src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.20 2000/04/05 14:40:04 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.3
   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 #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 "state.h"
  38 #include "types.h"
  39 #endif
  40
  41
  42 /*
  43  * Accumulation buffer notes
  44  *
  45  * Normally, accumulation buffer values are GLshorts with values in
  46  * [-32767, 32767] which represent floating point colors in [-1, 1],
  47  * as suggested by the OpenGL specification.
  48  *
  49  * We optimize for the common case used for full-scene antialiasing:
  50  *    // start with accum buffer cleared to zero
  51  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  52  *    glAccum(GL_ACCUM, w);
  53  *    ...
  54  *    glAccum(GL_ACCUM, w);
  55  *    glAccum(GL_RETURN, 1.0);
  56  * That is, we start with an empty accumulation buffer and accumulate
  57  * n images, each with weight w = 1/n.
  58  * In this scenario, we can simply store unscaled integer values in
  59  * the accum buffer instead of scaled integers.  We'll also keep track
  60  * of the w value so when we do GL_RETURN we simply divide the accumulated
  61  * values by n (=1/w).
  62  * This lets us avoid _many_ int->float->int conversions.
  63  */
  64
  65
  66 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  67
  68
  69
  70 void
  71 _mesa_alloc_accum_buffer( GLcontext *ctx )
  72 {
  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    ctx->IntegerAccumMode = GL_TRUE;
  89 #else
  90    ctx->IntegerAccumMode = GL_FALSE;
  91 #endif
  92    ctx->IntegerAccumScaler = 0.0;
  93 }
  94
  95
  96
  97 void
  98 _mesa_ClearAccum( GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
  99 {
 100    GET_CURRENT_CONTEXT(ctx);
 101    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 102
 103    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 104    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 105    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 106    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 107 }
 108
 109
 110
 111 /*
 112  * This is called when we fall out of optimized/unscaled accum buffer mode.
 113  * That is, we convert each unscaled accum buffer value into a scaled value
 114  * representing the range[-1, 1].
 115  */
 116 static void rescale_accum( GLcontext *ctx )
 117 {
 118    const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
 119    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 120    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / fChanMax);
 121    GLaccum *accum = ctx->DrawBuffer->Accum;
 122    GLuint i;
 123
 124    assert(ctx->IntegerAccumMode);
 125    assert(accum);
 126
 127    for (i = 0; i < n; i++) {
 128       accum[i] = (GLaccum) (accum[i] * s);
 129    }
 130
 131    ctx->IntegerAccumMode = GL_FALSE;
 132 }
 133
 134
 135
 136 void
 137 _mesa_Accum( GLenum op, GLfloat value )
 138 {
 139    GET_CURRENT_CONTEXT(ctx);
 140    GLuint xpos, ypos, width, height, width4;
 141    GLfloat acc_scale;
 142    GLubyte rgba[MAX_WIDTH][4];
 143    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 144    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 145
 146    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 147
 148    if (ctx->Visual->AccumRedBits == 0 || ctx->DrawBuffer != ctx->ReadBuffer) {
 149       gl_error(ctx, GL_INVALID_OPERATION, "glAccum");
 150       return;
 151    }
 152
 153    if (!ctx->DrawBuffer->Accum) {
 154       gl_warning(ctx, "Calling glAccum() without an accumulation buffer (low memory?)");
 155       return;
 156    }
 157
 158    if (sizeof(GLaccum)==1) {
 159       acc_scale = 127.0;
 160    }
 161    else if (sizeof(GLaccum)==2) {
 162       acc_scale = 32767.0;
 163    }
 164    else {
 165       /* sizeof(GLaccum) > 2 (Cray) */
 166       acc_scale = (float) SHRT_MAX;
 167    }
 168
 169    if (ctx->NewState)
 170       gl_update_state( ctx );
 171
 172    /* Determine region to operate upon. */
 173    if (ctx->Scissor.Enabled) {
 174       xpos = ctx->Scissor.X;
 175       ypos = ctx->Scissor.Y;
 176       width = ctx->Scissor.Width;
 177       height = ctx->Scissor.Height;
 178    }
 179    else {
 180       /* whole window */
 181       xpos = 0;
 182       ypos = 0;
 183       width = ctx->DrawBuffer->Width;
 184       height = ctx->DrawBuffer->Height;
 185    }
 186
 187    width4 = 4 * width;
 188
 189    switch (op) {
 190       case GL_ADD:
 191          {
 192             const GLaccum intVal = (GLaccum) (value * acc_scale);
 193             GLuint j;
 194             /* Leave optimized accum buffer mode */
 195             if (ctx->IntegerAccumMode)
 196                rescale_accum(ctx);
 197             for (j = 0; j < height; j++) {
 198                GLaccum * acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 199                GLuint i;
 200                for (i = 0; i < width4; i++) {
 201                   acc[i] += intVal;
 202                }
 203                ypos++;
 204             }
 205          }
 206          break;
 207
 208       case GL_MULT:
 209          {
 210             GLuint j;
 211             /* Leave optimized accum buffer mode */
 212             if (ctx->IntegerAccumMode)
 213                rescale_accum(ctx);
 214             for (j = 0; j < height; j++) {
 215                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 216                GLuint i;
 217                for (i = 0; i < width4; i++) {
 218                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 219                }
 220                ypos++;
 221             }
 222          }
 223          break;
 224
 225       case GL_ACCUM:
 226          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 227                                        ctx->Pixel.DriverReadBuffer );
 228
 229          /* May have to leave optimized accum buffer mode */
 230          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 231             ctx->IntegerAccumScaler = value;
 232          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 233             rescale_accum(ctx);
 234
 235          if (ctx->IntegerAccumMode) {
 236             /* simply add integer color values into accum buffer */
 237             GLuint j;
 238             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 239             assert(ctx->IntegerAccumScaler > 0.0);
 240             assert(ctx->IntegerAccumScaler <= 1.0);
 241             for (j = 0; j < height; j++) {
 242
 243                GLuint i, i4;
 244                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 245                for (i = i4 = 0; i < width; i++, i4+=4) {
 246                   acc[i4+0] += rgba[i][RCOMP];
 247                   acc[i4+1] += rgba[i][GCOMP];
 248                   acc[i4+2] += rgba[i][BCOMP];
 249                   acc[i4+3] += rgba[i][ACOMP];
 250                }
 251                acc += width4;
 252                ypos++;
 253             }
 254          }
 255          else {
 256             /* scaled integer accum buffer */
 257             const GLfloat rscale = value * acc_scale / fChanMax;
 258             const GLfloat gscale = value * acc_scale / fChanMax;
 259             const GLfloat bscale = value * acc_scale / fChanMax;
 260             const GLfloat ascale = value * acc_scale / fChanMax;
 261             GLuint j;
 262             for (j=0;j<height;j++) {
 263                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 264                GLuint i;
 265                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 266                for (i=0;i<width;i++) {
 267                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 268                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 269                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 270                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 271                }
 272                ypos++;
 273             }
 274          }
 275          /* restore read buffer = draw buffer (the default) */
 276          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 277                                        ctx->Color.DriverDrawBuffer );
 278          break;
 279
 280       case GL_LOAD:
 281          (*ctx->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
 282                                        ctx->Pixel.DriverReadBuffer );
 283
 284          /* This is a change to go into optimized accum buffer mode */
 285          if (value > 0.0 && value <= 1.0) {
 286 #ifdef USE_OPTIMIZED_ACCUM
 287             ctx->IntegerAccumMode = GL_TRUE;
 288 #else
 289             ctx->IntegerAccumMode = GL_FALSE;
 290 #endif
 291             ctx->IntegerAccumScaler = value;
 292          }
 293          else {
 294             ctx->IntegerAccumMode = GL_FALSE;
 295             ctx->IntegerAccumScaler = 0.0;
 296          }
 297
 298          if (ctx->IntegerAccumMode) {
 299             /* just copy values into accum buffer */
 300             GLuint j;
 301             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 302             assert(ctx->IntegerAccumScaler > 0.0);
 303             assert(ctx->IntegerAccumScaler <= 1.0);
 304             for (j = 0; j < height; j++) {
 305                GLuint i, i4;
 306                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 307                for (i = i4 = 0; i < width; i++, i4 += 4) {
 308                   acc[i4+0] = rgba[i][RCOMP];
 309                   acc[i4+1] = rgba[i][GCOMP];
 310                   acc[i4+2] = rgba[i][BCOMP];
 311                   acc[i4+3] = rgba[i][ACOMP];
 312                }
 313                acc += width4;
 314                ypos++;
 315             }
 316          }
 317          else {
 318             /* scaled integer accum buffer */
 319             const GLfloat rscale = value * acc_scale / fChanMax;
 320             const GLfloat gscale = value * acc_scale / fChanMax;
 321             const GLfloat bscale = value * acc_scale / fChanMax;
 322             const GLfloat ascale = value * acc_scale / fChanMax;
 323             const GLfloat d = 3.0 / acc_scale;
 324             GLuint i, j;
 325             for (j = 0; j < height; j++) {
 326                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 327                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 328                for (i=0;i<width;i++) {
 329                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 330                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 331                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 332                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 333                }
 334                ypos++;
 335             }
 336          }
 337
 338          /* restore read buffer = draw buffer (the default) */
 339          (*ctx->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
 340                                        ctx->Color.DriverDrawBuffer );
 341          break;
 342
 343       case GL_RETURN:
 344          /* May have to leave optimized accum buffer mode */
 345          if (ctx->IntegerAccumMode && value != 1.0)
 346             rescale_accum(ctx);
 347
 348          if (ctx->IntegerAccumMode && ctx->IntegerAccumScaler > 0) {
 349             /* build lookup table to avoid many floating point multiplies */
 350             const GLfloat mult = ctx->IntegerAccumScaler;
 351             static GLchan multTable[32768];
 352             static GLfloat prevMult = 0.0;
 353             GLuint j;
 354             const GLint max = (GLint) (256 / mult);
 355             if (mult != prevMult) {
 356                assert(max <= 32768);
 357                for (j = 0; j < max; j++)
 358                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 359                prevMult = mult;
 360             }
 361
 362             assert(ctx->IntegerAccumScaler > 0.0);
 363             assert(ctx->IntegerAccumScaler <= 1.0);
 364             for (j = 0; j < height; j++) {
 365                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 366                GLuint i, i4;
 367                for (i = i4 = 0; i < width; i++, i4 += 4) {
 368                   ASSERT(acc[i4+0] < max);
 369                   ASSERT(acc[i4+1] < max);
 370                   ASSERT(acc[i4+2] < max);
 371                   ASSERT(acc[i4+3] < max);
 372                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 373                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 374                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 375                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 376                }
 377                if (ctx->Color.SWmasking) {
 378                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 379                }
 380                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 381                                              (const GLubyte (*)[4])rgba, NULL );
 382                ypos++;
 383             }
 384          }
 385          else {
 386             const GLfloat rscale = value / acc_scale * fChanMax;
 387             const GLfloat gscale = value / acc_scale * fChanMax;
 388             const GLfloat bscale = value / acc_scale * fChanMax;
 389             const GLfloat ascale = value / acc_scale * fChanMax;
 390             GLuint i, j;
 391             for (j=0;j<height;j++) {
 392                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 393                for (i=0;i<width;i++) {
 394                   GLint r, g, b, a;
 395                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 396                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 397                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 398                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 399                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 400                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 401                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 402                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 403                }
 404                if (ctx->Color.SWmasking) {
 405                   _mesa_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 406                }
 407                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 408                                              (const GLubyte (*)[4])rgba, NULL );
 409                ypos++;
 410             }
 411          }
 412          break;
 413
 414       default:
 415          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 416    }
 417 }
 418
 419
 420
 421 /*
 422  * Clear the accumulation Buffer.
 423  */
 424 void
 425 _mesa_clear_accum_buffer( GLcontext *ctx )
 426 {
 427    GLuint buffersize;
 428    GLfloat acc_scale;
 429
 430    if (ctx->Visual->AccumRedBits==0) {
 431       /* No accumulation buffer! */
 432       return;
 433    }
 434
 435    if (sizeof(GLaccum)==1) {
 436       acc_scale = 127.0;
 437    }
 438    else if (sizeof(GLaccum)==2) {
 439       acc_scale = 32767.0;
 440    }
 441    else {
 442       /* sizeof(GLaccum) > 2 (Cray) */
 443       acc_scale = (float) SHRT_MAX;
 444    }
 445
 446    /* number of pixels */
 447    buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;
 448
 449    if (!ctx->DrawBuffer->Accum) {
 450       /* try to alloc accumulation buffer */
 451       ctx->DrawBuffer->Accum = (GLaccum *)
 452                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 453    }
 454
 455    if (ctx->DrawBuffer->Accum) {
 456       if (ctx->Scissor.Enabled) {
 457          /* Limit clear to scissor box */
 458          GLaccum r, g, b, a;
 459          GLint i, j;
 460          GLint width, height;
 461          GLaccum *row;
 462          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 463          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 464          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 465          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 466          /* size of region to clear */
 467          width = 4 * (ctx->DrawBuffer->Xmax - ctx->DrawBuffer->Xmin + 1);
 468          height = ctx->DrawBuffer->Ymax - ctx->DrawBuffer->Ymin + 1;
 469          /* ptr to first element to clear */
 470          row = ctx->DrawBuffer->Accum
 471                + 4 * (ctx->DrawBuffer->Ymin * ctx->DrawBuffer->Width
 472                       + ctx->DrawBuffer->Xmin);
 473          for (j=0;j<height;j++) {
 474             for (i=0;i<width;i+=4) {
 475                row[i+0] = r;
 476                row[i+1] = g;
 477                row[i+2] = b;
 478                row[i+3] = a;
 479             }
 480             row += 4 * ctx->DrawBuffer->Width;
 481          }
 482       }
 483       else {
 484          /* clear whole buffer */
 485          if (ctx->Accum.ClearColor[0]==0.0 &&
 486              ctx->Accum.ClearColor[1]==0.0 &&
 487              ctx->Accum.ClearColor[2]==0.0 &&
 488              ctx->Accum.ClearColor[3]==0.0) {
 489             /* Black */
 490             BZERO( ctx->DrawBuffer->Accum, buffersize * 4 * sizeof(GLaccum) );
 491          }
 492          else {
 493             /* Not black */
 494             GLaccum *acc, r, g, b, a;
 495             GLuint i;
 496
 497             acc = ctx->DrawBuffer->Accum;
 498             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 499             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 500             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 501             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 502             for (i=0;i<buffersize;i++) {
 503                *acc++ = r;
 504                *acc++ = g;
 505                *acc++ = b;
 506                *acc++ = a;
 507             }
 508          }
 509       }
 510
 511       /* update optimized accum state vars */
 512       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 513           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 514 #ifdef USE_OPTIMIZED_ACCUM
 515          ctx->IntegerAccumMode = GL_TRUE;
 516 #else
 517          ctx->IntegerAccumMode = GL_FALSE;
 518 #endif
 519          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 520       }
 521       else {
 522          ctx->IntegerAccumMode = GL_FALSE;
 523       }
 524    }
 525 }