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 databuffer; StructuredBuffer 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 } } }