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 VidMem v1.5 - Access Video Memory for Mode 13h   Geoff Speicher 20.08.1991

Подключаемый по $include модуль для прямого доступа к видео памяти в режиме 13h. VidMem v1.5 - Access to video memory (320x200x256 mode only) through Turbo Pascal. VidMem v1.5 has been rewritten in assembler for maximum speed and compatibility with different versions of TP.


VidMem v1.5 (Copyright 1991 by Geoff Speicher) - Access to video memory (320x200x256 mode only) through Turbo Pascal. VidMem v1.5 has been rewritten in assembler for maximum speed and compatibility with different versions of TP. The following are the procedures and functions in the VIDMEM.OBJ file: ----- Procedure InitMCGAMode; This puts your system into it's 320x200x256 graphics mode. A VGA or MCGA card is required. ----- Procedure DeInitMCGAMode; This puts your system back into text mode. ----- Procedure WriteVidMem(OfsVal: LongInt; Value: Byte); This writes a value directly to video memory, and thus, is the core of the graphics routines you will be using. The two parameters are set as follows: OfsVal - Offset, or location on the screen at which the pixel will be written. You have to imagine the screen as being a large array of bytes. Byte 0 is the upper left corner. Byte 64000 is the lower right. So, the center of the screen would be 32099. An easy rule to follow is this: Add 320 to a number, and it will move down exactly one scan line. Subtract 320, and it will move up one line. Add 1 and the location moves to the right 1 pixel. Of course, subtract 1 and the location moves 1 pixel to the left. Value - Value to be written at the specific location of video memory. In other words, the color you want the pixel to be. This can be set from 0 to 255. ----- Procedure ReadVidMem(OfsVal: LongInt; var Color: Byte); Reads the color of a pixel at a specific video location. Set OfsVal the same way you would if writing a pixel. The color (0-255) will be returned in ReadVidMem. ----- Procedure SetPaletteColorRGB(Number, RedVal, GreenVal, BlueVal: Byte); Sets an individual palette color. Number is the palette color (0-255). RedVal, GreenVal, and BlueVal are the Red, Green, and Blue shades that compose the color. Setting RedVal to 255, and GreenVal and BlueVal to 0 will produce a bright Red. The same is true for GreenVal and BlueVal. You can mix any combination of these three colors (setting all three to 255 will give you bright white). You can make almost any color using different combinations. The lower you set the value, the darker the color will be. ----- Procedure GetPaletteColorRGB(Number: Byte; var RedVal, GreenVal, BlueVal: Byte); Will return the red, green, and blue values for a certain palette color in RedVal, GreenVal, and BlueVal. Number is the palette color (0-255); ----- Procedure WriteImage(TopLeft, ImageSeg, ImageOfs, ImageSize: LongInt; Width: Integer); This will write a predefined image to the screen. The image MUST be defined as an array of bytes. This array can be as large or small as you want. Each byte value will be interpreted as the color to write on the screen. Here is an example of defining an image: Const ManyColors: Array[1..20] of Byte = (16,17,18,19,20,21,22,23,24, 25, 25,24,23,22,21,20,19,18,17,16); TopLeft is the screen location for the upper left corner of the image. ImageSeg is the segment of the image. ImageOfs is the offset, ImageSize is the size, and Width is the width of the image, in pixels. You could display the above image like this: WriteImage(32080,Seg(ManyColors),Ofs(ManyColors), Sizeof(ManyColors),5); The best way to get familiar with this procedure is to just fool around with it. And experiment with different images and width settings. For example, setting the width in the above to 20 would draw a horizontal line. However, setting the width to 1 would draw a vertical line! ----- Procedure ReadImage(TopLeft, ImageSeg, ImageOfs, ImageSize: LongInt; Width: Integer); Does the exact opposite of WriteImage. Pass the parameters the same way, and you've got it made! ----- -------------------------------- New procedures/functions to v1.5 -------------------------------- Procedure WritePixel(X,Y: Integer; Color: Byte); This will perform the same operation as WriteVidMem, but you can use an X,Y system of coordinates to name the pixel. ----- Procedure ReadPixel(X,Y: Integer; var Color: Byte); Same idea as WritePixel... ----- Function XYtoVM(X,Y: Integer): Word; Returns the single number (0-63999) equivalence of a set of X,Y coordinates passed to it. This enables you to use X,Y coordinates with other procedures, such as ReadImage and WriteImage. ----- That's it! Be on the lookout for future versions and updates! Any questions or comments can be sent to me by: 1) FidoNet Mail. Send it to Net/Node 1:268/310, addressed to Geoff Speicher. 2) EMail. If you don't want to wait for NetMail, you can call up my BBS: GROUND ZER0!!! BBS (717)876-5869 14.4k bps HST. And leave EMail to the Sysop (that's me). 3) If you're not really looking for a response, and don't like the first two methods, you can send a "real" letter to: Geoff Speicher P.O. Box 163 Archbald, Pa 18403