Intention of this tutorial is to make you comfortable with the basic concepts in graphics.If you want to learn graphics programming then Turbo C++ 3.0 is good choice.Under this tutorial i will cover some standard library functions,so you can probably figure out the remaining graphics functions on your own.Basically there are two diffrent modes,namely text mode and graphics mode.In text mode it is possibe to display or capture only text in terms of ASCII.But in graphics any type of figure can be displayed,captured and animated.
♥ First Impressions
To start with graphics programming,you have to set out some of the things on your own like compiler or it’s installation & configuration etc.Example in tutorial wil work no matter which compiler you use, of course some of the library functions have minor variations.I recommend using Turbo C++ 3.0,as it will be readily availbale and it is much easier to use.
♥ Requirement
If you want to start graphics programming then you need two files which are GRAPHICS.H and GRAPHICS.LIB. These files are provided as part of TURBO C++. Check these files. The graphic mode functions require a graphics monitor and adapter card such as CGA,EGA and VGA. I assume you have complete working compiler so here’s how to create circle on the screen.
/* Simple example to draw circle */
#include"graphics.h"
#include"conio.h"
void main()
{
int gd=DETECT,gm;
initgraph(&gd, &gm, "c:/tc/bgi ");
circle(330,180,100);
getch();
closegraph();
restorecrtmode();
}
♥ Code explaination
The first line to look at is: GRAPHICS.H ,this file contains definitions and explaination of all the graphic functions and constants.While GRAPHICS.LIB file contains standard graphic functions.
Turbo C++ graphic functions have two categaries :Text mode graphic functions and graphic mode functions.Here we are dealing with graphic mode function.so just forget about text mode function right now.To switch from text mode to graphic mode,we have function called as ” initgraph ” .
initgraph : This function initialises the graphic mode.It selects the best resolution and direct that value to mode in variable gm.The two int variables gd, gm are graphic driver and graphic mode respectively.The gm handles value that tells us which resolution and monitor we are using. The gd specifies the graphic driver to be used.In our program we have gd=DETECT means we have passed the highest possible value available for the detected driver.If you don’t want that value then you have to assign the constant value for gd,gm.The ” &” symbol is used for initgraph to pass address of the constants.
Path ( ” C:\\tc\\bgi”) : It specifies the directory path where initgraph looks for graphics drivers (*.BGI) first. If files are not there then initgraph will look for the current directory of your program.If it unable to find wihtin current working directory then it will parse an error.You can leave it blank ( ” ” ) if the *.BGI files are within the working directory.
Circle( ) : Circle function takes X and Y values with respect to top left corner of the screen and third co-ordinate is nothing but radius of circle.In our example we have passed X=330,Y=180 and radius equal to 100 in terms of pixels as arguments.
Closegraph( ) : The closegraph() swithces back the screen from grpahics mode to text mode. If you don’t use this function then you may have undesirable effects.Here this function is called afer the getch() function as screen shouldn’t switch to text mode till user hits any key.
Restorcrtmode( ) : This mode will restore the original video mode detected by initgraph function.
getch( ) : getch( ) function gets a character from console but does not echo it on screen.This is used to pause the screen till user hits any key.
Note:
1) Make sure you have entered the correct path for the include & library directories.You can change the path by pointing your mouse to :
Options > Directories.Enter the valid path for the include directory and libraries,and output directories.
2) After installation of Turbo C,you have to adjust the settings of linker.Go to
Options>Linker > Libraries> and then check the ”
Graphics Library“.This will help to solve the linker errors for the graphics programs.Please do not uncheck any other option already selected by compiler.
3) Graphic initialisation depends on the path mentioned in initgraph path.Be sure to enter slash between c,tc,bgi.The path C & TC depends on user if he installed TC in d: drive then it will be d,tc.Read the above code’s path carefully.
4) If you want help on specific function then point your mouse to “
Help> Contents“,and then browse the content for the function you want.If you want fast-help then put the cursor on the first letter of the function or term and press
CTRL+F1,it will point you to the help file of that term/function.
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