#pragma windows 300000,500000,"cwp_ico.rc" //means dosbox is not displayed
#include<stdio.h>
#include<math.h> 
#include<clib.h>
#include <windows.h>
#include <dbos\graphics.h> 

int main(void) 
{   
    float u=0, g, p, s, t, x01=0, y01=0, x02=0, y02=0;
    int x0=1, x1=1, x2=1, x3=1, y0=1, y1=1, y2=1, y3=1, w0=1, w1=1, w2=1, w3=1, np=1, hand1=1, ctrl; 


        winio("%bg%ca[Data Input Screen]&",RGB(100,255,100)); 
        winio("\tEnter in 4 values for the x coordinates: \t%rd\t%rd\t%rd\t%rd\n&", &x0, &x1, &x2, &x3); 
        winio("\tEnter in 4 values for the y coordinates: \t%rd\t%rd\t%rd\t%rd\n&",&y0, &y1, &y2, &y3); 
        winio("\tEnter in 4 values for the weighting points: \t%rd\t%rd\t%rd\t%rd\n&",&w0, &w1, &w2, &w3);         
        winio("\tEnter the number of points you wish to be on the line:\t\t\t\t\t\t%rd\n&",&np);
        winio("%bc[red]%bt[Draw]\n");//button to close the window so the next appears 
        {       
        
                u=1/np;//means the correct number of lines will be created
                for( int c=0 ; c<np ; c++) 
                {
                        p = (pow(1 - u, 3));//=(1-u)(1-u)(1-u),to the power of
                        g = (3 * (pow(1 - u, 2) * u));
                        s = (3 * pow((1 - u) * u, 2));
                        t = pow(u, 3);

                        x01=((p*w0*x0)+(g*w1*x1)+(s*w2*x2)+(t*w3*x3))/((p*w0)+(g*w1)
                        +(s*w2)+(t*w3));// starting x coordinate for the line
                     
                        y01=((p*w0*y0)+(g*w1*y1)+(s*w2*y2)+(t*w3*y3))/((p*w0)+(g*w1)
                        +(s*w2)+(t*w3));// starting y coordinate for the line

                        u=u+(1/np);
                        
                        p = (pow(1 - u, 3));//=(1-u)(1-u)(1-u),to the power of
                        g = (3 * (pow(1 - u, 2) * u));
                        s = (3 * pow((1 - u) * u, 2));
                        t = pow(u, 3);
                         
                        x02=((p*w0*x0)+(g*w1*x1)+(s*w2*x2)+(t*w3*x3))/((p*w0)+(g*w1)
                        +(s*w2)+(t*w3));// ending x coordinate for the line
                        y02 = ((p*w0*y0)+(g*w1*y1)+(s*w2*y2)+(t*w3*y3))/((p*w0)+(g*w1)
                        +(s*w2)+(t*w3));// ending x coordinate for the line
 
                        winio("%bg%ca[Graphics Tablet]&",RGB(0,0,0));
                        winio("%`gr&",400,300,hand1);//graphics tablet of size 400*300,reference name hand1
                        winio("%ww%lw",&ctrl);//this must b present with the line above
                        select_graphics_object(hand1);//makes sure the next lines refer to the tablet hand1
                        set_line_width(5);
                        draw_line(x01,y01,x02,y02,80);
                }         
        }        

}
int Draw()
        {
        return 0;//clears screen so graphics tablet can be displayed 
        }

printf(" np = %d, c = %d u = %f\n p = %f, g = %f, s = %f, t = %f\n", 
                                np, c, u, p, g, s, t);

pow(u, 3)

pow(1-u, 3)

 
#include<stdio.h>
#include<math.h> 
#include<clib.h>

int main(void) 
{
    float u=0, g, p, s, t, x01, y01, x02, y02, q, np;
    int x0, x1, x2, x3, y0, y1, y2, y3, w0, w1, w2, w3; 
    char cha;

    printf("Enter in r values for the x coordinates e.g. x0,x1,x2,x3\n");
    scanf("%d,%d,%d,%d", &x0, &x1, &x2, &x3);
    printf("Enter in r values for the y coordinates e.g. y0,y1,y2,y3\n");
    scanf("%d,%d,%d,%d", &y0, &y1, &y2, &y3);
    printf("Enter in w values in the format w0,w1,w2,w3\n");
    scanf("%d,%d,%d,%d", &w0, &w1, &w2, &w3);
    printf("Enter the number of points you wish to be on the line:\n");
    scanf("%f", &np);
    system("cls");
    u=1.0/np;  
    
    for( int c=0 ; c<np ; c++)
        {
                      
        p = (pow(1 - u, 3));//=(1-u)(1-u)(1-u),to the power of
        g = (3 * (pow(1 - u, 2) * u));
        s = (3 * pow((1 - u) * u, 2));
        t = pow(u, 3);

        x01 = ((p * w0 * x0) + (g * w1 * x1) + (s * w2 * x2) + (t * w3 * x3)) / ((p * w0) + (g * w1) + (s * w2) + (t * w3));// starting x coordinate for the line                       
        y01 = ((p * w0 * y0) + (g * w1 * y1) + (s * w2 * y2) + (t * w3 * y3)) / ((p * w0) + (g * w1) + (s * w2) + (t * w3));// starting y coordinate for the line
        printf("\nFor u = %f:   ", u);
        printf("\nx01  =  %f", x01);
        printf("\ty01  =  %f", y01); 
        u=u+(1/np);
                        
        p = (pow(1 - u, 3));//=(1-u)(1-u)(1-u),to the power of
        g = (3 * (pow(1 - u, 2) * u));
        s = (3 * pow((1 - u) * u, 2));
        t = pow(u, 3);
                         
        x02 = ((p * w0 * x0) + (g * w1 * x1) + (s * w2 * x2) + (t * w3 * x3)) / ((p * w0) + (g * w1) + (s * w2) + (t * w3));// ending x coordinate for the line
        y02 = ((p * w0 * y0) + (g * w1 * y1) + (s * w2 * y2) + (t * w3 * y3)) / ((p * w0) + (g * w1) + (s * w2) + (t * w3));// ending x coordinate for the line    
        printf("\nx02  =  %f", x02);
        printf("\ty02  =  %f", y02);                        
        
        
        
        q=c%12;//diplays 12 results at a time 
        
        if(q==0&&c!=0)
               {
               while(cha==13);//displays next 12 results when "enter" is pressed
                        {
                        getch();
                        }
                }
        }
}

int num;
float np;
np=(float)num;//converts num into a float 

=y0;
                        //given number on array,c, is equal to that of x01,y01
                        c++;//increment c so we get np points
                        }
                while(c<np);        
                winio("%bg%ca[Graphics Tablet]&",RGB(0,0,0));
                winio("%`gr&",400,400,hand);
                //graphics tablet of size 400*300,reference name hand1
                winio("%lw",&ctrl);//this must b present with the line above
                select_graphics_object(hand);
                //makes sure the next lines refer to the tablet hand1
                set_line_width(wid);
                polyline(x,y,np,col);
                //displays a polygon of np points, colour=col, x,y taken from array
                set_line_width(1);
                draw_line(x1,y1,x2,y2,29);//displays control polygon 
                draw_line(x2,y2,x3,y3,29);// 
                draw_line(x3,y3,x4,y4,29);//
                draw_text("Control Polygon",x2-10,y2-30,29);  
                } 
        }                
                
}  

int Draw()
        {         
        if (b1==0)//a function to determine the colour selected by the user
                {
                if(b2==0)
                        {
                        if(b3==0)
                                {
                                col=80;
                                }
                         else
                                {
                                col=48;
                                } 
                         }       
                else
                        {
                        col=53;
                        }        
                }
        else 
                {       
                col=40;
                } 
        if (r1==0)//line thickness selected by the user
                {
                if(r2==0)
                        {
                        wid=5;
                        }
                else
                        {
                        wid=3;
                        }
                }
        else
                {
                wid=1;
                }
                        
        return 0;//refreshes screen
        }