GIDEROS LUA SHADERS DISCOVERY

MoKaLux · November 2020

Ok, time to have some more fun with gideros: GIDEROS LUA SHADERS

I am playing around to see what I can understand from the gideros lua shader demo.

I have mixed two shaders wave + bloom and I see that I can get ~~the outline of the character~~ already

So my goal has become to "code" a shader to have the outline of my character

Please don't help me yet.

Relax cafe category

rrraptor · November 2020

Im thinking about visual shader editor using ImGui and node editor.
It works with lua already (but only in docking branch

)
https://github.com/MultiPain/Gideros_ImGui/blob/952ddd90a3cb54b8bdc4b3b793d2ad303025c6bb/main.cpp#L10346
So, I can give it a try.

MoKaLux · February 2

I need your help please.
For my 3d to spritesheet program I would like to add an outline option.
I have been trying to have this effect using luashader and stencyl but I have really no clue what I am doing

How could I draw an outline around a sprite. A 1 or 2 pixels black outline would be great.

Some charitable person?

Here is a project with me not successing

MoKaLux · February 3

the best I could get (well not very good) is making a duplicate, scaling it up a bit and put it behind the original. Result, either the outline is too big or the outline will not go around the entire sprite

:

MoKaLux · February 3

"best" so far

PS: I have read that stencyl do just what I want but I am clueless about how to use it (OpenGL).

rrraptor · February 3

Simple solution can be:

local OUTLINE_SIZE = 1 -- 1px or 2px is perfect, more - eeh
local tc = fTexCoord - fTextureInfo.zw
local original = lF4(fColor) * texture2D(fTexture, tc)
if (original.a == 0) then
	for y = -1, 1 do 
		for x = -1, 1 do 
			local offset = lF2(fTextureInfo.z * x * OUTLINE_SIZE, fTextureInfo.w * y * OUTLINE_SIZE)
			local frag = lF4(fColor) * texture2D(fTexture, tc + offset)
			if (frag.a ~= 0.0) then
				original = lF4(0, 1, 0, frag.a) -- setup outline color here
			end
		end
	end
end
return original

Same, but more precise:

local OUTLINE_SIZE = 10
local tc = fTexCoord - fTextureInfo.zw
local original = lF4(fColor) * texture2D(fTexture, tc)
if (original.a == 0) then
	--local STEP = 1.57079632679 -- PI / 2 (perfect for 1 or 2 px outline)
	--local STEP = 0.78539816339 -- PI / 4 (perfect for 3 or 4 px outline)
	local STEP = 0.39269908169 -- PI / 8 (OK for more than 4 px outline)
	for theta = 0, 6.28318530718, STEP do 
		local offset = lF2(fTextureInfo.z * cos(theta) * OUTLINE_SIZE, fTextureInfo.w * sin(theta) * OUTLINE_SIZE)
		local frag = lF4(fColor) * texture2D(fTexture, tc + offset)
		if (frag.a ~= 0.0) then
			original = lF4(0, 1, 0, frag.a)
		end
	end
end
return original

MoKaLux · February 3

I love you rrraptor

.
Both shaders work great!

rrraptor · February 4

So, Is there a way to use matrices in lua shaders? @SinisterSoft @hgy29

hgy29 · February 4

Yes, 2x2, 3x3 and 4x4 matrices are supported, but:
- You can only pass 4x4 matrices as cosntants from Gideros
- You can't access individual elements from the shader code (yet)
- Their type in lua shaders are respectively hF22, hF33 and hF44 (eg. high-precision Float 2x2, etc)
- The only math op currently supported are hF44*hF4 and hF33*hF3. Others can be added easily in luashader.lua

rrraptor · February 4

hgy29 said:
Yes, 2x2, 3x3 and 4x4 matrices are supported, but:
- You can only pass 4x4 matrices as cosntants from Gideros
- You can't access individual elements from the shader code (yet)
- Their type in lua shaders are respectively hF22, hF33 and hF44 (eg. high-precision Float 2x2, etc)
- The only math op currently supported are hF44*hF4 and hF33*hF3. Others can be added easily in luashader.lua

So, how to initialize a matrix then?)
And one more question. Is there a way to create a custom function inside a shader program and use it?

Something like:

function ()
	local function MyShaderFunc(vec1, vec2)
		return vec1 * vec2
	end
 
	local frag = lF4(fColor) * texture2D(fTexture, fTexCoord)
	if (frag.a == 0.0) then discard() end
 
	local transform = lF4(0, 1, 0, 1)
	return MyShaderFunc(frag, transform)
end

hgy29 · February 4

To intiialize matrices from lua shader code, use the matrix constructor (the type name), and give as many vectors of the right length required by the matrix:

local mat4=hF44(hF4(0,0,0,0),hF4(1,1,1,1),hF4(2,2,2,2),hF4(3,3,3,3))

And yes, you can define sub-functions in your shader program, but not sub-sub-functions. See 3D library big fragment shader for an example: https://github.com/gideros/gideros/blob/master/Library/3dbase/3DShaders.lua#L46
Those functions have to be declared to the lua-shader constructor, by supply a table describing the functions such as https://github.com/gideros/gideros/blob/master/Library/3dbase/3DShaders.lua#L172 as used in https://github.com/gideros/gideros/blob/master/Library/3dbase/3DLighting.lua#L110.
This is only supported for fragment shader currently, but it could be easilyb adapted to work with vertex functions.

rrraptor · February 6

For some reason I made this

SinisterSoft · February 7

@rrraptor Is there a text editor (like Scintilla) built into the Gideros imgui library now?

That tool looks great btw, should be one of the built-in tools!
@hgy29 Maybe if the tools system could also be a right-click menu option on the regular editors text? The highlighted text could be sent to the tool. When it's finished it could send it back?

rrraptor · February 7

SinisterSoft said:
@rrraptor Is there a text editor (like Scintilla) built into the Gideros imgui library now?

There is something like that:
https://github.com/ocornut/imgui/issues/108
I used: https://github.com/BalazsJako/ImGuiColorTextEdit

SinisterSoft · February 7

@hgy29 Is this the same one we spotted a while back (for adding to imgui)?

hgy29 · February 7

SinisterSoft said:
@hgy29 Is this the same one we spotted a while back (for adding to imgui)?

Yes, I think It is.

rrraptor · February 8

I can add "ImGuiColorTextEdit" to the gideros binding. The code is ready and works well.
Or I could try to add "Zep" editor. The problem is that the code may not compile for all platforms.

SinisterSoft · February 8

I think that one (https://github.com/BalazsJako/ImGuiColorTextEdit), rather than zep. It looks good and it should work on all platforms.

rrraptor · February 8

Ok, done.
https://github.com/gideros/gideros/pull/503
I will add the ability to edit the color theme from code.

SinisterSoft · February 8

I was wondering how to change the colours in a theme.

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