DirectDraw based graphics engine for Freepascal

One of the massive advantages to the pure pascal programming that represented my first initiations into the world of programming is the enormous degree of control one can excert over the state of the system. Using real-mode interupts, assembly language and direct memory access, you can achieve almost anything, with the incredibly pace of the unconstrained processor. There is one major problem with Turbo pascal however, and that is of compatability. Simple text-based 16-bit real mode programs will run under Windows XP, but attempt anything risky; especially DOS interupts, or access of the memory; and nearly all functionality is lost (annoyingly this includes Trooper II, which is, despite protracted fiddlings, still refusing to run under XP). For those that love the accessibility and speed of pascal programming, help is, however, at hand. The marvelous (and free) GNU Freepascal compiler, as well as a fully funtional IDE and text editor, can be used with almost complete compatability for Turbo 6.0 code to generate 32-bit windows applications, with no restrictions on memory usage (or much else). The power of pascal is intact; portions of assembly language can be included in the code as easily as before; and code runs with comparable speed, and greatly enhanced stability. The one area where conversion cannot occur easily is graphical routines, where the direct-VGA access and bank-switching code of the real-mode sVGA engine is totally inappropriate to a windows-managed display. An innovative solution is provided by Carsen Weachter's FPCX graphical units, which make use of precompiled .dll files generated from Delphi sources for the DirectX to generate a directdraw surface, which can be referenced and (with care) drawn onto as any other piece of memory. Using his code as a basis, I obtained the DirectX 9 headers for Delphi, compiled them using the delphi 3.0 command line compiler, and set about modifying the code to allow direct access to the graphical memory, optimised assembler routines for simple graphical procedures, and more complex tools such as image display and page flipping. All these routines are included in a modified .dll file, which can be linked into your freepascal programs to make these routines instantly available. The result is an extremely powerful graphics engine (it even seems to outclass the sVGA routines written in Turbo); the screenshot shows a demonstration program, displaying copies of an image of dimensions 500x500x16 bit at a rate of over 6000/sec (a data transfer of over 300 Mbytes/sec); coupled with almost total stability, and integration into the windows OS (screenshots and mouse control can be added with ease). Find included in the downloadable package both the DirectX9 headers (it should work with previous versions without modification, but no promises), the engine source (which uses the headers and should be compiled using the delphi command line compiler to give a .dll file), and several demonstrations of what the engine can do. Enjoy!

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