Seexpr pixel perfect grids, hexagonal grids, checkerboard and more!

[tiar]

Since @amyspark helped me build kseexpr recently, I finally managed to create a bundle of my seexpr scripts! It was made in Krita 5.0 master, so please do tell me if any of them doesn’t work for you.

How to use the grids

• Create a new Fill Layer, select the SeExpr script with the grid you want.
• Change the values so they fit your purpose.
• add a new Filter Mask with Color To Alpha to make the background of the grid transparent (there is no way in SeExpr to output transparent color).

Pixel perfect grids & checkerboards

Link: Tiar's_Seexpr_Grids.bundle - Google Drive

Content:

• pixel perfect absolute grid (so you choose what size the cell is)
• pixel perfect relative grid (so you choose into how many cells to divide the canvas into)
• golden rule grid
• hexagonal grid
• pixel perfect checkerboard (I believe this one is absolute too)
  Absolute grid:
  
  
  
  Relative grid:
  
  
  
  Golden rule:
  
  
  
  Checkerboard:
  
  
  
  Hexagonal:
  
  

Random test scripts

Link: Test_Seexpr_Scripts.bundle - Google Drive

Content:

• three point perspective grid (tedious to set up, and it will be obsolete in Krita 5.0 because of the 2pp assistant) from this thread: 3-point perspective grid in SeExpr, I want some feedback
• cross-hatching script from this thread: Custom SeExpr code help - #7 by tiar
  Three Point Perspective:
  
  
  
  Cross hatching:
  
  

[TheTwo]

@tiar

Cross hatching

It seems that Seexpr can also do some comic effects. Such as speed line, concentration line, etc.

[tiar]

Wolthera made some:

But the problem with them is, someone had to code them in Here I only gather scripts I already made when I was a bit more enthusiastic about this new possibility plus a few times when someone needed help.

Depending on the task it might be a bit difficult to code it up, though the code is usually short and self-contained and you see the results instantly, which is an advantage over coding Python plugins.

[TheTwo]

Can seexpr render transparent colors? I want to modify the “Relative grid” to make it a script for head-to-body comparison

[tiar]

No. it only returns three values, r, g and b.

[okuma_10]

Great pack I use the grid a lot.
Where can I find materials on learning SeExpr. I want to do a line halftone SeExpr, where I could adjust the line’s thickness, spacing, and rotation.
Something like this :

Shadertoy

[tiar]

Here: Introduction to SeExpr — Krita Manual 5.0.0 documentation though note that there are several other pages linked on top, so it’s better to start on that page but you might need to visit other ones too later.

[okuma_10]

Thanks, I looked at the links and kind of managed to copy the shader…although I’m not getting quite the same result.
If I post it here, can you give it a look?
Basically the smoothing or the ‘aa’ part ins not working correctly. When I copied the code to ShaderEd(software for shader prototyping) I got the same result. But on the SeExpr I get aliased jagged lines

[tiar]

Sure. (And if it becomes a longer discussion, someone can just move the comments to a new thread in Develop subforum etc.)

[okuma_10]

Ok thanks for taking the time to look at it

here it is

$lineRows = 10; # 0,100
$rotate = 45; # 0,090
$lineThickness = 0.03165; 

$ratiov = $h / $w;
$uv = [$u, $v * $ratiov, 0];

$uv = rotate(uv, [0,0,1], rad($rotate));

$uvRepeat = $uv*$lineRows - round($uv * $lineRows);

$aa = $w * 0.3;
$leftSide  = (1.0 - $aa*0.005) * $lineThickness;
$rightSide  = (1.0 + $aa*.005) * $lineThickness;
$col = smoothstep($leftSide, $rightSide, length(uvRepeat[1]-0.5));

$color = [$col,$col,$col];

$color