aboutsummaryrefslogtreecommitdiff
path: root/engines/sword2/render.cpp
blob: a47f8abe0df14765cd2e666a9fe9de4c049d97c3 (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
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * Additional copyright for this file:
 * Copyright (C) 1994-1998 Revolution Software Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 */


#include "common/endian.h"
#include "common/system.h"

#include "graphics/primitives.h"

#include "sword2/sword2.h"
#include "sword2/defs.h"
#include "sword2/screen.h"

namespace Sword2 {

#define RENDERAVERAGETOTAL 4

void Screen::updateRect(Common::Rect *r) {
	_vm->_system->copyRectToScreen(_buffer + r->top * _screenWide + r->left,
		_screenWide, r->left, r->top, r->right - r->left,
		r->bottom - r->top);
}

void Screen::blitBlockSurface(BlockSurface *s, Common::Rect *r, Common::Rect *clipRect) {
	if (!r->intersects(*clipRect))
		return;

	byte *src = s->data;

	if (r->top < clipRect->top) {
		src -= BLOCKWIDTH * (r->top - clipRect->top);
		r->top = clipRect->top;
	}
	if (r->left < clipRect->left) {
		src -= (r->left - clipRect->left);
		r->left = clipRect->left;
	}
	if (r->bottom > clipRect->bottom)
		r->bottom = clipRect->bottom;
	if (r->right > clipRect->right)
		r->right = clipRect->right;

	byte *dst = _buffer + r->top * _screenWide + r->left;
	int i;

	if (s->transparent) {
		for (i = 0; i < r->bottom - r->top; i++) {
			for (int j = 0; j < r->right - r->left; j++) {
				if (src[j])
					dst[j] = src[j];
			}
			src += BLOCKWIDTH;
			dst += _screenWide;
		}
	} else {
		for (i = 0; i < r->bottom - r->top; i++) {
			memcpy(dst, src, r->right - r->left);
			src += BLOCKWIDTH;
			dst += _screenWide;
		}
	}
}

// There are two different separate functions for scaling the image - one fast
// and one good. Or at least that's the theory. I'm sure there are better ways
// to scale an image than this. The latter is used at the highest graphics
// quality setting. Note that the "good" scaler takes extra parameters so that
// it can use the background image when calculating the average pixel value.
//
// This code isn't quite like the original DrawSprite(), but the result should
// be close enough, I hope.

void Screen::scaleImageFast(byte *dst, uint16 dstPitch, uint16 dstWidth, uint16 dstHeight, byte *src, uint16 srcPitch, uint16 srcWidth, uint16 srcHeight) {
	int x, y;

	for (x = 0; x < dstWidth; x++)
		_xScale[x] = (x * srcWidth) / dstWidth;

	for (y = 0; y < dstHeight; y++)
		_yScale[y] = (y * srcHeight) / dstHeight;

	for (y = 0; y < dstHeight; y++) {
		for (x = 0; x < dstWidth; x++) {
			dst[x] = src[_yScale[y] * srcPitch + _xScale[x]];
		}
		dst += dstPitch;
	}
}

void Screen::scaleImageGood(byte *dst, uint16 dstPitch, uint16 dstWidth, uint16 dstHeight, byte *src, uint16 srcPitch, uint16 srcWidth, uint16 srcHeight, byte *backBuf, int16 bbXPos, int16 bbYPos) {
	for (int y = 0; y < dstHeight; y++) {
		for (int x = 0; x < dstWidth; x++) {
			uint8 c1, c2, c3, c4;

			uint32 xPos = (x * srcWidth) / dstWidth;
			uint32 yPos = (y * srcHeight) / dstHeight;
			uint32 xFrac = dstWidth - (x * srcWidth) % dstWidth;
			uint32 yFrac = dstHeight - (y * srcHeight) % dstHeight;

			byte *srcPtr = src + yPos * srcPitch + xPos;

			bool transparent = true;

			if (*srcPtr) {
				c1 = *srcPtr;
				transparent = false;
			} else {
				if (bbXPos + x >= 0 &&
				    bbXPos + x < RENDERWIDE &&
				    bbYPos + y >= MENUDEEP &&
				    bbYPos + y < MENUDEEP + RENDERDEEP) {
					c1 = *(backBuf + _screenWide * (bbYPos + y) + bbXPos + x);
				} else {
					c1 = 0;
				}
			}

			if (x < dstWidth - 1) {
				if (*(srcPtr + 1)) {
					c2 = *(srcPtr + 1);
					transparent = false;
				} else {
					if (bbXPos + x + 1 >= 0 &&
					    bbXPos + x + 1 < RENDERWIDE &&
					    bbYPos + y >= MENUDEEP &&
					    bbYPos + y + 1 < MENUDEEP + RENDERDEEP) {
						c2 = *(backBuf + _screenWide * (bbYPos + y) + bbXPos + x + 1);
					} else {
						c2 = c1;
					}
				}
			} else {
				c2 = c1;
			}

			if (y < dstHeight - 1) {
				if (*(srcPtr + srcPitch)) {
					c3 = *(srcPtr + srcPitch);
					transparent = false;
				} else {
					if (bbXPos + x >= 0 &&
					    bbXPos + x < RENDERWIDE &&
					    bbYPos + y + 1 >= MENUDEEP &&
					    bbYPos + y + 1 < MENUDEEP + RENDERDEEP) {
						c3 = *(backBuf + _screenWide * (bbYPos + y + 1) + bbXPos);
					} else {
						c3 = c1;
					}
				}
			} else {
				c3 = c1;
			}

			if (x < dstWidth - 1 && y < dstHeight - 1) {
				if (*(srcPtr + srcPitch + 1)) {
					c4 = *(srcPtr + srcPitch + 1);
					transparent = false;
				} else {
					if (bbXPos + x + 1 >= 0 &&
					    bbXPos + x + 1 < RENDERWIDE &&
					    bbYPos + y + 1 >= MENUDEEP &&
					    bbYPos + y + 1 < MENUDEEP + RENDERDEEP) {
						c4 = *(backBuf + _screenWide * (bbYPos + y + 1) + bbXPos + x + 1);
					} else {
						c4 = c3;
					}
				}
			} else {
				c4 = c3;
			}

			if (!transparent) {
				uint32 r1 = _palette[c1 * 3 + 0];
				uint32 g1 = _palette[c1 * 3 + 1];
				uint32 b1 = _palette[c1 * 3 + 2];

				uint32 r2 = _palette[c2 * 3 + 0];
				uint32 g2 = _palette[c2 * 3 + 1];
				uint32 b2 = _palette[c2 * 3 + 2];

				uint32 r3 = _palette[c3 * 3 + 0];
				uint32 g3 = _palette[c3 * 3 + 1];
				uint32 b3 = _palette[c3 * 3 + 2];

				uint32 r4 = _palette[c4 * 3 + 0];
				uint32 g4 = _palette[c4 * 3 + 1];
				uint32 b4 = _palette[c4 * 3 + 2];

				uint32 r5 = (r1 * xFrac + r2 * (dstWidth - xFrac)) / dstWidth;
				uint32 g5 = (g1 * xFrac + g2 * (dstWidth - xFrac)) / dstWidth;
				uint32 b5 = (b1 * xFrac + b2 * (dstWidth - xFrac)) / dstWidth;

				uint32 r6 = (r3 * xFrac + r4 * (dstWidth - xFrac)) / dstWidth;
				uint32 g6 = (g3 * xFrac + g4 * (dstWidth - xFrac)) / dstWidth;
				uint32 b6 = (b3 * xFrac + b4 * (dstWidth - xFrac)) / dstWidth;

				uint32 r = (r5 * yFrac + r6 * (dstHeight - yFrac)) / dstHeight;
				uint32 g = (g5 * yFrac + g6 * (dstHeight - yFrac)) / dstHeight;
				uint32 b = (b5 * yFrac + b6 * (dstHeight - yFrac)) / dstHeight;

				dst[y * dstWidth + x] = quickMatch(r, g, b);
			} else
				dst[y * dstWidth + x] = 0;
		}
	}
}

/**
 * Plots a point relative to the top left corner of the screen. This is only
 * used for debugging.
 * @param x x-coordinate of the point
 * @param y y-coordinate of the point
 * @param color color of the point
 */

void Screen::plotPoint(int x, int y, uint8 color) {
	byte *buf = _buffer + MENUDEEP * RENDERWIDE;

	x -= _scrollX;
	y -= _scrollY;

	if (x >= 0 && x < RENDERWIDE && y >= 0 && y < RENDERDEEP) {
		buf[y * RENDERWIDE + x] = color;
		markAsDirty(x, y + MENUDEEP, x, y + MENUDEEP);
	}
}

static void plot(int x, int y, int color, void *data) {
	Screen *screen = (Screen *)data;
	screen->plotPoint(x, y, (uint8) color);
}

/**
 * Draws a line from one point to another. This is only used for debugging.
 * @param x0 x-coordinate of the start point
 * @param y0 y-coordinate of the start point
 * @param x1 x-coordinate of the end point
 * @param y1 y-coordinate of the end point
 * @param color color of the line
 */

void Screen::drawLine(int x0, int y0, int x1, int y1, uint8 color) {
	Graphics::drawLine(x0, y0, x1, y1, color, &plot, this);
}

/**
 * This function tells the driver the size of the background screen for the
 * current location.
 * @param w width of the current location
 * @param h height of the current location
 */

void Screen::setLocationMetrics(uint16 w, uint16 h) {
	_locationWide = w;
	_locationDeep = h;
	setNeedFullRedraw();
}

/**
 * Draws a parallax layer at the current position determined by the scroll. A
 * parallax can be either foreground, background or the main screen.
 */

void Screen::renderParallax(byte *ptr, int16 l) {
	int16 x, y;
	uint16 xRes, yRes;
	Common::Rect r;

	if (!ptr)
		return;

	// Fetch resolution data from parallax

	if (Sword2Engine::isPsx()) {
		xRes = READ_LE_UINT16(ptr);
		yRes = READ_LE_UINT16(ptr + 2) * 2;
	} else {
		Parallax p;

		p.read(ptr);
		xRes = p.w;
		yRes = p.h;
	}

	if (_locationWide == _screenWide)
		x = 0;
	else
		x = ((int32)((xRes - _screenWide) * _scrollX) / (int32)(_locationWide - _screenWide));

	if (_locationDeep == _screenDeep - MENUDEEP * 2)
		y = 0;
	else
		y = ((int32)((yRes - (_screenDeep - MENUDEEP * 2)) * _scrollY) / (int32)(_locationDeep - (_screenDeep - MENUDEEP * 2)));

	Common::Rect clipRect;

	// Leave enough space for the top and bottom menues

	clipRect.left = 0;
	clipRect.right = _screenWide;
	clipRect.top = MENUDEEP;
	clipRect.bottom = _screenDeep - MENUDEEP;

	for (int j = 0; j < _yBlocks[l]; j++) {
		for (int i = 0; i < _xBlocks[l]; i++) {
			if (_blockSurfaces[l][i + j * _xBlocks[l]]) {
				r.left = i * BLOCKWIDTH - x;
				r.right = r.left + BLOCKWIDTH;
				r.top = j * BLOCKHEIGHT - y + MENUDEEP;
				r.bottom = r.top + BLOCKHEIGHT;
				blitBlockSurface(_blockSurfaces[l][i + j * _xBlocks[l]], &r, &clipRect);
			}
		}
	}

	_parallaxScrollX = _scrollX - x;
	_parallaxScrollY = _scrollY - y;
}

// Uncomment this when benchmarking the drawing routines.
#define LIMIT_FRAME_RATE

/**
 * Initialises the timers before the render loop is entered.
 */

void Screen::initialiseRenderCycle() {
	_initialTime = _vm->_system->getMillis();
	_totalTime = _initialTime + (1000 / _vm->getFramesPerSecond());
}

/**
 * This function should be called when the game engine is ready to start the
 * render cycle.
 */

void Screen::startRenderCycle() {
	_scrollXOld = _scrollX;
	_scrollYOld = _scrollY;

	_startTime = _vm->_system->getMillis();

	if (_startTime + _renderAverageTime >= _totalTime)	{
		_scrollX = _scrollXTarget;
		_scrollY = _scrollYTarget;
		_renderTooSlow = true;
	} else {
		_scrollX = (int16)(_scrollXOld + ((_scrollXTarget - _scrollXOld) * (_startTime - _initialTime + _renderAverageTime)) / (_totalTime - _initialTime));
		_scrollY = (int16)(_scrollYOld + ((_scrollYTarget - _scrollYOld) * (_startTime - _initialTime + _renderAverageTime)) / (_totalTime - _initialTime));
		_renderTooSlow = false;
	}

	if (_scrollXOld != _scrollX || _scrollYOld != _scrollY)
		setNeedFullRedraw();

	_framesPerGameCycle = 0;
}

/**
 * This function should be called at the end of the render cycle.
 * @return true if the render cycle is to be terminated,
 *         or false if it should continue
 */

bool Screen::endRenderCycle() {
	static int32 renderTimeLog[4] = { 60, 60, 60, 60 };
	static int32 renderCountIndex = 0;
	int32 time;

	time = _vm->_system->getMillis();
	renderTimeLog[renderCountIndex] = time - _startTime;
	_startTime = time;
	_renderAverageTime = (renderTimeLog[0] + renderTimeLog[1] + renderTimeLog[2] + renderTimeLog[3]) >> 2;

	_framesPerGameCycle++;

	if (++renderCountIndex == RENDERAVERAGETOTAL)
		renderCountIndex = 0;

	if (_renderTooSlow) {
		initialiseRenderCycle();
		return true;
	}

	if (_startTime + _renderAverageTime >= _totalTime) {
		_totalTime += (1000 / _vm->getFramesPerSecond());
		_initialTime = time;
		return true;
	}

#ifdef LIMIT_FRAME_RATE
	if (_scrollXTarget == _scrollX && _scrollYTarget == _scrollY) {
		// If we have already reached the scroll target sleep for the
		// rest of the render cycle.
		_vm->sleepUntil(_totalTime);
		_initialTime = _vm->_system->getMillis();
		_totalTime += (1000 / _vm->getFramesPerSecond());
		return true;
	}
#endif

	// This is an attempt to ensure that we always reach the scroll target.
	// Otherwise the game frequently tries to pump out new interpolation
	// frames without ever getting anywhere.

	if (ABS(_scrollX - _scrollXTarget) <= 1 && ABS(_scrollY - _scrollYTarget) <= 1) {
		_scrollX = _scrollXTarget;
		_scrollY = _scrollYTarget;
	} else {
		_scrollX = (int16)(_scrollXOld + ((_scrollXTarget - _scrollXOld) * (_startTime - _initialTime + _renderAverageTime)) / (_totalTime - _initialTime));
		_scrollY = (int16)(_scrollYOld + ((_scrollYTarget - _scrollYOld) * (_startTime - _initialTime + _renderAverageTime)) / (_totalTime - _initialTime));
	}

	if (_scrollX != _scrollXOld || _scrollY != _scrollYOld)
		setNeedFullRedraw();

#ifdef LIMIT_FRAME_RATE
	// Give the other threads some breathing space. This apparently helps
	// against bug #875683, though I was never able to reproduce it for
	// myself.
	_vm->_system->delayMillis(10);
#endif

	return false;
}

/**
 * Reset scrolling stuff. This function is called from initBackground()
 */

void Screen::resetRenderEngine() {
	_parallaxScrollX = 0;
	_parallaxScrollY = 0;
	_scrollX = 0;
	_scrollY = 0;
}

/**
 * This function should be called five times with either the parallax layer
 * or a NULL pointer in order of background parallax to foreground parallax.
 */

int32 Screen::initialiseBackgroundLayer(byte *parallax) {
	Parallax p;
	uint16 i, j, k;
	byte *data;
	byte *dst;

	debug(2, "initialiseBackgroundLayer");

	assert(_layer < MAXLAYERS);

	if (!parallax) {
		_layer++;
		return RD_OK;
	}

	p.read(parallax);

	_xBlocks[_layer] = (p.w + BLOCKWIDTH - 1) / BLOCKWIDTH;
	_yBlocks[_layer] = (p.h + BLOCKHEIGHT - 1) / BLOCKHEIGHT;

	_blockSurfaces[_layer] = (BlockSurface **)calloc(_xBlocks[_layer] * _yBlocks[_layer], sizeof(BlockSurface *));
	if (!_blockSurfaces[_layer])
		return RDERR_OUTOFMEMORY;

	// Decode the parallax layer into a large chunk of memory

	byte *memchunk = (byte *)calloc(_xBlocks[_layer] * _yBlocks[_layer], BLOCKWIDTH * BLOCKHEIGHT);
	if (!memchunk)
		return RDERR_OUTOFMEMORY;

	for (i = 0; i < p.h; i++) {
		uint32 p_offset = READ_LE_UINT32(parallax + Parallax::size() + 4 * i);

		if (!p_offset)
			continue;

		byte *pLine = parallax + p_offset;
		uint16 packets = READ_LE_UINT16(pLine);
		uint16 offset = READ_LE_UINT16(pLine + 2);

		data = pLine + 4;
		dst = memchunk + i * p.w + offset;

		if (!packets) {
			memcpy(dst, data, p.w);
			continue;
		}

		bool zeros = false;

		for (j = 0; j < packets; j++) {
			if (zeros) {
				dst += *data;
				offset += *data;
				data++;
				zeros = false;
			} else if (!*data) {
				data++;
				zeros = true;
			} else {
				uint16 count = *data++;
				memcpy(dst, data, count);
				data += count;
				dst += count;
				offset += count;
				zeros = true;
			}
		}
	}

	// The large memory chunk is now divided into a number of smaller
	// surfaces. For most parallax layers, we'll end up using less memory
	// this way, and it will be faster to draw since completely transparent
	// surfaces are discarded.

	for (i = 0; i < _xBlocks[_layer] * _yBlocks[_layer]; i++) {
		bool block_has_data = false;
		bool block_is_transparent = false;

		int x = BLOCKWIDTH * (i % _xBlocks[_layer]);
		int y = BLOCKHEIGHT * (i / _xBlocks[_layer]);

		data = memchunk + p.w * y + x;

		for (j = 0; j < BLOCKHEIGHT; j++) {
			for (k = 0; k < BLOCKWIDTH; k++) {
				if (x + k < p.w && y + j < p.h) {
					if (data[j * p.w + k])
						block_has_data = true;
					else
						block_is_transparent = true;
				}
			}
		}

		//  Only assign a surface to the block if it contains data.

		if (block_has_data) {
			_blockSurfaces[_layer][i] = (BlockSurface *)malloc(sizeof(BlockSurface));

			//  Copy the data into the surfaces.
			dst = _blockSurfaces[_layer][i]->data;
			for (j = 0; j < BLOCKHEIGHT; j++) {
				memcpy(dst, data, BLOCKWIDTH);
				data += p.w;
				dst += BLOCKWIDTH;
			}

			_blockSurfaces[_layer][i]->transparent = block_is_transparent;

		} else
			_blockSurfaces[_layer][i] = NULL;
	}

	free(memchunk);
	_layer++;

	return RD_OK;
}

/**
 * This converts PSX format background data into a format that
 * can be understood by renderParallax functions.
 * PSX Backgrounds are divided into tiles of 64x32 (with aspect
 * ratio correction), while PC backgrounds are in tiles of 64x64.
 */

int32 Screen::initialisePsxBackgroundLayer(byte *parallax) {
	uint16 bgXres, bgYres;
	uint16 trueXres, stripeNumber, totStripes;
	uint32 baseAddress, stripePos;
	uint16 i, j;
	byte *dst;

	debug(2, "initialisePsxBackgroundLayer");

	assert(_layer < MAXLAYERS);

	if (!parallax) {
		_layer++;
		return RD_OK;
	}

	// Fetch data from buffer

	bgXres = READ_LE_UINT16(parallax);
	bgYres = READ_LE_UINT16(parallax + 2) * 2;
	baseAddress = READ_LE_UINT32(parallax + 4);
	parallax += 8;

	// Calculate TRUE resolution of background, must be
	// a multiple of 64

	trueXres = (bgXres % 64) ? ((bgXres/64) + 1) * 64 : bgXres;
	totStripes = trueXres / 64;

	_xBlocks[_layer] = (bgXres + BLOCKWIDTH - 1) / BLOCKWIDTH;
	_yBlocks[_layer] = (bgYres + BLOCKHEIGHT - 1) / BLOCKHEIGHT;

	uint16 remLines = bgYres % 64;

	byte *tileChunk = (byte *)malloc(BLOCKHEIGHT * BLOCKWIDTH);
	if (!tileChunk)
		return RDERR_OUTOFMEMORY;

	_blockSurfaces[_layer] = (BlockSurface **)calloc(_xBlocks[_layer] * _yBlocks[_layer], sizeof(BlockSurface *));
	if (!_blockSurfaces[_layer]) {
		free(tileChunk);
		return RDERR_OUTOFMEMORY;
	}

	// Group PSX background (64x32, when stretched vertically) tiles together,
	// to make them compatible with pc version (composed by 64x64 tiles)

	stripeNumber = 0;
	stripePos = 0;
	for (i = 0; i < _xBlocks[_layer] * _yBlocks[_layer]; i++) {
		bool block_has_data = false;
		bool block_is_transparent = false;

		int posX = i / _yBlocks[_layer];
		int posY = i % _yBlocks[_layer];

		uint32 stripeOffset = READ_LE_UINT32(parallax + stripeNumber * 8 + 4) + stripePos - baseAddress;

		memset(tileChunk, 1, BLOCKHEIGHT * BLOCKWIDTH);

		if (!(remLines && posY == _yBlocks[_layer] - 1))
			remLines = 32;

		for (j = 0; j < remLines; j++) {
			memcpy(tileChunk + j * BLOCKWIDTH * 2, parallax + stripeOffset + j * BLOCKWIDTH, BLOCKWIDTH);
			memcpy(tileChunk + j * BLOCKWIDTH * 2 + BLOCKWIDTH, parallax + stripeOffset + j * BLOCKWIDTH, BLOCKWIDTH);
		}

		for (j = 0; j < BLOCKHEIGHT * BLOCKWIDTH; j++) {
			if (tileChunk[j])
				block_has_data = true;
			else
				block_is_transparent = true;
		}

		int tileIndex = totStripes * posY + posX;

		//  Only assign a surface to the block if it contains data.

		if (block_has_data) {
			_blockSurfaces[_layer][tileIndex] = (BlockSurface *)malloc(sizeof(BlockSurface));

			//  Copy the data into the surfaces.
			dst = _blockSurfaces[_layer][tileIndex]->data;
			memcpy(dst, tileChunk, BLOCKWIDTH * BLOCKHEIGHT);

			_blockSurfaces[_layer][tileIndex]->transparent = block_is_transparent;

		} else
			_blockSurfaces[_layer][tileIndex] = NULL;

		if (posY == _yBlocks[_layer] - 1) {
			stripeNumber++;
			stripePos = 0;
		} else {
			stripePos += 0x800;
		}
	}

	free(tileChunk);
	_layer++;

	return RD_OK;
}

/**
 * This converts PSX format parallax data into a format that
 * can be understood by renderParallax functions.
 */

int32 Screen::initialisePsxParallaxLayer(byte *parallax) {
	uint16 plxXres, plxYres;
	uint16 xTiles, yTiles;
	uint16 i, j, k;
	byte *data;
	byte *dst;

	debug(2, "initialisePsxParallaxLayer");

	assert(_layer < MAXLAYERS);

	if (!parallax) {
		_layer++;
		return RD_OK;
	}

	plxXres = READ_LE_UINT16(parallax);
	plxYres = READ_LE_UINT16(parallax + 2);
	xTiles = READ_LE_UINT16(parallax + 4);
	yTiles = READ_LE_UINT16(parallax + 6);

	// Beginning of parallax table composed by uint32,
	// if word is 0, corresponding tile contains no data and must be skipped,
	// if word is 0x400 tile contains data.
	parallax += 8;

	// Beginning if tiles data.
	data = parallax + xTiles * yTiles * 4;

	_xBlocks[_layer] = xTiles;
	_yBlocks[_layer] = (yTiles / 2) + ((yTiles % 2) ? 1 : 0);
	bool oddTiles = ((yTiles % 2) ? true : false);

	_blockSurfaces[_layer] = (BlockSurface **)calloc(_xBlocks[_layer] * _yBlocks[_layer], sizeof(BlockSurface *));
	if (!_blockSurfaces[_layer])
		return RDERR_OUTOFMEMORY;

	// We have to check two tiles for every block in PSX version, if one of those
	// has data in it, the whole block has data. Also, tiles must be doublelined to
	// get correct aspect ratio.
	for (i = 0; i < _xBlocks[_layer] * _yBlocks[_layer]; i++) {
		bool block_has_data = false;
		bool block_is_transparent = false;
		bool firstTilePresent, secondTilePresent;

		int posX = i / _yBlocks[_layer];
		int posY = i % _yBlocks[_layer];

		if (oddTiles && posY == _yBlocks[_layer] - 1) {
			firstTilePresent = READ_LE_UINT32(parallax) == 0x400;
			secondTilePresent = false;
			parallax += 4;
		} else {
			firstTilePresent = READ_LE_UINT32(parallax) == 0x400;
			secondTilePresent = READ_LE_UINT32(parallax + 4) == 0x400;
			parallax += 8;
		}

		// If one of the two grouped tiles has data, then the whole block has data
		if (firstTilePresent || secondTilePresent) {
			block_has_data = true;

			// If one of the two grouped blocks is without data, then we also have transparency
			if (!firstTilePresent || !secondTilePresent)
				block_is_transparent = true;
		}

		// Now do a second check to see if we have a partially transparent block
		if (block_has_data && !block_is_transparent) {
			byte *block = data;
			if (firstTilePresent) {
				for (k = 0; k < 0x400; k++) {
					if (*(block + k) == 0) {
						block_is_transparent = true;
						break;
					}
				}
				block += 0x400; // On to next block...
			}

			// If we didn't find transparency in first block and we have
			// a second tile, check it
			if (secondTilePresent && !block_is_transparent) {
				for (k = 0; k < 0x400; k++) {
					if (*(block + k) == 0) {
						block_is_transparent = true;
						break;
					}
				}
			}
		}

		int tileIndex = xTiles * posY + posX;

		//  Only assign a surface to the block if it contains data.

		if (block_has_data) {
			_blockSurfaces[_layer][tileIndex] = (BlockSurface *)malloc(sizeof(BlockSurface));
			memset(_blockSurfaces[_layer][tileIndex], 0, BLOCKHEIGHT * BLOCKWIDTH);

			//  Copy the data into the surfaces.
			dst = _blockSurfaces[_layer][tileIndex]->data;

			if (firstTilePresent) { //There is data in the first tile
				for (j = 0; j < 16; j++) {
					memcpy(dst, data, BLOCKWIDTH);
					dst += BLOCKWIDTH;
					memcpy(dst, data, BLOCKWIDTH);
					dst += BLOCKWIDTH;
					data += BLOCKWIDTH;
				}
			} else {
				dst += 0x800;
			}

			if (secondTilePresent) {
				for (j = 0; j < 16; j++) {
					memcpy(dst, data, BLOCKWIDTH);
					dst += BLOCKWIDTH;
					memcpy(dst, data, BLOCKWIDTH);
					dst += BLOCKWIDTH;
					data += BLOCKWIDTH;
				}
			}

			_blockSurfaces[_layer][tileIndex]->transparent = block_is_transparent;
		} else
			_blockSurfaces[_layer][tileIndex] = NULL;
	}

	_layer++;

	return RD_OK;
}

/**
 * Should be called once after leaving the room to free up memory.
 */

void Screen::closeBackgroundLayer() {
	debug(2, "CloseBackgroundLayer");

	if (Sword2Engine::isPsx())
		flushPsxScrCache();

	for (int i = 0; i < MAXLAYERS; i++) {
		if (_blockSurfaces[i]) {
			for (int j = 0; j < _xBlocks[i] * _yBlocks[i]; j++)
				if (_blockSurfaces[i][j])
					free(_blockSurfaces[i][j]);
			free(_blockSurfaces[i]);
			_blockSurfaces[i] = NULL;
		}
	}

	_layer = 0;
}

} // End of namespace Sword2