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Topic: helix 1... (Read 3023 times) |
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arielm
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Re: helix 1...
« Reply #1 on: May 3rd, 2003, 2:47am » |
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hey (it's me again), if someone knows how to integrate:
d += dd / r;
r = r1 + d * dr;
from within the following context:
Code:
void drawHelix(float x, float y, float z, float turns, float r1, float r2, float h, float dd)
{
// draws an helix with equidistant points (dd being the distance between each of them)
float c = TWO_PI * turns;
float dr = (r2 - r1) / c;
float dz = h / c;
float r = r1;
float d = 0.0;
stroke(255, 224, 0);
beginShape(LINE_STRIP);
do
{
vertex(x - sin(d) * r, y + cos(d) * r, z + d * dz);
d += dd / r;
r = r1 + d * dr;
}
while(d < c);
endShape();
}
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... just let me know, 10-x!
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Ariel Malka | www.chronotext.org
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arielm
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Re: helix 1...
« Reply #2 on: May 8th, 2003, 3:05pm » |
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third part of this monologue 
i found a linear solution to my helix problem (i.e. now it is possible to slide along arbitralely)
the drawHelix() code should now look like:
Code:
void drawHelix(float x, float y, float z, float turns, float r1, float r2, float h, float dd)
{
// draws an helix with equidistant points (dd being the distance between 2 consecutive points)
float d;
float r = 0.0;
float dr = 0.0;
float l = TWO_PI * turns;
float L = PI * turns * (r1 + r2);
float dz = h / l;
boolean conical = (abs(r1 - r2) > 0.5); // avoids infinity and divisions by zero with cylindrical helices (r1 = r2)
if (conical)
{
dr = (r2 - r1) / l;
}
else
{
r = r1;
}
stroke(255, 224, 0);
beginShape(LINE_STRIP);
for (float D = 0.0; D < L; D += dd)
{
if (conical)
{
r = sqrt(r1 * r1 + 2.0f * dr * D);
d = (r - r1) / dr;
}
else
{
d = D / r;
}
vertex(x - sin(d) * r, y + cos(d) * r, z + d * dz);
}
endShape();
}
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p.s: why is it important to be able to draw a curve with equidistant points?.. because then, you have control on "distance", and you can just start writing (correctly spaced) text on it...
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| « Last Edit: May 12th, 2003, 11:26am by arielm » |
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Ariel Malka | www.chronotext.org
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