src/mesa/main/accum.c

   1 /* $Id: accum.c,v 1.6 1999/10/13 18:42:49 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 <limits.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #else
  38 #include "GL/xf86glx.h"
  39 #endif
  40 #include <assert.h>
  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 #ifdef XFree86Server
  48 #include "GL/xf86glx.h"
  49 #endif
  50 #endif
  51
  52
  53 /*
  54  * Accumulation buffer notes
  55  *
  56  * Normally, accumulation buffer values are GLshorts with values in
  57  * [-32767, 32767] which represent floating point colors in [-1, 1],
  58  * as suggested by the OpenGL specification.
  59  *
  60  * We optimize for the common case used for full-scene antialiasing:
  61  *    // start with accum buffer cleared to zero
  62  *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
  63  *    glAccum(GL_ACCUM, w);
  64  *    ...
  65  *    glAccum(GL_ACCUM, w);
  66  *    glAccum(GL_RETURN, 1.0);
  67  * That is, we start with an empty accumulation buffer and accumulate
  68  * n images, each with weight w = 1/n.
  69  * In this scenario, we can simply store unscaled integer values in
  70  * the accum buffer instead of scaled integers.  We'll also keep track
  71  * of the w value so when we do GL_RETURN we simply divide the accumulated
  72  * values by n (=1/w).
  73  * This lets us avoid _many_ int->float->int conversions.
  74  */
  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    ctx->IntegerAccumMode = GL_TRUE;
  95    ctx->IntegerAccumScaler = 0.0;
  96 }
  97
  98
  99
 100 void gl_ClearAccum( GLcontext *ctx,
 101                     GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
 102 {
 103    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 104
 105    ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
 106    ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
 107    ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
 108    ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
 109 }
 110
 111
 112
 113 /*
 114  * This is called when we fall out of optimized/unscaled accum buffer mode.
 115  * That is, we convert each unscaled accum buffer value into a scaled value
 116  * representing the range[-1, 1].
 117  */
 118 static void rescale_accum( GLcontext *ctx )
 119 {
 120    const GLuint n = ctx->Buffer->Width * ctx->Buffer->Height * 4;
 121    const GLfloat s = ctx->IntegerAccumScaler * (32767.0 / 255.0);
 122    GLaccum *accum = ctx->Buffer->Accum;
 123    GLuint i;
 124
 125    assert(ctx->IntegerAccumMode);
 126    assert(sizeof(GLchan) == 1);  /* if not true, 255.0 above must be fixed */
 127    assert(accum);
 128
 129    for (i = 0; i < n; i++) {
 130       accum[i] = (GLaccum) (accum[i] * s);
 131    }
 132
 133    ctx->IntegerAccumMode = GL_FALSE;
 134 }
 135
 136
 137
 138 void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
 139 {
 140    GLuint xpos, ypos, width, height, width4;
 141    GLfloat acc_scale;
 142    GLubyte rgba[MAX_WIDTH][4];
 143
 144    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAccum");
 145
 146    if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
 147       /* No accumulation buffer! */
 148       gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
 149       return;
 150    }
 151
 152    if (sizeof(GLaccum)==1) {
 153       acc_scale = 127.0;
 154    }
 155    else if (sizeof(GLaccum)==2) {
 156       acc_scale = 32767.0;
 157    }
 158    else {
 159       /* sizeof(GLaccum) > 2 (Cray) */
 160       acc_scale = (float) SHRT_MAX;
 161    }
 162
 163    if (ctx->NewState)
 164       gl_update_state( ctx );
 165
 166    /* Determine region to operate upon. */
 167    if (ctx->Scissor.Enabled) {
 168       xpos = ctx->Scissor.X;
 169       ypos = ctx->Scissor.Y;
 170       width = ctx->Scissor.Width;
 171       height = ctx->Scissor.Height;
 172    }
 173    else {
 174       /* whole window */
 175       xpos = 0;
 176       ypos = 0;
 177       width = ctx->Buffer->Width;
 178       height = ctx->Buffer->Height;
 179    }
 180
 181    width4 = 4 * width;
 182
 183    switch (op) {
 184       case GL_ADD:
 185          {
 186             const GLaccum intVal = (GLaccum) (value * acc_scale);
 187             GLuint j;
 188             /* May have to leave optimized accum buffer mode */
 189             if (ctx->IntegerAccumMode)
 190                rescale_accum(ctx);
 191             for (j = 0; j < height; j++) {
 192                GLaccum * acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 193                GLuint i;
 194                for (i = 0; i < width4; i++) {
 195                   acc[i] += intVal;
 196                }
 197                ypos++;
 198             }
 199          }
 200          break;
 201
 202       case GL_MULT:
 203          {
 204             GLuint j;
 205             /* May have to leave optimized accum buffer mode */
 206             if (ctx->IntegerAccumMode)
 207                rescale_accum(ctx);
 208             for (j = 0; j < height; j++) {
 209                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + 4 * xpos;
 210                GLuint i;
 211                for (i = 0; i < width4; i++) {
 212                   acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
 213                }
 214                ypos++;
 215             }
 216          }
 217          break;
 218
 219       case GL_ACCUM:
 220          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 221
 222          /* May have to leave optimized accum buffer mode */
 223          if (ctx->IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
 224             ctx->IntegerAccumScaler = value;
 225          if (ctx->IntegerAccumMode && value != ctx->IntegerAccumScaler)
 226             rescale_accum(ctx);
 227
 228          if (ctx->IntegerAccumMode) {
 229             /* simply add integer color values into accum buffer */
 230             GLuint j;
 231             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 232             assert(ctx->IntegerAccumScaler > 0.0);
 233             assert(ctx->IntegerAccumScaler <= 1.0);
 234             for (j = 0; j < height; j++) {
 235
 236                GLuint i, i4;
 237                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 238                for (i = i4 = 0; i < width; i++, i4+=4) {
 239                   acc[i4+0] += rgba[i][RCOMP];
 240                   acc[i4+1] += rgba[i][GCOMP];
 241                   acc[i4+2] += rgba[i][BCOMP];
 242                   acc[i4+3] += rgba[i][ACOMP];
 243                }
 244                acc += width4;
 245                ypos++;
 246             }
 247          }
 248          else {
 249             /* scaled integer accum buffer */
 250             const GLfloat rscale = value * acc_scale / 255.0;
 251             const GLfloat gscale = value * acc_scale / 255.0;
 252             const GLfloat bscale = value * acc_scale / 255.0;
 253             const GLfloat ascale = value * acc_scale / 255.0;
 254             GLuint j;
 255             for (j=0;j<height;j++) {
 256                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 257                GLuint i;
 258                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 259                for (i=0;i<width;i++) {
 260                   *acc += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );  acc++;
 261                   *acc += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );  acc++;
 262                   *acc += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );  acc++;
 263                   *acc += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );  acc++;
 264                }
 265                ypos++;
 266             }
 267          }
 268          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 269          break;
 270
 271       case GL_LOAD:
 272          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.DriverReadBuffer );
 273
 274          /* This is a change to go into optimized accum buffer mode */
 275          if (value > 0.0 && value <= 1.0) {
 276             ctx->IntegerAccumMode = GL_TRUE;
 277             ctx->IntegerAccumScaler = value;
 278          }
 279          else {
 280             ctx->IntegerAccumMode = GL_FALSE;
 281             ctx->IntegerAccumScaler = 0.0;
 282          }
 283
 284          if (ctx->IntegerAccumMode) {
 285             /* just copy values into accum buffer */
 286             GLuint j;
 287             GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 288             assert(ctx->IntegerAccumScaler > 0.0);
 289             assert(ctx->IntegerAccumScaler <= 1.0);
 290             for (j = 0; j < height; j++) {
 291                GLuint i, i4;
 292                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 293                for (i = i4 = 0; i < width; i++, i4 += 4) {
 294                   acc[i4+0] = rgba[i][RCOMP];
 295                   acc[i4+1] = rgba[i][GCOMP];
 296                   acc[i4+2] = rgba[i][BCOMP];
 297                   acc[i4+3] = rgba[i][ACOMP];
 298                }
 299                acc += width4;
 300                ypos++;
 301             }
 302          }
 303          else {
 304             /* scaled integer accum buffer */
 305             const GLfloat rscale = value * acc_scale / 255.0;
 306             const GLfloat gscale = value * acc_scale / 255.0;
 307             const GLfloat bscale = value * acc_scale / 255.0;
 308             const GLfloat ascale = value * acc_scale / 255.0;
 309             GLuint i, j;
 310             for (j = 0; j < height; j++) {
 311                GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos * 4;
 312                gl_read_rgba_span(ctx, width, xpos, ypos, rgba);
 313                for (i=0;i<width;i++) {
 314                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );
 315                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );
 316                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );
 317                   *acc++ = (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );
 318                }
 319                ypos++;
 320             }
 321          }
 322          (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DriverDrawBuffer );
 323          break;
 324
 325       case GL_RETURN:
 326          /* May have to leave optimized accum buffer mode */
 327          if (ctx->IntegerAccumMode && value != 1.0)
 328             rescale_accum(ctx);
 329
 330          if (ctx->IntegerAccumMode) {
 331             /* build lookup table to avoid integer divides */
 332             GLint divisor = (GLint) ((1.0F / ctx->IntegerAccumScaler) + 0.5F);
 333             static GLubyte divTable[32768];
 334             static GLint prevDivisor = 0.0;
 335             GLuint j;
 336             if (divisor != prevDivisor) {
 337                assert(divisor * 256 <= 32768);
 338                for (j = 0; j < divisor * 256; j++)
 339                   divTable[j] = j / divisor;
 340                prevDivisor = divisor;
 341             }
 342
 343             assert(ctx->IntegerAccumScaler > 0.0);
 344             assert(ctx->IntegerAccumScaler <= 1.0);
 345             for (j = 0; j < height; j++) {
 346                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 347                GLuint i, i4;
 348                for (i = i4 = 0; i < width; i++, i4 += 4) {
 349                   ASSERT(acc[i4+0] < divisor * 256);
 350                   ASSERT(acc[i4+1] < divisor * 256);
 351                   ASSERT(acc[i4+2] < divisor * 256);
 352                   ASSERT(acc[i4+3] < divisor * 256);
 353                   rgba[i][RCOMP] = divTable[acc[i4+0]];
 354                   rgba[i][GCOMP] = divTable[acc[i4+1]];
 355                   rgba[i][BCOMP] = divTable[acc[i4+2]];
 356                   rgba[i][ACOMP] = divTable[acc[i4+3]];
 357                }
 358                if (ctx->Color.SWmasking) {
 359                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 360                }
 361                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 362                                              (const GLubyte (*)[4])rgba, NULL );
 363                ypos++;
 364             }
 365          }
 366          else {
 367             const GLfloat rscale = value / acc_scale * 255.0F;
 368             const GLfloat gscale = value / acc_scale * 255.0F;
 369             const GLfloat bscale = value / acc_scale * 255.0F;
 370             const GLfloat ascale = value / acc_scale * 255.0F;
 371             GLuint i, j;
 372             for (j=0;j<height;j++) {
 373                const GLaccum *acc = ctx->Buffer->Accum + ypos * width4 + xpos*4;
 374                for (i=0;i<width;i++) {
 375                   GLint r, g, b, a;
 376                   r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
 377                   g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
 378                   b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
 379                   a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
 380                   rgba[i][RCOMP] = CLAMP( r, 0, 255 );
 381                   rgba[i][GCOMP] = CLAMP( g, 0, 255 );
 382                   rgba[i][BCOMP] = CLAMP( b, 0, 255 );
 383                   rgba[i][ACOMP] = CLAMP( a, 0, 255 );
 384                }
 385                if (ctx->Color.SWmasking) {
 386                   gl_mask_rgba_span( ctx, width, xpos, ypos, rgba );
 387                }
 388                (*ctx->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
 389                                              (const GLubyte (*)[4])rgba, NULL );
 390                ypos++;
 391             }
 392          }
 393          break;
 394
 395       default:
 396          gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
 397    }
 398 }
 399
 400
 401
 402 /*
 403  * Clear the accumulation Buffer.
 404  */
 405 void gl_clear_accum_buffer( GLcontext *ctx )
 406 {
 407    GLuint buffersize;
 408    GLfloat acc_scale;
 409
 410    if (ctx->Visual->AccumBits==0) {
 411       /* No accumulation buffer! */
 412       return;
 413    }
 414
 415    if (sizeof(GLaccum)==1) {
 416       acc_scale = 127.0;
 417    }
 418    else if (sizeof(GLaccum)==2) {
 419       acc_scale = 32767.0;
 420    }
 421    else {
 422       /* sizeof(GLaccum) > 2 (Cray) */
 423       acc_scale = (float) SHRT_MAX;
 424    }
 425
 426    /* number of pixels */
 427    buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 428
 429    if (!ctx->Buffer->Accum) {
 430       /* try to alloc accumulation buffer */
 431       ctx->Buffer->Accum = (GLaccum *)
 432                            MALLOC( buffersize * 4 * sizeof(GLaccum) );
 433    }
 434
 435    if (ctx->Buffer->Accum) {
 436       if (ctx->Scissor.Enabled) {
 437          /* Limit clear to scissor box */
 438          GLaccum r, g, b, a;
 439          GLint i, j;
 440          GLint width, height;
 441          GLaccum *row;
 442          r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 443          g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 444          b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 445          a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 446          /* size of region to clear */
 447          width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
 448          height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
 449          /* ptr to first element to clear */
 450          row = ctx->Buffer->Accum
 451                + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
 452                       + ctx->Buffer->Xmin);
 453          for (j=0;j<height;j++) {
 454             for (i=0;i<width;i+=4) {
 455                row[i+0] = r;
 456                row[i+1] = g;
 457                row[i+2] = b;
 458                row[i+3] = a;
 459             }
 460             row += 4 * ctx->Buffer->Width;
 461          }
 462       }
 463       else {
 464          /* clear whole buffer */
 465          if (ctx->Accum.ClearColor[0]==0.0 &&
 466              ctx->Accum.ClearColor[1]==0.0 &&
 467              ctx->Accum.ClearColor[2]==0.0 &&
 468              ctx->Accum.ClearColor[3]==0.0) {
 469             /* Black */
 470             MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
 471          }
 472          else {
 473             /* Not black */
 474             GLaccum *acc, r, g, b, a;
 475             GLuint i;
 476
 477             acc = ctx->Buffer->Accum;
 478             r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
 479             g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
 480             b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
 481             a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
 482             for (i=0;i<buffersize;i++) {
 483                *acc++ = r;
 484                *acc++ = g;
 485                *acc++ = b;
 486                *acc++ = a;
 487             }
 488          }
 489       }
 490
 491       /* update optimized accum state vars */
 492       if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
 493           ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
 494          ctx->IntegerAccumMode = GL_TRUE;
 495          ctx->IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
 496       }
 497       else {
 498          ctx->IntegerAccumMode = GL_FALSE;
 499       }
 500    }
 501 }