void draw_line(double x0, double y0, double x1, double y1)
{
int i;
double x,y;
double dx,dy;
double xinc,yinc;
double lenosuh;
int result;
int width,height;
/* set the clipping window */
osuGetFramebufferSize (&width, &height);
set_clip_window (0.0f, 0.0f, width - 0.51f, height - 0.51f);
/* clip the line in 2D */
result = clip_line (&x0, &y0, &x1, &y1);
/* return if line is entirely outside the clip window */
if (result == 0)
return;
/* incremental line drawing */
dx = x1 - x0;
dy = y1 - y0;
/* determine whether horizontal or vertical change is larger */
if (fabs(dx) > fabs(dy))
lenosuh = (double)fabs(dx);
else
lenosuh = (double)fabs(dy);
/* special case to avoid dividing by zero */
if (lenosuh == 0) {
osuWritePixel ((int) floor(x0+0.5), (int) floor(y0+0.5), 255, 255, 255);
return;
}
xinc = dx / lenosuh;
yinc = dy / lenosuh;
x = x0;
y = y0;
/* write "lenosuh" number of pixels along the line */
for (i = 0; i <= lenosuh; i++) {
osuWritePixel ((int) floor(x+0.5), (int) floor(y+0.5), 255, 255, 255);
x += xinc;
y += yinc;
}
}
void draw_line(float x0, float y0, float x1, float y1) {
GLint viewport[4];
int i;
float x, y;
float dx, dy;
float xinc, yinc;
float length = 0.;
int result;
int width, height;
Pixel white = { 1, 1, 1 };
/* set the clipping window */
glGetIntegerv(GL_VIEWPORT, viewport);
width = abs(viewport[2] - viewport[0]);
height = abs(viewport[3] - viewport[1]);
set_clip_window(0.0, 0.0, width - 0.51, height - 0.51);
/* clip the line in 2D */
result = clip_line(&x0, &y0, &x1, &y1);
/* return if line is entirely outside the clip window */
if (result == 0)
return;
/* incremental line drawing */
dx = x1 - x0;
dy = y1 - y0;
/* determine whether horizontal or vertical change is larger */
if (fabs(dx) > fabs(dy))
length = fabs(dx);
else
length = fabs(dy);
/* special case to avoid dividing by zero */
if (length == 0) {
setPixel(x0, y0, white);
return;
}
xinc = dx / length;
yinc = dy / length;
x = x0;
y = y0;
/* write "length" number of pixels along the line */
for (i = 0; i <= length; i++) {
if (x < displayImage.width && y < displayImage.height)
setPixel(y, x, white);
x += xinc;
y += yinc;
}
glFlush();
}
void Streamline::streamline_creator(
VectorField *field,
float xx,
float yy,
float len1,
float len2,
float dlen
)
{
int i;
float x,y;
/* integrate to midpoint */
#if 1
float dl = 0.5 * (len1 - len2);
int num = abs ((int) (dl / dlen)) + 1;
float dt = dl / num;
x = xx;
y = yy;
for (i = 0; i < num; i++) {
x += dt * field->xval(x,y);
y += dt * field->yval(x,y);
}
xx = x;
yy = y;
float new_len = 0.5 * (len1 + len2);
len1 = len2 = new_len;
#endif
/* origin must be within [0,1] x [0,aspect] */
if (xx < 0 || xx > 1 || yy < 0 || yy > field->getaspect()) {
float x = xx;
float y = yy;
clamp_to_screen (x, y, field->getaspect());
xx = x;
yy = y;
}
/* set values */
vf = field;
xorig = xx;
yorig = yy;
length1 = len1;
length2 = len2;
delta = dlen;
frozen = 0; /* a "frozen" streamline is one that isn't to be moved */
label = label_default;
start_reduction = start_reduction_default;
end_reduction = end_reduction_default;
arrow_type = arrow_type_default;
arrow_length = arrow_length_default;
arrow_width = arrow_width_default;
arrow_steps = arrow_steps_default;
intensity = intensity_default;
taper_head = taper_head_default;
taper_tail = taper_tail_default;
tail_clipped = 0;
head_clipped = 0;
/* values at pixels */
num_values = 0;
max_values = 10;
values = new PixelValue[max_values];
/* determine spacing of sample points */
int samples1 = (int) (length1 / delta);
int samples2 = (int) (length2 / delta);
delta = (length1+length2) / (samples1+samples2);
samples = samples1 + samples2 + 1;
pts = new SamplePoint[samples];
/* calculate sample points along streamline */
x = xorig;
y = yorig;
xs(samples2) = x;
ys(samples2) = y;
#define MIN_STEP 0.2
/* step forward */
int count1 = 0;
for (i = 0; i < samples1; i++) {
float slen = vf->integrate (x, y, delta, 0, x, y);
if (slen < MIN_STEP)
break;
xs(samples2 + i + 1) = x;
ys(samples2 + i + 1) = y;
count1++;
/* clip to screen */
if (x < 0 || x > 1 || y < 0 || y > vf->getaspect()) {
set_clip_window (0.0, 1.0, 0.0, vf->getaspect());
float x0 = xs(samples2 + i);
float y0 = ys(samples2 + i);
// printf ("clip #1 before: %f %f %f %f\n", x0, y0, x, y);
clip_line (x0, y0, x, y);
// printf ("clip #1 after: %f %f %f %f\n", x0, y0, x, y);
// printf ("\n");
xs(samples2 + i + 1) = x;
ys(samples2 + i + 1) = y;
head_clipped = 1;
break; /* we're off the screen, so don't extend streamline further */
}
}
/* step backwards */
x = xorig;
y = yorig;
int count2 = 0;
for (i = samples2-1; i >= 0; i--) {
float slen = vf->integrate (x, y, -delta, 0, x, y);
if (slen < MIN_STEP)
break;
xs(i) = x;
ys(i) = y;
count2++;
/* clip to screen */
if (x < 0 || x > 1 || y < 0 || y > vf->getaspect()) {
set_clip_window (0.0, 1.0, 0.0, vf->getaspect());
float x0 = xs(i+1);
float y0 = ys(i+1);
// printf ("clip #2 before: %f %f %f %f\n", x0, y0, x, y);
clip_line (x0, y0, x, y);
// printf ("clip #2 after: %f %f %f %f\n", x0, y0, x, y);
// printf ("\n");
xs(i) = x;
ys(i) = y;
tail_clipped = 1;
break; /* we're off the screen, so don't extend streamline further */
}
}
/* compute number of samples, taking into account the portions of */
/* the streamline that may have been clipped */
samples = count1 + count2 + 1;
/* may have to shift the sample points */
int diff2 = samples2 - count2;
if (diff2 > 0)
for (i = 0; i < samples; i++) {
xs(i) = xs(i + diff2);
ys(i) = ys(i + diff2);
}
int smp = samples - 1;
if (xs(0) < 0 || xs(0) > 1 || ys(0) < 0 || ys(0) > vf->getaspect() ||
xs(smp) < 0 || xs(smp) > 1 || ys(smp) < 0 || ys(smp) > vf->getaspect()) {
printf ("origin: %f %f\n", xx, yy);
printf ("ends: %f %f %f %f\n", xs(0), ys(0), xs(smp), ys(smp));
printf ("\n");
}
/* compute intensity tapering */
for (i = 0; i < samples; i++) {
float t = i / (samples - 1.0);
if (t < taper_tail) {
t = t / taper_tail;
pts[i].intensity = t;
}
else if (1 - t < taper_head) {
t = (1 - t) / taper_head;
pts[i].intensity = t;
}
else
pts[i].intensity = 1.0;
}
}