREE( ctx->Buffer->Accum );
  75       ctx->Buffer->Accum = NULL;
  76    }
  77
  78    /* allocate accumulation buffer if not already present */
  79    n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
  80    ctx->Buffer->Accum = (GLaccum *) MALLOC( n );
  81    if (!ctx->Buffer->Accum) {
  82       /* unable to setup accumulation buffer */
  83       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  84    }
  85 #ifdef USE_OPTIMIZED_ACCUM
  86    ctx->IntegerAccumMode = GL_TRUE;
  87 #else
  88    ctx->IntegerAccumMode = GL_FALSE;
  89 #endif
  90    ctx->IntegerAccumScaler = 0.0;
  91 }
  92
  93
  94
  95 void
  96 _mesa_ClearAccum( GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
  97 {
  98    GET_CURRENT_CONTEXT(ctx);
  99    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 100
 101    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 102    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 103    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 104    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 105 }
 106
 107
 108
 109 /*
 110  * This is called when we fall out of optimized/unscaled accum buffer mode.
 111  * That is, we convert each unscaled accum buffer value into a scaled value
 112  * representing the range[-1, 1].
 113  */
 114 static void rescale_accum( GLcontext *ctx )
 115 {
 116    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 117    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 118    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / fChanMax);
 119    GLaccum *accum = ctx->Buffer->Accum;
 120    GLuint i;
 121
 122    assert(ctx->IntegerAccumMode);
 123    assert(accum);
 124
 125    for (i = 0; i < n; i++) {
 126       accum[i] = (GLaccum) (accum[i] * s);
 127    }
 128
 129    ctx->IntegerAccumMode = GL_FALSE;
 130 }
 131
 132
 133
 134 void
 135 _mesa_Accum( GLenum op, GLfloat value )
 136 {
 137    GET_CURRENT_CONTEXT(ctx);
 138    GLuint xpos, ypos, width, height, width4;
 139    GLfloat acc_scale;
 140    GLubyte rgba[MAX_WIDTH][4];
 141    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 142    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 143
 144    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 145
 146    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 147       /* No accumulation buffer! */
 148       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 149       return;
 150    }
 151
 152    if (sizeof(GLaccum)==1) {
 153       acc_scale = 127.0;
 154    }
 155    else if (sizeof(GLaccum)==2) {
 156       acc_scale = 32767.0;
 157    }
 158    else {
 159       /* sizeof(GLaccum) > 2 (Cray) */
 160       acc_scale = (float) SHRT_MAX;
 161    }
 162
 163    if (ctx->NewState)
 164       gl_update_state( ctx );
 165
 166    /* Determine region to operate upon. */
 167    if (ctx->Scissor.Enabled) {
 168       xpos = ctx->Scissor.X;
 169       ypos = ctx->Scissor.Y;
 170       width = ctx->Scissor.Width;
 171       height = ctx->Scissor.Height;
 172    }
 173    else {
 174       /* whole window */
 175       xpos = 0;
 176       ypos = 0;
 177       width = ctx->Buffer->Width;
 178       height = ctx->Buffer->Height;
 179    }
 180
 181    width4 = 4 * width;
 182
 183    switch (op) {
 184       case GL_ADD:
 185          {
 186             const GLaccum intVal = (GLaccum) (value * acc_scale);
 187             GLuint j;
 188             /* Leave optimized accum buffer mode */
 189             if (ctx->IntegerAccumMode)
 190                rescale_accum(ctx);
 191             for (j = 0; j < height; j++) {
 192                GLaccum * acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 193                GLuint i;
 194                for (i = 0; i < width4; i++) {
 195                   acc[i] += intVal;
 196                }
 197                ypos++;
 198             }
 199          }
 200          break;
 201
 202       case GL_MULT:
 203          {
 204             GLuint j;
 205             /* Leave optimized accum buffer mode */
 206             if (ctx->IntegerAccumMode)
 207                rescale_accum(ctx);
 208             for (j = 0; j < height; j++) {
 209                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 210                GLuint i;
 211                for (i = 0; i < width4; i++) {
 212                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 213                }
 214                ypos++;
 215             }
 216          }
 217          break;
 218
 219       case GL_ACCUM:
 220          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 221
 222          /* May have to leave optimized accum buffer mode */
 223          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 224             ctx->IntegerAccumScaler = value;
 225          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 226             rescale_accum(ctx);
 227
 228          if (ctx->IntegerAccumMode) {
 229             /* simply add integer color values into accum buffer */
 230             GLuint j;
 231             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 232             assert(ctx->IntegerAccumScaler > 0.0);
 233             assert(ctx->IntegerAccumScaler <= 1.0);
 234             for (j = 0; j < height; j++) {
 235
 236                GLuint i, i4;
 237                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 238                for (i = i4 = 0; i < width; i++, i4+=4) {
 239                   acc[i4+0] += rgba[i][RCOMP];
 240                   acc[i4+1] += rgba[i][GCOMP];
 241                   acc[i4+2] += rgba[i][BCOMP];
 242                   acc[i4+3] += rgba[i][ACOMP];
 243                }
 244                acc += width4;
 245                ypos++;
 246             }
 247          }
 248          else {
 249             /* scaled integer accum buffer */
 250             const GLfloat rscale = value * acc_scale / fChanMax;
 251             const GLfloat gscale = value * acc_scale / fChanMax;
 252             const GLfloat bscale = value * acc_scale / fChanMax;
 253             const GLfloat ascale = value * acc_scale / fChanMax;
 254             GLuint j;
 255             for (j=0;j<height;j++) {
 256                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 257                GLuint i;
 258                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 259                for (i=0;i<width;i++) {
 260                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 261                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 262                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 263                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 264                }
 265                ypos++;
 266             }
 267          }
 268          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 269          break;
 270
 271       case GL_LOAD:
 272          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 273
 274          /* This is a change to go into optimized accum buffer mode */
 275          if (value > 0.0 && value <= 1.0) {
 276 #ifdef USE_OPTIMIZED_ACCUM
 277             ctx->IntegerAccumMode = GL_TRUE;
 278 #else
 279             ctx->IntegerAccumMode = GL_FALSE;
 280 #endif
 281             ctx->IntegerAccumScaler = value;
 282          }
 283          else {
 284             ctx->IntegerAccumMode = GL_FALSE;
 285             ctx->IntegerAccumScaler = 0.0;
 286          }
 287
 288          if (ctx->IntegerAccumMode) {
 289             /* just copy values into accum buffer */
 290             GLuint j;
 291             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 292             assert(ctx->IntegerAccumScaler > 0.0);
 293             assert(ctx->IntegerAccumScaler <= 1.0);
 294             for (j = 0; j < height; j++) {
 295                GLuint i, i4;
 296                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 297                for (i = i4 = 0; i < width; i++, i4 += 4) {
 298                   acc[i4+0] = rgba[i][RCOMP];
 299                   acc[i4+1] = rgba[i][GCOMP];
 300                   acc[i4+2] = rgba[i][BCOMP];
 301                   acc[i4+3] = rgba[i][ACOMP];
 302                }
 303                acc += width4;
 304                ypos++;
 305             }
 306          }
 307          else {
 308             /* scaled integer accum buffer */
 309             const GLfloat rscale = value * acc_scale / fChanMax;
 310             const GLfloat gscale = value * acc_scale / fChanMax;
 311             const GLfloat bscale = value * acc_scale / fChanMax;
 312             const GLfloat ascale = value * acc_scale / fChanMax;
 313             const GLfloat d = 3.0 / acc_scale;
 314             GLuint i, j;
 315             for (j = 0; j < height; j++) {
 316                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 317                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 318                for (i=0;i<width;i++) {
 319                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 320                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 321                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 322                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 323                }
 324                ypos++;
 325             }
 326          }
 327          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 328          break;
 329
 330       case GL_RETURN:
 331          /* May have to leave optimized accum buffer mode */
 332          if (ctx->IntegerAccumMode && value != 1.0)
 333             rescale_accum(ctx);
 334
 335          if (ctx->IntegerAccumMode) {
 336             /* build lookup table to avoid many floating point multiplies */
 337             const GLfloat mult = ctx->IntegerAccumScaler;
 338             static GLchan multTable[32768];
 339             static GLfloat prevMult = 0.0;
 340             GLuint j;
 341             const GLint max = 256 / mult;
 342             if (mult != prevMult) {
 343                assert(max <= 32768);
 344                for (j = 0; j < max; j++)
 345                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 346                prevMult = mult;
 347             }
 348
 349             assert(ctx->IntegerAccumScaler > 0.0);
 350             assert(ctx->IntegerAccumScaler <= 1.0);
 351             for (j = 0; j < height; j++) {
 352                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 353                GLuint i, i4;
 354                for (i = i4 = 0; i < width; i++, i4 += 4) {
 355                   ASSERT(acc[i4+0] < max);
 356                   ASSERT(acc[i4+1] < max);
 357                   ASSERT(acc[i4+2] < max);
 358                   ASSERT(acc[i4+3] < max);
 359                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 360                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 361                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 362                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 363                }
 364                if (ctx->Color.SWmasking) {
 365                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 366                }
 367                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 368                                              (const GLubyte (*)[4])rgba, NULL );
 369                ypos++;
 370             }
 371          }
 372          else {
 373             const GLfloat rscale = value / acc_scale * fChanMax;
 374             const GLfloat gscale = value / acc_scale * fChanMax;
 375             const GLfloat bscale = value / acc_scale * fChanMax;
 376             const GLfloat ascale = value / acc_scale * fChanMax;
 377             GLuint i, j;
 378             for (j=0;j<height;j++) {
 379                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 380                for (i=0;i<width;i++) {
 381                   GLint r, g, b, a;
 382                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 383                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 384                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 385                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 386                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 387                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 388                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 389                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 390                }
 391                if (ctx->Color.SWmasking) {
 392                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 393                }
 394                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 395                                              (const GLubyte (*)[4])rgba, NULL );
 396                ypos++;
 397             }
 398          }
 399          break;
 400
 401       default:
 402          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 403    }
 404 }
 405
 406
 407
 408 /*
 409  * Clear the accumulation Buffer.
 410  */
 411 void gl_clear_accum_buffer( GLcontext *ctx )
 412 {
 413    GLuint buffersize;
 414    GLfloat acc_scale;
 415
 416    if (ctx->Visual->AccumBits==0) {
 417       /* No accumulation buffer! */
 418       return;
 419    }
 420
 421    if (sizeof(GLaccum)==1) {
 422       acc_scale = 127.0;
 423    }
 424    else if (sizeof(GLaccum)==2) {
 425       acc_scale = 32767.0;
 426    }
 427    else {
 428       /* sizeof(GLaccum) > 2 (Cray) */
 429       acc_scale = (float) SHRT_MAX;
 430    }
 431
 432    /* number of pixels */
 433    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 434
 435    if (!ctx->Buffer->Accum) {
 436       /* try to alloc accumulation buffer */
 437       ctx->Buffer->Accum = (GLaccum *)
 438                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 439    }
 440
 441    if (ctx->Buffer->Accum) {
 442       if (ctx->Scissor.Enabled) {
 443          /* Limit clear to scissor box */
 444          GLaccum r, g, b, a;
 445          GLint i, j;
 446          GLint width, height;
 447          GLaccum *row;
 448          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 449          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 450          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 451          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 452          /* size of region to clear */
 453          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 454          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 455          /* ptr to first element to clear */
 456          row = ctx->Buffer->Accum
 457                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 458                       + ctx->Buffer->Xmin);
 459          for (j=0;j<height;j++) {
 460             for (i=0;i<width;i+=4) {
 461                row[i+0] = r;
 462                row[i+1] = g;
 463                row[i+2] = b;
 464                row[i+3] = a;
 465             }
 466             row += 4 * ctx->Buffer->Width;
 467          }
 468       }
 469       else {
 470          /* clear whole buffer */
 471          if (ctx->Accum.ClearColor[0]==0.0 &&
 472              ctx->Accum.ClearColor[1]==0.0 &&
 473              ctx->Accum.ClearColor[2]==0.0 &&
 474              ctx->Accum.ClearColor[3]==0.0) {
 475             /* Black */
 476             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 477          }
 478          else {
 479             /* Not black */
 480             GLaccum *acc, r, g, b, a;
 481             GLuint i;
 482
 483             acc = ctx->Buffer->Accum;
 484             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 485             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 486             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 487             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 488             for (i=0;i<buffersize;i++) {
 489                *acc++ = r;
 490                *acc++ = g;
 491                *acc++ = b;
 492                *acc++ = a;
 493             }
 494          }
 495       }
 496
 497       /* update optimized accum state vars */
 498       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 499           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 500 #ifdef USE_OPTIMIZED_ACCUM
 501          ctx->IntegerAccumMode = GL_TRUE;
 502 #else
 503          ctx->IntegerAccumMode = GL_FALSE;
 504 #endif
 505          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 506       }
 507       else {
 508          ctx->IntegerAccumMode = GL_FALSE;
 509       }
 510    }
 511 }