src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.3 1999/10/08 09:27:09 keithw 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 <limits.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #else
  38 #include "GL/xf86glx.h"
  39 #endif
  40 #include "accum.h"
  41 #include "context.h"
  42 #include "macros.h"
  43 #include "masking.h"
  44 #include "span.h"
  45 #include "types.h"
  46 #ifdef XFree86Server
  47 #include "GL/xf86glx.h"
  48 #endif
  49 #endif
  50
  51
  52 /*
  53  * Accumulation buffer notes
  54  *
  55  * Normally, accumulation buffer values are GLshorts with values in
  56  * [-32767, 32767] which represent floating point colors in [-1, 1],
  57  * as suggested by the OpenGL specification.
  58  *
  59  * We optimize for the common case used for full-scene antialiasing:
  60  *    // start with accum buffer cleared to zero
  61  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  62  *    glAccum(GL_ACCUM, w);
  63  *    ...
  64  *    glAccum(GL_ACCUM, w);
  65  *    glAccum(GL_RETURN, 1.0);
  66  * That is, we start with an empty accumulation buffer and accumulate
  67  * n images, each with weight w = 1/n.
  68  * In this scenario, we can simply store unscaled integer values in
  69  * the accum buffer instead of scaled integers.  We'll also keep track
  70  * of the w value so when we do GL_RETURN we simply divide the accumulated
  71  * values by n (=1/w).
  72  * This lets us avoid _many_ int->float->int conversions.
  73  */
  74
  75
  76
  77 void gl_alloc_accum_buffer( GLcontext *ctx )
  78 {
  79    GLint n;
  80
  81    if (ctx->Buffer->Accum) {
  82       free( ctx->Buffer->Accum );
  83       ctx->Buffer->Accum = NULL;
  84    }
  85
  86    /* allocate accumulation buffer if not already present */
  87    n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
  88    ctx->Buffer->Accum = (GLaccum *) malloc( n );
  89    if (!ctx->Buffer->Accum) {
  90       /* unable to setup accumulation buffer */
  91       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  92    }
  93    ctx->IntegerAccumMode = GL_TRUE;
  94    ctx->IntegerAccumScaler = 0.0;
  95 }
  96
  97
  98
  99 void gl_ClearAccum( GLcontext *ctx,
 100                     GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
 101 {
 102    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 103
 104    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 105    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 106    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 107    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 108 }
 109
 110
 111
 112 /*
 113  * This is called when we fall out of optimized/unscaled accum buffer mode.
 114  * That is, we convert each unscaled accum buffer value into a scaled value
 115  * representing the range[-1, 1].
 116  */
 117 static void rescale_accum( GLcontext *ctx )
 118 {
 119    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 120    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / 255.0);
 121    GLaccum *accum = ctx->Buffer->Accum;
 122    GLuint i;
 123
 124    assert(ctx->IntegerAccumMode);
 125    assert(sizeof(GLchan) == 1);  /* if not true, 255.0 above must be fixed */
 126    assert(accum);
 127
 128    for (i = 0; i < n; i++) {
 129       accum[i] = (GLaccum) (accum[i] * s);
 130    }
 131
 132    ctx->IntegerAccumMode = GL_FALSE;
 133 }
 134
 135
 136
 137 void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
 138 {
 139    GLuint xpos, ypos, width, height, width4;
 140    GLfloat acc_scale;
 141    GLubyte rgba[MAX_WIDTH][4];
 142
 143    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 144
 145    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 146       /* No accumulation buffer! */
 147       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 148       return;
 149    }
 150
 151    if (sizeof(GLaccum)==1) {
 152       acc_scale = 127.0;
 153    }
 154    else if (sizeof(GLaccum)==2) {
 155       acc_scale = 32767.0;
 156    }
 157    else {
 158       /* sizeof(GLaccum) > 2 (Cray) */
 159       acc_scale = (float) SHRT_MAX;
 160    }
 161
 162    if (ctx->NewState)
 163       gl_update_state( ctx );
 164
 165    /* Determine region to operate upon. */
 166    if (ctx->Scissor.Enabled) {
 167       xpos = ctx->Scissor.X;
 168       ypos = ctx->Scissor.Y;
 169       width = ctx->Scissor.Width;
 170       height = ctx->Scissor.Height;
 171    }
 172    else {
 173       /* whole window */
 174       xpos = 0;
 175       ypos = 0;
 176       width = ctx->Buffer->Width;
 177       height = ctx->Buffer->Height;
 178    }
 179
 180    width4 = 4 * width;
 181
 182    switch (op) {
 183       case GL_ADD:
 184          {
 185             const GLaccum intVal = (GLaccum) (value * acc_scale);
 186             GLuint j;
 187             /* May have to leave optimized accum buffer mode */
 188             if (ctx->IntegerAccumMode)
 189                rescale_accum(ctx);
 190             for (j = 0; j < height; j++) {
 191                GLaccum * acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 192                GLuint i;
 193                for (i = 0; i < width4; i++) {
 194                   acc[i] += intVal;
 195                }
 196                ypos++;
 197             }
 198          }
 199          break;
 200
 201       case GL_MULT:
 202          {
 203             GLuint j;
 204             /* May have to leave optimized accum buffer mode */
 205             if (ctx->IntegerAccumMode)
 206                rescale_accum(ctx);
 207             for (j = 0; j < height; j++) {
 208                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 209                GLuint i;
 210                for (i = 0; i < width4; i++) {
 211                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 212                }
 213                ypos++;
 214             }
 215          }
 216          break;
 217
 218       case GL_ACCUM:
 219          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 220
 221          /* May have to leave optimized accum buffer mode */
 222          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 223             ctx->IntegerAccumScaler = value;
 224          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 225             rescale_accum(ctx);
 226
 227          if (ctx->IntegerAccumMode) {
 228             /* simply add integer color values into accum buffer */
 229             GLuint j;
 230             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 231             assert(ctx->IntegerAccumScaler > 0.0);
 232             assert(ctx->IntegerAccumScaler <= 1.0);
 233             for (j = 0; j < height; j++) {
 234
 235                GLuint i, i4;
 236                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 237                for (i = i4 = 0; i < width; i++, i4+=4) {
 238                   acc[i4+0] += rgba[i][RCOMP];
 239                   acc[i4+1] += rgba[i][GCOMP];
 240                   acc[i4+2] += rgba[i][BCOMP];
 241                   acc[i4+3] += rgba[i][ACOMP];
 242                }
 243                acc += width4;
 244                ypos++;
 245             }
 246          }
 247          else {
 248             /* scaled integer accum buffer */
 249             const GLfloat rscale = value * acc_scale / 255.0;
 250             const GLfloat gscale = value * acc_scale / 255.0;
 251             const GLfloat bscale = value * acc_scale / 255.0;
 252             const GLfloat ascale = value * acc_scale / 255.0;
 253             GLuint j;
 254             for (j=0;j<height;j++) {
 255                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 256                GLuint i;
 257                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 258                for (i=0;i<width;i++) {
 259                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 260                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 261                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 262                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 263                }
 264                ypos++;
 265             }
 266          }
 267          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 268          break;
 269
 270       case GL_LOAD:
 271          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 272
 273          /* This is a change to go into optimized accum buffer mode */
 274          if (value > 0.0 && value <= 1.0) {
 275             ctx->IntegerAccumMode = GL_TRUE;
 276             ctx->IntegerAccumScaler = value;
 277          }
 278          else {
 279             ctx->IntegerAccumMode = GL_FALSE;
 280             ctx->IntegerAccumScaler = 0.0;
 281          }
 282
 283          if (ctx->IntegerAccumMode) {
 284             /* just copy values into accum buffer */
 285             GLuint j;
 286             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 287             assert(ctx->IntegerAccumScaler > 0.0);
 288             assert(ctx->IntegerAccumScaler <= 1.0);
 289             for (j = 0; j < height; j++) {
 290                GLuint i, i4;
 291                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 292                for (i = i4 = 0; i < width; i++, i4 += 4) {
 293                   acc[i4+0] = rgba[i][RCOMP];
 294                   acc[i4+1] = rgba[i][GCOMP];
 295                   acc[i4+2] = rgba[i][BCOMP];
 296                   acc[i4+3] = rgba[i][ACOMP];
 297                }
 298                acc += width4;
 299                ypos++;
 300             }
 301          }
 302          else {
 303             /* scaled integer accum buffer */
 304             const GLfloat rscale = value * acc_scale / 255.0;
 305             const GLfloat gscale = value * acc_scale / 255.0;
 306             const GLfloat bscale = value * acc_scale / 255.0;
 307             const GLfloat ascale = value * acc_scale / 255.0;
 308             GLuint i, j;
 309             for (j = 0; j < height; j++) {
 310                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 311                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 312                for (i=0;i<width;i++) {
 313                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );
 314                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );
 315                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );
 316                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );
 317                }
 318                ypos++;
 319             }
 320          }
 321          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 322          break;
 323
 324       case GL_RETURN:
 325          /* May have to leave optimized accum buffer mode */
 326          if (ctx->IntegerAccumMode && value != 1.0)
 327             rescale_accum(ctx);
 328
 329          if (ctx->IntegerAccumMode) {
 330             /* build lookup table to avoid integer divides */
 331             GLint divisor = (GLint) ((1.0F / ctx->IntegerAccumScaler) + 0.5F);
 332             static GLubyte divTable[32768];
 333             static GLint prevDivisor = 0.0;
 334             GLuint j;
 335             if (divisor != prevDivisor) {
 336                assert(divisor * 256 <= 32768);
 337                for (j = 0; j < divisor * 256; j++)
 338                   divTable[j] = j / divisor;
 339                prevDivisor = divisor;
 340             }
 341
 342             assert(ctx->IntegerAccumScaler > 0.0);
 343             assert(ctx->IntegerAccumScaler <= 1.0);
 344             for (j = 0; j < height; j++) {
 345                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 346                GLuint i, i4;
 347                for (i = i4 = 0; i < width; i++, i4 += 4) {
 348                   ASSERT(acc[i4+0] < divisor * 256);
 349                   ASSERT(acc[i4+1] < divisor * 256);
 350                   ASSERT(acc[i4+2] < divisor * 256);
 351                   ASSERT(acc[i4+3] < divisor * 256);
 352                   rgba[i][RCOMP] = divTable[acc[i4+0]];
 353                   rgba[i][GCOMP] = divTable[acc[i4+1]];
 354                   rgba[i][BCOMP] = divTable[acc[i4+2]];
 355                   rgba[i][ACOMP] = divTable[acc[i4+3]];
 356                }
 357                if (ctx->Color.SWmasking) {
 358                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 359                }
 360                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 361                                              (const GLubyte (*)[4])rgba, NULL );
 362                ypos++;
 363             }
 364          }
 365          else {
 366             const GLfloat rscale = value / acc_scale * 255.0F;
 367             const GLfloat gscale = value / acc_scale * 255.0F;
 368             const GLfloat bscale = value / acc_scale * 255.0F;
 369             const GLfloat ascale = value / acc_scale * 255.0F;
 370             GLuint i, j;
 371             for (j=0;j<height;j++) {
 372                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 373                for (i=0;i<width;i++) {
 374                   GLint r, g, b, a;
 375                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 376                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 377                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 378                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 379                   rgba[i][RCOMP] = CLAMP( r, 0, 255 );
 380                   rgba[i][GCOMP] = CLAMP( g, 0, 255 );
 381                   rgba[i][BCOMP] = CLAMP( b, 0, 255 );
 382                   rgba[i][ACOMP] = CLAMP( a, 0, 255 );
 383                }
 384                if (ctx->Color.SWmasking) {
 385                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 386                }
 387                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 388                                              (const GLubyte (*)[4])rgba, NULL );
 389                ypos++;
 390             }
 391          }
 392          break;
 393
 394       default:
 395          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 396    }
 397 }
 398
 399
 400
 401 /*
 402  * Clear the accumulation Buffer.
 403  */
 404 void gl_clear_accum_buffer( GLcontext *ctx )
 405 {
 406    GLuint buffersize;
 407    GLfloat acc_scale;
 408
 409    if (ctx->Visual->AccumBits==0) {
 410       /* No accumulation buffer! */
 411       return;
 412    }
 413
 414    if (sizeof(GLaccum)==1) {
 415       acc_scale = 127.0;
 416    }
 417    else if (sizeof(GLaccum)==2) {
 418       acc_scale = 32767.0;
 419    }
 420    else {
 421       /* sizeof(GLaccum) > 2 (Cray) */
 422       acc_scale = (float) SHRT_MAX;
 423    }
 424
 425    /* number of pixels */
 426    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 427
 428    if (!ctx->Buffer->Accum) {
 429       /* try to alloc accumulation buffer */
 430       ctx->Buffer->Accum = (GLaccum *)
 431                            malloc( buffersize * 4 * sizeof(GLaccum) );
 432    }
 433
 434    if (ctx->Buffer->Accum) {
 435       if (ctx->Scissor.Enabled) {
 436          /* Limit clear to scissor box */
 437          GLaccum r, g, b, a;
 438          GLint i, j;
 439          GLint width, height;
 440          GLaccum *row;
 441          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 442          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 443          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 444          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 445          /* size of region to clear */
 446          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 447          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 448          /* ptr to first element to clear */
 449          row = ctx->Buffer->Accum
 450                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 451                       + ctx->Buffer->Xmin);
 452          for (j=0;j<height;j++) {
 453             for (i=0;i<width;i+=4) {
 454                row[i+0] = r;
 455                row[i+1] = g;
 456                row[i+2] = b;
 457                row[i+3] = a;
 458             }
 459             row += 4 * ctx->Buffer->Width;
 460          }
 461       }
 462       else {
 463          /* clear whole buffer */
 464          if (ctx->Accum.ClearColor[0]==0.0 &&
 465              ctx->Accum.ClearColor[1]==0.0 &&
 466              ctx->Accum.ClearColor[2]==0.0 &&
 467              ctx->Accum.ClearColor[3]==0.0) {
 468             /* Black */
 469             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 470          }
 471          else {
 472             /* Not black */
 473             GLaccum *acc, r, g, b, a;
 474             GLuint i;
 475
 476             acc = ctx->Buffer->Accum;
 477             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 478             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 479             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 480             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 481             for (i=0;i<buffersize;i++) {
 482                *acc++ = r;
 483                *acc++ = g;
 484                *acc++ = b;
 485                *acc++ = a;
 486             }
 487          }
 488       }
 489
 490       /* update optimized accum state vars */
 491       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 492           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 493          ctx->IntegerAccumMode = GL_TRUE;
 494          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 495       }
 496       else {
 497          ctx->IntegerAccumMode = GL_FALSE;
 498       }
 499    }
 500 }