38 lines
942 B
GLSL
38 lines
942 B
GLSL
varying lowp vec2 coord;
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uniform lowp vec4 color;
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uniform lowp float spreadRadius;
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uniform lowp float blurRadius;
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uniform lowp float opacity;
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/*
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arc.xy: cos/sin of the angle of the midpoint
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arc.zw: cos/sin of the angle between midpoint/endpoint
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*/
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uniform lowp vec4 arc;
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mat2 rotation( vec2 v ) { return mat2( v.x, -v.y, v.y, v.x ); }
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void main()
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{
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float radius = 0.5 - blurRadius - spreadRadius;
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float dist = abs( length( coord ) - radius ) - spreadRadius;
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if ( ( arc.z < 1.0 ) && ( dist < 1.0 ) )
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{
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vec2 v = coord * rotation( arc.xy ); // x-axial symmetric
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v.y = abs( v.y );
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v *= rotation( arc.wz ); // end point at 90°
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if ( v.x < 0.0 )
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{
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v.y = max( 0.0, abs( v.y - radius ) - spreadRadius );
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dist = max( dist, length( v ) );
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}
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}
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float a = 1.0 - smoothstep( 0.0, blurRadius, dist );
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gl_FragColor = color * a * opacity;
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}
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