Programming Windows 95 Part 3.ppt

Programming Windows 95 Part 3 DirectX Multimedia Direct what? COM-based multimedia for Win32 Hardware abstraction Full acceleration support Good emulation model Low-level High-performance What抯 with the 慩? DirectDraw DirectSound/DirectSound3D DirectInput DirectPlay Direct3D DirectDraw Accelerated drawing and animation Blit support Stretching/Interpolation Quick access to offscreen memory flipping functionality DirectSound / DirectSound3D Low-latency sound playback / mixing 3D positioning Software now Hardware later Full COM Support IUnknown is supported AddRef()/Release() QueryInterface() Full class factory (CoCreateInstance works) Custom object creation entry points HRESULT return codes DirectDraw Concepts Setting Up DirectDraw DirectDrawCreate() or CoCreateInstance() Get the IID_IDirectDraw interface pointer SetCooperativeLevel() SetDisplayMode() Fill in a DDSURFACEDESC CreateSurface() Ah! Flipping Surfaces?!?!? 揊ront surface?and 揃ack surface? Create a 揻lipping chain?For double-buffering, the primary surface is created with one 揳ttached surface?-- this is called the back buffer GetAttachedSurface() Draw on the back buffer Call Flip() on the primary Notes on Flipping lpddsBack is always the same and lpddsFront is always the same A Flip() does not flip these pointers as far as you抮e concerned You抮e simply drawing on different RAM Two Ways to Render to a Surface IDirectDrawSurface::GetDC() Do Windows GDI calls IDirectDrawSurface::ReleaseDC() IDirectDrawSurface::Lock() Party on the pointer IDirectDrawSurface::Unlock() 揥here抯 PutPixel()?? DirectDraw is low-level There are no such drawing routines GDI, but it抯 butt slow Write your own Most algorithms are easily adapted to DirectDraw if you simply account for the Lock, Unlock, and the lPitch Partying on a surface pointer 揙bey the lPitch, Luke!?Don抰 get cute You can抰 write a better Blt() than Microsoft Debugging your routines is rough Loading Graphics Data No format filters or any such high-leve