src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.10 1999/11/08 07:36:43 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 /* $XFree86: xc/lib/GL/mesa/src/accum.c,v 1.3 1999/04/04 00:20:17 dawes Exp $ */
  29
  30 #ifdef PC_HEADER
  31 #include "all.h"
  32 #else
  33 #ifndef XFree86Server
  34 #include <assert.h>
  35 #include <limits.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #else
  39 #include "GL/xf86glx.h"
  40 #endif
  41 #include "accum.h"
  42 #include "context.h"
  43 #include "macros.h"
  44 #include "masking.h"
  45 #include "span.h"
  46 #include "types.h"
  47 #endif
  48
  49
  50 /*
  51  * Accumulation buffer notes
  52  *
  53  * Normally, accumulation buffer values are GLshorts with values in
  54  * [-32767, 32767] which represent floating point colors in [-1, 1],
  55  * as suggested by the OpenGL specification.
  56  *
  57  * We optimize for the common case used for full-scene antialiasing:
  58  *    // start with accum buffer cleared to zero
  59  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  60  *    glAccum(GL_ACCUM, w);
  61  *    ...
  62  *    glAccum(GL_ACCUM, w);
  63  *    glAccum(GL_RETURN, 1.0);
  64  * That is, we start with an empty accumulation buffer and accumulate
  65  * n images, each with weight w = 1/n.
  66  * In this scenario, we can simply store unscaled integer values in
  67  * the accum buffer instead of scaled integers.  We'll also keep track
  68  * of the w value so when we do GL_RETURN we simply divide the accumulated
  69  * values by n (=1/w).
  70  * This lets us avoid _many_ int->float->int conversions.
  71  */
  72
  73
  74 #define USE_OPTIMIZED_ACCUM   /* enable the optimization */
  75
  76
  77
  78 void gl_alloc_accum_buffer( GLcontext *ctx )
  79 {
  80    GLint n;
  81
  82    if (ctx->Buffer->Accum) {
  83       FREE( ctx->Buffer->Accum );
  84       ctx->Buffer->Accum = NULL;
  85    }
  86
  87    /* allocate accumulation buffer if not already present */
  88    n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
  89    ctx->Buffer->Accum = (GLaccum *) MALLOC( n );
  90    if (!ctx->Buffer->Accum) {
  91       /* unable to setup accumulation buffer */
  92       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  93    }
  94 #ifdef USE_OPTIMIZED_ACCUM
  95    ctx->IntegerAccumMode = GL_TRUE;
  96 #else
  97    ctx->IntegerAccumMode = GL_FALSE;
  98 #endif
  99    ctx->IntegerAccumScaler = 0.0;
 100 }
 101
 102
 103
 104 void gl_ClearAccum( GLcontext *ctx,
 105                     GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
 106 {
 107    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 108
 109    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 110    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 111    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 112    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 113 }
 114
 115
 116
 117 /*
 118  * This is called when we fall out of optimized/unscaled accum buffer mode.
 119  * That is, we convert each unscaled accum buffer value into a scaled value
 120  * representing the range[-1, 1].
 121  */
 122 static void rescale_accum( GLcontext *ctx )
 123 {
 124    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 125    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 126    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / fChanMax);
 127    GLaccum *accum = ctx->Buffer->Accum;
 128    GLuint i;
 129
 130    assert(ctx->IntegerAccumMode);
 131    assert(accum);
 132
 133    for (i = 0; i < n; i++) {
 134       accum[i] = (GLaccum) (accum[i] * s);
 135    }
 136
 137    ctx->IntegerAccumMode = GL_FALSE;
 138 }
 139
 140
 141
 142 void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
 143 {
 144    GLuint xpos, ypos, width, height, width4;
 145    GLfloat acc_scale;
 146    GLubyte rgba[MAX_WIDTH][4];
 147    const GLint iChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 148    const GLfloat fChanMax = (1 << (sizeof(GLchan) * 8)) - 1;
 149
 150    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 151
 152    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 153       /* No accumulation buffer! */
 154       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 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->Buffer->Width;
 184       height = ctx->Buffer->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->Buffer->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->Buffer->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          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 227
 228          /* May have to leave optimized accum buffer mode */
 229          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 230             ctx->IntegerAccumScaler = value;
 231          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 232             rescale_accum(ctx);
 233
 234          if (ctx->IntegerAccumMode) {
 235             /* simply add integer color values into accum buffer */
 236             GLuint j;
 237             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 238             assert(ctx->IntegerAccumScaler > 0.0);
 239             assert(ctx->IntegerAccumScaler <= 1.0);
 240             for (j = 0; j < height; j++) {
 241
 242                GLuint i, i4;
 243                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 244                for (i = i4 = 0; i < width; i++, i4+=4) {
 245                   acc[i4+0] += rgba[i][RCOMP];
 246                   acc[i4+1] += rgba[i][GCOMP];
 247                   acc[i4+2] += rgba[i][BCOMP];
 248                   acc[i4+3] += rgba[i][ACOMP];
 249                }
 250                acc += width4;
 251                ypos++;
 252             }
 253          }
 254          else {
 255             /* scaled integer accum buffer */
 256             const GLfloat rscale = value * acc_scale / fChanMax;
 257             const GLfloat gscale = value * acc_scale / fChanMax;
 258             const GLfloat bscale = value * acc_scale / fChanMax;
 259             const GLfloat ascale = value * acc_scale / fChanMax;
 260             GLuint j;
 261             for (j=0;j<height;j++) {
 262                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 263                GLuint i;
 264                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 265                for (i=0;i<width;i++) {
 266                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 267                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 268                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 269                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 270                }
 271                ypos++;
 272             }
 273          }
 274          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 275          break;
 276
 277       case GL_LOAD:
 278          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 279
 280          /* This is a change to go into optimized accum buffer mode */
 281          if (value > 0.0 && value <= 1.0) {
 282 #ifdef USE_OPTIMIZED_ACCUM
 283             ctx->IntegerAccumMode = GL_TRUE;
 284 #else
 285             ctx->IntegerAccumMode = GL_FALSE;
 286 #endif
 287             ctx->IntegerAccumScaler = value;
 288          }
 289          else {
 290             ctx->IntegerAccumMode = GL_FALSE;
 291             ctx->IntegerAccumScaler = 0.0;
 292          }
 293
 294          if (ctx->IntegerAccumMode) {
 295             /* just copy values into accum buffer */
 296             GLuint j;
 297             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 298             assert(ctx->IntegerAccumScaler > 0.0);
 299             assert(ctx->IntegerAccumScaler <= 1.0);
 300             for (j = 0; j < height; j++) {
 301                GLuint i, i4;
 302                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 303                for (i = i4 = 0; i < width; i++, i4 += 4) {
 304                   acc[i4+0] = rgba[i][RCOMP];
 305                   acc[i4+1] = rgba[i][GCOMP];
 306                   acc[i4+2] = rgba[i][BCOMP];
 307                   acc[i4+3] = rgba[i][ACOMP];
 308                }
 309                acc += width4;
 310                ypos++;
 311             }
 312          }
 313          else {
 314             /* scaled integer accum buffer */
 315             const GLfloat rscale = value * acc_scale / fChanMax;
 316             const GLfloat gscale = value * acc_scale / fChanMax;
 317             const GLfloat bscale = value * acc_scale / fChanMax;
 318             const GLfloat ascale = value * acc_scale / fChanMax;
 319             const GLfloat d = 3.0 / acc_scale;
 320             GLuint i, j;
 321             for (j = 0; j < height; j++) {
 322                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 323                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 324                for (i=0;i<width;i++) {
 325                   *acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
 326                   *acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
 327                   *acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
 328                   *acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
 329                }
 330                ypos++;
 331             }
 332          }
 333          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 334          break;
 335
 336       case GL_RETURN:
 337          /* May have to leave optimized accum buffer mode */
 338          if (ctx->IntegerAccumMode && value != 1.0)
 339             rescale_accum(ctx);
 340
 341          if (ctx->IntegerAccumMode) {
 342             /* build lookup table to avoid many floating point multiplies */
 343             const GLfloat mult = ctx->IntegerAccumScaler;
 344             static GLchan multTable[32768];
 345             static GLfloat prevMult = 0.0;
 346             GLuint j;
 347             const GLint max = 256 / mult;
 348             if (mult != prevMult) {
 349                assert(max <= 32768);
 350                for (j = 0; j < max; j++)
 351                   multTable[j] = (GLint) ((GLfloat) j * mult + 0.5F);
 352                prevMult = mult;
 353             }
 354
 355             assert(ctx->IntegerAccumScaler > 0.0);
 356             assert(ctx->IntegerAccumScaler <= 1.0);
 357             for (j = 0; j < height; j++) {
 358                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 359                GLuint i, i4;
 360                for (i = i4 = 0; i < width; i++, i4 += 4) {
 361                   ASSERT(acc[i4+0] < max);
 362                   ASSERT(acc[i4+1] < max);
 363                   ASSERT(acc[i4+2] < max);
 364                   ASSERT(acc[i4+3] < max);
 365                   rgba[i][RCOMP] = multTable[acc[i4+0]];
 366                   rgba[i][GCOMP] = multTable[acc[i4+1]];
 367                   rgba[i][BCOMP] = multTable[acc[i4+2]];
 368                   rgba[i][ACOMP] = multTable[acc[i4+3]];
 369                }
 370                if (ctx->Color.SWmasking) {
 371                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 372                }
 373                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 374                                              (const GLubyte (*)[4])rgba, NULL );
 375                ypos++;
 376             }
 377          }
 378          else {
 379             const GLfloat rscale = value / acc_scale * fChanMax;
 380             const GLfloat gscale = value / acc_scale * fChanMax;
 381             const GLfloat bscale = value / acc_scale * fChanMax;
 382             const GLfloat ascale = value / acc_scale * fChanMax;
 383             GLuint i, j;
 384             for (j=0;j<height;j++) {
 385                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 386                for (i=0;i<width;i++) {
 387                   GLint r, g, b, a;
 388                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 389                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 390                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 391                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 392                   rgba[i][RCOMP] = CLAMP( r, 0, iChanMax );
 393                   rgba[i][GCOMP] = CLAMP( g, 0, iChanMax );
 394                   rgba[i][BCOMP] = CLAMP( b, 0, iChanMax );
 395                   rgba[i][ACOMP] = CLAMP( a, 0, iChanMax );
 396                }
 397                if (ctx->Color.SWmasking) {
 398                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 399                }
 400                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 401                                              (const GLubyte (*)[4])rgba, NULL );
 402                ypos++;
 403             }
 404          }
 405          break;
 406
 407       default:
 408          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 409    }
 410 }
 411
 412
 413
 414 /*
 415  * Clear the accumulation Buffer.
 416  */
 417 void gl_clear_accum_buffer( GLcontext *ctx )
 418 {
 419    GLuint buffersize;
 420    GLfloat acc_scale;
 421
 422    if (ctx->Visual->AccumBits==0) {
 423       /* No accumulation buffer! */
 424       return;
 425    }
 426
 427    if (sizeof(GLaccum)==1) {
 428       acc_scale = 127.0;
 429    }
 430    else if (sizeof(GLaccum)==2) {
 431       acc_scale = 32767.0;
 432    }
 433    else {
 434       /* sizeof(GLaccum) > 2 (Cray) */
 435       acc_scale = (float) SHRT_MAX;
 436    }
 437
 438    /* number of pixels */
 439    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 440
 441    if (!ctx->Buffer->Accum) {
 442       /* try to alloc accumulation buffer */
 443       ctx->Buffer->Accum = (GLaccum *)
 444                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 445    }
 446
 447    if (ctx->Buffer->Accum) {
 448       if (ctx->Scissor.Enabled) {
 449          /* Limit clear to scissor box */
 450          GLaccum r, g, b, a;
 451          GLint i, j;
 452          GLint width, height;
 453          GLaccum *row;
 454          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 455          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 456          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 457          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 458          /* size of region to clear */
 459          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 460          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 461          /* ptr to first element to clear */
 462          row = ctx->Buffer->Accum
 463                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 464                       + ctx->Buffer->Xmin);
 465          for (j=0;j<height;j++) {
 466             for (i=0;i<width;i+=4) {
 467                row[i+0] = r;
 468                row[i+1] = g;
 469                row[i+2] = b;
 470                row[i+3] = a;
 471             }
 472             row += 4 * ctx->Buffer->Width;
 473          }
 474       }
 475       else {
 476          /* clear whole buffer */
 477          if (ctx->Accum.ClearColor[0]==0.0 &&
 478              ctx->Accum.ClearColor[1]==0.0 &&
 479              ctx->Accum.ClearColor[2]==0.0 &&
 480              ctx->Accum.ClearColor[3]==0.0) {
 481             /* Black */
 482             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 483          }
 484          else {
 485             /* Not black */
 486             GLaccum *acc, r, g, b, a;
 487             GLuint i;
 488
 489             acc = ctx->Buffer->Accum;
 490             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 491             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 492             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 493             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 494             for (i=0;i<buffersize;i++) {
 495                *acc++ = r;
 496                *acc++ = g;
 497                *acc++ = b;
 498                *acc++ = a;
 499             }
 500          }
 501       }
 502
 503       /* update optimized accum state vars */
 504       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 505           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 506 #ifdef USE_OPTIMIZED_ACCUM
 507          ctx->IntegerAccumMode = GL_TRUE;
 508 #else
 509          ctx->IntegerAccumMode = GL_FALSE;
 510 #endif
 511          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 512       }
 513       else {
 514          ctx->IntegerAccumMode = GL_FALSE;
 515       }
 516    }
 517 }