src/mesa/swrast/s_readpix.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  7.0.3
   4  *
   5  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25
  26 #include "main/glheader.h"
  27 #include "main/colormac.h"
  28 #include "main/feedback.h"
  29 #include "main/formats.h"
  30 #include "main/format_unpack.h"
  31 #include "main/image.h"
  32 #include "main/imports.h"
  33 #include "main/macros.h"
  34 #include "main/pack.h"
  35 #include "main/pbo.h"
  36 #include "main/state.h"
  37
  38 #include "s_context.h"
  39 #include "s_depth.h"
  40 #include "s_span.h"
  41 #include "s_stencil.h"
  42
  43 /**
  44  * Tries to implement glReadPixels() of GL_DEPTH_COMPONENT using memcpy of the
  45  * mapping.
  46  */
  47 static GLboolean
  48 fast_read_depth_pixels( struct gl_context *ctx,
  49                         GLint x, GLint y,
  50                         GLsizei width, GLsizei height,
  51                         GLenum type, GLvoid *pixels,
  52                         const struct gl_pixelstore_attrib *packing )
  53 {
  54    struct gl_framebuffer *fb = ctx->ReadBuffer;
  55    struct gl_renderbuffer *rb = fb->Attachment[BUFFER_DEPTH].Renderbuffer;
  56    GLubyte *map, *dst;
  57    int stride, dstStride, j;
  58
  59    if (ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0)
  60       return GL_FALSE;
  61
  62    if (packing->SwapBytes)
  63       return GL_FALSE;
  64
  65    if (_mesa_get_format_datatype(rb->Format) != GL_UNSIGNED_INT)
  66       return GL_FALSE;
  67
  68    if (!((type == GL_UNSIGNED_SHORT && rb->Format == MESA_FORMAT_Z16) ||
  69          type == GL_UNSIGNED_INT))
  70       return GL_FALSE;
  71
  72    ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height, GL_MAP_READ_BIT,
  73                                &map, &stride);
  74
  75    dstStride = _mesa_image_row_stride(packing, width, GL_DEPTH_COMPONENT, type);
  76    dst = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
  77                                            GL_DEPTH_COMPONENT, type, 0, 0);
  78
  79    for (j = 0; j < height; j++) {
  80       if (type == GL_UNSIGNED_INT) {
  81          _mesa_unpack_uint_z_row(rb->Format, width, map, (GLuint *)dst);
  82       } else {
  83          ASSERT(type == GL_UNSIGNED_SHORT && rb->Format == MESA_FORMAT_Z16);
  84          memcpy(dst, map, width * 2);
  85       }
  86
  87       map += stride;
  88       dst += dstStride;
  89    }
  90    ctx->Driver.UnmapRenderbuffer(ctx, rb);
  91
  92    return GL_TRUE;
  93 }
  94
  95 /**
  96  * Read pixels for format=GL_DEPTH_COMPONENT.
  97  */
  98 static void
  99 read_depth_pixels( struct gl_context *ctx,
 100                    GLint x, GLint y,
 101                    GLsizei width, GLsizei height,
 102                    GLenum type, GLvoid *pixels,
 103                    const struct gl_pixelstore_attrib *packing )
 104 {
 105    struct gl_framebuffer *fb = ctx->ReadBuffer;
 106    struct gl_renderbuffer *rb = fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 107    GLint j;
 108    GLubyte *dst, *map;
 109    int dstStride, stride;
 110
 111    if (!rb)
 112       return;
 113
 114    /* clipping should have been done already */
 115    ASSERT(x >= 0);
 116    ASSERT(y >= 0);
 117    ASSERT(x + width <= (GLint) rb->Width);
 118    ASSERT(y + height <= (GLint) rb->Height);
 119    /* width should never be > MAX_WIDTH since we did clipping earlier */
 120    ASSERT(width <= MAX_WIDTH);
 121
 122    if (fast_read_depth_pixels(ctx, x, y, width, height, type, pixels, packing))
 123       return;
 124
 125    dstStride = _mesa_image_row_stride(packing, width, GL_DEPTH_COMPONENT, type);
 126    dst = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
 127                                            GL_DEPTH_COMPONENT, type, 0, 0);
 128
 129    ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height, GL_MAP_READ_BIT,
 130                                &map, &stride);
 131
 132    /* General case (slower) */
 133    for (j = 0; j < height; j++, y++) {
 134       GLfloat depthValues[MAX_WIDTH];
 135       _mesa_unpack_float_z_row(rb->Format, width, map, depthValues);
 136       _mesa_pack_depth_span(ctx, width, dst, type, depthValues, packing);
 137
 138       dst += dstStride;
 139       map += stride;
 140    }
 141
 142    ctx->Driver.UnmapRenderbuffer(ctx, rb);
 143 }
 144
 145
 146 /**
 147  * Read pixels for format=GL_STENCIL_INDEX.
 148  */
 149 static void
 150 read_stencil_pixels( struct gl_context *ctx,
 151                      GLint x, GLint y,
 152                      GLsizei width, GLsizei height,
 153                      GLenum type, GLvoid *pixels,
 154                      const struct gl_pixelstore_attrib *packing )
 155 {
 156    struct gl_framebuffer *fb = ctx->ReadBuffer;
 157    struct gl_renderbuffer *rb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 158    GLint j;
 159    GLubyte *map;
 160    GLint stride;
 161
 162    if (!rb)
 163       return;
 164
 165    /* width should never be > MAX_WIDTH since we did clipping earlier */
 166    ASSERT(width <= MAX_WIDTH);
 167
 168    ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height, GL_MAP_READ_BIT,
 169                                &map, &stride);
 170
 171    /* process image row by row */
 172    for (j = 0; j < height; j++) {
 173       GLvoid *dest;
 174       GLstencil stencil[MAX_WIDTH];
 175
 176       _mesa_unpack_ubyte_stencil_row(rb->Format, width, map, stencil);
 177       dest = _mesa_image_address2d(packing, pixels, width, height,
 178                                    GL_STENCIL_INDEX, type, j, 0);
 179
 180       _mesa_pack_stencil_span(ctx, width, type, dest, stencil, packing);
 181
 182       map += stride;
 183    }
 184
 185    ctx->Driver.UnmapRenderbuffer(ctx, rb);
 186 }
 187
 188
 189
 190 /**
 191  * Optimized glReadPixels for particular pixel formats when pixel
 192  * scaling, biasing, mapping, etc. are disabled.
 193  * \return GL_TRUE if success, GL_FALSE if unable to do the readpixels
 194  */
 195 static GLboolean
 196 fast_read_rgba_pixels( struct gl_context *ctx,
 197                        GLint x, GLint y,
 198                        GLsizei width, GLsizei height,
 199                        GLenum format, GLenum type,
 200                        GLvoid *pixels,
 201                        const struct gl_pixelstore_attrib *packing,
 202                        GLbitfield transferOps)
 203 {
 204    struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
 205
 206    if (!rb)
 207       return GL_FALSE;
 208
 209    ASSERT(rb->_BaseFormat == GL_RGBA ||
 210           rb->_BaseFormat == GL_RGB ||
 211           rb->_BaseFormat == GL_RG ||
 212           rb->_BaseFormat == GL_RED ||
 213           rb->_BaseFormat == GL_LUMINANCE ||
 214           rb->_BaseFormat == GL_INTENSITY ||
 215           rb->_BaseFormat == GL_LUMINANCE_ALPHA ||
 216           rb->_BaseFormat == GL_ALPHA);
 217
 218    /* clipping should have already been done */
 219    ASSERT(x + width <= (GLint) rb->Width);
 220    ASSERT(y + height <= (GLint) rb->Height);
 221
 222    /* check for things we can't handle here */
 223    if (transferOps ||
 224        packing->SwapBytes ||
 225        packing->LsbFirst) {
 226       return GL_FALSE;
 227    }
 228
 229    if (format == GL_RGBA && rb->DataType == type) {
 230       const GLint dstStride = _mesa_image_row_stride(packing, width,
 231                                                      format, type);
 232       GLubyte *dest
 233          = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
 234                                              format, type, 0, 0);
 235       GLint row;
 236       ASSERT(rb->GetRow);
 237       for (row = 0; row < height; row++) {
 238          rb->GetRow(ctx, rb, width, x, y + row, dest);
 239          dest += dstStride;
 240       }
 241       return GL_TRUE;
 242    }
 243
 244    if (format == GL_RGB &&
 245        rb->DataType == GL_UNSIGNED_BYTE &&
 246        type == GL_UNSIGNED_BYTE) {
 247       const GLint dstStride = _mesa_image_row_stride(packing, width,
 248                                                      format, type);
 249       GLubyte *dest
 250          = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
 251                                              format, type, 0, 0);
 252       GLint row;
 253       ASSERT(rb->GetRow);
 254       for (row = 0; row < height; row++) {
 255          GLubyte tempRow[MAX_WIDTH][4];
 256          GLint col;
 257          rb->GetRow(ctx, rb, width, x, y + row, tempRow);
 258          /* convert RGBA to RGB */
 259          for (col = 0; col < width; col++) {
 260             dest[col * 3 + 0] = tempRow[col][0];
 261             dest[col * 3 + 1] = tempRow[col][1];
 262             dest[col * 3 + 2] = tempRow[col][2];
 263          }
 264          dest += dstStride;
 265       }
 266       return GL_TRUE;
 267    }
 268
 269    /* not handled */
 270    return GL_FALSE;
 271 }
 272
 273 static GLboolean
 274 fast_read_rgba_pixels_memcpy( struct gl_context *ctx,
 275                               GLint x, GLint y,
 276                               GLsizei width, GLsizei height,
 277                               GLenum format, GLenum type,
 278                               GLvoid *pixels,
 279                               const struct gl_pixelstore_attrib *packing,
 280                               GLbitfield transferOps )
 281 {
 282    struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
 283    GLubyte *dst, *map;
 284    int dstStride, stride, j, texelBytes;
 285
 286    if (!_mesa_format_matches_format_and_type(rb->Format, format, type))
 287       return GL_FALSE;
 288
 289    /* check for things we can't handle here */
 290    if (packing->SwapBytes ||
 291        packing->LsbFirst) {
 292       return GL_FALSE;
 293    }
 294
 295    dstStride = _mesa_image_row_stride(packing, width, format, type);
 296    dst = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
 297                                            format, type, 0, 0);
 298
 299    ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height, GL_MAP_READ_BIT,
 300                                &map, &stride);
 301
 302    texelBytes = _mesa_get_format_bytes(rb->Format);
 303    for (j = 0; j < height; j++) {
 304       memcpy(dst, map, width * texelBytes);
 305       dst += dstStride;
 306       map += stride;
 307    }
 308
 309    ctx->Driver.UnmapRenderbuffer(ctx, rb);
 310
 311    return GL_TRUE;
 312 }
 313
 314
 315 /**
 316  * When we're using a low-precision color buffer (like 16-bit 5/6/5)
 317  * we have to adjust our color values a bit to pass conformance.
 318  * The problem is when a 5 or 6-bit color value is converted to an 8-bit
 319  * value and then a floating point value, the floating point values don't
 320  * increment uniformly as the 5 or 6-bit value is incremented.
 321  *
 322  * This function adjusts floating point values to compensate.
 323  */
 324 static void
 325 adjust_colors(const struct gl_framebuffer *fb, GLuint n, GLfloat rgba[][4])
 326 {
 327    const GLuint rShift = 8 - fb->Visual.redBits;
 328    const GLuint gShift = 8 - fb->Visual.greenBits;
 329    const GLuint bShift = 8 - fb->Visual.blueBits;
 330    GLfloat rScale = 1.0F / (GLfloat) ((1 << fb->Visual.redBits  ) - 1);
 331    GLfloat gScale = 1.0F / (GLfloat) ((1 << fb->Visual.greenBits) - 1);
 332    GLfloat bScale = 1.0F / (GLfloat) ((1 << fb->Visual.blueBits ) - 1);
 333    GLuint i;
 334
 335    if (fb->Visual.redBits == 0)
 336       rScale = 0;
 337    if (fb->Visual.greenBits == 0)
 338       gScale = 0;
 339    if (fb->Visual.blueBits == 0)
 340       bScale = 0;
 341
 342    for (i = 0; i < n; i++) {
 343       GLint r, g, b;
 344       /* convert float back to ubyte */
 345       CLAMPED_FLOAT_TO_UBYTE(r, rgba[i][RCOMP]);
 346       CLAMPED_FLOAT_TO_UBYTE(g, rgba[i][GCOMP]);
 347       CLAMPED_FLOAT_TO_UBYTE(b, rgba[i][BCOMP]);
 348       /* using only the N most significant bits of the ubyte value, convert to
 349        * float in [0,1].
 350        */
 351       rgba[i][RCOMP] = (GLfloat) (r >> rShift) * rScale;
 352       rgba[i][GCOMP] = (GLfloat) (g >> gShift) * gScale;
 353       rgba[i][BCOMP] = (GLfloat) (b >> bShift) * bScale;
 354    }
 355 }
 356
 357
 358
 359 /*
 360  * Read R, G, B, A, RGB, L, or LA pixels.
 361  */
 362 static void
 363 read_rgba_pixels( struct gl_context *ctx,
 364                   GLint x, GLint y,
 365                   GLsizei width, GLsizei height,
 366                   GLenum format, GLenum type, GLvoid *pixels,
 367                   const struct gl_pixelstore_attrib *packing )
 368 {
 369    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 370    GLbitfield transferOps = ctx->_ImageTransferState;
 371    struct gl_framebuffer *fb = ctx->ReadBuffer;
 372    struct gl_renderbuffer *rb = fb->_ColorReadBuffer;
 373
 374    if (!rb)
 375       return;
 376
 377    if ((ctx->Color._ClampReadColor == GL_TRUE || type != GL_FLOAT) &&
 378        !_mesa_is_integer_format(format)) {
 379       transferOps |= IMAGE_CLAMP_BIT;
 380    }
 381
 382    if (!transferOps) {
 383       /* Try the optimized paths first. */
 384       if (fast_read_rgba_pixels_memcpy(ctx, x, y, width, height,
 385                                        format, type, pixels, packing,
 386                                        transferOps)) {
 387          return;
 388       }
 389
 390       if (fast_read_rgba_pixels(ctx, x, y, width, height,
 391                                 format, type, pixels, packing, transferOps)) {
 392          return;
 393       }
 394    }
 395
 396    /* width should never be > MAX_WIDTH since we did clipping earlier */
 397    ASSERT(width <= MAX_WIDTH);
 398
 399    {
 400       const GLint dstStride
 401          = _mesa_image_row_stride(packing, width, format, type);
 402       GLfloat (*rgba)[4] = swrast->SpanArrays->attribs[FRAG_ATTRIB_COL0];
 403       GLint row;
 404       GLubyte *dst
 405          = (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
 406                                              format, type, 0, 0);
 407
 408       for (row = 0; row < height; row++, y++) {
 409
 410          /* Get float rgba pixels */
 411          _swrast_read_rgba_span(ctx, rb, width, x, y, GL_FLOAT, rgba);
 412
 413          /* apply fudge factor for shallow color buffers */
 414          if ((fb->Visual.redBits < 8 && fb->Visual.redBits != 0) ||
 415              (fb->Visual.greenBits < 8 && fb->Visual.greenBits != 0) ||
 416              (fb->Visual.blueBits < 8 && fb->Visual.blueBits != 0)) {
 417             adjust_colors(fb, width, rgba);
 418          }
 419
 420          /* pack the row of RGBA pixels into user's buffer */
 421          _mesa_pack_rgba_span_float(ctx, width, rgba, format, type, dst,
 422                                     packing, transferOps);
 423
 424          dst += dstStride;
 425       }
 426    }
 427 }
 428
 429 /**
 430  * For a packed depth/stencil buffer being read as depth/stencil, just memcpy the
 431  * data (possibly swapping 8/24 vs 24/8 as we go).
 432  */
 433 static GLboolean
 434 fast_read_depth_stencil_pixels(struct gl_context *ctx,
 435                                GLint x, GLint y,
 436                                GLsizei width, GLsizei height,
 437                                GLvoid *dst, int dstStride)
 438 {
 439    struct gl_framebuffer *fb = ctx->ReadBuffer;
 440    struct gl_renderbuffer *rb = fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 441    struct gl_renderbuffer *stencilRb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 442    GLubyte *map;
 443    int stride, i;
 444
 445    if (rb != stencilRb)
 446       return GL_FALSE;
 447
 448    if (rb->Format != MESA_FORMAT_Z24_S8 &&
 449        rb->Format != MESA_FORMAT_S8_Z24)
 450       return GL_FALSE;
 451
 452    ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height, GL_MAP_READ_BIT,
 453                                &map, &stride);
 454
 455    for (i = 0; i < height; i++) {
 456       _mesa_unpack_uint_24_8_depth_stencil_row(rb->Format, width,
 457                                                map, (GLuint *)dst);
 458       map += stride;
 459       dst += dstStride;
 460    }
 461
 462    ctx->Driver.UnmapRenderbuffer(ctx, rb);
 463
 464    return GL_TRUE;
 465 }
 466
 467
 468 /**
 469  * For non-float-depth and stencil buffers being read as 24/8 depth/stencil,
 470  * copy the integer data directly instead of converting depth to float and
 471  * re-packing.
 472  */
 473 static GLboolean
 474 fast_read_depth_stencil_pixels_separate(struct gl_context *ctx,
 475                                         GLint x, GLint y,
 476                                         GLsizei width, GLsizei height,
 477                                         uint32_t *dst, int dstStride)
 478 {
 479    struct gl_framebuffer *fb = ctx->ReadBuffer;
 480    struct gl_renderbuffer *depthRb = fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 481    struct gl_renderbuffer *stencilRb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 482    GLubyte *depthMap, *stencilMap;
 483    int depthStride, stencilStride, i, j;
 484
 485    if (_mesa_get_format_datatype(depthRb->Format) != GL_UNSIGNED_INT)
 486       return GL_FALSE;
 487
 488    ctx->Driver.MapRenderbuffer(ctx, depthRb, x, y, width, height,
 489                                GL_MAP_READ_BIT, &depthMap, &depthStride);
 490    ctx->Driver.MapRenderbuffer(ctx, stencilRb, x, y, width, height,
 491                                GL_MAP_READ_BIT, &stencilMap, &stencilStride);
 492
 493    for (j = 0; j < height; j++) {
 494       GLstencil stencilVals[MAX_WIDTH];
 495
 496       _mesa_unpack_uint_z_row(depthRb->Format, width, depthMap, dst);
 497       _mesa_unpack_ubyte_stencil_row(stencilRb->Format, width,
 498                                      stencilMap, stencilVals);
 499
 500       for (i = 0; i < width; i++) {
 501          dst[i] = (dst[i] & 0xffffff00) | stencilVals[i];
 502       }
 503
 504       depthMap += depthStride;
 505       stencilMap += stencilStride;
 506       dst += dstStride / 4;
 507    }
 508
 509    ctx->Driver.UnmapRenderbuffer(ctx, depthRb);
 510    ctx->Driver.UnmapRenderbuffer(ctx, stencilRb);
 511
 512    return GL_TRUE;
 513 }
 514
 515 static void
 516 slow_read_depth_stencil_pixels_separate(struct gl_context *ctx,
 517                                         GLint x, GLint y,
 518                                         GLsizei width, GLsizei height,
 519                                         GLenum type,
 520                                         const struct gl_pixelstore_attrib *packing,
 521                                         GLubyte *dst, int dstStride)
 522 {
 523    struct gl_framebuffer *fb = ctx->ReadBuffer;
 524    struct gl_renderbuffer *depthRb = fb->Attachment[BUFFER_DEPTH].Renderbuffer;
 525    struct gl_renderbuffer *stencilRb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
 526    GLubyte *depthMap, *stencilMap;
 527    int depthStride, stencilStride, j;
 528
 529    ctx->Driver.MapRenderbuffer(ctx, depthRb, x, y, width, height,
 530                                GL_MAP_READ_BIT, &depthMap, &depthStride);
 531    ctx->Driver.MapRenderbuffer(ctx, stencilRb, x, y, width, height,
 532                                GL_MAP_READ_BIT, &stencilMap, &stencilStride);
 533
 534    for (j = 0; j < height; j++) {
 535       GLstencil stencilVals[MAX_WIDTH];
 536       GLfloat depthVals[MAX_WIDTH];
 537
 538       _mesa_unpack_float_z_row(depthRb->Format, width, depthMap, depthVals);
 539       _mesa_unpack_ubyte_stencil_row(stencilRb->Format, width,
 540                                      stencilMap, stencilVals);
 541
 542       _mesa_pack_depth_stencil_span(ctx, width, type, (GLuint *)dst,
 543                                     depthVals, stencilVals, packing);
 544
 545       depthMap += depthStride;
 546       stencilMap += stencilStride;
 547       dst += dstStride;
 548    }
 549
 550    ctx->Driver.UnmapRenderbuffer(ctx, depthRb);
 551    ctx->Driver.UnmapRenderbuffer(ctx, stencilRb);
 552 }
 553
 554
 555 /**
 556  * Read combined depth/stencil values.
 557  * We'll have already done error checking to be sure the expected
 558  * depth and stencil buffers really exist.
 559  */
 560 static void
 561 read_depth_stencil_pixels(struct gl_context *ctx,
 562                           GLint x, GLint y,
 563                           GLsizei width, GLsizei height,
 564                           GLenum type, GLvoid *pixels,
 565                           const struct gl_pixelstore_attrib *packing )
 566 {
 567    const GLboolean scaleOrBias
 568       = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
 569    const GLboolean stencilTransfer = ctx->Pixel.IndexShift
 570       || ctx->Pixel.IndexOffset || ctx->Pixel.MapStencilFlag;
 571    GLubyte *dst;
 572    int dstStride;
 573
 574    dst = (GLubyte *) _mesa_image_address2d(packing, pixels,
 575                                            width, height,
 576                                            GL_DEPTH_STENCIL_EXT,
 577                                            type, 0, 0);
 578    dstStride = _mesa_image_row_stride(packing, width,
 579                                       GL_DEPTH_STENCIL_EXT, type);
 580
 581    /* Fast 24/8 reads. */
 582    if (type == GL_UNSIGNED_INT_24_8 &&
 583        !scaleOrBias && !stencilTransfer && !packing->SwapBytes) {
 584       if (fast_read_depth_stencil_pixels(ctx, x, y, width, height,
 585                                          dst, dstStride))
 586          return;
 587
 588       if (fast_read_depth_stencil_pixels_separate(ctx, x, y, width, height,
 589                                                   (uint32_t *)dst, dstStride))
 590          return;
 591    }
 592
 593    slow_read_depth_stencil_pixels_separate(ctx, x, y, width, height,
 594                                            type, packing,
 595                                            dst, dstStride);
 596 }
 597
 598
 599
 600 /**
 601  * Software fallback routine for ctx->Driver.ReadPixels().
 602  * By time we get here, all error checking will have been done.
 603  */
 604 void
 605 _swrast_ReadPixels( struct gl_context *ctx,
 606                     GLint x, GLint y, GLsizei width, GLsizei height,
 607                     GLenum format, GLenum type,
 608                     const struct gl_pixelstore_attrib *packing,
 609                     GLvoid *pixels )
 610 {
 611    SWcontext *swrast = SWRAST_CONTEXT(ctx);
 612    struct gl_pixelstore_attrib clippedPacking = *packing;
 613
 614    if (ctx->NewState)
 615       _mesa_update_state(ctx);
 616
 617    /* Need to do swrast_render_start() before clipping or anything else
 618     * since this is where a driver may grab the hw lock and get an updated
 619     * window size.
 620     */
 621    swrast_render_start(ctx);
 622
 623    if (swrast->NewState)
 624       _swrast_validate_derived( ctx );
 625
 626    /* Do all needed clipping here, so that we can forget about it later */
 627    if (_mesa_clip_readpixels(ctx, &x, &y, &width, &height, &clippedPacking)) {
 628
 629       pixels = _mesa_map_pbo_dest(ctx, &clippedPacking, pixels);
 630
 631       if (pixels) {
 632          switch (format) {
 633          case GL_STENCIL_INDEX:
 634             read_stencil_pixels(ctx, x, y, width, height, type, pixels,
 635                                 &clippedPacking);
 636             break;
 637          case GL_DEPTH_COMPONENT:
 638             read_depth_pixels(ctx, x, y, width, height, type, pixels,
 639                               &clippedPacking);
 640             break;
 641          case GL_DEPTH_STENCIL_EXT:
 642             read_depth_stencil_pixels(ctx, x, y, width, height, type, pixels,
 643                                       &clippedPacking);
 644             break;
 645          default:
 646             /* all other formats should be color formats */
 647             read_rgba_pixels(ctx, x, y, width, height, format, type, pixels,
 648                              &clippedPacking);
 649          }
 650
 651          _mesa_unmap_pbo_dest(ctx, &clippedPacking);
 652       }
 653    }
 654
 655    swrast_render_finish(ctx);
 656 }