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 · April 2021

still trying to understand shaders

For normal shaders (glsl for example), I need 2 files: 1 for the vertex shader and 1 for the fragment shader. Then we pass them to Shader.new(...).

For lua shaders, we must include (or link to) Gideros\Library\luashader files in our projects. Then we write our vertex shader and our fragment shader in lua. Then lua shaders calls Shader.new(...).

Is that correct? I am trying to sort out shaders in the wiki

PS: there is a typo in luashader.lua?

function Shader.lua(vf,ff,opt,uniforms,attrs,varying,funcs,const,debug)
	local lang=Shader.getShaderLanguage()
	local mtd=Shader["lua_"..lang]
	assert(mtd,"Language not supported: "..lang)
	local _vshader,_fshader=mtd(vf,ff,opt,uniforms,attrs,varying,funcs or {},const)
	if funcs then for _,fg in ipairs(funcs) do fg.code=nil end end
	if debug then print("VSHADER_CODE:\n".._vshader) print("FSHADER_CODE:\n".._fshader) end
	if not vdebug then return Shader.new(_vshader,_fshader,Shader.FLAG_FROM_CODE|opt,uniforms,attrs) end
end

vdebug is never declared?

hgy29 · April 2021

Oops, a left-over of a debug. The whole condition should be removed.

MoKaLux · March 2022

I need your help guys implementing a shader which draws an outline of a sprite, shader experts to the rescue please

I have this old outline shader made by great mister rrraptor

--!NEEDS:luashader/luashader.lua
 
local function makeEffect(name, vshader, fshader)
...
end
 
Effect={}
 
-- <a href="https://forum.gideros.rocks/profile/rrraptor" rel="nofollow">@rrraptor</a> V1 -- 1px outline
Effect.outline = makeEffect(
	"Outline",
	function (vVertex, vColor, vTexCoord)
		local vertex = hF4(vVertex, 0.0, 1.0)
		fTexCoord = vTexCoord
		return vMatrix*vertex
	end,
	function ()
		local outlinesize = 1
		local tc = fTexCoord - fTextureInfo.zw
		local original = lF4(fColor) * texture2D(fTexture, tc)
		if original.a == 0 then
			local step = 1.57079632679 -- math.pi/2 -- perfect for 1 to 2 pixels outline
			for theta = 0, 6.28318530718, step do -- 2 PI
				local offset = lF2(fTextureInfo.z * cos(theta) * outlinesize, fTextureInfo.w * sin(theta) * outlinesize)
				local frag = lF4(fColor) * texture2D(fTexture, tc + offset)
				if frag.a ~= 0 then
					original = lF4(0, 0, 0, frag.a) -- change outline color here
				end
			end
		end
		return original
	end
)

It works great prior gideros 2022.1. My problem is I still don't understand nothing about shaders and I would like to port it to newer gideros version 2022.3.1

This is my attempt but gideros doesn't like it and throws errors:

local Outline1Effect=Core.class(ShaderEffect)
ShaderEffect.Outline1=Outline1Effect
 
makeEffect("Outline1", vertexShader,
	function (vVertex, vColor, vTexCoord): Shader
		local vertex = hF4(vVertex, 0.0, 1.0)
		fTexCoord = vTexCoord
		return vMatrix*vertex
 
THIS HAS BEEN REMOVED, NSFW ;-)

~~I tried to understand the other shaders as an example but I couldn't wrap my head around those, somebody please help me~~

MoKaLux · March 2022

oh that works

and it was easier than I thought

hgy29 you are so kind to us, I knew it since day 1 but this shader thing, you gave everything to make our lifes simpler. I trully respect the LOVE you put in gideros and its users (us). So thank you, thank you, thank you.

After starting afresh I realised I had everything at my disposal in the gideros samples

So I picked the shader example and it was using the same logic as previous gideros (which I was more used to) with minor tweaks. And, to my surprise, I had clear explanations of what was not working!!! (hgy29 super kindness in action):

1st attempt:
FragmentShader:
0(28) : error C0000: syntax error, unexpected '~', expecting ',' or ')' at token "~"
0(34) : error C1503: undefined variable "original"
0(36) : error C0000: syntax error, unexpected '}' at token "}"

2nd attempt:
FragmentShader:
0(28) : error C7011: implicit cast from "float" to "bool"
0(28) : error C1020: invalid operands to "=="

And the working result:

Effect={}
 
-- <a href="https://forum.gideros.rocks/profile/hgy29" rel="nofollow">@hgy29</a>
Effect.none=makeEffect("None",
	function (vVertex,vColor,vTexCoord) : Shader
		local vertex = hF4(vVertex,0.0,1.0)
		fTexCoord=vTexCoord
		return vMatrix*vertex
	end,
	function () : Shader
		local frag=lF4(fColor)*texture2D(fTexture, fTexCoord)
		if (frag.a==0.0) then discard() end
		return frag
	end)	
 
-- <a href="https://forum.gideros.rocks/profile/rrraptor" rel="nofollow">@rrraptor</a> V1 luau -- 1px outline
Effect.outline=makeEffect("Outline",
	function (vVertex,vColor,vTexCoord) : Shader
		local vertex = hF4(vVertex,0.0,1.0)
		fTexCoord = vTexCoord
		return vMatrix*vertex
	end,
	function () : Shader
		local outlinesize=1
		local tc=fTexCoord-fTextureInfo.zw
		local original=lF4(fColor)*texture2D(fTexture, tc)
		if (original.a==0) then
			local step = 1.57079632679 -- math.pi/2 -- perfect for 1 to 2 pixels outline
--			local step = 0.78539816339 -- math.pi/4 -- perfect for 3 to 4 pixels outline
--			local step = 0.39269908169 -- PI/8 -- ok for 4+ pixels outline
			for theta = 0, 6.28318530718, step do -- 2 PI
				local offset = lF2(fTextureInfo.z * cos(theta) * outlinesize, fTextureInfo.w * sin(theta) * outlinesize)
				local frag = lF4(fColor)*texture2D(fTexture, tc+offset)
--				if frag.a ~= 0 then
--				if (not frag.a == 0) then
				if frag.a==0 then --discard()
				else original=lF4(0,0,0, frag.a) -- change outline color here
				end
			end
		end
		return original
	end)

I will let you do the cleaning

I wish you all the best, a special thought for our friend Oleg and his people, and my best wishes to you Nicolas (alias hgy29)

PS: this outline shader is the work of genius mister RRRAPTOR, THANK YOU!

Viva Gideros Luau, Peace &

MoKaLux · March 2022

and here is a sample use case:

function TheStage:xRenderTarget()
	-- first render target so we can apply shaders
	local rt = RenderTarget.new(self.canvasw or 8, self.canvash or 8)
	local rbmp = Bitmap.new(rt)
	rt:clear(0x0, 0)
	rt:draw(self.camera.view)
	if self.outline then rbmp:setShader(Effect.outline) end
	-- then the actual output image
	self.rt2:clear(0x0, 0)
	self.rt2:draw(rbmp)
	self.bmprt:setTexture(self.rt2) -- to show actual frame in the app (not needed for the output image)
end

...

hgy29 · March 2022

I think there is a bug in the luau shader compiler, it doesn’t seem to translate properly the ~= operator into != in C

Yan · March 2022

spriteOutline = {}
 
spriteOutline.VS_GL = [[
 
	uniform highp mat4 vMatrix;
 
	attribute highp vec3 vVertex;
	attribute mediump vec2 vTexCoord;
 
	varying mediump vec2 fTexCoord;
 
	void main() {
		vec4 vertex = vec4(vVertex, 1.0);
		gl_Position = vMatrix*vertex;
		fTexCoord = vTexCoord;
	}
]]
 
spriteOutline.FS_GL = [[
 
	#ifdef GL_ES
		precision highp float;
	#endif
 
	const float offseta = 0.010;
 
	uniform lowp vec4 fColor;
	uniform mediump vec4 fTexSize;
	uniform lowp sampler2D fTexture;
 
	uniform lowp int fSwitch;
 
	varying mediump vec2 fTexCoord;
 
	vec4 getSample(float x, float y, float offset, float num)
	{
		vec4 result = vec4(0);
		float size = 360.0 / num;
 
		for (float a; a <= 360.0; a += size)
		{
			vec2 coord = vec2(cos(a) * offset + x, sin(a) * offset + y);
 
			result += texture2D(fTexture, coord);
		}
 
		return result;
	}
 
	void main()
	{
		vec4 col = texture2D(fTexture, fTexCoord);
 
		float nums = 32.0;
 
		if (fSwitch == 1)
		{
			vec4 nb = getSample(fTexCoord.x, fTexCoord.y, 0.020, nums);
 
			if (col.a > 0. && nb.a < nums)
			{
				col.a = nb.a / nums;
				col.r = nb.a / nums;
				col.g = 0.0;
				col.b = 0.0;
			}
		}
 
		gl_FragColor = col;
	}
]]
 
spriteOutline.Shader=Shader.new(spriteOutline.VS_GL,spriteOutline.FS_GL,Shader.FLAG_FROM_CODE, {
	{name="vMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WVP,vertex=true},
	{name="fColor",type=Shader.CFLOAT4,sys=Shader.SYS_COLOR,vertex=false},
	{name="fTexture",type=Shader.CTEXTURE,vertex=false},
	{name="fSwitch",type=Shader.CINT,vertex=false},
},
{
	{name="vVertex",type=Shader.DFLOAT,mult=3,slot=0,offset=0},
	{name="vColor",type=Shader.DUBYTE,mult=4,slot=1,offset=0},
	{name="vTexCoord",type=Shader.DFLOAT,mult=2,slot=2,offset=0},
});

Thats all.

MoKaLux · June 2022

dear gideros people, do you know if it is possible to change the lighting color in the 3dbase shader (3DLighting.lua)?
There are those values

	local color0 = lF4(g_Color)
local LightingShaderConstants={ -- I can add my own variables here (for example specular...) XXX
{name="g_MVPMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WVP, vertex=true},
{name="g_MVMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WORLD, vertex=true},
{name="g_NMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WIT3, vertex=true},
{name="g_LMatrix",type=Shader.CMATRIX, vertex=true},
{name="g_Color",type=Shader.CFLOAT4,mult=1,sys=Shader.SYS_COLOR},
...
	if OPT_TEXTURED then color0 = color0*texture2D(g_Texture,texCoord) end
	local color1 = lF3(0.5, 0.5, 0.5)
	local normal = normalize(normalCoord)
 
	local diff = max(0.0, dot(normal, lightDir))
	local spec =0.0 -- specular XXX
    -- calculate shadow
	local shadow=1.0
	if OPT_SHADOWS then shadow = ShadowCalculation(lightSpace,FragCoord) end
	if (diff>=1) then -- 0 = ugly light halo!, >=1 = no ugly light halo! new 20220629 XXX
		local nh = max(0.0, dot(reflect(-lightDir,normal),viewDir))
		spec = pow(nh, 32.0)*shadow -- specular default = 32 (good value)
	end
 
	diff=max(diff*shadow,ambient);
	local frag = lF4(color0.rgb * diff + color1 * spec, color0.a)
	return frag

I believe the light color is WHITE but I don't see anywhere in the shader files where the color is set

(3DShaders.lua, luashader.lua, ... ?)

Can somebody point me in the right direction? Thank you for your help

MoKaLux · January 2023

MoKaLux said:
dear gideros people, do you know if it is possible to change the lighting color in the 3dbase shader (~~3DLighting.lua~~)?

A beginning of an answer

it seems to be in 3DShaders.lua

	local color0 = lF4(g_Color)
	local mycolor = lF4(1.0,0.0,0.0,1.0) --< here?
--	if OPT_TEXTURED then color0 = color0*texture2D(g_Texture,texCoord) end
	if OPT_TEXTURED then color0 = color0*texture2D(g_Texture,texCoord)*mycolor end

to be continued...

MoKaLux · January 2023

How could I pass some external values (parameters) to work in this lua shader please?
3DShaders.lua

function D3._FLUA_Shader() : Shader
	--mat3 cotangent_frame(vec3 N, vec3 p, vec2 uv)
	function cotangent_frame(N,p,uv)
		--// récupère les vecteurs du triangle composant le pixel
		local dp1 = dFdx( p )
...
	end
 
	--vec3 perturb_normal( vec3 N, vec3 V, vec2 texcoord )
	function perturb_normal( N, V, texcoord )
		--// N, la normale interpolée et
		--// V, le vecteur vue (vertex dirigé vers l'œil)
		local ret=hF3(0,0,0)
...
	end
...
	if OPT_NORMMAP then normal=perturb_normal(normal, viewDir, texCoord) end
 
	local diff = max(0.0, dot(normal, lightDir)) -- 0.0 => CHANGE THIS ONE?
	local spec = 0.0 --			=> MAYBE THIS ONE TOO?
    -- calculate shadow
	local shadow=1.0 -- 1.0, 0.5, -- this seems to control the shadow width, in practice this blows the light!
	if (diff>=1) then
		local nh = max(0.0, dot(reflect(-lightDir,normal),viewDir))
		spec = pow(nh, 64.0)*shadow --  => 64.0 AND MAYBE THIS ONE TOO?
	end
	diff=max(diff*shadow,ambient);
 
	local frag = lF4(color0.rgb * diff + color1 * spec, color0.a)
 
	return frag
end

Some pointers please

Thank you

EDIT: https://wiki.gideros.rocks/index.php/Shader:setConstant

hgy29 · February 2023

Yes, you can use Shader.setConstant if you want to set a property on a shader for all sprites that use this shader, or Sprite:setShaderConstant if you want to set a constant specifically for a given Sprite

MoKaLux · July 2024

in Lua Shader, how can I use round, trunc, ..?

round round(x) Returns a value equal to the nearest integer to x.
https://wiki.gideros.rocks/index.php/Lua_Shader_Common_Functions

Some functions seem not implemented?

I tried with this code:

frag.r += (round(frag.r * colors - dither) / colors) * c
frag.g += (round(frag.g * colors - dither) / colors) * c
frag.b += (round(frag.b * colors - dither) / colors) * c
--frag.r += (floor(frag.r * colors - dither) / colors) * c -- this works

Error: luashader/luau_codegen.lua:54: Unknown global round

I tried with math.round but not working

Is there a work around please?

EDIT: looking into luashader.lua

hgy29 · July 2024

@MoKaLux,

Shaders have floor() and ceil(), so trunc(n)=floor(n) if n is positive or ceil(n) otherwise.
round(n) is same as floor(n+0.5) for n positive and ceil(n+0.5) for n negative.

But you can add bindings for trunc and floor in luashader.lua, for all three languages (GLSL,HLSL and MSL)

MoKaLux · July 2024

thank you hgy29, I almost got this cc0 godot shader working in Gideros

https://godotshaders.com/shader/color-reduction-and-dither/#comment-1927

Gideros:

-- attempted gideros
Effect.emphasize = makeEffect("emphasize",
	function (vVertex, vColor, vTexCoord) : Shader
		local vertex = hF4(vVertex, 0.0, 1.0)
		fTexCoord = vTexCoord
		fVertex=vVertex.xy
		return vMatrix * vertex
	end,
	function () : Shader
--		local colors = lF2(1.0, 16.0)
--		local dither = lF2(0.0, 0.5)
		local colors = lF1(8.0) -- 8.0
		local dither = lF1(0.5) -- 0.25
		local frag = lF4(fColor) * texture2D(fTexture, fTexCoord)
--		local a = floor(mod(UV.x / TEXTURE_PIXEL_SIZE.x, 2.0))
--		local b = floor(mod(UV.y / TEXTURE_PIXEL_SIZE.y, 2.0))
--		local a = floor(mod(fVertex.x / fTextureInfo.x, 2.0))
--		local b = floor(mod(fVertex.y / fTextureInfo.y, 2.0))
		local a = floor(mod(fVertex.x / fTextureInfo.x, 2.0))
		local b = floor(mod(fVertex.y / fTextureInfo.y, 2.0))
		local c = mod(a + b, 2.0) -- 2.0
 
--		frag.r = (round(frag.r * colors + dither) / colors) * c
--		frag.g = (round(frag.g * colors + dither) / colors) * c
--		frag.b = (round(frag.b * colors + dither) / colors) * c
		frag.r = ((floor(frag.r * colors + dither)+0.5) / colors) * c
		frag.g = ((floor(frag.g * colors + dither)+0.5) / colors) * c
		frag.b = ((floor(frag.b * colors + dither)+0.5) / colors) * c
		c = 1.0 - c
		if c < 0 then
--			frag.r += (round(frag.r * colors - dither) / colors) * c
--			frag.g += (round(frag.g * colors - dither) / colors) * c
--			frag.b += (round(frag.b * colors - dither) / colors) * c
			frag.r += ((ceil(frag.r * colors - dither)+0.5) / colors) * c
			frag.g += ((ceil(frag.g * colors - dither)+0.5) / colors) * c
--			frag.b += (floor(fColor.b * colors - dither) / colors) * c
			frag.b += ((ceil(frag.b * colors - dither)+0.5) / colors) * c
		else
--			frag.r += (round(frag.r * colors - dither) / colors) * c
--			frag.g += (round(frag.g * colors - dither) / colors) * c
--			frag.b += (round(frag.b * colors - dither) / colors) * c
			frag.r += ((floor(frag.r * colors - dither)+0.5) / colors) * c
			frag.g += ((floor(frag.g * colors - dither)+0.5) / colors) * c
--			frag.b += (floor(fColor.b * colors - dither) / colors) * c
			frag.b += ((floor(frag.b * colors - dither)+0.5) / colors) * c
		end
 
		if (frag.a == 0.0) then discard() end
		return frag
	end)

I think I got this cc0 one working as expected?
https://godotshaders.com/shader/256-colour-pixelation/
Gideros:

Effect.colour_pixelation2 = makeEffect("colour_pixelation2",
	function (vVertex, vColor, vTexCoord) : Shader
		local vertex = hF4(vVertex, 0.0, 1.0)
		fTexCoord = vTexCoord
		return vMatrix * vertex
	end,
	function () : Shader
		local resX = 128.0 -- 32
		local resY = 128.0 -- 32
		-- 0.100392156862 is the cube root of 255
		local rgb255 = lF3(0.100392156862, 0.100392156862, 0.100392156862)
		local uvX = fTexCoord.x - mod(fTexCoord.x * resX, 1) / resX
		local uvY = fTexCoord.y - mod(fTexCoord.y * resY, 1) / resY
		local grid_uv = lF2(uvX, uvY)
		local frag = lF4(fColor) * texture2D(fTexture, grid_uv)
		if(frag.r < 1.0 and frag.g < 1.0 and frag.b < 1.0) then
			local remainder = mod(frag.rgb, rgb255)
			frag.rgb = frag.rgb - remainder
		end
		-- emphasize
		local e = lF1(1.15)
		frag.rgb = lF3(frag.r^e, frag.g^e, frag.b^e)
		if (frag.a == 0.0) then discard() end
 
		return frag
	end)

Viva Gideros

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