// ====================================================
// ＢＯＸ(x1,y1) - (x2,y2),c
// ====================================================
void box_sub(int x1,int y1,int x2,int y2,int c1,int c2,int c3,int c4)
{
gr_hline(x1,y1,x2,y1,c1);
gr_hline(x1,y2,x2,y2,c3);
gr_vline(x1,y1,x1,y2,c2);
gr_vline(x2,y1,x2,y2,c4);
}
// ====================================================
// ＢＯＸ(x1,y1) - (x2,y2),c
// ====================================================
void gr_box(int x1,int y1,int x2,int y2,int c)
{
gr_hline(x1,y1,x2,y1,c);
gr_hline(x1,y2,x2,y2,c);
gr_vline(x1,y1,x1,y2,c);
gr_vline(x2,y1,x2,y2,c);
}
void gr_universal_uline(int a1, int b1, int a2, int b2)
{
int dx, dy, incr1, incr2, D, x, y, xend, c, pixels_left;
int x1, y1;
int sign_x = 1, sign_y = 1, step, reverse, i;
if (a1==a2) {
gr_vline(b1,b2,a1);
return;
}
if (b1==b2) {
gr_hline(a1,a2,b1);
return;
}
dx = a2 - a1;
dy = b2 - b1;
if (dx < 0) {
sign_x = -1;
dx *= -1;
}
if (dy < 0) {
sign_y = -1;
dy *= -1;
}
/* decide increment sign by the slope sign */
if (sign_x == sign_y)
step = 1;
else
step = -1;
if (dy > dx) { /* chooses axis of greatest movement (make * dx) */
EXCHG(a1, b1);
EXCHG(a2, b2);
EXCHG(dx, dy);
reverse = 1;
} else
reverse = 0;
/* note error check for dx==0 should be included here */
if (a1 > a2) { /* start from the smaller coordinate */
x = a2;
y = b2;
x1 = a1;
y1 = b1;
} else {
x = a1;
y = b1;
x1 = a2;
y1 = b2;
}
/* Note dx=n implies 0 - n or (dx+1) pixels to be set */
/* Go round loop dx/4 times then plot last 0,1,2 or 3 pixels */
/* In fact (dx-1)/4 as 2 pixels are already plottted */
xend = (dx - 1) / 4;
pixels_left = (dx - 1) % 4; /* number of pixels left over at the
* end */
plot(x, y, reverse);
plot(x1, y1, reverse); /* plot first two points */
incr2 = 4 * dy - 2 * dx;
if (incr2 < 0) { /* slope less than 1/2 */
c = 2 * dy;
incr1 = 2 * c;
D = incr1 - dx;
for (i = 0; i < xend; i++) { /* plotting loop */
++x;
--x1;
if (D < 0) {
/* pattern 1 forwards */
plot(x, y, reverse);
plot(++x, y, reverse);
/* pattern 1 backwards */
plot(x1, y1, reverse);
plot(--x1, y1, reverse);
D += incr1;
} else {
if (D < c) {
/* pattern 2 forwards */
plot(x, y, reverse);
plot(++x, y += step, reverse);
/* pattern 2 backwards */
plot(x1, y1, reverse);
plot(--x1, y1 -= step, reverse);
} else {
/* pattern 3 forwards */
plot(x, y += step, reverse);
plot(++x, y, reverse);
/* pattern 3 backwards */
plot(x1, y1 -= step, reverse);
plot(--x1, y1, reverse);
}
D += incr2;
}
} /* end for */
/* plot last pattern */
if (pixels_left) {
if (D < 0) {
plot(++x, y, reverse); /* pattern 1 */
if (pixels_left > 1)
plot(++x, y, reverse);
if (pixels_left > 2)
plot(--x1, y1, reverse);
} else {
if (D < c) {
plot(++x, y, reverse); /* pattern 2 */
if (pixels_left > 1)
plot(++x, y += step, reverse);
if (pixels_left > 2)
plot(--x1, y1, reverse);
} else {
/* pattern 3 */
plot(++x, y += step, reverse);
if (pixels_left > 1)
plot(++x, y, reverse);
if (pixels_left > 2)
plot(--x1, y1 -= step, reverse);
}
}
} /* end if pixels_left */
}
/* end slope < 1/2 */
else { /* slope greater than 1/2 */
c = 2 * (dy - dx);
incr1 = 2 * c;
D = incr1 + dx;
for (i = 0; i < xend; i++) {
++x;
--x1;
if (D > 0) {
/* pattern 4 forwards */
plot(x, y += step, reverse);
plot(++x, y += step, reverse);
/* pattern 4 backwards */
plot(x1, y1 -= step, reverse);
plot(--x1, y1 -= step, reverse);
D += incr1;
} else {
if (D < c) {
/* pattern 2 forwards */
plot(x, y, reverse);
plot(++x, y += step, reverse);
/* pattern 2 backwards */
plot(x1, y1, reverse);
plot(--x1, y1 -= step, reverse);
} else {
/* pattern 3 forwards */
plot(x, y += step, reverse);
plot(++x, y, reverse);
/* pattern 3 backwards */
plot(x1, y1 -= step, reverse);
plot(--x1, y1, reverse);
}
D += incr2;
}
} /* end for */
/* plot last pattern */
if (pixels_left) {
if (D > 0) {
plot(++x, y += step, reverse); /* pattern 4 */
if (pixels_left > 1)
plot(++x, y += step, reverse);
if (pixels_left > 2)
plot(--x1, y1 -= step, reverse);
} else {
if (D < c) {
plot(++x, y, reverse); /* pattern 2 */
if (pixels_left > 1)
plot(++x, y += step, reverse);
if (pixels_left > 2)
plot(--x1, y1, reverse);
} else {
/* pattern 3 */
plot(++x, y += step, reverse);
if (pixels_left > 1)
plot(++x, y, reverse);
if (pixels_left > 2) {
if (D > c) /* step 3 */
plot(--x1, y1 -= step, reverse);
else /* step 2 */
plot(--x1, y1, reverse);
}
}
}
}
}
}
