Programming and Graphics

256 Introduction to C++ Programming and Graphics

In this case, the invoked functionblankclears the screen to the color set

by the third command in the main program.

The blank-screen code will be our basic template for developing further appli-
cations.

Teap ot

The following C++ code contained in the fileglutshapes.ccconsists of
the main program and the user-defined functionshowme. The code opens a
window and draws the wire-frame image of a teapot:

#include <freeglut.h>

using namespace std;

void disp(void);

int main(int argc, char **argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUTDEPTH|GLUTSINGLE|GLUTRGBA);

glutInitWindowPosition(100,100);

glutInitWindowSize(320,320);

glOrtho(-1.2, 1.2, -1.2, 1.2, -1.2, 1.2);

glutCreateWindow("Teapot");

glutDisplayFunc(showme);

glClearColor(0.2,0.5,0.2,0.2);

glutMainLoop();

return 0;

}

//--- showme

void showme(void)

{

glClear(GLCOLORBUFFERBIT); // clear the screen

glutWireTeapot(0.6);

}

The graphics output of the code on the desktop is shown in Figure 8.1.1(b).
Three newGlutfunctions have been introduced to set the display mode and
specify the location and size of the graphics window:

glutInitDisplayMode

glutInitWindowPosition

glutInitWindowSize

In addition, the OpenGL functionglOrthowas invoked to set the lower and