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Get all points within a triangle is causing an overflow

Well I'm lacking GraphicsPath in Unity (to fills polygon, draw them with and outline and utilities with shapes in general), so I'm doing my own implementation of it. Well, we could debate also which is the best option, but actually, I prefer this because I'm learning a lot.
The idea is the following, given a polygon, we do an offset polygon (inwards and outwards) with ClipperLib, and later with LibTessDotNet we triangulate it, outputing this:
Green, blue and yellow pixels are the sides of every triangle. LibTessDotNet output like 501 triangles for this shape.
So, thanks to #SimpleVar I done this:
public static IEnumerable<T> PointsInTriangle<T>(T pt1, T pt2, T pt3)
where T : IPoint
{
/*
// https://www.geeksforgeeks.org/check-whether-triangle-valid-not-sides-given/
a + b > c
a + c > b
b + c > a
*/
float a = Vector2.Distance(new Vector2(pt1.x, pt1.y), new Vector2(pt2.x, pt2.y)),
b = Vector2.Distance(new Vector2(pt2.x, pt2.y), new Vector2(pt3.x, pt3.y)),
c = Vector2.Distance(new Vector2(pt3.x, pt3.y), new Vector2(pt1.x, pt1.y));
// (new[] { pt1, pt2, pt3 }).Distinct(new PointComparer()).Count() == 0
if (a + b <= c || a + c <= b || b + c <= a)
{
Debug.LogWarning($"The given points must form a triangle. {{{pt1}, {pt2}, {pt3}}}");
yield break;
}
T tmp;
if (pt2.x < pt1.x)
{
tmp = pt1;
pt1 = pt2;
pt2 = tmp;
}
if (pt3.x < pt2.x)
{
tmp = pt2;
pt2 = pt3;
pt3 = tmp;
if (pt2.x < pt1.x)
{
tmp = pt1;
pt1 = pt2;
pt2 = tmp;
}
}
var baseFunc = CreateFunc(pt1, pt3);
var line1Func = pt1.x == pt2.x ? (x => pt2.y) : CreateFunc(pt1, pt2);
for (var x = pt1.x; x < pt2.x; ++x)
{
int maxY;
int minY = GetRange(line1Func(x), baseFunc(x), out maxY);
for (int y = minY; y <= maxY; ++y)
yield return (T)Activator.CreateInstance(typeof(T), x, y);
}
var line2Func = pt2.x == pt3.x ? (x => pt2.y) : CreateFunc(pt2, pt3);
for (var x = pt2.x; x <= pt3.x; ++x)
{
int maxY;
int minY = GetRange(line2Func(x), baseFunc(x), out maxY);
for (int y = minY; y <= maxY; ++y)
yield return (T)Activator.CreateInstance(typeof(T), x, y);
}
}
private static int GetRange(float y1, float y2, out int maxY)
{
if (y1 < y2)
{
maxY = Mathf.FloorToInt(y2);
return Mathf.CeilToInt(y1);
}
maxY = Mathf.FloorToInt(y1);
return Mathf.CeilToInt(y2);
}
private static Func<int, float> CreateFunc<T>(T pt1, T pt2)
where T : IPoint
{
var y0 = pt1.y;
if (y0 == pt2.y)
return x => y0;
float m = (float)(pt2.y - y0) / (pt2.x - pt1.x);
return x => m * (x - pt1.x) + y0;
}
Actually it works, but not too fine. Because it causes overflows (I have to kill Unity process with Process Explorer due to the big amount of RAM used by this code).
I have debugged this thing with breakpoints, but I can't figure where is the problem actually.
I think the problem are in for (var x = pt1.x; x < pt2.x; ++x) or for (int y = minY; y <= maxY; ++y) or in the next block... But as I said I can't debug like I'm get used to in WinForms. When the overflow is reached Visual Studio stops debugging and Unity crashes, so I'm a little bit stucked.
I tried to do a DotNetFiddle doing an overflow but I can't figure out nothing here... So... I don't know what can I do to improve the code.
Explain me everything you find is unoptimized, as well as, approaches I could do to improve my main goal.

Ok, I solved it the problem was that triangles with an area equal or less to 1 was doing the overflow. Checking this with the Heron's formula I solved it:
public static float TriangleArea(Point p1, Point p2, Point p3)
{
float a, b, c;
if (!CheckIfValidTriangle(p1, p2, p3, out a, out b, out c))
return 0;
return TriangleArea(a, b, c);
}
public static float TriangleArea(float a, float b, float c)
{
// Thanks to: http://james-ramsden.com/area-of-a-triangle-in-3d-c-code/
float s = (a + b + c) / 2.0f;
return Mathf.Sqrt(s * (s - a) * (s - b) * (s - c));
}
And then:
if (TriangleArea(pt1, pt2, pt3) <= 1)
return;
Maybe (I didn't tested) but it could be caused by generics.
In any case, I posted on Gist Github this nice TriangleUtils. Given a list of triangles tesselated with LibTessDotNet we can rasterize it: https://gist.github.com/z3nth10n/7d60f22c7e906f645d53c9622507c23b
I uploaded the following video showing what I achieved: https://youtu.be/7yY3MIyRtPw

C# setHue (or alternatively, convert HSL to RGB and set RGB)

C# has a very convenient getHue method, but I can't find a setHue method. Is there one?
If not, I think the best way to define a color after changing the hue would be to convert the HSL value to RGB, and then set the RGB value. I know there are formulas on the internet for doing this, but how would I best go about performing this conversion from HSL to RGB using C#?
Thank You

To set the Hue you create a new Color, maybe from a given one by using GetHue and GetSaturation. See below for the getBrightness function!
I'm using this:
Color SetHue(Color oldColor)
{
var temp = new HSV();
temp.h = oldColor.GetHue();
temp.s = oldColor.GetSaturation();
temp.v = getBrightness(oldColor);
return ColorFromHSL(temp);
}
// A common triple float struct for both HSL & HSV
// Actually this should be immutable and have a nice constructor!!
public struct HSV { public float h; public float s; public float v;}
// the Color Converter
static public Color ColorFromHSL(HSV hsl)
{
if (hsl.s == 0)
{ int L = (int)hsl.v; return Color.FromArgb(255, L, L, L); }
double min, max, h;
h = hsl.h / 360d;
max = hsl.v < 0.5d ? hsl.v * (1 + hsl.s) : (hsl.v + hsl.s) - (hsl.v * hsl.s);
min = (hsl.v * 2d) - max;
Color c = Color.FromArgb(255, (int)(255 * RGBChannelFromHue(min, max,h + 1 / 3d)),
(int)(255 * RGBChannelFromHue(min, max,h)),
(int)(255 * RGBChannelFromHue(min, max,h - 1 / 3d)));
return c;
}
static double RGBChannelFromHue(double m1, double m2, double h)
{
h = (h + 1d) % 1d;
if (h < 0) h += 1;
if (h * 6 < 1) return m1 + (m2 - m1) * 6 * h;
else if (h * 2 < 1) return m2;
else if (h * 3 < 2) return m1 + (m2 - m1) * 6 * (2d / 3d - h);
else return m1;
}
Do not use the built-in GetBrightness method! It returns the same value (0.5f) for red, magenta, cyan, blue and yellow (!). This is better:
// color brightness as perceived:
float getBrightness(Color c)
{ return (c.R * 0.299f + c.G * 0.587f + c.B *0.114f) / 256f; }

System.Drawing.Color is a value type, which are almost always made immutable, especially in frameworks. That's why you can't setHue on it, you can only construct a new value type with fields you need.
So, if you have a function that will give you RGB values for your HSB values, you can do it like this
Color oldColor = ...;
int red, green, blue;
FromHSB(oldColor.GetHue(), oldColor.GetSaturation(), oldColor.GetBrightness(), out red, out green out blue);
Color newColor = Color.FromArgb(oldColor.A, red, green, blue);
where FromHSB looks like this
void FromHSB(float hue, float saturation, float brightness, out int red, out int green, out int blue)
{
// ...
}

How to append two brush classes [closed]

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Is there any way or workaround to combine/append two System.Drawing.Brush classes together?
e.g. Brush b1 = GetFromSomewhere();
Brush b2 = GetFromSomewhereElse();
(something like that...)
Brush b3 = b1 + b2;
Eventually my purpose is to do something like:
Graphics graphics = new Graphics;
graphics.FillRectangle(b3, rectangle);
Update:
I have a third party library (have no control over it) which gives me a predefined Brush instance (represents a fill pattern, e.g. ++++ or #####). I want to "overlay" that instance with my "own" brush pattern.

Update:
Since you have finally clarified what you want here is a solution to mix two TextureBrushes:
I assume you have the pattern for your TextureBrush in the Image img2. Use the simple method below to mix two images of the same size and create the new brush by using the combined patterns:
TextureBrush brush3 = new TextureBrush(
mixBitmaps( (Bitmap)(brush1.Image), (Bitmap) img2) );
Now you can paint or fill stuff with it..
Bitmap mixBitmaps(Bitmap bmp1, Bitmap bmp2)
{
using (Graphics G = Graphics.FromImage(bmp1) )
{
G.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceOver;
G.DrawImage(bmp2, Point.Empty);
}
return bmp1;
}
Here is an example:
I leave the old answer, since some folks were interested in it, too:
If you want to mix the Colors you can do it easily, maybe like this:
SolidBrush MixColor(SolidBrush b1, SolidBrush b2)
{
return new SolidBrush(Color.FromArgb(Math.Max(b1.Color.A, b2.Color.A),
(b1.Color.R + b2.Color.R) / 2, (b1.Color.G + b2.Color.G) / 2,
(b1.Color.B + b2.Color.B) / 2));
}
You may want to set the alpha channel to a fixed value of 255 instead.
However this is a simplistic average caculation, which will not work well if the colors are not close.
For a better mix you would mix the hues separatly from the saturation and the brightness values, that is you would have to convert to HSL or HSV, mix there and convert back to RGB..
Here is a version that should do just that:
SolidBrush MixBrushes(SolidBrush br1, SolidBrush br2)
{
return new SolidBrush ( MixColorHSV( br1.Color, br2.Color) );
}
Color MixColorHSV(Color c1 , Color c2 )
{
double h1 = c1.GetHue();
double h2 = c2.GetHue();
double d = (h2 - h1) / 2d;
double h = h1 + d;
if (d > 90) h -= 180; else if (d < -90) h += 180; // correction 1!
if (h < 0) h += 360; else if (h > 360) h -= 360; // correction 2!
int max1 = Math.Max(c1.R, Math.Max(c1.G, c1.B));
int min1 = Math.Min(c1.R, Math.Min(c1.G, c1.B));
double s1 = (max1 == 0) ? 0 : 1d - (1d * min1 / max1);
double v1 = max1 / 255d;
int max2 = Math.Max(c2.R, Math.Max(c2.G, c2.B));
int min2 = Math.Min(c2.R, Math.Min(c2.G, c2.B));
double s2 = (max2 == 0) ? 0 : 1d - (1d * min2 / max2);
double v2 = max2 / 255d;
double s = (s1 + s2) / 2d;
double v = (v1 + v2) / 2d;
return ColorFromHSV(h,s,v);
}
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);
}
See this post for parts of the conversion!
Here is a color chart that compares the two mixes adding Red with colors each 30° farther away. Note how many of the simple mixes are murkier with less saturation:

How to change color hue in XNA?

I have a color of class Microsoft.Xna.Framework.Color. How can I change its hue (or get a new color with slightly different hue). Should I convert it to System.Drawing.Color, then somehow change it and convert back? I can't find any useful information on this anywhere.
EDIT
Example:
I have red color R:255, G:0, B:0. Now I want to get slightly more orange color. Then if I get this color and transform it again I'll get even more orange color, then after some transformations I'll go to yellow, green etc. I don't know exact values of ARGB of each color and I don't need them. I just need to change hue of a color by some factor (for example 10 degrees).

You should use the A R G B properties and change the values to get different nyansers.
For example:
Color color = new Color(0,0,0);
//Then you can change the argb properties:
color.A = 10;
color.R = 15;
color.G = 9;
color.B = 25;
If I understand you need something like this:
public static class Utilities
{
public static void Increase(this Color color, int value)
{
if(color.R >= color.G && color.R >= color.B)
color.R += value;
else if(color.G >= color.R && color.G >= color.B)
color.G += value;
else
color.B += value;
}
public static void Decrease(this Color color, int value)
{
if(color.R <= color.G && color.R <= color.B)
color.R -= value;
else if(color.G <= color.R && color.G <= color.B)
color.G -= value;
else
color.B -= value;
}
}
Then:
Color myColor = new Color(10,0,0);
myColor.Increase(10);
//or
myColor.Decrease(10);

according to this documentation, you can pass whatever RGB(A) values you want into the XNA color class constructor. You can also use the R, B, and G properties to change them afterwards
example:
Color myColor = new Color(150, 100, 100);
myColor.R = 200
that example will change a red to a slightly deeper red.
An example of making a color go from Red to orange to yellow to green would be
Color myColor = new Color(255, 0, 0);
for(int i=0; i<255; i++)
{
myColor.R--;
myColor.G++
}
Red and Green make yellow, so higher numbers of red will make it redder, higher numbers of green will make it greener. same of both numbers make it redder.
You can change color incrementally in other ways too, so long as you know how the primary colors of light work.
You're never ever going to find a function called Color.MakeRedder() or Color.MakeGreener() It will always focus on some sort of mathmatical representation of the color, (RBG is most common but there are other representations)
If you want to convert Hue to RBG Here is a guide on how to do it
What would probably be easiest is to keep track of a System.Drawing.Color class as your base color class, and modify your XNA Color Class based on your System.Drawing.Color class accordingly.
If you want to get really adventurous, you can see if it is possible to make a class that extends(inherits from) Microsoft.Xna.Framework.Color, override the R, G, and B properties, so that they are based off of an underlying System.Drawing.Color object

I did some research and found this post which has C++ code:
http://www.cs.rit.edu/~ncs/color/t_convert.html
I've modified the code to be C#, to have an IncreaseHueBy method, and to fix a few bugs:
public static void IncreaseHueBy(ref Color color, float value, out float hue)
{
float h, s, v;
RgbToHsv(color.R, color.G, color.B, out h, out s, out v);
h += value;
float r, g, b;
HsvToRgb(h, s, v, out r, out g, out b);
color.R = (byte)(r);
color.G = (byte)(g);
color.B = (byte)(b);
hue = h;
}
static void RgbToHsv(float r, float g, float b, out float h, out float s, out float v)
{
float min, max, delta;
min = System.Math.Min(System.Math.Min(r, g), b);
max = System.Math.Max(System.Math.Max(r, g), b);
v = max; // v
delta = max - min;
if (max != 0)
{
s = delta / max; // s
if (r == max)
h = (g - b) / delta; // between yellow & magenta
else if (g == max)
h = 2 + (b - r) / delta; // between cyan & yellow
else
h = 4 + (r - g) / delta; // between magenta & cyan
h *= 60; // degrees
if (h < 0)
h += 360;
}
else
{
// r = g = b = 0 // s = 0, v is undefined
s = 0;
h = -1;
}
}
static void HsvToRgb(float h, float s, float v, out float r, out float g, out float b)
{
// Keeps h from going over 360
h = h - ((int)(h / 360) * 360);
int i;
float f, p, q, t;
if (s == 0)
{
// achromatic (grey)
r = g = b = v;
return;
}
h /= 60; // sector 0 to 5
i = (int)h;
f = h - i; // factorial part of h
p = v * (1 - s);
q = v * (1 - s * f);
t = v * (1 - s * (1 - f));
switch (i)
{
case 0:
r = v;
g = t;
b = p;
break;
case 1:
r = q;
g = v;
b = p;
break;
case 2:
r = p;
g = v;
b = t;
break;
case 3:
r = p;
g = q;
b = v;
break;
case 4:
r = t;
g = p;
b = v;
break;
default: // case 5:
r = v;
g = p;
b = q;
break;
}
}
I tested it by using a value of 1 to increase the hue by 1 every frame and it worked fairly well. Notice there may be some rounding errors.

How to Convert RGB Color to HSV?

How can I convert a RGB Color to HSV using C#?
I've searched for a fast method without using any external library.

Note that Color.GetSaturation() and Color.GetBrightness() return HSL values, not HSV.
The following code demonstrates the difference.
Color original = Color.FromArgb(50, 120, 200);
// original = {Name=ff3278c8, ARGB=(255, 50, 120, 200)}
double hue;
double saturation;
double value;
ColorToHSV(original, out hue, out saturation, out value);
// hue = 212.0
// saturation = 0.75
// value = 0.78431372549019607
Color copy = ColorFromHSV(hue, saturation, value);
// copy = {Name=ff3278c8, ARGB=(255, 50, 120, 200)}
// Compare that to the HSL values that the .NET framework provides:
original.GetHue(); // 212.0
original.GetSaturation(); // 0.6
original.GetBrightness(); // 0.490196079
The following C# code is what you want. It converts between RGB and HSV using the algorithms described on Wikipedia. The ranges are 0 - 360 for hue, and 0 - 1 for saturation or value.
public static void ColorToHSV(Color color, out double hue, out double saturation, out double value)
{
int max = Math.Max(color.R, Math.Max(color.G, color.B));
int min = Math.Min(color.R, Math.Min(color.G, color.B));
hue = color.GetHue();
saturation = (max == 0) ? 0 : 1d - (1d * min / max);
value = max / 255d;
}
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);
}

Have you considered simply using System.Drawing namespace? For example:
System.Drawing.Color color = System.Drawing.Color.FromArgb(red, green, blue);
float hue = color.GetHue();
float saturation = color.GetSaturation();
float lightness = color.GetBrightness();
Note that it's not exactly what you've asked for (see differences between HSL and HSV and the Color class does not have a conversion back from HSL/HSV but the latter is reasonably easy to add.

The EasyRGB has many color space conversions. Here is the code for the RGB->HSV conversion.

There's a C implementation here:
http://www.cs.rit.edu/~ncs/color/t_convert.html
Should be very straightforward to convert to C#, as almost no functions are called - just calculations.
found via Google

This is the VB.net version which works fine for me ported from the C code in BlaM's post.
There's a C implementation here:
http://www.cs.rit.edu/~ncs/color/t_convert.html
Should be very straightforward to convert to C#, as almost no functions are called - just > calculations.
Public Sub HSVtoRGB(ByRef r As Double, ByRef g As Double, ByRef b As Double, ByVal h As Double, ByVal s As Double, ByVal v As Double)
Dim i As Integer
Dim f, p, q, t As Double
If (s = 0) Then
' achromatic (grey)
r = v
g = v
b = v
Exit Sub
End If
h /= 60 'sector 0 to 5
i = Math.Floor(h)
f = h - i 'factorial part of h
p = v * (1 - s)
q = v * (1 - s * f)
t = v * (1 - s * (1 - f))
Select Case (i)
Case 0
r = v
g = t
b = p
Exit Select
Case 1
r = q
g = v
b = p
Exit Select
Case 2
r = p
g = v
b = t
Exit Select
Case 3
r = p
g = q
b = v
Exit Select
Case 4
r = t
g = p
b = v
Exit Select
Case Else 'case 5:
r = v
g = p
b = q
Exit Select
End Select
End Sub

I've ended up here by having the same need.
Bellow I'm sharing the best and simpler solution I could find so far.
This is a modified answer from Greg's (found here); but with a humbler and understandable code.
For those who are learning I've added a few references that are worth checking for the sake of understanding.
References
"Lukas Stratmann" HSV Model Tool (Incl. Other Model Systems: CMY / CMYK / HSL)
"The HSV Color Model in Graphic Design"
"Formula to Determine Perceived Brightness of RGB Color"
Fastest Formula to Get Hue from RGB
"Color Conversion Algorithms"
"Program to Change RGB color model to HSV color model"
"RGB to HSV Color Conversion Algorithm"
"RGB to HSV Color Space Conversion (C)"
"How to Convert RGB Color to HSV"
Code
/// <summary> Convert RGB Color to HSV. </summary>
/// <param name="color"></param>
/// <returns> A double[] Containing HSV Color Values. </returns>
public double[] rgbToHSV(Color color)
{
double[] output = new double[3];
double hue, saturation, value;
int max = Math.Max(color.R, Math.Max(color.G, color.B));
int min = Math.Min(color.R, Math.Min(color.G, color.B));
hue = color.GetHue();
saturation = (max == 0) ? 0 : 1d - (1d * min / max);
value = max / 255d;
output[0] = hue;
output[1] = saturation;
output[2] = value;
return output;
}

FIRST: make sure you have a color as a bitmap, like this:
Bitmap bmp = (Bitmap)pictureBox1.Image.Clone();
paintcolor = bmp.GetPixel(e.X, e.Y);
(e is from the event handler wich picked my color!)
What I did when I had this problem a whilke ago, I first got the rgba (red, green, blue and alpha) values.
Next I created 3 floats: float hue, float saturation, float brightness. Then you simply do:
hue = yourcolor.Gethue;
saturation = yourcolor.GetSaturation;
brightness = yourcolor.GetBrightness;
The whole lot looks like this:
Bitmap bmp = (Bitmap)pictureBox1.Image.Clone();
paintcolor = bmp.GetPixel(e.X, e.Y);
float hue;
float saturation;
float brightness;
hue = paintcolor.GetHue();
saturation = paintcolor.GetSaturation();
brightness = paintcolor.GetBrightness();
If you now want to display them in a label, just do:
yourlabelname.Text = hue.ToString;
yourlabelname.Text = saturation.ToString;
yourlabelname.Text = brightness.ToString;
Here you go, you now have RGB Values into HSV values :)
Hope this helps