# Shared Flashcard Set

OpenGL
Test1 2D objects
22
Computer Science
02/21/2012

## Additional Computer Science Flashcards

Term
 glClear(GL_COLOR_BUFFER_BIT);
Definition
 clears color buffer-a region of memory where the image to be drawn is stored (usually on graphics card)
Term
 glColor3f(0,0,0);
Definition
 defines the color of the object about to be drawn. In RGB color and using numbers 0-1
Term
 glRectf(-1,1,1,-1);
Definition
 Draws a retangle using two points
Term
 glPointSize(4);
Definition
 defines the size of points that are to be drawn. This one indicates that each point will contain four pixels and creates a 2x2 box. (Note: does not really create circular points. For example if you declared the point size to be 10, it will create a 5x5 box)
Term
 glBegin(x*****); a***; b***;glEnd();
Definition
 Will draw a polygon, triangle, points, lines, etc. when you put the correct words in x*****;a*** sometimes declares what color the following will be drawn with using glColor3f() or glColor3ub();b*** usually is glVertex2f(x,y) to tell the program exactly where the points of the vertex of the object is
Term
 glVertex2f(a,b);
Definition
 a and b correspond to x and y coordinates. It will declare a point exactly at a,b for whatever function you are using.
Term
 glFlush();
Definition
 forces previously buffered OpenGL commands to execute. Often used in void functions the user creates and not in main();
Term
 glutInit(&argc, argv);
Definition
 (used in int main() ) inits the open GL utility library so that its functions can be used by the program
Term
 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
Definition
 (used in int main() )requests single buffering and RGB display mode so that colors are displayed
Term
 glutWindowSize(600,600);
Definition
 (used in int main() )sets the display window size to 600 in horiz and 600 in vertical
Term
 glutInitWindowPosition(50,50);
Definition
 (used in int main() )sets window position with upper left hand corner at (250, 100);if changed to (500,50) it will move to the right in the screenif changed to (50,500) it will move down the screen
Term
 glutCreateWindow("Blah");
Definition
 (used in int main() )creates the 600 x 600 pixel window on the screen. Also titles it "Blah"
Term
 glClearColor(1.0,1.0,0.0,0.0)
Definition
 (used in int main() )In this case it sets the background color to yellow. the values relate to (R,G,B,opacity). Opacity also means the transparency of the background color.
Term
 glutDisplayFunc(myDisplay);
Definition
 (used in int main() )indicates the function ("myDisplay") to be called each time the window is drawn. (myDisplay is usually a user created function)
Term
 glutMainLoop();
Definition
 (used in int main() )causes the program to enter an event processing loop (a loop that executes as long as the window is on the screen)
Term
 gluOrtho2D(XWL,XWR,YWBot,YWTop);
Definition
 function to define world space clipping window with X width and Y height. Used in user created function.Only needs to be defined in myDisplay func. It does not need anything else in int main()
Term
 glLineWidth(3.0);
Definition
 Sets line width to 3.0generally used in user created functions
Term
 Clipping Windows
Definition
 Used to change to view of the window to a different part. Say the window originally shows 0 to 5 on the x and 0 to 5 on the y. You can change the window to different specifications such as -5 to 5 for both x and y
Term
Definition
 generate an identity matrix for use in developing a world-to-viewpoint transform matrixused in user created function (myDisplay)
Term
 glutPostRedisplay();
Definition
 forces display function to be calleduser created function (ex. myKeybdFun or used when using the function to enable zooming)
Term
 glutKeyboardFunc(myKeyFunc);
Definition
 sets keyboard callback for the current windowused in int main()
Term
 what are the parameters for the void myKeyFunc(a,b,c)?
Definition
 a = unsigned char k;b = int xx;c = int yy;
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