Algoritmos

Círculo

Algoritmo basado en la ecuación del círculo

void PlotPoint(Graphics g, int xc, int yc, int x, int y)

{

g.drawLine(,xc + x,yc + y);

g.drawLine(,xc - x,yc + y);

g.drawLine(,xc + x,yc - y);

g.drawLine(,xc - x,yc - y);

g.drawLine(,xc + x,yc + x);

g.drawLine(,xc - y,yc + x);

g.drawLine(,xc + y,yc - x);

g.drawLine(,xc - y,yc - x);

}

void CircleSimple(Graphics g, int xc, int yc, int r){

int x,y;

double yr;

x = 0;

y = r;

yr = r;

PlotPoint(x,y);

/* se cicla hasta trazar todo un octante */

while (x < yr){

x = x + 1;

yr = Math.sqrt(r*r-x*x);

y = (int)Math.round(yr);

PlotPoint(x,y);

}

}

Elipse

Algoritmo de punto medio para elipse

public void Elipse(Graphics g, int xc, int yc, int rx, int ry){

int x, y, p, px, py;

int rx2, ry2, tworx2, twory2;

ry2 = ry*ry;

rx2 = rx*rx;

twory2 = 2 * ry2;

tworx2 = 2 * rx2;

/* región 1 */

x = 0;

y = ry;

PlotPoint(x,y);

p = (int)Math.round(ry2 - rx2*ry + 0.25*rx2);

px = 0;

py = tworx2*y;

while (px < py) { /* se cicla hasta trazar la región 1 */

x = x + 1;

px = px + twory2;

if (p < 0)

p = p + ry2 + px;

else {

y = y - 1;

py = py - tworx2;

p = p + ry2 + px - py;

}

PlotPoint(x,y);

}

/* región 2 */

p = (int)Math.round(ry2*(x+0.5)*(x+0.5) + rx2*(y-1)*(y-1) - rx2*ry2);

px = 0;

py = tworx2*y;

while (y > 0) { /* se cicla hasta trazar la región 2 */

y = y - 1;

py = py - tworx2;

if (p > 0)

p = p + rx2 - py;

else {

x = x + 1;

px = px + twory2;

p = p + rx2 + py + px;

}

PlotPoint(x,y);

}

}

Parábola

Algoritmo de punto medio para parábolas

public void parabola(Graphics g,int xc, int yc, int p, int bound){

int x,y,d;

int p2, p4;

p2 = 2*p;

p4 = 2*p2;

x = 0;

y = 0;

d = 1 - p;

//region 1

while(y < p && x<=bound){

g.drawLine(xc+x,yc+y,xc+x,yc+y);

g.drawLine(xc+x,yc-y,xc+x,yc-y);

if(d >= 0){

x++;

d = d - p2;

}

y++;

d = d + 2*y +1;

}

if(d == 1) d = 1 - p4;

else d = 1 - p2;

//region 2

while(x<=bound){

g.drawLine(xc+x,yc+y,xc+x,yc+y);

g.drawLine(xc+x,yc-y,xc+x,yc-y);

if(d <= 0){

y++;

d = d + 4*y;

}

x++;

d = d - p4;

}

}

Hipérbola

Algoritmo de punto medio para hipérbola

public void hiperbola(Graphics g,int xc, int yc, long a,long b, int bound){

long a_sqr,b_sqr,a22,b22,a42,b42,x_slope,y_slope;

long d,mida,midb;

long x,y;

x = a;

y = 0;

a_sqr = a*a;

b_sqr = b*b;

a22 = 2*a_sqr;

b22 = 2*b_sqr;

a42 = 2*a22;

b42 = 2*b22;

x_slope = b42*(x+1);//x_slope = 4*b^2*(x+1)

y_slope = a42; //y_slope = 4*a^2*(y-1)

mida = a_sqr/2;

midb = b_sqr/2;

d = a22-b_sqr*(1+2*a)+midb;

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