10. Program to display a set of values { fij } as a rectangular mesh.

Description:

A polygon mesh is a collection of vertices, edges and faces that defines the shape of a polyhedral object in 3D computer graphics and solid modeling. The faces usually consist of triangles (triangle mesh), quadrilaterals, or other simple convex polygons, since this simplifies rendering, but may also be composed of more general concave polygons, or polygons with holes. The study of polygon meshes is a large sub-field of computer graphics and geometric modeling. Different representations of polygon meshes are used for different applications and goals. As polygonal meshes are extensively used in computer graphics, algorithms also exist for collision detection, and rigid-body dynamics of polygon meshes. The objective of this program is to develop a polygonal mesh using a set of values.

Program:

#include<stdio.h>

#include<GL/glut.h>

#define dx 15

#define dy 10

GLfloat x[100],y[100];

GLfloat x0=50, y0=50; //initial values for x,y

GLint i,j;

int maxx,maxy;

void display(void)

{

            glClearColor(1.0,1.0,1.0,1.0);

            glClear(GL_COLOR_BUFFER_BIT);

            glMatrixMode(GL_PROJECTION);

            glLoadIdentity();

            gluOrtho2D(0.0,499.0,0.0,499.0);

            glMatrixMode(GL_MODELVIEW);

            glLoadIdentity();

            for(i=0;i<=maxy;i++)

                        x[i]=x0+i*dx; //Compute x[i]

            for(j=0;j<=maxx;j++)

                        y[j]=y0+j*dy; //compute y[i]

            glColor3f(0.0,0.0,1.0);

            for(i=0;i<maxy;i++)

                        for(j=0;j<maxx;j++)

                        {

                                    glColor3f(0.0,0.0,1.0);

                                    glBegin(GL_LINE_LOOP);

                                    glVertex2f(x[i],y[j]);

                                    glVertex2f(x[i],y[j+1]);

                                    glVertex2f(x[i+1],y[j+1]);

                                    glVertex2f(x[i+1],y[j]);

                                    glEnd();

                        }

                        glFlush();

}

void main(int argc, char **argv)

{

            printf("Enter rows & Columns\n");

            scanf("%d%d",&maxx,&maxy);

            glutInit(&argc,argv);

            glutInitWindowPosition(10,10);

            glutInitWindowSize(500,500);

            glutCreateWindow("Rectangular Mesh");

            glutDisplayFunc(display);

            glutMainLoop();

}

Output 1:

sahyadrids1@sahyadrids1-Veriton-Series:~/cg_16$ ./mesh

Enter rows & Columns

10 11

Output 2:

sahyadrids1@sahyadrids1-Veriton-Series:~/cg_16$ ./mesh

Enter rows & Columns

25 20