Code:
#include <stdio.h>
#include <graphics_lib.h>


char user_input;


int main(void)
{


        char c;
        int i = 0;


        printf("Please enter r, b or g:  \n");
        scanf(" %c", &c);


        /* Open a graphics window */
        /* Make it 640 pixels wide by 480 pixels high */
        initwindow(1200, 680);


        /* choose red pen colour */


        switch (c)
        {
            case 'r':
            case 'R':
                setcolor(RED);
                break;
            case 'b':
            case 'B':
                setcolor(BLUE);
                break;
            case 'g':
            case 'G':
                setcolor(GREEN);
                break;
            default:
                printf("Please run the program again and enter a valid character");
                return 0;
        }


        /* draw a circle on the screen buffer
         at x_position, y_position
         with radius 10 and line thickness 2 */
        line(40+i, 600, 70+i, 520, 2);
        line(70+i, 520, 100+i, 600, 2);
        line(70+i, 520, 70+i, 440, 2);
        line(70+i, 460, 100+i, 500, 2);
        line(70+i, 460, 40+i, 500, 2);
        circle(70+i, 410, 30+i, 2);
        circle(55+i, 400, 5+i, 2);
        circle(85+i, 400, 5+i, 2);
        arc(70+i, 395, 30, 45, 90, 2);
        line(0, 600, 1200, 600, 2);


        update_display();






        float pos_x, pos_y, init_pos_x, init_pos_y, vel_x, vel_y;
        float time, gravity;


        init_pos_x = 100;
        init_pos_y = 500;


        gravity = 9.81;


        printf("What do you want to do next? (t for throw projectile, r for move right and l for move left) \n");
        scanf("%c", &user_input);
        getch();


        if (user_input == 't'){


            printf("What is the Velocity in the X direction? \n");
            scanf("%f", &vel_x);
            getch();


            printf("What is the Velocity in the Y direction? \n");
            scanf("%f", &vel_y);
            getch();


                moveto((int)init_pos_x, (int)init_pos_y);


                    for (pos_x = init_pos_x; pos_y <= 600; pos_x++)
                    {
                        /* Calculate new height */
                        time = (pos_x - init_pos_x) / vel_x;
                        pos_y = init_pos_y - (vel_y * time) + (gravity * time * time)/2;


                        /* Draw a line */
                        lineto((int)pos_x, (int)pos_y, 1);
                        update_display();
                    }
            }
        else if (user_input == 'r'){


            i = 150;
            cleardevice();
            line(40+i, 600, 70+i, 520, 2);
            line(70+i, 520, 100+i, 600, 2);
            line(70+i, 520, 70+i, 440, 2);
            line(70+i, 460, 100+i, 500, 2);
            line(70+i, 460, 40+i, 500, 2);
            circle(70+i, 410, 30+i, 2);
            circle(55+i, 400, 5+i, 2);
            circle(85+i, 400, 5+i, 2);
            arc(70+i, 395, 30, 45, 90, 2);
            line(0, 600, 1200, 600, 2);
            update_display();


        }
        else if (user_input == 'l') {


        i = -150;
            cleardevice();
            line(40+i, 600, 70+i, 520, 2);
            line(70+i, 520, 100+i, 600, 2);
            line(70+i, 520, 70+i, 440, 2);
            line(70+i, 460, 100+i, 500, 2);
            line(70+i, 460, 40+i, 500, 2);
            circle(70+i, 410, 30+i, 2);
            circle(55+i, 400, 5+i, 2);
            circle(85+i, 400, 5+i, 2);
            arc(70+i, 395, 30, 45, 90, 2);
            line(0, 600, 1200, 600, 2);
            update_display();
        }


        /* Wait for a key press */
        getch();




        /* remove the display */
        closegraph();




return 0;
}