src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.2 1999/08/19 11:54:28 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
  29 #ifdef PC_HEADER
  30 #include "all.h"
  31 #else
  32 #include <assert.h>
  33 #include <limits.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include "accum.h"
  37 #include "context.h"
  38 #include "macros.h"
  39 #include "masking.h"
  40 #include "span.h"
  41 #include "types.h"
  42 #ifdef XFree86Server
  43 #include "GL/xf86glx.h"
  44 #endif
  45 #endif
  46
  47
  48 /*
  49  * Accumulation buffer notes
  50  *
  51  * Normally, accumulation buffer values are GLshorts with values in
  52  * [-32767, 32767] which represent floating point colors in [-1, 1],
  53  * as suggested by the OpenGL specification.
  54  *
  55  * We optimize for the common case used for full-scene antialiasing:
  56  *    // start with accum buffer cleared to zero
  57  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  58  *    glAccum(GL_ACCUM, w);
  59  *    ...
  60  *    glAccum(GL_ACCUM, w);
  61  *    glAccum(GL_RETURN, 1.0);
  62  * That is, we start with an empty accumulation buffer and accumulate
  63  * n images, each with weight w = 1/n.
  64  * In this scenario, we can simply store unscaled integer values in
  65  * the accum buffer instead of scaled integers.  We'll also keep track
  66  * of the w value so when we do GL_RETURN we simply divide the accumulated
  67  * values by n (=1/w).
  68  * This lets us avoid _many_ int->float->int conversions.
  69  */
  70
  71
  72
  73 void gl_alloc_accum_buffer( GLcontext *ctx )
  74 {
  75    GLint n;
  76
  77    if (ctx->Buffer->Accum) {
  78       free( ctx->Buffer->Accum );
  79       ctx->Buffer->Accum = NULL;
  80    }
  81
  82    /* allocate accumulation buffer if not already present */
  83    n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
  84    ctx->Buffer->Accum = (GLaccum *) malloc( n );
  85    if (!ctx->Buffer->Accum) {
  86       /* unable to setup accumulation buffer */
  87       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  88    }
  89    ctx->IntegerAccumMode = GL_TRUE;
  90    ctx->IntegerAccumScaler = 0.0;
  91 }
  92
  93
  94
  95 void gl_ClearAccum( GLcontext *ctx,
  96                     GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
  97 {
  98    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
  99
 100    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 101    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 102    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 103    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 104 }
 105
 106
 107
 108 /*
 109  * This is called when we fall out of optimized/unscaled accum buffer mode.
 110  * That is, we convert each unscaled accum buffer value into a scaled value
 111  * representing the range[-1, 1].
 112  */
 113 static void rescale_accum( GLcontext *ctx )
 114 {
 115    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 116    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / 255.0);
 117    GLaccum *accum = ctx->Buffer->Accum;
 118    GLuint i;
 119
 120    assert(ctx->IntegerAccumMode);
 121    assert(sizeof(GLchan) == 1);  /* if not true, 255.0 above must be fixed */
 122    assert(accum);
 123
 124    for (i = 0; i < n; i++) {
 125       accum[i] = (GLaccum) (accum[i] * s);
 126    }
 127
 128    ctx->IntegerAccumMode = GL_FALSE;
 129 }
 130
 131
 132
 133 void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
 134 {
 135    GLuint xpos, ypos, width, height, width4;
 136    GLfloat acc_scale;
 137    GLubyte rgba[MAX_WIDTH][4];
 138
 139    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 140
 141    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 142       /* No accumulation buffer! */
 143       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 144       return;
 145    }
 146
 147    if (sizeof(GLaccum)==1) {
 148       acc_scale = 127.0;
 149    }
 150    else if (sizeof(GLaccum)==2) {
 151       acc_scale = 32767.0;
 152    }
 153    else {
 154       /* sizeof(GLaccum) > 2 (Cray) */
 155       acc_scale = (float) SHRT_MAX;
 156    }
 157
 158    if (ctx->NewState)
 159       gl_update_state( ctx );
 160
 161    /* Determine region to operate upon. */
 162    if (ctx->Scissor.Enabled) {
 163       xpos = ctx->Scissor.X;
 164       ypos = ctx->Scissor.Y;
 165       width = ctx->Scissor.Width;
 166       height = ctx->Scissor.Height;
 167    }
 168    else {
 169       /* whole window */
 170       xpos = 0;
 171       ypos = 0;
 172       width = ctx->Buffer->Width;
 173       height = ctx->Buffer->Height;
 174    }
 175
 176    width4 = 4 * width;
 177
 178    switch (op) {
 179       case GL_ADD:
 180          {
 181             const GLaccum intVal = (GLaccum) (value * acc_scale);
 182             GLuint j;
 183             /* May have to leave optimized accum buffer mode */
 184             if (ctx->IntegerAccumMode)
 185                rescale_accum(ctx);
 186             for (j = 0; j < height; j++) {
 187                GLaccum * acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 188                GLuint i;
 189                for (i = 0; i < width4; i++) {
 190                   acc[i] += intVal;
 191                }
 192                ypos++;
 193             }
 194          }
 195          break;
 196
 197       case GL_MULT:
 198          {
 199             GLuint j;
 200             /* May have to leave optimized accum buffer mode */
 201             if (ctx->IntegerAccumMode)
 202                rescale_accum(ctx);
 203             for (j = 0; j < height; j++) {
 204                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 205                GLuint i;
 206                for (i = 0; i < width4; i++) {
 207                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 208                }
 209                ypos++;
 210             }
 211          }
 212          break;
 213
 214       case GL_ACCUM:
 215          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 216
 217          /* May have to leave optimized accum buffer mode */
 218          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 219             ctx->IntegerAccumScaler = value;
 220          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 221             rescale_accum(ctx);
 222
 223          if (ctx->IntegerAccumMode) {
 224             /* simply add integer color values into accum buffer */
 225             GLuint j;
 226             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 227             assert(ctx->IntegerAccumScaler > 0.0);
 228             assert(ctx->IntegerAccumScaler <= 1.0);
 229             for (j = 0; j < height; j++) {
 230
 231                GLuint i, i4;
 232                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 233                for (i = i4 = 0; i < width; i++, i4+=4) {
 234                   acc[i4+0] += rgba[i][RCOMP];
 235                   acc[i4+1] += rgba[i][GCOMP];
 236                   acc[i4+2] += rgba[i][BCOMP];
 237                   acc[i4+3] += rgba[i][ACOMP];
 238                }
 239                acc += width4;
 240                ypos++;
 241             }
 242          }
 243          else {
 244             /* scaled integer accum buffer */
 245             const GLfloat rscale = value * acc_scale / 255.0;
 246             const GLfloat gscale = value * acc_scale / 255.0;
 247             const GLfloat bscale = value * acc_scale / 255.0;
 248             const GLfloat ascale = value * acc_scale / 255.0;
 249             GLuint j;
 250             for (j=0;j<height;j++) {
 251                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 252                GLuint i;
 253                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 254                for (i=0;i<width;i++) {
 255                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 256                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 257                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 258                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 259                }
 260                ypos++;
 261             }
 262          }
 263          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 264          break;
 265
 266       case GL_LOAD:
 267          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 268
 269          /* This is a change to go into optimized accum buffer mode */
 270          if (value > 0.0 && value <= 1.0) {
 271             ctx->IntegerAccumMode = GL_TRUE;
 272             ctx->IntegerAccumScaler = value;
 273          }
 274          else {
 275             ctx->IntegerAccumMode = GL_FALSE;
 276             ctx->IntegerAccumScaler = 0.0;
 277          }
 278
 279          if (ctx->IntegerAccumMode) {
 280             /* just copy values into accum buffer */
 281             GLuint j;
 282             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 283             assert(ctx->IntegerAccumScaler > 0.0);
 284             assert(ctx->IntegerAccumScaler <= 1.0);
 285             for (j = 0; j < height; j++) {
 286                GLuint i, i4;
 287                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 288                for (i = i4 = 0; i < width; i++, i4 += 4) {
 289                   acc[i4+0] = rgba[i][RCOMP];
 290                   acc[i4+1] = rgba[i][GCOMP];
 291                   acc[i4+2] = rgba[i][BCOMP];
 292                   acc[i4+3] = rgba[i][ACOMP];
 293                }
 294                acc += width4;
 295                ypos++;
 296             }
 297          }
 298          else {
 299             /* scaled integer accum buffer */
 300             const GLfloat rscale = value * acc_scale / 255.0;
 301             const GLfloat gscale = value * acc_scale / 255.0;
 302             const GLfloat bscale = value * acc_scale / 255.0;
 303             const GLfloat ascale = value * acc_scale / 255.0;
 304             GLuint i, j;
 305             for (j = 0; j < height; j++) {
 306                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 307                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 308                for (i=0;i<width;i++) {
 309                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );
 310                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );
 311                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );
 312                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );
 313                }
 314                ypos++;
 315             }
 316          }
 317          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 318          break;
 319
 320       case GL_RETURN:
 321          /* May have to leave optimized accum buffer mode */
 322          if (ctx->IntegerAccumMode && value != 1.0)
 323             rescale_accum(ctx);
 324
 325          if (ctx->IntegerAccumMode) {
 326             /* build lookup table to avoid integer divides */
 327             GLint divisor = (GLint) ((1.0F / ctx->IntegerAccumScaler) + 0.5F);
 328             static GLubyte divTable[32768];
 329             static GLint prevDivisor = 0.0;
 330             GLuint j;
 331             if (divisor != prevDivisor) {
 332                assert(divisor * 256 <= 32768);
 333                for (j = 0; j < divisor * 256; j++)
 334                   divTable[j] = j / divisor;
 335                prevDivisor = divisor;
 336             }
 337
 338             assert(ctx->IntegerAccumScaler > 0.0);
 339             assert(ctx->IntegerAccumScaler <= 1.0);
 340             for (j = 0; j < height; j++) {
 341                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 342                GLuint i, i4;
 343                for (i = i4 = 0; i < width; i++, i4 += 4) {
 344                   ASSERT(acc[i4+0] < divisor * 256);
 345                   ASSERT(acc[i4+1] < divisor * 256);
 346                   ASSERT(acc[i4+2] < divisor * 256);
 347                   ASSERT(acc[i4+3] < divisor * 256);
 348                   rgba[i][RCOMP] = divTable[acc[i4+0]];
 349                   rgba[i][GCOMP] = divTable[acc[i4+1]];
 350                   rgba[i][BCOMP] = divTable[acc[i4+2]];
 351                   rgba[i][ACOMP] = divTable[acc[i4+3]];
 352                }
 353                if (ctx->Color.SWmasking) {
 354                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 355                }
 356                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 357                                              (const GLubyte (*)[4])rgba, NULL );
 358                ypos++;
 359             }
 360          }
 361          else {
 362             const GLfloat rscale = value / acc_scale * 255.0F;
 363             const GLfloat gscale = value / acc_scale * 255.0F;
 364             const GLfloat bscale = value / acc_scale * 255.0F;
 365             const GLfloat ascale = value / acc_scale * 255.0F;
 366             GLuint i, j;
 367             for (j=0;j<height;j++) {
 368                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 369                for (i=0;i<width;i++) {
 370                   GLint r, g, b, a;
 371                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 372                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 373                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 374                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 375                   rgba[i][RCOMP] = CLAMP( r, 0, 255 );
 376                   rgba[i][GCOMP] = CLAMP( g, 0, 255 );
 377                   rgba[i][BCOMP] = CLAMP( b, 0, 255 );
 378                   rgba[i][ACOMP] = CLAMP( a, 0, 255 );
 379                }
 380                if (ctx->Color.SWmasking) {
 381                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 382                }
 383                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 384                                              (const GLubyte (*)[4])rgba, NULL );
 385                ypos++;
 386             }
 387          }
 388          break;
 389
 390       default:
 391          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 392    }
 393 }
 394
 395
 396
 397 /*
 398  * Clear the accumulation Buffer.
 399  */
 400 void gl_clear_accum_buffer( GLcontext *ctx )
 401 {
 402    GLuint buffersize;
 403    GLfloat acc_scale;
 404
 405    if (ctx->Visual->AccumBits==0) {
 406       /* No accumulation buffer! */
 407       return;
 408    }
 409
 410    if (sizeof(GLaccum)==1) {
 411       acc_scale = 127.0;
 412    }
 413    else if (sizeof(GLaccum)==2) {
 414       acc_scale = 32767.0;
 415    }
 416    else {
 417       /* sizeof(GLaccum) > 2 (Cray) */
 418       acc_scale = (float) SHRT_MAX;
 419    }
 420
 421    /* number of pixels */
 422    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 423
 424    if (!ctx->Buffer->Accum) {
 425       /* try to alloc accumulation buffer */
 426       ctx->Buffer->Accum = (GLaccum *)
 427                            malloc( buffersize * 4 * sizeof(GLaccum) );
 428    }
 429
 430    if (ctx->Buffer->Accum) {
 431       if (ctx->Scissor.Enabled) {
 432          /* Limit clear to scissor box */
 433          GLaccum r, g, b, a;
 434          GLint i, j;
 435          GLint width, height;
 436          GLaccum *row;
 437          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 438          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 439          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 440          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 441          /* size of region to clear */
 442          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 443          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 444          /* ptr to first element to clear */
 445          row = ctx->Buffer->Accum
 446                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 447                       + ctx->Buffer->Xmin);
 448          for (j=0;j<height;j++) {
 449             for (i=0;i<width;i+=4) {
 450                row[i+0] = r;
 451                row[i+1] = g;
 452                row[i+2] = b;
 453                row[i+3] = a;
 454             }
 455             row += 4 * ctx->Buffer->Width;
 456          }
 457       }
 458       else {
 459          /* clear whole buffer */
 460          if (ctx->Accum.ClearColor[0]==0.0 &&
 461              ctx->Accum.ClearColor[1]==0.0 &&
 462              ctx->Accum.ClearColor[2]==0.0 &&
 463              ctx->Accum.ClearColor[3]==0.0) {
 464             /* Black */
 465             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 466          }
 467          else {
 468             /* Not black */
 469             GLaccum *acc, r, g, b, a;
 470             GLuint i;
 471
 472             acc = ctx->Buffer->Accum;
 473             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 474             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 475             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 476             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 477             for (i=0;i<buffersize;i++) {
 478                *acc++ = r;
 479                *acc++ = g;
 480                *acc++ = b;
 481                *acc++ = a;
 482             }
 483          }
 484       }
 485
 486       /* update optimized accum state vars */
 487       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 488           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 489          ctx->IntegerAccumMode = GL_TRUE;
 490          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 491       }
 492       else {
 493          ctx->IntegerAccumMode = GL_FALSE;
 494       }
 495    }
 496 }