src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.1 1999/08/19 00:55:41 jtg 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 #ifdef PC_HEADER
  29 #include "all.h"
  30 #else
  31 #include <assert.h>
  32 #include <limits.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include "accum.h"
  36 #include "context.h"
  37 #include "macros.h"
  38 #include "masking.h"
  39 #include "span.h"
  40 #include "types.h"
  41 #ifdef XFree86Server
  42 #include "GL/xf86glx.h"
  43 #endif
  44 #endif
  45
  46
  47 /*
  48  * Accumulation buffer notes
  49  *
  50  * Normally, accumulation buffer values are GLshorts with values in
  51  * [-32767, 32767] which represent floating point colors in [-1, 1],
  52  * as suggested by the OpenGL specification.
  53  *
  54  * We optimize for the common case used for full-scene antialiasing:
  55  *    // start with accum buffer cleared to zero
  56  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  57  *    glAccum(GL_ACCUM, w);
  58  *    ...
  59  *    glAccum(GL_ACCUM, w);
  60  *    glAccum(GL_RETURN, 1.0);
  61  * That is, we start with an empty accumulation buffer and accumulate
  62  * n images, each with weight w = 1/n.
  63  * In this scenario, we can simply store unscaled integer values in
  64  * the accum buffer instead of scaled integers.  We'll also keep track
  65  * of the w value so when we do GL_RETURN we simply divide the accumulated
  66  * values by n (=1/w).
  67  * This lets us avoid _many_ int->float->int conversions.
  68  */
  69
  70
  71
  72 void gl_alloc_accum_buffer( GLcontext *ctx )
  73 {
  74    GLint n;
  75
  76    if (ctx->Buffer->Accum) {
  77       free( ctx->Buffer->Accum );
  78       ctx->Buffer->Accum = NULL;
  79    }
  80
  81    /* allocate accumulation buffer if not already present */
  82    n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
  83    ctx->Buffer->Accum = (GLaccum *) malloc( n );
  84    if (!ctx->Buffer->Accum) {
  85       /* unable to setup accumulation buffer */
  86       gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
  87    }
  88    ctx->IntegerAccumMode = GL_TRUE;
  89    ctx->IntegerAccumScaler = 0.0;
  90 }
  91
  92
  93
  94 void gl_ClearAccum( GLcontext *ctx,
  95                     GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
  96 {
  97    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
  98
  99    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 100    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 101    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 102    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 103 }
 104
 105
 106
 107 /*
 108  * This is called when we fall out of optimized/unscaled accum buffer mode.
 109  * That is, we convert each unscaled accum buffer value into a scaled value
 110  * representing the range[-1, 1].
 111  */
 112 static void rescale_accum( GLcontext *ctx )
 113 {
 114    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 115    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / 255.0);
 116    GLaccum *accum = ctx->Buffer->Accum;
 117    GLuint i;
 118
 119    assert(ctx->IntegerAccumMode);
 120    assert(sizeof(GLchan) == 1);  /* if not true, 255.0 above must be fixed */
 121    assert(accum);
 122
 123    for (i = 0; i < n; i++) {
 124       accum[i] = (GLaccum) (accum[i] * s);
 125    }
 126
 127    ctx->IntegerAccumMode = GL_FALSE;
 128 }
 129
 130
 131
 132 void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
 133 {
 134    GLuint xpos, ypos, width, height, width4;
 135    GLfloat acc_scale;
 136    GLubyte rgba[MAX_WIDTH][4];
 137
 138    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 139
 140    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 141       /* No accumulation buffer! */
 142       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 143       return;
 144    }
 145
 146    if (sizeof(GLaccum)==1) {
 147       acc_scale = 127.0;
 148    }
 149    else if (sizeof(GLaccum)==2) {
 150       acc_scale = 32767.0;
 151    }
 152    else {
 153       /* sizeof(GLaccum) > 2 (Cray) */
 154       acc_scale = (float) SHRT_MAX;
 155    }
 156
 157    if (ctx->NewState)
 158       gl_update_state( ctx );
 159
 160    /* Determine region to operate upon. */
 161    if (ctx->Scissor.Enabled) {
 162       xpos = ctx->Scissor.X;
 163       ypos = ctx->Scissor.Y;
 164       width = ctx->Scissor.Width;
 165       height = ctx->Scissor.Height;
 166    }
 167    else {
 168       /* whole window */
 169       xpos = 0;
 170       ypos = 0;
 171       width = ctx->Buffer->Width;
 172       height = ctx->Buffer->Height;
 173    }
 174
 175    width4 = 4 * width;
 176
 177    switch (op) {
 178       case GL_ADD:
 179          {
 180             const GLaccum intVal = (GLaccum) (value * acc_scale);
 181             GLuint j;
 182             /* May have to leave optimized accum buffer mode */
 183             if (ctx->IntegerAccumMode)
 184                rescale_accum(ctx);
 185             for (j = 0; j < height; j++) {
 186                GLaccum * acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 187                GLuint i;
 188                for (i = 0; i < width4; i++) {
 189                   acc[i] += intVal;
 190                }
 191                ypos++;
 192             }
 193          }
 194          break;
 195
 196       case GL_MULT:
 197          {
 198             GLuint j;
 199             /* May have to leave optimized accum buffer mode */
 200             if (ctx->IntegerAccumMode)
 201                rescale_accum(ctx);
 202             for (j = 0; j < height; j++) {
 203                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 204                GLuint i;
 205                for (i = 0; i < width4; i++) {
 206                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 207                }
 208                ypos++;
 209             }
 210          }
 211          break;
 212
 213       case GL_ACCUM:
 214          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 215
 216          /* May have to leave optimized accum buffer mode */
 217          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 218             ctx->IntegerAccumScaler = value;
 219          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 220             rescale_accum(ctx);
 221
 222          if (ctx->IntegerAccumMode) {
 223             /* simply add integer color values into accum buffer */
 224             GLuint j;
 225             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 226             assert(ctx->IntegerAccumScaler > 0.0);
 227             assert(ctx->IntegerAccumScaler <= 1.0);
 228             for (j = 0; j < height; j++) {
 229
 230                GLuint i, i4;
 231                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 232                for (i = i4 = 0; i < width; i++, i4+=4) {
 233                   acc[i4+0] += rgba[i][RCOMP];
 234                   acc[i4+1] += rgba[i][GCOMP];
 235                   acc[i4+2] += rgba[i][BCOMP];
 236                   acc[i4+3] += rgba[i][ACOMP];
 237                }
 238                acc += width4;
 239                ypos++;
 240             }
 241          }
 242          else {
 243             /* scaled integer accum buffer */
 244             const GLfloat rscale = value * acc_scale / 255.0;
 245             const GLfloat gscale = value * acc_scale / 255.0;
 246             const GLfloat bscale = value * acc_scale / 255.0;
 247             const GLfloat ascale = value * acc_scale / 255.0;
 248             GLuint j;
 249             for (j=0;j<height;j++) {
 250                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 251                GLuint i;
 252                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 253                for (i=0;i<width;i++) {
 254                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 255                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 256                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 257                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 258                }
 259                ypos++;
 260             }
 261          }
 262          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 263          break;
 264
 265       case GL_LOAD:
 266          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 267
 268          /* This is a change to go into optimized accum buffer mode */
 269          if (value > 0.0 && value <= 1.0) {
 270             ctx->IntegerAccumMode = GL_TRUE;
 271             ctx->IntegerAccumScaler = value;
 272          }
 273          else {
 274             ctx->IntegerAccumMode = GL_FALSE;
 275             ctx->IntegerAccumScaler = 0.0;
 276          }
 277
 278          if (ctx->IntegerAccumMode) {
 279             /* just copy values into accum buffer */
 280             GLuint j;
 281             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 282             assert(ctx->IntegerAccumScaler > 0.0);
 283             assert(ctx->IntegerAccumScaler <= 1.0);
 284             for (j = 0; j < height; j++) {
 285                GLuint i, i4;
 286                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 287                for (i = i4 = 0; i < width; i++, i4 += 4) {
 288                   acc[i4+0] = rgba[i][RCOMP];
 289                   acc[i4+1] = rgba[i][GCOMP];
 290                   acc[i4+2] = rgba[i][BCOMP];
 291                   acc[i4+3] = rgba[i][ACOMP];
 292                }
 293                acc += width4;
 294                ypos++;
 295             }
 296          }
 297          else {
 298             /* scaled integer accum buffer */
 299             const GLfloat rscale = value * acc_scale / 255.0;
 300             const GLfloat gscale = value * acc_scale / 255.0;
 301             const GLfloat bscale = value * acc_scale / 255.0;
 302             const GLfloat ascale = value * acc_scale / 255.0;
 303             GLuint i, j;
 304             for (j = 0; j < height; j++) {
 305                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 306                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 307                for (i=0;i<width;i++) {
 308                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );
 309                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );
 310                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );
 311                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );
 312                }
 313                ypos++;
 314             }
 315          }
 316          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 317          break;
 318
 319       case GL_RETURN:
 320          /* May have to leave optimized accum buffer mode */
 321          if (ctx->IntegerAccumMode && value != 1.0)
 322             rescale_accum(ctx);
 323
 324          if (ctx->IntegerAccumMode) {
 325             /* build lookup table to avoid integer divides */
 326             GLint divisor = (GLint) ((1.0F / ctx->IntegerAccumScaler) + 0.5F);
 327             static GLubyte divTable[32768];
 328             static GLint prevDivisor = 0.0;
 329             GLuint j;
 330             if (divisor != prevDivisor) {
 331                assert(divisor * 256 <= 32768);
 332                for (j = 0; j < divisor * 256; j++)
 333                   divTable[j] = j / divisor;
 334                prevDivisor = divisor;
 335             }
 336
 337             assert(ctx->IntegerAccumScaler > 0.0);
 338             assert(ctx->IntegerAccumScaler <= 1.0);
 339             for (j = 0; j < height; j++) {
 340                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 341                GLuint i, i4;
 342                for (i = i4 = 0; i < width; i++, i4 += 4) {
 343                   ASSERT(acc[i4+0] < divisor * 256);
 344                   ASSERT(acc[i4+1] < divisor * 256);
 345                   ASSERT(acc[i4+2] < divisor * 256);
 346                   ASSERT(acc[i4+3] < divisor * 256);
 347                   rgba[i][RCOMP] = divTable[acc[i4+0]];
 348                   rgba[i][GCOMP] = divTable[acc[i4+1]];
 349                   rgba[i][BCOMP] = divTable[acc[i4+2]];
 350                   rgba[i][ACOMP] = divTable[acc[i4+3]];
 351                }
 352                if (ctx->Color.SWmasking) {
 353                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 354                }
 355                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 356                                              (const GLubyte (*)[4])rgba, NULL );
 357                ypos++;
 358             }
 359          }
 360          else {
 361             const GLfloat rscale = value / acc_scale * 255.0F;
 362             const GLfloat gscale = value / acc_scale * 255.0F;
 363             const GLfloat bscale = value / acc_scale * 255.0F;
 364             const GLfloat ascale = value / acc_scale * 255.0F;
 365             GLuint i, j;
 366             for (j=0;j<height;j++) {
 367                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 368                for (i=0;i<width;i++) {
 369                   GLint r, g, b, a;
 370                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 371                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 372                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 373                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 374                   rgba[i][RCOMP] = CLAMP( r, 0, 255 );
 375                   rgba[i][GCOMP] = CLAMP( g, 0, 255 );
 376                   rgba[i][BCOMP] = CLAMP( b, 0, 255 );
 377                   rgba[i][ACOMP] = CLAMP( a, 0, 255 );
 378                }
 379                if (ctx->Color.SWmasking) {
 380                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 381                }
 382                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 383                                              (const GLubyte (*)[4])rgba, NULL );
 384                ypos++;
 385             }
 386          }
 387          break;
 388
 389       default:
 390          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 391    }
 392 }
 393
 394
 395
 396 /*
 397  * Clear the accumulation Buffer.
 398  */
 399 void gl_clear_accum_buffer( GLcontext *ctx )
 400 {
 401    GLuint buffersize;
 402    GLfloat acc_scale;
 403
 404    if (ctx->Visual->AccumBits==0) {
 405       /* No accumulation buffer! */
 406       return;
 407    }
 408
 409    if (sizeof(GLaccum)==1) {
 410       acc_scale = 127.0;
 411    }
 412    else if (sizeof(GLaccum)==2) {
 413       acc_scale = 32767.0;
 414    }
 415    else {
 416       /* sizeof(GLaccum) > 2 (Cray) */
 417       acc_scale = (float) SHRT_MAX;
 418    }
 419
 420    /* number of pixels */
 421    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 422
 423    if (!ctx->Buffer->Accum) {
 424       /* try to alloc accumulation buffer */
 425       ctx->Buffer->Accum = (GLaccum *)
 426                            malloc( buffersize * 4 * sizeof(GLaccum) );
 427    }
 428
 429    if (ctx->Buffer->Accum) {
 430       if (ctx->Scissor.Enabled) {
 431          /* Limit clear to scissor box */
 432          GLaccum r, g, b, a;
 433          GLint i, j;
 434          GLint width, height;
 435          GLaccum *row;
 436          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 437          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 438          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 439          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 440          /* size of region to clear */
 441          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 442          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 443          /* ptr to first element to clear */
 444          row = ctx->Buffer->Accum
 445                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 446                       + ctx->Buffer->Xmin);
 447          for (j=0;j<height;j++) {
 448             for (i=0;i<width;i+=4) {
 449                row[i+0] = r;
 450                row[i+1] = g;
 451                row[i+2] = b;
 452                row[i+3] = a;
 453             }
 454             row += 4 * ctx->Buffer->Width;
 455          }
 456       }
 457       else {
 458          /* clear whole buffer */
 459          if (ctx->Accum.ClearColor[0]==0.0 &&
 460              ctx->Accum.ClearColor[1]==0.0 &&
 461              ctx->Accum.ClearColor[2]==0.0 &&
 462              ctx->Accum.ClearColor[3]==0.0) {
 463             /* Black */
 464             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 465          }
 466          else {
 467             /* Not black */
 468             GLaccum *acc, r, g, b, a;
 469             GLuint i;
 470
 471             acc = ctx->Buffer->Accum;
 472             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 473             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 474             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 475             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 476             for (i=0;i<buffersize;i++) {
 477                *acc++ = r;
 478                *acc++ = g;
 479                *acc++ = b;
 480                *acc++ = a;
 481             }
 482          }
 483       }
 484
 485       /* update optimized accum state vars */
 486       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 487           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 488          ctx->IntegerAccumMode = GL_TRUE;
 489          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 490       }
 491       else {
 492          ctx->IntegerAccumMode = GL_FALSE;
 493       }
 494    }
 495 }