--label:装飾
--track@l:Length, 0, 4000, 200, 1
--track@a:Angle, -1280, 1280, 0, 1
--track@alpha:Alpha, 0, 1, 1, 0.01
--color@c1:Start,0xffffff
--check@grad:Grad,1
--color@c2:End,0x000000
--check@trp:Transparent,0
--check@shadowOnly:ShadowOnly,0
--check@fixRot:FixRotate,1
--check@flat:Flat,0

--[[pixelshader@psmain:
Texture2D InputTexture : register(t0);

cbuffer constant0 : register(b0) {
	float l; float2 delta; float alpha;
	float3 c1;
	float _pad1;
	float3 c2;
	float trp;
};

float4 psmain(float4 pos : SV_Position) : SV_Target {
    float4 base = InputTexture[uint2(pos.xy)];
    float4 result = base;
    for (int i = 1; i <= l; i++) {
        int2 src = int2(pos.xy - delta * i);
        float4 sample = InputTexture[src];
        if (sample.a > 0.01) {
            float t = i / l;
            float3 grad = lerp(c1, c2, t);
            float a = trp ? (1 - t) * alpha : alpha;
            return float4(grad * a, a);
        }
    }
    return result;
}
]]

--[[pixelshader@psmix:
Texture2D t0 : register(t0);
Texture2D t1 : register(t1);

cbuffer constant0: register(b0) {
    float2 offset;
};

float4 psmix(float4 pos : SV_Position) : SV_Target {
    float4 c0 = t0[uint2(pos.xy)];
    float4 c1 = t1[uint2(pos.xy - offset)];
    if (pos.x < offset.x || pos.y < offset.y) return c0;
    else return float4(c0*(1-c1.a)+c1);
}
]]

obj.copybuffer("cache:_longshadow_org","obj")
if grad==0 then c2=c1 end
local r1, g1, b1 = RGB(c1)
local r2, g2, b2 = RGB(c2)

local angle = a
if (fixRot==1) then angle = a-obj.rz end
local rad=math.rad(angle)

local dx = math.cos(rad)
local dy = math.sin(rad)
local right,left,up,down = 0,0,0,0
if dx<0 then left = -dx*l else right = dx*l end
if dy<0 then up = -dy*l else down = dy*l end
obj.effect("領域拡張","上",up,"下",down,"右",right,"左",left)

if l>0 then obj.pixelshader("psmain", "object", "object", {l, dx, dy, alpha, r1/255,g1/255,b1/255, 0, r2/255,g2/255,b2/255 ,trp}) end

if (flat==1) then --この部分の実装はAodarumaさんのFlatShadow(https://github.com/Aodaruma/FlatShadow)に影響を受けています。問題があったら連絡ください。
    if obj.num > 1 then
        obj.effect("グラデーション", "color", c1, "color2", c2, "角度", angle - 90, "幅", l)
    else
        if dy < 0 then
            obj.effect("グラデーション", "color", c1, "color2", c2, "角度", 180, "幅", l, "中心Y", -dy * l / 4)
        else
            obj.effect("グラデーション", "color", c1, "color2", c2, "角度", 0, "幅", l, "中心Y", -dy * l / 4)
        end
    end
end

if (shadowOnly==0) then obj.pixelshader("psmix","object",{"object","cache:_longshadow_org"}, {left, up}) end

obj.cx=obj.cx+(left-right)/2
obj.cy=obj.cy+(up-down)/2