glutshapes.h

#ifndef _GLUT_SHAPES_H_
#define _GLUT_SHAPES_H_

#include <GL/glut.h>
#include<math.h>

#define pi (2*acos(0.0))

void drawAxes(int drawaxes);
void drawSquare(double a);
void drawGrid(int drawgrid);
void drawCircle(double radius,int segments);
void drawCone(double radius,double height,int segments);
void drawSphere(double radius,int slices,int stacks);

void drawAxes(int drawaxes)
{
    if(drawaxes == 1) {
        glColor3f(1.0, 0.0, 0.0);
        glBegin(GL_LINES); {
            glColor3f(1.0, 0.0, 0.0);
            glVertex3f( 100,0,0);
            glVertex3f(-100,0,0);

            glColor3f(0.0, 1.0, 0.0);
            glVertex3f(0,-100,0);
            glVertex3f(0, 100,0);

            glColor3f(0.0, 0.0, 1.0);
            glVertex3f(0,0, 100);
            glVertex3f(0,0,-100);
        } glEnd();
    }
}

void drawGrid(int drawgrid)
{
    int i;
    if(drawgrid == 1) {
        glColor3f(0.6, 0.6, 0.6);   //grey
        glBegin(GL_LINES); {
            for(i = -8; i <= 8; i++){

                if(i == 0)
                    continue;   //SKIP the MAIN axes

                //lines parallel to Y-axis
                glVertex3f(i*10, -90, 0);
                glVertex3f(i*10,  90, 0);

                //lines parallel to X-axis
                glVertex3f(-90, i*10, 0);
                glVertex3f( 90, i*10, 0);
            }
        } glEnd();
    }
}

void drawSquare(double a)
{
    //glColor3f(1.0,0.0,0.0);
    glBegin(GL_QUADS);  {
        glVertex3f( a, a, 2);
        glVertex3f( a,-a, 2);
        glVertex3f(-a,-a, 2);
        glVertex3f(-a, a, 2);
    } glEnd();
}

void drawCircle(double radius,int segments)
{
    int i;
    struct vector3d points[100];
    glColor3f(0.7,0.7,0.7);
    //generate points
    for(i = 0; i <= segments; i++) {
        points[i].x = radius * cos(((double)i / (double)segments) * 2*pi);
        points[i].y = radius * sin(((double)i / (double)segments) * 2*pi);
    }
    //draw segments using generated points
    for(i = 0; i < segments; i++) {
        glBegin(GL_LINES); {
            glVertex3f(points[i].x, points[i].y, 0);
            glVertex3f(points[i+1].x, points[i+1].y, 0);
        } glEnd();
    }
}

void drawCone(double radius,double height,int segments)
{
    int i;
    double shade;
    struct vector3d points[100];
    //generate points
    for(i = 0; i <= segments; i++) {
        points[i].x = radius * cos(((double)i / (double)segments) * 2*pi);
        points[i].y = radius * sin(((double)i / (double)segments) * 2*pi);
    }
    //draw triangles using generated points
    for(i = 0; i < segments; i++) {
        //create shading effect
        if (i < segments/2)
            shade = 2 * (double)i / (double)segments;
        else
            shade = 2 * (1.0 - (double)i / (double)segments);

        glColor3f(shade, shade, shade);
        glBegin(GL_TRIANGLES); {
            glVertex3f(0, 0, height);
            glVertex3f(points[i].x, points[i].y, 0);
            glVertex3f(points[i+1].x, points[i+1].y, 0);
        } glEnd();
    }
}

void drawSphere(double radius, int slices, int stacks)
{
    struct vector3d points[100][100];
    int i, j;
    double h, r;
    //generate points
    for(i = 0; i <= stacks; i++) {
        h = radius * sin(((double)i / (double)stacks) * (pi/2));
        r = radius * cos(((double)i / (double)stacks) * (pi/2));
        for(j = 0; j <= slices; j++) {
            points[i][j].x = r * cos(((double)j / (double)slices) * 2*pi);
            points[i][j].y = r * sin(((double)j / (double)slices) * 2*pi);
            points[i][j].z = h;
        }
    }
    //draw quads using generated points
    for(i = 0; i < stacks; i++) {
        glColor3f((double)i / (double)stacks,
                  (double)i / (double)stacks,
                  (double)i / (double)stacks);

        for(j = 0; j < slices; j++) {
            glBegin(GL_QUADS); {
                //upper hemisphere
                glVertex3f(points[i][j].x,points[i][j].y,points[i][j].z);
                glVertex3f(points[i][j+1].x,points[i][j+1].y,points[i][j+1].z);
                glVertex3f(points[i+1][j+1].x,points[i+1][j+1].y,points[i+1][j+1].z);
                glVertex3f(points[i+1][j].x,points[i+1][j].y,points[i+1][j].z);
                //lower hemisphere
                glVertex3f(points[i][j].x,points[i][j].y,-points[i][j].z);
                glVertex3f(points[i][j+1].x,points[i][j+1].y,-points[i][j+1].z);
                glVertex3f(points[i+1][j+1].x,points[i+1][j+1].y,-points[i+1][j+1].z);
                glVertex3f(points[i+1][j].x,points[i+1][j].y,-points[i+1][j].z);
            } glEnd();
        }
    }
}


#endif // _GLUT_SHAPES_H_