Lua Shader Examples
From GiderosMobile
Parent: Writing Lua Shaders
Requirements: In order to use Lua Shaders you need to include luashader standard library in your projects luashader standard library is available in your Gideros installation folder under Library
Shader Saturate
function vssaturate(vVertex, vColor, vTexCoord) : Shader
local vertex = hF4(vVertex, 0.0, 1.0)
fTexCoord = vTexCoord
return vMatrix * vertex
end
function fssaturate() : Shader
local frad = (1 + sin(fTime*7)) * 0.5
local frag = lF4(fColor) * texture2D(fTexture, fTexCoord)
local coef = lF3(0.2125, 0.7154, 0.0721)
local dp = dot(frag.rgb, coef)
if fSwitch == 22.0 then -- switched via lua code
frag.rgb = mix(frag.rgb, frag.rgb / dp, frad)
end
if (frag.a == 0.0) then discard() end
return frag
end
local saturate = Shader.lua(vssaturate, fssaturate, 0,
{
{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="fTextureInfo", type=Shader.CFLOAT4, sys=Shader.SYS_TEXTUREINFO, vertex=false},
{name="fTime", type=Shader.CFLOAT, sys=Shader.SYS_TIMER, vertex=false},
{name="fSwitch", type=Shader.CFLOAT, vertex=false}, -- CFLOAT type to be more platforms compliant
},
{
{name="vVertex", type=Shader.DFLOAT, mult=2, 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},
},
{
{name="fTexCoord", type=Shader.CFLOAT2},
}
)
-- bg color
application:setBackgroundColor(0x909090)
-- a texture and a bitmap
local tex = Texture.new("gfx/test.png")
local bmp = Bitmap.new(tex, true)
local bmp2 = bmp:clone()
-- position
bmp:setPosition(32*4, 32*4)
bmp2:setPosition(32*4, 32*8)
-- lua shader
bmp:setShader(saturate)
bmp2:setShader(saturate)
bmp:setShaderConstant("fSwitch", Shader.CFLOAT, 1, 22.0) -- switch is on
bmp2:setShaderConstant("fSwitch", Shader.CFLOAT, 1, -38.0) -- switch is off
-- order
stage:addChild(bmp)
stage:addChild(bmp2)
-- loop
stage:addEventListener(Event.ENTER_FRAME, function(e)
bmp:setX(bmp:getX() + 0.5)
if bmp:getX() > 400 then bmp:setX(-80) end
end)
Rain drops demo - by Hgy29
Rain drops shader effect
-- Custom shader for a plain colored pixel (BASIC PROGRAM)
local shader=StandardShaders:getShaderSpecification(Shader.SHADER_PROGRAM_BASIC)
-- We will need vertex position in fragment shader
function shader:vertexShader(vVertex,vColor,vTexCoord) : Shader
local vertex = hF4(vVertex,0.0,1.0)
fVertex=vVertex.xy
return vMatrix*vertex
end
-- Fragment shader will compute caustics and ripples
function shader:fragmentShader() : Shader
local tp = hF2(1.0/32.0,1.0/16.0)
local mt = fVertex/1024.0
local p = mod(mt*6.28, 6.28)-360.0
local i = p
local c = 1.0
local inten = .005
for n=1,3 do
local t = fTime*0.5 * (1.0 - (3.0 / hF1(n)))
i = p + hF2(cos(t - i.x) + sin(t + i.y), sin(t - i.y) + cos(t + i.x))
c += 1.0/length(hF2(p.x / (sin(i.x+t)/inten),p.y / (cos(i.y+t)/inten)))
end
for n=1,32 do
local fr=fRippleT[n]
if (fr>0.0) then
local pd=length(fVertex-fRippleC[n])
local rd=1.0-smoothstep(0.0,128.0,pd)
if (rd>0.0) then
local td=(fTime-fr)*10.0
local dr=min(1.0,max(0.0,1.0-abs(td-(1.0-rd)*20.0)/10.0))
c+=sin(rd*20.0+td)*rd*dr
end
end
end
c /= 3
c = (1.5-c^.5)^4
return lF4((hF4(c,c,c,1.0) + hF4(0.0, 0.3, 0.5, 1.0))*fColor)
end
-- Add our custom constants and inter-stage varibale
local NDROPS=32
table.insert(shader.uniforms,{name="fRippleC",type=Shader.CFLOAT2,vertex=false,mult=NDROPS})
table.insert(shader.uniforms,{name="fTime",type=Shader.CFLOAT,sys=Shader.SYS_TIMER,vertex=false})
table.insert(shader.uniforms,{name="fRippleT",type=Shader.CFLOAT,vertex=false,mult=NDROPS})
table.insert(shader.varying,{name="fVertex",type=Shader.CFLOAT2})
-- A plain blue screen wide Pixel with our shader
local ax,ay,aw,ah=application:getLogicalBounds()
local p=Pixel.new(0x5678CD,1,aw-ax,ah-ay) p:setPosition(ax,ay)
p:setShader(shader:build())
stage:addChild(p)
-- Main loop: create random rain drops
local drop=0
local dropsP,dropsT={},{}
for i=1,NDROPS do dropsP[i*2-1]=0 dropsP[i*2]=0 dropsT[i]=0 end
Core.asyncCall(function()
while true do
Core.yield(.05)
drop+=1
if drop==(NDROPS+1) then drop=1 end
dropsP[drop*2-1]=math.random(aw-ax)
dropsP[drop*2]=math.random(ah-ay)
dropsT[drop]=os:timer()
p:setShaderConstant("fRippleC",Shader.CFLOAT2,NDROPS,dropsP)
p:setShaderConstant("fRippleT",Shader.CFLOAT,NDROPS,dropsT)
end
end)
