Get a line or a curve with every point coloured in different colour

Replies to This Discussion

Permalink Reply by David Rutten on July 24, 2017 at 2:26pm

There's two relatively easy ways to do it and probably lots of hard ways. You can either keep generating random colours whenever you need another one, or, find some way to generate a logical progression of colours ahead of time and then randomise the list.

I'd go for the former. Create a new System.Random instance, create a HashSet<int>, and then whenever you need a new colour create random R, G, and B channels, construct your colour and see if the int-flavour already exists in the hash set; if not, add it to the hash and continue on your way, if yes, generate another random colour.

You can probably put the colours directly into the HashSet, but I know for sure that ints work.

// Utterly untested code...

Random random = new Random(1);

HashSet<int> hash = new HashSet<int>();

List<Color> colours = new List<Color>(1000)

for (int i = 0; i < 1000; i++)

{

  Color c;

  while (true)

  {

    int r = random.Next(0, 256);

    int g = random.Next(0, 256);

    int b = random.Next(0, 256);

    c = Color.FromArgb(r, g, b);

    int rgb = c.ToArgb();

    if (hash.Contains(rgb)) continue;

    hash.Add(rgb);

    break;

  }

  colours.Add(c);

}

Permalink Reply by Yajnavalkya Bandyopadhyay on July 25, 2017 at 1:07pm

Hi, Thanks for the suggestion, but how to use that in a line! I am new to Grasshopper API and I am learning bits by bits.

Will the line be in a custom display.?

Can you please help me with it!

Permalink Reply by David Rutten on July 26, 2017 at 2:35am

You output the list of colours and then you can use a [Custom Display] component to show your points using these colours.

If you also want to draw the points yourself, then you'll have to override the display methods on your component as well.

Permalink Reply by David Rutten on July 26, 2017 at 2:47am

Try the attached. 

Attachments:

• confetti.gh, 3 KB

Permalink Reply by Yajnavalkya Bandyopadhyay on July 26, 2017 at 10:51am

Mind sharing the code please! 

Permalink Reply by David Rutten on July 26, 2017 at 3:13pm

Double click the C# component to see the code.

Permalink Reply by Yajnavalkya Bandyopadhyay on July 27, 2017 at 11:13am

I checked and the output is horrible even when I am increasing the number of point division.

Attachments:

• Capture1.JPG, 14 KB

Permalink Reply by David Rutten on July 27, 2017 at 4:32pm

Looks like you're drawing points using a white centre. There should be solid display options even in Rhino5.

In Rhino6 you get even more shape options:

Permalink Reply by Yajnavalkya Bandyopadhyay on July 26, 2017 at 12:44pm

Atleast can you show me a way by which I can do the ways, rest I have figured it out

1. Draw  a line in grasshopper using C# (Start point and end point can be chosen randomly, I will just provide the length of the line)

2. Using a iteration I could be able to have all the coordinates present in the line.

If these two are provided I can use a custom display to do the rest

Permalink Reply by Yajnavalkya Bandyopadhyay on July 27, 2017 at 12:25pm

This is the code I have written, mind editing it?

private void RunScript(Curve C)
{
int l = 2000;
Rhino.Display.CustomDisplay cd = new Rhino.Display.CustomDisplay(true);
cd.Clear();

Point3d a, b;
a = new Point3d(0, 0, 0);
b = new Point3d(0, 0, l);
Line x = new Line(a, b);
Curve m = x.ToNurbsCurve();

if (x == null) return;

Point3d[] points;
m.DivideByCount(50, true, out points);

//for (double itr = 0; itr < 50; itr = itr + 0.01)
//{
double frac = 50 / 230;
int itr = 0;
foreach (Point3d point in points)
{
while (true)
{
double imtr = (50 - itr) / frac;
itr++;
Color colour = ColorFromHSV(imtr, 1, 0.5);
int rgb = colour.ToArgb();
if (_hash.Contains(rgb))
continue;

_hash.Add(rgb);
_points.Add(point);
_colours.Add(colour);
break;
}
//}
}
for (int i = 0; i < _points.Count; i++)
cd.AddPoint(_points[i], _colours[i]);
}

// <Custom additional code>
private readonly HashSet<int> _hash = new HashSet<int>();
private readonly List<Point3d> _points = new List<Point3d>();
private readonly List<Color> _colours = new List<Color>();

/// <summary>
/// This method will be called once every solution, before any calls to RunScript.
/// </summary>
public override void BeforeRunScript()
{
_hash.Clear();
_points.Clear();
_colours.Clear();
}
public static Color ColorFromHSV(double hue, double saturation, double value)
{
int hi = Convert.ToInt32(Math.Floor(hue / 60)) % 6;
double f = hue / 60 - Math.Floor(hue / 60);

value = value * 255;
int v = Convert.ToInt32(value);
int p = Convert.ToInt32(value * (1 - saturation));
int q = Convert.ToInt32(value * (1 - f * saturation));
int t = Convert.ToInt32(value * (1 - (1 - f) * saturation));

if (hi == 0)
return Color.FromArgb(255, v, t, p);
else if (hi == 1)
return Color.FromArgb(255, q, v, p);
else if (hi == 2)
return Color.FromArgb(255, p, v, t);
else if (hi == 3)
return Color.FromArgb(255, p, q, v);
else if (hi == 4)
return Color.FromArgb(255, t, p, v);
else
return Color.FromArgb(255, v, p, q);
}

Gives this error

1. Value was either too large or too small for an Int32. (line: 0)

Permalink Reply by Masaaki Miki on July 27, 2017 at 6:22pm

This line: double frac = 50 / 230;

integer 50 / integer 230 is zero. You should write

var frac=50d/230d;