aboutsummaryrefslogtreecommitdiff
path: root/mesalib/src/mesa/swrast/s_drawpix.c
blob: 4231bb4bdf0ae48629c41674ef924f1564320eca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
/*
 * Mesa 3-D graphics library
 * Version:  7.1
 *
 * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


#include "main/glheader.h"
#include "main/bufferobj.h"
#include "main/colormac.h"
#include "main/condrender.h"
#include "main/context.h"
#include "main/format_pack.h"
#include "main/image.h"
#include "main/imports.h"
#include "main/macros.h"
#include "main/pack.h"
#include "main/pbo.h"
#include "main/pixeltransfer.h"
#include "main/state.h"

#include "s_context.h"
#include "s_span.h"
#include "s_stencil.h"
#include "s_zoom.h"


/**
 * Handle a common case of drawing GL_RGB/GL_UNSIGNED_BYTE into a
 * MESA_FORMAT_XRGB888 or MESA_FORMAT_ARGB888 renderbuffer.
 */
static void
fast_draw_rgb_ubyte_pixels(struct gl_context *ctx,
                           struct gl_renderbuffer *rb,
                           GLint x, GLint y,
                           GLsizei width, GLsizei height,
                           const struct gl_pixelstore_attrib *unpack,
                           const GLvoid *pixels)
{
   const GLubyte *src = (const GLubyte *)
      _mesa_image_address2d(unpack, pixels, width,
                            height, GL_RGB, GL_UNSIGNED_BYTE, 0, 0);
   const GLint srcRowStride = _mesa_image_row_stride(unpack, width,
                                                     GL_RGB, GL_UNSIGNED_BYTE);
   GLint i, j;
   GLubyte *dst;
   GLint dstRowStride;

   ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height,
                               GL_MAP_WRITE_BIT, &dst, &dstRowStride);

   if (!dst) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glDrawPixels");
      return;
   }

   if (ctx->Pixel.ZoomY == -1.0f) {
      dst = dst + (height - 1) * dstRowStride;
      dstRowStride = -dstRowStride;
   }

   for (i = 0; i < height; i++) {
      GLuint *dst4 = (GLuint *) dst;
      for (j = 0; j < width; j++) {
         dst4[j] = PACK_COLOR_8888(0xff, src[j*3+0], src[j*3+1], src[j*3+2]);
      }
      dst += dstRowStride;
      src += srcRowStride;
   }

   ctx->Driver.UnmapRenderbuffer(ctx, rb);
}


/**
 * Handle a common case of drawing GL_RGBA/GL_UNSIGNED_BYTE into a
 * MESA_FORMAT_ARGB888 or MESA_FORMAT_xRGB888 renderbuffer.
 */
static void
fast_draw_rgba_ubyte_pixels(struct gl_context *ctx,
                           struct gl_renderbuffer *rb,
                           GLint x, GLint y,
                           GLsizei width, GLsizei height,
                           const struct gl_pixelstore_attrib *unpack,
                           const GLvoid *pixels)
{
   const GLubyte *src = (const GLubyte *)
      _mesa_image_address2d(unpack, pixels, width,
                            height, GL_RGBA, GL_UNSIGNED_BYTE, 0, 0);
   const GLint srcRowStride =
      _mesa_image_row_stride(unpack, width, GL_RGBA, GL_UNSIGNED_BYTE);
   GLint i, j;
   GLubyte *dst;
   GLint dstRowStride;

   ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height,
                               GL_MAP_WRITE_BIT, &dst, &dstRowStride);

   if (!dst) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glDrawPixels");
      return;
   }

   if (ctx->Pixel.ZoomY == -1.0f) {
      dst = dst + (height - 1) * dstRowStride;
      dstRowStride = -dstRowStride;
   }

   for (i = 0; i < height; i++) {
      GLuint *dst4 = (GLuint *) dst;
      for (j = 0; j < width; j++) {
         dst4[j] = PACK_COLOR_8888(src[j*4+3], src[j*4+0],
                                   src[j*4+1], src[j*4+2]);
      }
      dst += dstRowStride;
      src += srcRowStride;
   }

   ctx->Driver.UnmapRenderbuffer(ctx, rb);
}


/**
 * Handle a common case of drawing a format/type combination that
 * exactly matches the renderbuffer format.
 */
static void
fast_draw_generic_pixels(struct gl_context *ctx,
                         struct gl_renderbuffer *rb,
                         GLint x, GLint y,
                         GLsizei width, GLsizei height,
                         GLenum format, GLenum type,
                         const struct gl_pixelstore_attrib *unpack,
                         const GLvoid *pixels)
{
   const GLubyte *src = (const GLubyte *)
      _mesa_image_address2d(unpack, pixels, width,
                            height, format, type, 0, 0);
   const GLint srcRowStride =
      _mesa_image_row_stride(unpack, width, format, type);
   const GLint rowLength = width * _mesa_get_format_bytes(rb->Format);
   GLint i;
   GLubyte *dst;
   GLint dstRowStride;

   ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height,
                               GL_MAP_WRITE_BIT, &dst, &dstRowStride);

   if (!dst) {
      _mesa_error(ctx, GL_OUT_OF_MEMORY, "glDrawPixels");
      return;
   }

   if (ctx->Pixel.ZoomY == -1.0f) {
      dst = dst + (height - 1) * dstRowStride;
      dstRowStride = -dstRowStride;
   }

   for (i = 0; i < height; i++) {
      memcpy(dst, src, rowLength);
      dst += dstRowStride;
      src += srcRowStride;
   }

   ctx->Driver.UnmapRenderbuffer(ctx, rb);
}


/**
 * Try to do a fast and simple RGB(a) glDrawPixels.
 * Return:  GL_TRUE if success, GL_FALSE if slow path must be used instead
 */
static GLboolean
fast_draw_rgba_pixels(struct gl_context *ctx, GLint x, GLint y,
                      GLsizei width, GLsizei height,
                      GLenum format, GLenum type,
                      const struct gl_pixelstore_attrib *userUnpack,
                      const GLvoid *pixels)
{
   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   struct gl_pixelstore_attrib unpack;

   if (!rb)
      return GL_TRUE; /* no-op */

   if (ctx->DrawBuffer->_NumColorDrawBuffers > 1 ||
       (swrast->_RasterMask & ~CLIP_BIT) ||
       ctx->Texture._EnabledCoordUnits ||
       userUnpack->SwapBytes ||
       ctx->Pixel.ZoomX != 1.0f ||
       fabsf(ctx->Pixel.ZoomY) != 1.0f ||
       ctx->_ImageTransferState) {
      /* can't handle any of those conditions */
      return GL_FALSE;
   }

   unpack = *userUnpack;

   /* clipping */
   if (!_mesa_clip_drawpixels(ctx, &x, &y, &width, &height, &unpack)) {
      /* image was completely clipped: no-op, all done */
      return GL_TRUE;
   }

   if (format == GL_RGB &&
       type == GL_UNSIGNED_BYTE &&
       (rb->Format == MESA_FORMAT_XRGB8888 ||
        rb->Format == MESA_FORMAT_ARGB8888)) {
      fast_draw_rgb_ubyte_pixels(ctx, rb, x, y, width, height,
                                 &unpack, pixels);
      return GL_TRUE;
   }

   if (format == GL_RGBA &&
       type == GL_UNSIGNED_BYTE &&
       (rb->Format == MESA_FORMAT_XRGB8888 ||
        rb->Format == MESA_FORMAT_ARGB8888)) {
      fast_draw_rgba_ubyte_pixels(ctx, rb, x, y, width, height,
                                  &unpack, pixels);
      return GL_TRUE;
   }

   if (_mesa_format_matches_format_and_type(rb->Format, format, type)) {
      fast_draw_generic_pixels(ctx, rb, x, y, width, height,
                               format, type, &unpack, pixels);
      return GL_TRUE;
   }

   /* can't handle this pixel format and/or data type */
   return GL_FALSE;
}



/*
 * Draw stencil image.
 */
static void
draw_stencil_pixels( struct gl_context *ctx, GLint x, GLint y,
                     GLsizei width, GLsizei height,
                     GLenum type,
                     const struct gl_pixelstore_attrib *unpack,
                     const GLvoid *pixels )
{
   const GLboolean zoom = ctx->Pixel.ZoomX != 1.0 || ctx->Pixel.ZoomY != 1.0;
   const GLenum destType = GL_UNSIGNED_BYTE;
   GLint skipPixels;

   /* if width > MAX_WIDTH, have to process image in chunks */
   skipPixels = 0;
   while (skipPixels < width) {
      const GLint spanX = x + skipPixels;
      const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
      GLint row;
      for (row = 0; row < height; row++) {
         const GLint spanY = y + row;
         GLubyte values[MAX_WIDTH];
         const GLvoid *source = _mesa_image_address2d(unpack, pixels,
                                                      width, height,
                                                      GL_STENCIL_INDEX, type,
                                                      row, skipPixels);
         _mesa_unpack_stencil_span(ctx, spanWidth, destType, values,
                                   type, source, unpack,
                                   ctx->_ImageTransferState);
         if (zoom) {
            _swrast_write_zoomed_stencil_span(ctx, x, y, spanWidth,
                                              spanX, spanY, values);
         }
         else {
            _swrast_write_stencil_span(ctx, spanWidth, spanX, spanY, values);
         }
      }
      skipPixels += spanWidth;
   }
}


/*
 * Draw depth image.
 */
static void
draw_depth_pixels( struct gl_context *ctx, GLint x, GLint y,
                   GLsizei width, GLsizei height,
                   GLenum type,
                   const struct gl_pixelstore_attrib *unpack,
                   const GLvoid *pixels )
{
   const GLboolean scaleOrBias
      = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
   const GLboolean zoom = ctx->Pixel.ZoomX != 1.0 || ctx->Pixel.ZoomY != 1.0;
   SWspan span;

   INIT_SPAN(span, GL_BITMAP);
   span.arrayMask = SPAN_Z;
   _swrast_span_default_attribs(ctx, &span);

   if (type == GL_UNSIGNED_SHORT
       && ctx->DrawBuffer->Visual.depthBits == 16
       && !scaleOrBias
       && !zoom
       && width <= MAX_WIDTH
       && !unpack->SwapBytes) {
      /* Special case: directly write 16-bit depth values */
      GLint row;
      for (row = 0; row < height; row++) {
         const GLushort *zSrc = (const GLushort *)
            _mesa_image_address2d(unpack, pixels, width, height,
                                  GL_DEPTH_COMPONENT, type, row, 0);
         GLint i;
         for (i = 0; i < width; i++)
            span.array->z[i] = zSrc[i];
         span.x = x;
         span.y = y + row;
         span.end = width;
         _swrast_write_rgba_span(ctx, &span);
      }
   }
   else if (type == GL_UNSIGNED_INT
            && !scaleOrBias
            && !zoom
            && width <= MAX_WIDTH
            && !unpack->SwapBytes) {
      /* Special case: shift 32-bit values down to Visual.depthBits */
      const GLint shift = 32 - ctx->DrawBuffer->Visual.depthBits;
      GLint row;
      for (row = 0; row < height; row++) {
         const GLuint *zSrc = (const GLuint *)
            _mesa_image_address2d(unpack, pixels, width, height,
                                  GL_DEPTH_COMPONENT, type, row, 0);
         if (shift == 0) {
            memcpy(span.array->z, zSrc, width * sizeof(GLuint));
         }
         else {
            GLint col;
            for (col = 0; col < width; col++)
               span.array->z[col] = zSrc[col] >> shift;
         }
         span.x = x;
         span.y = y + row;
         span.end = width;
         _swrast_write_rgba_span(ctx, &span);
      }
   }
   else {
      /* General case */
      const GLuint depthMax = ctx->DrawBuffer->_DepthMax;
      GLint skipPixels = 0;

      /* in case width > MAX_WIDTH do the copy in chunks */
      while (skipPixels < width) {
         const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
         GLint row;
         ASSERT(span.end <= MAX_WIDTH);
         for (row = 0; row < height; row++) {
            const GLvoid *zSrc = _mesa_image_address2d(unpack,
                                                      pixels, width, height,
                                                      GL_DEPTH_COMPONENT, type,
                                                      row, skipPixels);

            /* Set these for each row since the _swrast_write_* function may
             * change them while clipping.
             */
            span.x = x + skipPixels;
            span.y = y + row;
            span.end = spanWidth;

            _mesa_unpack_depth_span(ctx, spanWidth,
                                    GL_UNSIGNED_INT, span.array->z, depthMax,
                                    type, zSrc, unpack);
            if (zoom) {
               _swrast_write_zoomed_depth_span(ctx, x, y, &span);
            }
            else {
               _swrast_write_rgba_span(ctx, &span);
            }
         }
         skipPixels += spanWidth;
      }
   }
}



/**
 * Draw RGBA image.
 */
static void
draw_rgba_pixels( struct gl_context *ctx, GLint x, GLint y,
                  GLsizei width, GLsizei height,
                  GLenum format, GLenum type,
                  const struct gl_pixelstore_attrib *unpack,
                  const GLvoid *pixels )
{
   const GLint imgX = x, imgY = y;
   const GLboolean zoom = ctx->Pixel.ZoomX!=1.0 || ctx->Pixel.ZoomY!=1.0;
   GLfloat *convImage = NULL;
   GLbitfield transferOps = ctx->_ImageTransferState;
   SWspan span;

   /* Try an optimized glDrawPixels first */
   if (fast_draw_rgba_pixels(ctx, x, y, width, height, format, type,
                             unpack, pixels)) {
      return;
   }

   swrast_render_start(ctx);

   INIT_SPAN(span, GL_BITMAP);
   _swrast_span_default_attribs(ctx, &span);
   span.arrayMask = SPAN_RGBA;
   span.arrayAttribs = FRAG_BIT_COL0; /* we're fill in COL0 attrib values */

   if (ctx->DrawBuffer->_NumColorDrawBuffers > 0 &&
       ctx->DrawBuffer->_ColorDrawBuffers[0]->DataType != GL_FLOAT &&
       ctx->Color.ClampFragmentColor != GL_FALSE) {
      /* need to clamp colors before applying fragment ops */
      transferOps |= IMAGE_CLAMP_BIT;
   }

   /*
    * General solution
    */
   {
      const GLbitfield interpMask = span.interpMask;
      const GLbitfield arrayMask = span.arrayMask;
      const GLint srcStride
         = _mesa_image_row_stride(unpack, width, format, type);
      GLint skipPixels = 0;
      /* use span array for temp color storage */
      GLfloat *rgba = (GLfloat *) span.array->attribs[FRAG_ATTRIB_COL0];

      /* if the span is wider than MAX_WIDTH we have to do it in chunks */
      while (skipPixels < width) {
         const GLint spanWidth = MIN2(width - skipPixels, MAX_WIDTH);
         const GLubyte *source
            = (const GLubyte *) _mesa_image_address2d(unpack, pixels,
                                                      width, height, format,
                                                      type, 0, skipPixels);
         GLint row;

         for (row = 0; row < height; row++) {
            /* get image row as float/RGBA */
            _mesa_unpack_color_span_float(ctx, spanWidth, GL_RGBA, rgba,
                                     format, type, source, unpack,
                                     transferOps);
	    /* Set these for each row since the _swrast_write_* functions
	     * may change them while clipping/rendering.
	     */
	    span.array->ChanType = GL_FLOAT;
	    span.x = x + skipPixels;
	    span.y = y + row;
	    span.end = spanWidth;
	    span.arrayMask = arrayMask;
	    span.interpMask = interpMask;
	    if (zoom) {
	       _swrast_write_zoomed_rgba_span(ctx, imgX, imgY, &span, rgba);
	    }
	    else {
	       _swrast_write_rgba_span(ctx, &span);
	    }

            source += srcStride;
         } /* for row */

         skipPixels += spanWidth;
      } /* while skipPixels < width */

      /* XXX this is ugly/temporary, to undo above change */
      span.array->ChanType = CHAN_TYPE;
   }

   if (convImage) {
      free(convImage);
   }

   swrast_render_finish(ctx);
}


/**
 * Draw depth+stencil values into a MESA_FORAMT_Z24_S8 or MESA_FORMAT_S8_Z24
 * renderbuffer.  No masking, zooming, scaling, etc.
 */
static void
fast_draw_depth_stencil(struct gl_context *ctx, GLint x, GLint y,
                        GLsizei width, GLsizei height,
                        const struct gl_pixelstore_attrib *unpack,
                        const GLvoid *pixels)
{
   const GLenum format = GL_DEPTH_STENCIL_EXT;
   const GLenum type = GL_UNSIGNED_INT_24_8;
   struct gl_renderbuffer *rb =
      ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
   GLubyte *src, *dst;
   GLint srcRowStride, dstRowStride;
   GLint i;

   src = _mesa_image_address2d(unpack, pixels, width, height,
                               format, type, 0, 0);
   srcRowStride = _mesa_image_row_stride(unpack, width, format, type);

   dst = _swrast_pixel_address(rb, x, y);
   dstRowStride = rb->RowStride * 4;

   for (i = 0; i < height; i++) {
      _mesa_pack_uint_24_8_depth_stencil_row(rb->Format, width,
                                             (const GLuint *) src, dst);
      dst += dstRowStride;
      src += srcRowStride;
   }
}



/**
 * This is a bit different from drawing GL_DEPTH_COMPONENT pixels.
 * The only per-pixel operations that apply are depth scale/bias,
 * stencil offset/shift, GL_DEPTH_WRITEMASK and GL_STENCIL_WRITEMASK,
 * and pixel zoom.
 * Also, only the depth buffer and stencil buffers are touched, not the
 * color buffer(s).
 */
static void
draw_depth_stencil_pixels(struct gl_context *ctx, GLint x, GLint y,
                          GLsizei width, GLsizei height, GLenum type,
                          const struct gl_pixelstore_attrib *unpack,
                          const GLvoid *pixels)
{
   const GLint imgX = x, imgY = y;
   const GLboolean scaleOrBias
      = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
   const GLuint stencilMask = ctx->Stencil.WriteMask[0];
   const GLenum stencilType = GL_UNSIGNED_BYTE;
   const GLboolean zoom = ctx->Pixel.ZoomX != 1.0 || ctx->Pixel.ZoomY != 1.0;
   struct gl_renderbuffer *depthRb, *stencilRb;
   struct gl_pixelstore_attrib clippedUnpack = *unpack;

   if (!zoom) {
      if (!_mesa_clip_drawpixels(ctx, &x, &y, &width, &height,
                                 &clippedUnpack)) {
         /* totally clipped */
         return;
      }
   }
   
   depthRb = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
   stencilRb = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
   ASSERT(depthRb);
   ASSERT(stencilRb);

   if (depthRb == stencilRb &&
       (depthRb->Format == MESA_FORMAT_Z24_S8 ||
        depthRb->Format == MESA_FORMAT_S8_Z24) &&
       type == GL_UNSIGNED_INT_24_8 &&
       !scaleOrBias &&
       !zoom &&
       ctx->Depth.Mask &&
       (stencilMask & 0xff) == 0xff) {
      fast_draw_depth_stencil(ctx, x, y, width, height,
                              &clippedUnpack, pixels);
   }
   else {
      /* sub-optimal cases:
       * Separate depth/stencil buffers, or pixel transfer ops required.
       */
      /* XXX need to handle very wide images (skippixels) */
      GLint i;

      for (i = 0; i < height; i++) {
         const GLuint *depthStencilSrc = (const GLuint *)
            _mesa_image_address2d(&clippedUnpack, pixels, width, height,
                                  GL_DEPTH_STENCIL_EXT, type, i, 0);

         if (ctx->Depth.Mask) {
            GLuint zValues[MAX_WIDTH];  /* 32-bit Z values */
            _mesa_unpack_depth_span(ctx, width,
                                    GL_UNSIGNED_INT, /* dest type */
                                    zValues,         /* dest addr */
                                    0xffffffff,      /* depth max */
                                    type,            /* src type */
                                    depthStencilSrc, /* src addr */
                                    &clippedUnpack);
            if (zoom) {
               _swrast_write_zoomed_z_span(ctx, imgX, imgY, width, x,
                                           y + i, zValues);
            }
            else {
               GLubyte *dst = _swrast_pixel_address(depthRb, x, y + i);
               _mesa_pack_uint_z_row(depthRb->Format, width, zValues, dst);
            }
         }

         if (stencilMask != 0x0) {
            GLubyte stencilValues[MAX_WIDTH];
            /* get stencil values, with shift/offset/mapping */
            _mesa_unpack_stencil_span(ctx, width, stencilType, stencilValues,
                                      type, depthStencilSrc, &clippedUnpack,
                                      ctx->_ImageTransferState);
            if (zoom)
               _swrast_write_zoomed_stencil_span(ctx, imgX, imgY, width,
                                                  x, y + i, stencilValues);
            else
               _swrast_write_stencil_span(ctx, width, x, y + i, stencilValues);
         }
      }
   }
}


/**
 * Execute software-based glDrawPixels.
 * By time we get here, all error checking will have been done.
 */
void
_swrast_DrawPixels( struct gl_context *ctx,
		    GLint x, GLint y,
		    GLsizei width, GLsizei height,
		    GLenum format, GLenum type,
		    const struct gl_pixelstore_attrib *unpack,
		    const GLvoid *pixels )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   GLboolean save_vp_override = ctx->VertexProgram._Overriden;

   if (!_mesa_check_conditional_render(ctx))
      return; /* don't draw */

   /* We are creating fragments directly, without going through vertex
    * programs.
    *
    * This override flag tells the fragment processing code that its input
    * comes from a non-standard source, and it may therefore not rely on
    * optimizations that assume e.g. constant color if there is no color
    * vertex array.
    */
   _mesa_set_vp_override(ctx, GL_TRUE);

   if (ctx->NewState)
      _mesa_update_state(ctx);

   if (swrast->NewState)
      _swrast_validate_derived( ctx );

   pixels = _mesa_map_pbo_source(ctx, unpack, pixels);
   if (!pixels) {
      _mesa_set_vp_override(ctx, save_vp_override);
      return;
   }

   /*
    * By time we get here, all error checking should have been done.
    */
   switch (format) {
   case GL_STENCIL_INDEX:
      swrast_render_start(ctx);
      draw_stencil_pixels( ctx, x, y, width, height, type, unpack, pixels );
      swrast_render_finish(ctx);
      break;
   case GL_DEPTH_COMPONENT:
      swrast_render_start(ctx);
      draw_depth_pixels( ctx, x, y, width, height, type, unpack, pixels );
      swrast_render_finish(ctx);
      break;
   case GL_DEPTH_STENCIL_EXT:
      swrast_render_start(ctx);
      draw_depth_stencil_pixels(ctx, x, y, width, height, type, unpack, pixels);
      swrast_render_finish(ctx);
      break;
   default:
      /* all other formats should be color formats */
      draw_rgba_pixels(ctx, x, y, width, height, format, type, unpack, pixels);
   }

   _mesa_set_vp_override(ctx, save_vp_override);

   _mesa_unmap_pbo_source(ctx, unpack);
}