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123 行
4.2 KiB

Shader "UIWidgets/ShadowRBox_cb"
{
//originally from http://madebyevan.com/shaders/fast-rounded-rectangle-shadows/
Properties
{
_StencilComp("_StencilComp", Float) = 8 // - Equal, 8 - Always
}
SubShader
{
ZTest Always
ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha
Stencil {
Ref 128
Comp [_StencilComp]
}
Pass {
CGPROGRAM
#pragma require compute
float4 _sb_box;
float4 _viewport;
float _sb_sigma;
float4 _sb_color;
float _sb_corner;
float _mat[9];
struct vdata
{
float2 vertex;
float2 uv;
};
StructuredBuffer<vdata> databuffer;
StructuredBuffer<int> indexbuffer;
int _startVertex;
struct v2f
{
float4 vertex : SV_POSITION;
float2 coord : TEXCOORD0;
};
float gaussian(float x, float sigma)
{
float pi = 3.141592653589793;
return exp(-(x*x) / (2.0 * sigma * sigma)) / (sqrt(2.0 * pi) * sigma);
}
float2 erf(float2 x)
{
float2 s = sign(x);
float2 a = abs(x);
x = 1.0 + (0.278393 + (0.230389 + 0.078108 * (a * a)) * a) * a;
x = x * x;
return s - s / (x * x);
return s;
}
float roundedBoxShadowX(float x, float y, float sigma, float corner, float2 halfSize)
{
float delta = min(halfSize.y - corner - abs(y), 0.0);
float curved = halfSize.x - corner + sqrt(max(0.0, corner * corner - delta * delta));
float2 integral = 0.5 + 0.5 * erf((x + float2(-curved, curved)) * (sqrt(0.5)/sigma));
return integral.y - integral.x;
}
float roundedBoxShadow(float2 lower, float2 upper, float2 pnt, float sigma, float corner)
{
float2 center = (lower + upper) * 0.5;
float2 halfSize = (upper - lower) * 0.5;
pnt -= center;
float low = pnt.y - halfSize.y;
float high = pnt.y + halfSize.y;
float start = clamp(-3.0 * sigma, low, high);
float end = clamp(3.0 * sigma, low, high);
float step = (end - start) / 4.0;
float y = start + step * 0.5;
float value = 0.0;
for(int i=0; i<4;i++)
{
value += roundedBoxShadowX(pnt.x, pnt.y - y, sigma, corner, halfSize) * gaussian(y, sigma) * step;
y += step;
}
return value;
}
v2f vert(uint vertex_id: SV_VertexID){
v2f o;
vdata v = databuffer[indexbuffer[_startVertex + vertex_id]];
float padding = 3.0 * _sb_sigma;
o.coord = lerp(_sb_box.xy - padding, _sb_box.zw + padding, v.vertex.xy);
float3x3 mat = float3x3(_mat[0], _mat[1], _mat[2], _mat[3], _mat[4], _mat[5], 0, 0, 1);
float2 p = mul(mat, float3(o.coord.xy, 1.0)).xy - _viewport.xy;
#if UNITY_UV_STARTS_AT_TOP
o.vertex = float4(2.0 * p.x / _viewport.z - 1.0, 2.0 * p.y / _viewport.w - 1.0, 0, 1);
#else
o.vertex = float4(2.0 * p.x / _viewport.z - 1.0, 1.0 - 2.0 * p.y / _viewport.w, 0, 1);
#endif
return o;
}
float4 frag(v2f i) : SV_TARGET {
float4 fragColor = _sb_color;
fragColor.a = fragColor.a * roundedBoxShadow(_sb_box.xy, _sb_box.zw, i.coord, _sb_sigma, _sb_corner);
return fragColor;
}
#pragma vertex vert
#pragma fragment frag
ENDCG
}
}
}