How to Write an Effect Plugin (Part 3 of 4 - Complex)

[BoltBait]

I've never been happy with the C# Code Syntax Highlighter here on this site, so this tutorial has been moved here:

How to Write an Effect Plugin (Part 3 of 4 - Complex)
This tutorial contains an overview of how to use effect composition in CodeLab to create complex effects.

If you have questions about the tutorial, you can post them here in this thread and I will address them.

[Ego Eram Reputo]

Woah! What a marvelous tutorial!

Now we'll get a landslide of new plugins from a host of new authors

Thank you for explaining it so well.

[Ego Eram Reputo]

As an amendment to BoltBait's excellent tutorial, here a codelab script that renders clouds based on @Sepcot's original Perlin Noise code.

Note that this cloud effect is not exactly the same as the Cloud effect built in to PDN.

/* ===================== */
/* */
/* Perlin Noise.cs */
/* */
/* Description: Draws clouds based on Sepcot's Perlin Noise routines 	*/
/* */
/* ==================== */

// Name: Sepcot's Perlin Noise
// Author: Ego Eram Reputo
// Submenu: Render
// URL: http://www.getpaint.net/redirect/plugins.html

#region UICode 
double Amount1 = 1.5; // [1, 12] Frequency
double Amount2 = 65; // [20, 70] Persistence (edge blur)
double Amount3 = 8.0; // [2,14] Octaves
double Amount4 = 1.0; // [0,5] Amplitude (brightness or density)
double Amount5 = 0.0; // [-2,3] cloudCoverage
double Amount6 = 1.0; // [0,4] cloudDensity
#endregion

void Render(Surface dst, Surface src, Rectangle rect)
{
// Delete any of these lines you don't need
Rectangle selection = this.EnvironmentParameters.GetSelection(src.Bounds).GetBoundsInt();
long CenterX = (long)(((selection.Right - selection.Left) / 2)+selection.Left);
long CenterY = (long)(((selection.Bottom - selection.Top) / 2)+selection.Top);
ColorBgra PrimaryColor = (ColorBgra)EnvironmentParameters.PrimaryColor;
ColorBgra SecondaryColor = (ColorBgra)EnvironmentParameters.SecondaryColor;
int BrushWidth = (int)EnvironmentParameters.BrushWidth;

//	ColorBgra srcBgra;
for(int y = rect.Top; y < rect.Bottom; y++)
{
	for (int x = rect.Left; x < rect.Right; x++)
	{
	ColorBgra srcBgra = src[x, y];
	byte c = (byte)(PerlinNoise2d(x, y) * 255);
	dst[x, y] = ColorBgra.FromBgra(srcBgra.B, srcBgra.G, srcBgra.R, c);
	}
}
}

static Random r = new Random();
int r1 = r.Next(1000, 10000);
int r2 = r.Next(100000, 1000000);
int r3 = r.Next(1000000000, 2000000000);

double PerlinNoise2d(int x, int y)
{
double total = 0.0;
double frequency = Amount1/100; 	// was .015;	// USER ADJUSTABLE
double persistence = Amount2/100; // was .65; // USER ADJUSTABLE
double octaves = Amount3; 	// was 8; 	// USER ADJUSTABLE
double amplitude = Amount4; 	// was 1; 	// USER ADJUSTABLE
double cloudCoverage = Amount5; 	// was 0; // USER ADJUSTABLE
double cloudDensity = Amount6; 	// was 1;	// USER ADJUSTABLE

for(int lcv = 0; lcv < octaves; lcv++)
{
	total = total + Smooth(x * frequency, y * frequency) * amplitude;
	frequency = frequency * 2;
	amplitude = amplitude * persistence;
}

total = (total + cloudCoverage) * cloudDensity;

if(total < 0) total = 0.0;
if(total > 1) total = 1.0;

return total;
}

double Smooth(double x, double y)
{
double n1 = Noise((int)x, (int)y);
double n2 = Noise((int)x + 1, (int)y);
double n3 = Noise((int)x, (int)y + 1);
double n4 = Noise((int)x + 1, (int)y + 1);

double i1 = Interpolate(n1, n2, x - (int)x);
double i2 = Interpolate(n3, n4, x - (int)x);

return Interpolate(i1, i2, y - (int)y);
}

double Noise(int x, int y)
{
int n = x + y * 57;
n = (n<<13) ^ n;

return ( 1.0 - ( (n * (n * n * r1 + r2) + r3) & 0x7fffffff) / 1073741824.0);
}

double Interpolate(double x, double y, double a)
{
double val = (1 - Math.Cos(a * Math.PI)) * .5;
return x * (1 - val) + y * val;
}

[ninja]

Lol, this is heavily confusing need a cup of tea now

Where did you learn to do this stuff?.

Edited July 18, 2010 by ninja

[csm725]

BoltBait, thank you for 4 amazing tutorials. I am learning .NET C# and these examples help me understand the basics of writing a plugin. Thank you.

[RFX]

Is there a list or examples of the actions in Paint.net similar to the composite effects list / effects examples that were given such as "gaussian blur", "emboss", "add noise", etc. ?

In particular things like "cut selection", "copy selection", "delete selection", and "paste selection" is what I'm trying to find or is that something completely different? I know that copying and such are actions and emboss and whatnot are effects but I can't find any examples which explains how to use actions, or maybe I just missed / overlooked them.

[pyrochild]

None of those are possible. Only effects and adjustments.

[BoltBait]

None of those are possible. Only effects and adjustments.

What he said ^^

[RFX]

lol well there goes my idea There is an alternate method to what I have in mind however there are a few plug ins that already exist and sort of relate to it, just nothing I've seen that does exactly what I had in mind. Thanks though for the info guys, I'll do a bit more research on it.

[Ego Eram Reputo]

Have a look at this list of what plugins can and cannot do: plugin limitations

[RFX]

Thanks EER! I checked it out and I think what I had in mind is just not possible, an plotted section cutter similar to Gimp's path tool. As it can't cut or make the selected area transparent, perhaps I can try a different approach from those 2 ideas and try an area-to-fill but I'm not sure if a plotted path is even possible to do as an effect. Something like this:

 

[Ego Eram Reputo]

Looks like you need to write a tool interface like Smudge or Liquify.  Possible, but very difficult compared to 'standard' plugins.