--information:AlphaDither v1.00 by CatWithNeko
--label:抽出
--track@alpha:Alpha,0,100,100,0.01
--track@size:Size,1,1000,1,1
--track@seed:Seed,0,4000,0,1
--[[pixelshader@psmain:
Texture2D tex0 : register(t0);
cbuffer constant0 : register(b0) {float2 resolution;float size;float alpha;float seed;};
float4 psmain(float4 pos : SV_Position,float2 UV : TEXCOORD0) : SV_Target {
    int2 gridpos=int2((pos.xy-resolution/2)/size);
    float rand=float(frac(sin(dot(gridpos, float2(12.9898, 78.233)) + seed * 437.585) * 43758.5453123));;
    float4 ta=tex0[pos.xy];
    return rand<tex0[gridpos*size+resolution/2].a*alpha ? float4(ta.rgb/ta.a,1):0;
}
]]

local w,h=obj.getpixel()
obj.pixelshader("psmain","object","object",{w,h,size,alpha/100,seed})