src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.12 1999/11/24 18:48:30 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.3
   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->DrawBuffer->Accum) {
  74       FREE( ctx->DrawBuffer->Accum );
  75       ctx->DrawBuffer->Accum = NULL;
  76    }
  77
  78    /* allocate accumulation buffer if not already present */
  79    n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4 * sizeof(GLaccum);
  80    ctx->DrawBuffer->Accum = (GLaccum *) MALLOC( n );
  81    if (!ctx->DrawBuffer->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->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
 117    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 118    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / fChanMax);
 119    GLaccum *accum = ctx->DrawBuffer->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->DrawBuffer != ctx->ReadBuffer) {
 147       gl_error(ctx, GL_INVALID_OPERATION, "glAccum");
 148       return;
 149    }
 150
 151    if (!ctx->DrawBuffer->Accum) {
 152       gl_warning(ctx, "Calling glAccum() without an accumulation buffer (low memory?)");
 153       return;
 154    }
 155
 156    if (sizeof(GLaccum)==1) {
 157       acc_scale = 127.0;
 158    }
 159    else if (sizeof(GLaccum)==2) {
 160       acc_scale = 32767.0;
 161    }
 162    else {
 163       /* sizeof(GLaccum) > 2 (Cray) */
 164       acc_scale = (float) SHRT_MAX;
 165    }
 166
 167    if (ctx->NewState)
 168       gl_update_state( ctx );
 169
 170    /* Determine region to operate upon. */
 171    if (ctx->Scissor.Enabled) {
 172       xpos = ctx->Scissor.X;
 173       ypos = ctx->Scissor.Y;
 174       width = ctx->Scissor.Width;
 175       height = ctx->Scissor.Height;
 176    }
 177    else {
 178       /* whole window */
 179       xpos = 0;
 180       ypos = 0;
 181       width = ctx->DrawBuffer->Width;
 182       height = ctx->DrawBuffer->Height;
 183    }
 184
 185    width4 = 4 * width;
 186
 187    switch (op) {
 188       case GL_ADD:
 189          {
 190             const GLaccum intVal = (GLaccum) (value * acc_scale);
 191             GLuint j;
 192             /* Leave optimized accum buffer mode */
 193             if (ctx->IntegerAccumMode)
 194                rescale_accum(ctx);
 195             for (j = 0; j < height; j++) {
 196                GLaccum * acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 197                GLuint i;
 198                for (i = 0; i < width4; i++) {
 199                   acc[i] += intVal;
 200                }
 201                ypos++;
 202             }
 203          }
 204          break;
 205
 206       case GL_MULT:
 207          {
 208             GLuint j;
 209             /* Leave optimized accum buffer mode */
 210             if (ctx->IntegerAccumMode)
 211                rescale_accum(ctx);
 212             for (j = 0; j < height; j++) {
 213                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
 214                GLuint i;
 215                for (i = 0; i < width4; i++) {
 216                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 217                }
 218                ypos++;
 219             }
 220          }
 221          break;
 222
 223       case GL_ACCUM:
 224          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 225
 226          /* May have to leave optimized accum buffer mode */
 227          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 228             ctx->IntegerAccumScaler = value;
 229          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 230             rescale_accum(ctx);
 231
 232          if (ctx->IntegerAccumMode) {
 233             /* simply add integer color values into accum buffer */
 234             GLuint j;
 235             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 236             assert(ctx->IntegerAccumScaler > 0.0);
 237             assert(ctx->IntegerAccumScaler <= 1.0);
 238             for (j = 0; j < height; j++) {
 239
 240                GLuint i, i4;
 241                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 242                for (i = i4 = 0; i < width; i++, i4+=4) {
 243                   acc[i4+0] += rgba[i][RCOMP];
 244                   acc[i4+1] += rgba[i][GCOMP];
 245                   acc[i4+2] += rgba[i][BCOMP];
 246                   acc[i4+3] += rgba[i][ACOMP];
 247                }
 248                acc += width4;
 249                ypos++;
 250             }
 251          }
 252          else {
 253             /* scaled integer accum buffer */
 254             const GLfloat rscale = value * acc_scale / fChanMax;
 255             const GLfloat gscale = value * acc_scale / fChanMax;
 256             const GLfloat bscale = value * acc_scale / fChanMax;
 257             const GLfloat ascale = value * acc_scale / fChanMax;
 258             GLuint j;
 259             for (j=0;j<height;j++) {
 260                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 261                GLuint i;
 262                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 263                for (i=0;i<width;i++) {
 264                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 265                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 266                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 267                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 268                }
 269                ypos++;
 270             }
 271          }
 272          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 273          break;
 274
 275       case GL_LOAD:
 276          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 277
 278          /* This is a change to go into optimized accum buffer mode */
 279          if (value > 0.0 && value <= 1.0) {
 280 #ifdef USE_OPTIMIZED_ACCUM
 281             ctx->IntegerAccumMode = GL_TRUE;
 282 #else
 283             ctx->IntegerAccumMode = GL_FALSE;
 284 #endif
 285             ctx->IntegerAccumScaler = value;
 286          }
 287          else {
 288             ctx->IntegerAccumMode = GL_FALSE;
 289             ctx->IntegerAccumScaler = 0.0;
 290          }
 291
 292          if (ctx->IntegerAccumMode) {
 293             /* just copy values into accum buffer */
 294             GLuint j;
 295             GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 296             assert(ctx->IntegerAccumScaler > 0.0);
 297             assert(ctx->IntegerAccumScaler <= 1.0);
 298             for (j = 0; j < height; j++) {
 299                GLuint i, i4;
 300                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 301                for (i = i4 = 0; i < width; i++, i4 += 4) {
 302                   acc[i4+0] = rgba[i][RCOMP];
 303                   acc[i4+1] = rgba[i][GCOMP];
 304                   acc[i4+2] = rgba[i][BCOMP];
 305                   acc[i4+3] = rgba[i][ACOMP];
 306                }
 307                acc += width4;
 308                ypos++;
 309             }
 310          }
 311          else {
 312             /* scaled integer accum buffer */
 313             const GLfloat rscale = value * acc_scale / fChanMax;
 314             const GLfloat gscale = value * acc_scale / fChanMax;
 315             const GLfloat bscale = value * acc_scale / fChanMax;
 316             const GLfloat ascale = value * acc_scale / fChanMax;
 317             const GLfloat d = 3.0 / acc_scale;
 318             GLuint i, j;
 319             for (j = 0; j < height; j++) {
 320                GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
 321                gl_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
 322                for (i=0;i<width;i++) {
 323                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 324                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 325                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 326                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 327                }
 328                ypos++;
 329             }
 330          }
 331          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 332          break;
 333
 334       case GL_RETURN:
 335          /* May have to leave optimized accum buffer mode */
 336          if (ctx->IntegerAccumMode && value != 1.0)
 337             rescale_accum(ctx);
 338
 339          if (ctx->IntegerAccumMode) {
 340             /* build lookup table to avoid many floating point multiplies */
 341             const GLfloat mult = ctx->IntegerAccumScaler;
 342             static GLchan multTable[32768];
 343             static GLfloat prevMult = 0.0;
 344             GLuint j;
 345             const GLint max = 256 / mult;
 346             if (mult != prevMult) {
 347                assert(max <= 32768);
 348                for (j = 0; j < max; j++)
 349                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 350                prevMult = mult;
 351             }
 352
 353             assert(ctx->IntegerAccumScaler > 0.0);
 354             assert(ctx->IntegerAccumScaler <= 1.0);
 355             for (j = 0; j < height; j++) {
 356                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 357                GLuint i, i4;
 358                for (i = i4 = 0; i < width; i++, i4 += 4) {
 359                   ASSERT(acc[i4+0] < max);
 360                   ASSERT(acc[i4+1] < max);
 361                   ASSERT(acc[i4+2] < max);
 362                   ASSERT(acc[i4+3] < max);
 363                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 364                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 365                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 366                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 367                }
 368                if (ctx->Color.SWmasking) {
 369                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 370                }
 371                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 372                                              (const GLubyte (*)[4])rgba, NULL );
 373                ypos++;
 374             }
 375          }
 376          else {
 377             const GLfloat rscale = value / acc_scale * fChanMax;
 378             const GLfloat gscale = value / acc_scale * fChanMax;
 379             const GLfloat bscale = value / acc_scale * fChanMax;
 380             const GLfloat ascale = value / acc_scale * fChanMax;
 381             GLuint i, j;
 382             for (j=0;j<height;j++) {
 383                const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
 384                for (i=0;i<width;i++) {
 385                   GLint r, g, b, a;
 386                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 387                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 388                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 389                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 390                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 391                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 392                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 393                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 394                }
 395                if (ctx->Color.SWmasking) {
 396                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 397                }
 398                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 399                                              (const GLubyte (*)[4])rgba, NULL );
 400                ypos++;
 401             }
 402          }
 403          break;
 404
 405       default:
 406          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 407    }
 408 }
 409
 410
 411
 412 /*
 413  * Clear the accumulation Buffer.
 414  */
 415 void gl_clear_accum_buffer( GLcontext *ctx )
 416 {
 417    GLuint buffersize;
 418    GLfloat acc_scale;
 419
 420    if (ctx->Visual->AccumBits==0) {
 421       /* No accumulation buffer! */
 422       return;
 423    }
 424
 425    if (sizeof(GLaccum)==1) {
 426       acc_scale = 127.0;
 427    }
 428    else if (sizeof(GLaccum)==2) {
 429       acc_scale = 32767.0;
 430    }
 431    else {
 432       /* sizeof(GLaccum) > 2 (Cray) */
 433       acc_scale = (float) SHRT_MAX;
 434    }
 435
 436    /* number of pixels */
 437    buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;
 438
 439    if (!ctx->DrawBuffer->Accum) {
 440       /* try to alloc accumulation buffer */
 441       ctx->DrawBuffer->Accum = (GLaccum *)
 442                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 443    }
 444
 445    if (ctx->DrawBuffer->Accum) {
 446       if (ctx->Scissor.Enabled) {
 447          /* Limit clear to scissor box */
 448          GLaccum r, g, b, a;
 449          GLint i, j;
 450          GLint width, height;
 451          GLaccum *row;
 452          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 453          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 454          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 455          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 456          /* size of region to clear */
 457          width = 4 * (ctx->DrawBuffer->Xmax - ctx->DrawBuffer->Xmin + 1);
 458          height = ctx->DrawBuffer->Ymax - ctx->DrawBuffer->Ymin + 1;
 459          /* ptr to first element to clear */
 460          row = ctx->DrawBuffer->Accum
 461                + 4 * (ctx->DrawBuffer->Ymin * ctx->DrawBuffer->Width
 462                       + ctx->DrawBuffer->Xmin);
 463          for (j=0;j<height;j++) {
 464             for (i=0;i<width;i+=4) {
 465                row[i+0] = r;
 466                row[i+1] = g;
 467                row[i+2] = b;
 468                row[i+3] = a;
 469             }
 470             row += 4 * ctx->DrawBuffer->Width;
 471          }
 472       }
 473       else {
 474          /* clear whole buffer */
 475          if (ctx->Accum.ClearColor[0]==0.0 &&
 476              ctx->Accum.ClearColor[1]==0.0 &&
 477              ctx->Accum.ClearColor[2]==0.0 &&
 478              ctx->Accum.ClearColor[3]==0.0) {
 479             /* Black */
 480             MEMSET( ctx->DrawBuffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 481          }
 482          else {
 483             /* Not black */
 484             GLaccum *acc, r, g, b, a;
 485             GLuint i;
 486
 487             acc = ctx->DrawBuffer->Accum;
 488             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 489             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 490             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 491             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 492             for (i=0;i<buffersize;i++) {
 493                *acc++ = r;
 494                *acc++ = g;
 495                *acc++ = b;
 496                *acc++ = a;
 497             }
 498          }
 499       }
 500
 501       /* update optimized accum state vars */
 502       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 503           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 504 #ifdef USE_OPTIMIZED_ACCUM
 505          ctx->IntegerAccumMode = GL_TRUE;
 506 #else
 507          ctx->IntegerAccumMode = GL_FALSE;
 508 #endif
 509          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 510       }
 511       else {
 512          ctx->IntegerAccumMode = GL_FALSE;
 513       }
 514    }
 515 }