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+/*
+ * cocos2d for iPhone: http://www.cocos2d-iphone.org
+ *
+ * Copyright (c) 2009-2010 Ricardo Quesada
+ * Copyright (c) 2011 Zynga Inc.
+ * 
+ * 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 THE
+ * AUTHORS OR COPYRIGHT HOLDERS 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.
+ *
+ *
+ * TMX Tiled Map support:
+ * http://www.mapeditor.org
+ *
+ */
+
+#import "CCTMXLayer.h"
+#import "CCTMXTiledMap.h"
+#import "CCTMXXMLParser.h"
+#import "CCSprite.h"
+#import "CCSpriteBatchNode.h"
+#import "CCTextureCache.h"
+#import "Support/CGPointExtension.h"
+
+#pragma mark -
+#pragma mark CCSpriteBatchNode Extension
+
+@interface CCSpriteBatchNode (TMXTiledMapExtensions)
+-(id) addSpriteWithoutQuad:(CCSprite*)child z:(NSUInteger)z tag:(NSInteger)aTag;
+-(void) addQuadFromSprite:(CCSprite*)sprite quadIndex:(NSUInteger)index;
+@end
+
+/* IMPORTANT XXX IMPORTNAT:
+ * These 2 methods can't be part of CCTMXLayer since they call [super add...], and CCSpriteBatchNode#add SHALL not be called
+ */
+@implementation CCSpriteBatchNode (TMXTiledMapExtension)
+
+/* Adds a quad into the texture atlas but it won't be added into the children array.
+ This method should be called only when you are dealing with very big AtlasSrite and when most of the CCSprite won't be updated.
+ For example: a tile map (CCTMXMap) or a label with lots of characgers (CCLabelBMFont)
+ */
+-(void) addQuadFromSprite:(CCSprite*)sprite quadIndex:(NSUInteger)index
+{
+        NSAssert( sprite != nil, @"Argument must be non-nil");
+        NSAssert( [sprite isKindOfClass:[CCSprite class]], @"CCSpriteBatchNode only supports CCSprites as children");
+        
+        
+        while(index >= textureAtlas_.capacity || textureAtlas_.capacity == textureAtlas_.totalQuads )
+                [self increaseAtlasCapacity];
+
+        //
+        // update the quad directly. Don't add the sprite to the scene graph
+        //
+
+        [sprite useBatchNode:self];
+        [sprite setAtlasIndex:index];
+
+        ccV3F_C4B_T2F_Quad quad = [sprite quad];
+        [textureAtlas_ insertQuad:&quad atIndex:index];
+        
+        // XXX: updateTransform will update the textureAtlas too using updateQuad.
+        // XXX: so, it should be AFTER the insertQuad
+        [sprite setDirty:YES];
+        [sprite updateTransform];
+}
+
+/* This is the opposite of "addQuadFromSprite.
+ It add the sprite to the children and descendants array, but it doesn't update add it to the texture atlas
+ */
+-(id) addSpriteWithoutQuad:(CCSprite*)child z:(NSUInteger)z tag:(NSInteger)aTag
+{
+        NSAssert( child != nil, @"Argument must be non-nil");
+        NSAssert( [child isKindOfClass:[CCSprite class]], @"CCSpriteBatchNode only supports CCSprites as children");
+        
+        // quad index is Z
+        [child setAtlasIndex:z];
+        
+        // XXX: optimize with a binary search
+        int i=0;
+        for( CCSprite *c in descendants_ ) {
+                if( c.atlasIndex >= z )
+                        break;
+                i++;
+        }
+        [descendants_ insertObject:child atIndex:i];
+        
+        
+        // IMPORTANT: Call super, and not self. Avoid adding it to the texture atlas array
+        [super addChild:child z:z tag:aTag];
+        return self;    
+}
+@end
+
+
+#pragma mark -
+#pragma mark CCTMXLayer
+
+int compareInts (const void * a, const void * b);
+
+
+@interface CCTMXLayer ()
+-(CGPoint) positionForIsoAt:(CGPoint)pos;
+-(CGPoint) positionForOrthoAt:(CGPoint)pos;
+-(CGPoint) positionForHexAt:(CGPoint)pos;
+
+-(CGPoint) calculateLayerOffset:(CGPoint)offset;
+
+/* optimization methos */
+-(CCSprite*) appendTileForGID:(uint32_t)gid at:(CGPoint)pos;
+-(CCSprite*) insertTileForGID:(uint32_t)gid at:(CGPoint)pos;
+-(CCSprite*) updateTileForGID:(uint32_t)gid at:(CGPoint)pos;
+
+/* The layer recognizes some special properties, like cc_vertez */
+-(void) parseInternalProperties;
+
+-(NSInteger) vertexZForPos:(CGPoint)pos;
+
+// index
+-(NSUInteger) atlasIndexForExistantZ:(NSUInteger)z;
+-(NSUInteger) atlasIndexForNewZ:(NSUInteger)z;
+@end
+
+@implementation CCTMXLayer
+@synthesize layerSize = layerSize_, layerName = layerName_, tiles = tiles_;
+@synthesize tileset = tileset_;
+@synthesize layerOrientation = layerOrientation_;
+@synthesize mapTileSize = mapTileSize_;
+@synthesize properties = properties_;
+
+#pragma mark CCTMXLayer - init & alloc & dealloc
+
++(id) layerWithTilesetInfo:(CCTMXTilesetInfo*)tilesetInfo layerInfo:(CCTMXLayerInfo*)layerInfo mapInfo:(CCTMXMapInfo*)mapInfo
+{
+        return [[[self alloc] initWithTilesetInfo:tilesetInfo layerInfo:layerInfo mapInfo:mapInfo] autorelease];
+}
+
+-(id) initWithTilesetInfo:(CCTMXTilesetInfo*)tilesetInfo layerInfo:(CCTMXLayerInfo*)layerInfo mapInfo:(CCTMXMapInfo*)mapInfo
+{       
+        // XXX: is 35% a good estimate ?
+        CGSize size = layerInfo.layerSize;
+        float totalNumberOfTiles = size.width * size.height;
+        float capacity = totalNumberOfTiles * 0.35f + 1; // 35 percent is occupied ?
+        
+        CCTexture2D *tex = nil;
+        if( tilesetInfo )
+                tex = [[CCTextureCache sharedTextureCache] addImage:tilesetInfo.sourceImage];
+        
+        if((self = [super initWithTexture:tex capacity:capacity])) {            
+
+                // layerInfo
+                self.layerName = layerInfo.name;
+                layerSize_ = layerInfo.layerSize;
+                tiles_ = layerInfo.tiles;
+                minGID_ = layerInfo.minGID;
+                maxGID_ = layerInfo.maxGID;
+                opacity_ = layerInfo.opacity;
+                self.properties = [NSMutableDictionary dictionaryWithDictionary:layerInfo.properties];
+
+                // tilesetInfo
+                self.tileset = tilesetInfo;
+                
+                // mapInfo
+                mapTileSize_ = mapInfo.tileSize;
+                layerOrientation_ = mapInfo.orientation;
+                
+                // offset (after layer orientation is set);
+                CGPoint offset = [self calculateLayerOffset:layerInfo.offset];
+                [self setPositionInPixels:offset];
+                
+                atlasIndexArray_ = ccCArrayNew(totalNumberOfTiles);
+                
+                [self setContentSizeInPixels: CGSizeMake( layerSize_.width * mapTileSize_.width, layerSize_.height * mapTileSize_.height )];
+                
+                useAutomaticVertexZ_= NO;
+                vertexZvalue_ = 0;
+                alphaFuncValue_ = 0;
+
+        }
+        return self;
+}
+
+- (void) dealloc
+{
+        [layerName_ release];
+        [tileset_ release];
+        [reusedTile_ release];
+        [properties_ release];
+        
+        if( atlasIndexArray_ ) {
+                ccCArrayFree(atlasIndexArray_);
+                atlasIndexArray_ = NULL;
+        }
+        
+        if( tiles_ ) {
+                free(tiles_);
+                tiles_ = NULL;
+        }
+        
+        [super dealloc];
+}
+
+-(void) releaseMap
+{
+        if( tiles_) {
+                free( tiles_);
+                tiles_ = NULL;
+        }
+        
+        if( atlasIndexArray_ ) {
+                ccCArrayFree(atlasIndexArray_);
+                atlasIndexArray_ = NULL;
+        }
+}
+
+#pragma mark CCTMXLayer - setup Tiles
+
+-(void) setupTiles
+{       
+        // Optimization: quick hack that sets the image size on the tileset
+        tileset_.imageSize = [textureAtlas_.texture contentSizeInPixels];
+        
+        // By default all the tiles are aliased
+        // pros:
+        //  - easier to render
+        // cons:
+        //  - difficult to scale / rotate / etc.
+        [textureAtlas_.texture setAliasTexParameters];
+        
+        CFByteOrder o = CFByteOrderGetCurrent();
+                
+        // Parse cocos2d properties
+        [self parseInternalProperties];
+        
+        for( NSUInteger y=0; y < layerSize_.height; y++ ) {
+                for( NSUInteger x=0; x < layerSize_.width; x++ ) {
+                        
+                        NSUInteger pos = x + layerSize_.width * y;
+                        uint32_t gid = tiles_[ pos ];
+                        
+                        // gid are stored in little endian.
+                        // if host is big endian, then swap
+                        if( o == CFByteOrderBigEndian )
+                                gid = CFSwapInt32( gid );
+                        
+                        // XXX: gid == 0 --> empty tile
+                        if( gid != 0 ) {
+                                [self appendTileForGID:gid at:ccp(x,y)];
+                                
+                                // Optimization: update min and max GID rendered by the layer
+                                minGID_ = MIN(gid, minGID_);
+                                maxGID_ = MAX(gid, maxGID_);
+                        }
+                }
+        }
+        
+        NSAssert( maxGID_ >= tileset_.firstGid &&
+                         minGID_ >= tileset_.firstGid, @"TMX: Only 1 tilset per layer is supported");   
+}
+
+#pragma mark CCTMXLayer - Properties
+
+-(id) propertyNamed:(NSString *)propertyName 
+{
+        return [properties_ valueForKey:propertyName];
+}
+
+-(void) parseInternalProperties
+{
+        // if cc_vertex=automatic, then tiles will be rendered using vertexz
+
+        NSString *vertexz = [self propertyNamed:@"cc_vertexz"];
+        if( vertexz ) {
+                if( [vertexz isEqualToString:@"automatic"] )
+                        useAutomaticVertexZ_ = YES;
+                else
+                        vertexZvalue_ = [vertexz intValue];
+        }
+        
+        NSString *alphaFuncVal = [self propertyNamed:@"cc_alpha_func"];
+        alphaFuncValue_ = [alphaFuncVal floatValue];
+}
+
+#pragma mark CCTMXLayer - obtaining tiles/gids
+
+-(CCSprite*) tileAt:(CGPoint)pos
+{
+        NSAssert( pos.x < layerSize_.width && pos.y < layerSize_.height && pos.x >=0 && pos.y >=0, @"TMXLayer: invalid position");
+        NSAssert( tiles_ && atlasIndexArray_, @"TMXLayer: the tiles map has been released");
+        
+        CCSprite *tile = nil;
+        uint32_t gid = [self tileGIDAt:pos];
+        
+        // if GID == 0, then no tile is present
+        if( gid ) {
+                int z = pos.x + pos.y * layerSize_.width;
+                tile = (CCSprite*) [self getChildByTag:z];
+                
+                // tile not created yet. create it
+                if( ! tile ) {
+                        CGRect rect = [tileset_ rectForGID:gid];                        
+                        tile = [[CCSprite alloc] initWithBatchNode:self rectInPixels:rect];
+                        [tile setPositionInPixels: [self positionAt:pos]];
+                        [tile setVertexZ: [self vertexZForPos:pos]];
+                        tile.anchorPoint = CGPointZero;
+                        [tile setOpacity:opacity_];
+                        
+                        NSUInteger indexForZ = [self atlasIndexForExistantZ:z];
+                        [self addSpriteWithoutQuad:tile z:indexForZ tag:z];
+                        [tile release];
+                }
+        }
+        return tile;
+}
+
+-(uint32_t) tileGIDAt:(CGPoint)pos
+{
+        NSAssert( pos.x < layerSize_.width && pos.y < layerSize_.height && pos.x >=0 && pos.y >=0, @"TMXLayer: invalid position");
+        NSAssert( tiles_ && atlasIndexArray_, @"TMXLayer: the tiles map has been released");
+        
+        NSInteger idx = pos.x + pos.y * layerSize_.width;
+        return tiles_[ idx ];
+}
+
+#pragma mark CCTMXLayer - adding helper methods
+
+-(CCSprite*) insertTileForGID:(uint32_t)gid at:(CGPoint)pos
+{
+        CGRect rect = [tileset_ rectForGID:gid];
+        
+        NSInteger z = pos.x + pos.y * layerSize_.width;
+        
+        if( ! reusedTile_ )
+                reusedTile_ = [[CCSprite alloc] initWithBatchNode:self rectInPixels:rect];
+        else
+                [reusedTile_ initWithBatchNode:self rectInPixels:rect];
+        
+        [reusedTile_ setPositionInPixels: [self positionAt:pos]];
+        [reusedTile_ setVertexZ: [self vertexZForPos:pos]];
+        reusedTile_.anchorPoint = CGPointZero;
+        [reusedTile_ setOpacity:opacity_];
+        
+        // get atlas index
+        NSUInteger indexForZ = [self atlasIndexForNewZ:z];
+        
+        // Optimization: add the quad without adding a child
+        [self addQuadFromSprite:reusedTile_ quadIndex:indexForZ];
+        
+        // insert it into the local atlasindex array
+        ccCArrayInsertValueAtIndex(atlasIndexArray_, (void*)z, indexForZ);
+        
+        // update possible children
+        CCSprite *sprite;
+        CCARRAY_FOREACH(children_, sprite) {
+                NSUInteger ai = [sprite atlasIndex];
+                if( ai >= indexForZ)
+                        [sprite setAtlasIndex: ai+1];
+        }
+        
+        tiles_[z] = gid;
+        
+        return reusedTile_;
+}
+
+-(CCSprite*) updateTileForGID:(uint32_t)gid at:(CGPoint)pos
+{
+        CGRect rect = [tileset_ rectForGID:gid];
+        
+        int z = pos.x + pos.y * layerSize_.width;
+        
+        if( ! reusedTile_ )
+                reusedTile_ = [[CCSprite alloc] initWithBatchNode:self rectInPixels:rect];
+        else
+                [reusedTile_ initWithBatchNode:self rectInPixels:rect];
+        
+        [reusedTile_ setPositionInPixels: [self positionAt:pos]];
+        [reusedTile_ setVertexZ: [self vertexZForPos:pos]];
+        reusedTile_.anchorPoint = CGPointZero;
+        [reusedTile_ setOpacity:opacity_];
+        
+        // get atlas index
+        NSUInteger indexForZ = [self atlasIndexForExistantZ:z];
+
+        [reusedTile_ setAtlasIndex:indexForZ];
+        [reusedTile_ setDirty:YES];
+        [reusedTile_ updateTransform];
+        tiles_[z] = gid;
+        
+        return reusedTile_;
+}
+
+
+// used only when parsing the map. useless after the map was parsed
+// since lot's of assumptions are no longer true
+-(CCSprite*) appendTileForGID:(uint32_t)gid at:(CGPoint)pos
+{
+        CGRect rect = [tileset_ rectForGID:gid];
+        
+        NSInteger z = pos.x + pos.y * layerSize_.width;
+        
+        if( ! reusedTile_ )
+                reusedTile_ = [[CCSprite alloc] initWithBatchNode:self rectInPixels:rect];
+        else
+                [reusedTile_ initWithBatchNode:self rectInPixels:rect];
+        
+        [reusedTile_ setPositionInPixels: [self positionAt:pos]];
+        [reusedTile_ setVertexZ: [self vertexZForPos:pos]];
+        reusedTile_.anchorPoint = CGPointZero;
+        [reusedTile_ setOpacity:opacity_];
+        
+        // optimization:
+        // The difference between appendTileForGID and insertTileforGID is that append is faster, since
+        // it appends the tile at the end of the texture atlas
+        NSUInteger indexForZ = atlasIndexArray_->num;
+
+
+        // don't add it using the "standard" way.
+        [self addQuadFromSprite:reusedTile_ quadIndex:indexForZ];
+        
+        
+        // append should be after addQuadFromSprite since it modifies the quantity values
+        ccCArrayInsertValueAtIndex(atlasIndexArray_, (void*)z, indexForZ);
+        
+        return reusedTile_;
+}
+
+#pragma mark CCTMXLayer - atlasIndex and Z
+
+int compareInts (const void * a, const void * b)
+{
+        return ( *(int*)a - *(int*)b );
+}
+
+-(NSUInteger) atlasIndexForExistantZ:(NSUInteger)z
+{
+        NSInteger key = z;
+        NSInteger *item = bsearch((void*)&key, (void*)&atlasIndexArray_->arr[0], atlasIndexArray_->num, sizeof(void*), compareInts);
+        
+        NSAssert( item, @"TMX atlas index not found. Shall not happen");
+
+        NSUInteger index = ((NSInteger)item - (NSInteger)atlasIndexArray_->arr) / sizeof(void*);
+        return index;
+}
+
+-(NSUInteger)atlasIndexForNewZ:(NSUInteger)z
+{
+        // XXX: This can be improved with a sort of binary search
+        NSUInteger i = 0;
+        for(i = 0; i< atlasIndexArray_->num; i++) {
+                NSUInteger val = (NSUInteger) atlasIndexArray_->arr[i];
+                if( z < val )
+                        break;
+        }       
+        return i;
+}
+
+#pragma mark CCTMXLayer - adding / remove tiles
+
+-(void) setTileGID:(uint32_t)gid at:(CGPoint)pos
+{
+        NSAssert( pos.x < layerSize_.width && pos.y < layerSize_.height && pos.x >=0 && pos.y >=0, @"TMXLayer: invalid position");
+        NSAssert( tiles_ && atlasIndexArray_, @"TMXLayer: the tiles map has been released");
+        NSAssert( gid == 0 || gid >= tileset_.firstGid, @"TMXLayer: invalid gid" );
+
+        uint32_t currentGID = [self tileGIDAt:pos];
+        
+        if( currentGID != gid ) {
+                
+                // setting gid=0 is equal to remove the tile
+                if( gid == 0 )
+                        [self removeTileAt:pos];
+
+                // empty tile. create a new one
+                else if( currentGID == 0 )
+                        [self insertTileForGID:gid at:pos];
+
+                // modifying an existing tile with a non-empty tile
+                else {
+
+                        NSUInteger z = pos.x + pos.y * layerSize_.width;
+                        id sprite = [self getChildByTag:z];
+                        if( sprite ) {
+                                CGRect rect = [tileset_ rectForGID:gid];
+                                [sprite setTextureRectInPixels:rect rotated:NO untrimmedSize:rect.size];
+                                tiles_[z] = gid;
+                        } else
+                                [self updateTileForGID:gid at:pos];
+                }
+        }
+}
+
+-(void) addChild: (CCNode*)node z:(NSInteger)z tag:(NSInteger)tag
+{
+        NSAssert(NO, @"addChild: is not supported on CCTMXLayer. Instead use setTileGID:at:/tileAt:");
+}
+
+-(void) removeChild:(CCSprite*)sprite cleanup:(BOOL)cleanup
+{
+        // allows removing nil objects
+        if( ! sprite )
+                return;
+
+        NSAssert( [children_ containsObject:sprite], @"Tile does not belong to TMXLayer");
+        
+        NSUInteger atlasIndex = [sprite atlasIndex];
+        NSUInteger zz = (NSUInteger) atlasIndexArray_->arr[atlasIndex];
+        tiles_[zz] = 0;
+        ccCArrayRemoveValueAtIndex(atlasIndexArray_, atlasIndex);
+        [super removeChild:sprite cleanup:cleanup];
+}
+
+-(void) removeTileAt:(CGPoint)pos
+{
+        NSAssert( pos.x < layerSize_.width && pos.y < layerSize_.height && pos.x >=0 && pos.y >=0, @"TMXLayer: invalid position");
+        NSAssert( tiles_ && atlasIndexArray_, @"TMXLayer: the tiles map has been released");
+
+        uint32_t gid = [self tileGIDAt:pos];
+        
+        if( gid ) {
+                
+                NSUInteger z = pos.x + pos.y * layerSize_.width;
+                NSUInteger atlasIndex = [self atlasIndexForExistantZ:z];
+                
+                // remove tile from GID map
+                tiles_[z] = 0;
+
+                // remove tile from atlas position array
+                ccCArrayRemoveValueAtIndex(atlasIndexArray_, atlasIndex);
+                
+                // remove it from sprites and/or texture atlas
+                id sprite = [self getChildByTag:z];
+                if( sprite )
+                        [super removeChild:sprite cleanup:YES];
+                else {
+                        [textureAtlas_ removeQuadAtIndex:atlasIndex];
+
+                        // update possible children
+                        CCARRAY_FOREACH(children_, sprite) {
+                                NSUInteger ai = [sprite atlasIndex];
+                                if( ai >= atlasIndex) {
+                                        [sprite setAtlasIndex: ai-1];
+                                }
+                        }
+                }
+        }
+}
+
+#pragma mark CCTMXLayer - obtaining positions, offset
+
+-(CGPoint) calculateLayerOffset:(CGPoint)pos
+{
+        CGPoint ret = CGPointZero;
+        switch( layerOrientation_ ) {
+                case CCTMXOrientationOrtho:
+                        ret = ccp( pos.x * mapTileSize_.width, -pos.y *mapTileSize_.height);
+                        break;
+                case CCTMXOrientationIso:
+                        ret = ccp( (mapTileSize_.width /2) * (pos.x - pos.y),
+                                          (mapTileSize_.height /2 ) * (-pos.x - pos.y) );
+                        break;
+                case CCTMXOrientationHex:
+                        NSAssert(CGPointEqualToPoint(pos, CGPointZero), @"offset for hexagonal map not implemented yet");
+                        break;
+        }
+        return ret;     
+}
+
+-(CGPoint) positionAt:(CGPoint)pos
+{
+        CGPoint ret = CGPointZero;
+        switch( layerOrientation_ ) {
+                case CCTMXOrientationOrtho:
+                        ret = [self positionForOrthoAt:pos];
+                        break;
+                case CCTMXOrientationIso:
+                        ret = [self positionForIsoAt:pos];
+                        break;
+                case CCTMXOrientationHex:
+                        ret = [self positionForHexAt:pos];
+                        break;
+        }
+        return ret;
+}
+
+-(CGPoint) positionForOrthoAt:(CGPoint)pos
+{
+        CGPoint xy = {
+                pos.x * mapTileSize_.width,
+                (layerSize_.height - pos.y - 1) * mapTileSize_.height,
+        };
+        return xy;
+}
+
+-(CGPoint) positionForIsoAt:(CGPoint)pos
+{
+        CGPoint xy = {
+                mapTileSize_.width /2 * ( layerSize_.width + pos.x - pos.y - 1),
+                mapTileSize_.height /2 * (( layerSize_.height * 2 - pos.x - pos.y) - 2),
+        };
+        return xy;
+}
+
+-(CGPoint) positionForHexAt:(CGPoint)pos
+{
+        float diffY = 0;
+        if( (int)pos.x % 2 == 1 )
+                diffY = -mapTileSize_.height/2 ;
+        
+        CGPoint xy = {
+                pos.x * mapTileSize_.width*3/4,
+                (layerSize_.height - pos.y - 1) * mapTileSize_.height + diffY
+        };
+        return xy;
+}
+
+-(NSInteger) vertexZForPos:(CGPoint)pos
+{
+        NSInteger ret = 0;
+        NSUInteger maxVal = 0;
+        if( useAutomaticVertexZ_ ) {
+                switch( layerOrientation_ ) {
+                        case CCTMXOrientationIso:
+                                maxVal = layerSize_.width + layerSize_.height;
+                                ret = -(maxVal - (pos.x + pos.y));
+                                break;
+                        case CCTMXOrientationOrtho:
+                                ret = -(layerSize_.height-pos.y);
+                                break;
+                        case CCTMXOrientationHex:
+                                NSAssert(NO,@"TMX Hexa zOrder not supported");
+                                break;
+                        default:
+                                NSAssert(NO,@"TMX invalid value");
+                                break;
+                }
+        } else
+                ret = vertexZvalue_;
+        
+        return ret;
+}
+
+#pragma mark CCTMXLayer - draw
+
+-(void) draw
+{
+        if( useAutomaticVertexZ_ ) {
+                glEnable(GL_ALPHA_TEST);
+                glAlphaFunc(GL_GREATER, alphaFuncValue_);
+        }
+        
+        [super draw];
+        
+        if( useAutomaticVertexZ_ )
+                glDisable(GL_ALPHA_TEST);
+}
+@end
+