I'm still working on my tile editor and I'm having some problems with layers. We all know it is a pain in the arse to blit non-rectangular images to a device context in Windows.
But I remember back in the days of BASIC programming that if you created a mask of the image - blitted it using the bitwise AND operator and then blitted the color image using the bitwise OR operator, it was akin to color keying.
So I thought I'd try it in Windows but it doesn't quite work. It does blit the transparency correctly, but when it is blitted over an already existing image it whitens those pixels that show through.
Here is my code: You might have to be fairly adept at C++ and Win32 API to understand what I'm doing here.
That code creates the mask and the image. I'm extracting tiles from a much larger bitmap and sticking them into a TileManager list which manages the global list of all available tiles that you can put down on the maps.Code:///////////////////////////////////////////////////////////////////////////// // CZeldaEditorDoc commands void CZeldaEditorDoc::AddToTileList(CString strFilename,CBitmap *Image,CDC *ImageDC, DWORD mRed,DWORD mGreen,DWORD mBlue) { if (!Image) { ::MessageBox(0,"CBitmap *Image not valid","CZeldaEditorDoc::SetTileList",0); return; } if (!ImageDC) { ::MessageBox(0,"CDC *ImageDC not valid","CZeldaEditorDoc::SetTileList",0); return; } m_strFilename=strFilename; //Get bitmap info BITMAP info; //::MessageBox(0,"Getting bitmap object","CZeldaEditorDoc::SetTileList()",0); Image->GetObject(sizeof(BITMAP),&info); DWORD ImageWidth=info.bmWidth; DWORD ImageHeight=info.bmHeight; //Tile size DWORD TileSize=m_iTileSize; //Allocate buffer for tile and mask //::MessageBox(0,"Allocating temp tile buffer","CZeldaEditorDoc::SetTileList",0); DWORD *TileBuffer=new DWORD[TileSize*TileSize]; DWORD *InvTileBuffer=new DWORD[TileSize*TileSize]; //Check for valid pointers if (!TileBuffer) { ::MessageBox(0,"Unable to create tile buffer","CZeldaEditorDoc::SetTileList()",0); return; } if (!InvTileBuffer) { ::MessageBox(0,"Unable to create tile mask buffer","CZeldaEditorDoc::SetTileList()",0); return; } //Find out how many tiles horiz and vert int NumHoriz=ImageWidth/TileSize; int NumVert=ImageHeight/TileSize; //Setup some variables we need DWORD WidthCounter=0; DWORD HeightCounter=0; DWORD StartX=0,StartY=0; DWORD CurrentX=0,CurrentY=0; DWORD TileOffset=0; DWORD PixelColor,Red,Green,Blue; DWORD NumTilesCreated=0; //Debugging text string if we need it CString DebugText; //Huge loop do { do { do { //Get the pixel color from the image PixelColor=ImageDC->GetPixel(CurrentX,CurrentY); //Extract the red green and blue components Red=(PixelColor & 0xFF0000) >> 16; Green=(PixelColor & 0xFF00) >>8; Blue=(PixelColor & 0xFF); //Stick RGBs into tile buffer TileBuffer[TileOffset]=RGB(Red,Green,Blue); //If pixel matches transparent, set to white, else black if ((Red==mRed) && (Green==mGreen) && (Blue==mBlue)) { //::MessageBox(0,"Transparent found",0,0); InvTileBuffer[TileOffset]=RGB(255,255,255); } else InvTileBuffer[TileOffset]=0; CurrentX++; TileOffset++; WidthCounter++; } while (WidthCounter<TileSize); WidthCounter=0; CurrentX=StartX; CurrentY++; HeightCounter++; } while (HeightCounter<TileSize); //Reset TileOffset TileOffset=0; //Add tile to tile manager m_pTileManager->Add(*ImageDC,TileSize,TileSize,1,32,TileBuffer,InvTileBuffer); //Increment counter NumTilesCreated++; StartX+=TileSize; //Check for wrap on X if (StartX>=ImageWidth) { StartX=0; StartY+=TileSize; } CurrentX=StartX; CurrentY=StartY; HeightCounter=0; } while (StartY<ImageHeight); //Clean up delete [] TileBuffer; delete [] InvTileBuffer; }
Here is the tile manager add function. It is inlined, hence the lack of a class type before the function name:
And here is the CTile::Create() function, again inlined in the code:Code:bool Add(CDC &pDC,DWORD iHoriz,DWORD iVert,int iPlanes,int iColorDepth, DWORD *pBuffer,DWORD *pMaskBuffer) { CTile *tile=new CTile(); tile->Create(pDC,iHoriz,iVert,iPlanes,iColorDepth,pBuffer,pMaskBuffer); tile->m_dwID=TileVector.size(); TileVector.push_back(tile); return true; }
Ok, now that sets everything up for rendering. This is the CZeldaEditorView::OnDraw() function.Code:void Create(CDC &dc,DWORD iHoriz,DWORD iVert,int iPlanes,int iColorDepth, DWORD *pBuffer,DWORD *pMaskBuffer) { //Setup class vars m_pTileImage=new CBitmap; m_pInvTileImage=new CBitmap; //Create bitmap and check if valid BOOL ok=m_pTileImage->CreateBitmap(iHoriz,iVert,iPlanes,iColorDepth,pBuffer); if (!ok) { ::MessageBox(0,"TileManager::Create() - Failed to create bitmap",0,0); } //Create mask bitmap and check if valid ok=m_pInvTileImage->CreateBitmap(iHoriz,iVert,iPlanes,iColorDepth,pMaskBuffer); if (!ok) { ::MessageBox(0,"TileManager::Create() - Failed to create mask bitmap",0,0); } //Get bitmap info for image - same for mask m_pTileImage->GetObject(sizeof(BITMAP),&m_pInfo); //Create compatible DC for image ImageDC.CreateCompatibleDC(&dc); //Select bitmap into DC ImageDC.SelectObject((CBitmap *)m_pTileImage); //Create compatible DC for mask AndImageDC.CreateCompatibleDC(&dc); //Select bitmap into DC AndImageDC.SelectObject((CBitmap *)m_pInvTileImage); }
I know it's a lot of code but you can see I've done nearly all the work here. I just need to know why the AND mask blit coupled with the OR mask blit is not working.Code:void CZeldaEditorView::OnDraw(CDC* pDC) { //Get pointer to document class CZeldaEditorDoc* pDoc = (CZeldaEditorDoc *)GetDocument(); // TODO: add draw code here //Get pointer to main frame class CMainFrame *ptrFrame=(CMainFrame *)AfxGetMainWnd(); //Get number of maps in manager (number of layers) DWORD numMaps=pDoc->m_pMapManager->GetNumberOfMaps(); //If tile manager is valid and this is not the move map (layer 0) //then draw tile map if (pDoc->m_pTileManager && numMaps>1) { //Get tile size from document int TileSize=pDoc->m_iTileSize; //Get our client rect CRect rect; GetClientRect(&rect); //Create black solid brush CBrush brush; brush.CreateSolidBrush(RGB(0,0,0)); //Rect for use later CRect boxrect; //Do some math to set up the render based on scrollx //scrolly, mapsizex, mapsizey, etc int iOffsetHoriz=abs(m_iScrollX/m_iGridSize); int iOffsetVert=abs(m_iScrollY/m_iGridSize); int iStartTile=iOffsetVert*m_iMapSizeX+iOffsetVert; int iCurTile=iStartTile; //Iterate through all layers (all maps) for (DWORD map=m_dwStartMapNum;map<m_dwEndMapNum;map++) { //Get pointer to Map class CMap *ptrMap=pDoc->m_pMapManager->GetMapClass(map); //Get pointer to movement map //CMap *ptrMove=pDoc->m_pMapManager->GetMapClass(0); //Debug string object CString debug; //Setup variables for render int CurrentY=(-m_iScrollY/(m_iGridSize+2)); int CurrentX=(-m_iScrollX/(m_iGridSize+2)); int OriginX=CurrentX; DWORD offset=CurrentY*pDoc->m_iMapSizeX+CurrentX; int offsetx=m_iScrollX % (m_iGridSize+2); int offsety=m_iScrollY % (m_iGridSize+2); DWORD startoffset=offset; //Another rect structure RECT grect; for (int i=offsety;i<rect.bottom;i+=(m_iGridSize+2)) { for (int j=offsetx;j<rect.right;j+=(m_iGridSize+2)) { //Get ID in map at current rendering offset DWORD ID=ptrMap->GetValueAtOffset(offset); //Get movement state of tile //DWORD MoveState=ptrMove->GetValueAtOffset(offset); //Setup rect grect.left=j; grect.top=i; grect.right=j+m_iGridSize+2; grect.bottom=i+m_iGridSize+2; //Draw frame rect with black brush pDC->FrameRect(&grect,&brush); //Tint cell red if movement == false //if (m_dwEndMapNum-m_dwStartMapNum==1) //{ // if (MoveState!=0) pDC->FillRect(&grect,new CBrush(RGB(255,0,0))); //} //If cell is not empty if (ID!=0xFFFFFFFF) { //Get DC from tile manager for tile ID CDC *tempDC=pDoc->m_pTileManager->GetTileDC(ID); //Get mask DC from tile manager for tile ID CDC *tempAndDC=pDoc->m_pTileManager->GetMaskDC(ID); //Stretch/shrink mask to fit grid size - AND blit pDC->StretchBlt(j+1,i+1,m_iGridSize,m_iGridSize,tempAndDC,0,0,TileSize,TileSize,SRCAND); //Stretch shrink bitmap to fit grid size - OR blit pDC->StretchBlt(j+1,i+1,m_iGridSize,m_iGridSize,tempDC,0,0,TileSize,TileSize,SRCPAINT); } //Increment vars offset++; CurrentX++; //Are we off the map on horiz? //Possible to be off the map, but not out of client rect if (CurrentX>=pDoc->m_iMapSizeX-1) break; } //Move down one row CurrentX=OriginX; startoffset+=pDoc->m_iMapSizeX; offset=startoffset; CurrentY++; //Are we off the map on vert if (CurrentY>pDoc->m_iMapSizeY-1) break; } } } //Layer print out CString layer; //To view one layer set m_dwEndMapMum to desired layer+1 //and set m_dwStartMapNum to desired layer //If difference is only 1 we are only viewing one layer if (m_dwEndMapNum-m_dwStartMapNum>1) { layer="Viewing all layers"; } else { layer.Format("Viewing layer %u",m_dwCurrentMapNum); } //Write info to client DC pDC->TextOut(0,0,layer); }
Don't worry too much about the structure.
Here it is:
CTile - tile class
CTileManager - vector of tiles
CMap - map class
CMapManager - vector of maps (each map is one layer)
