add a small gap between sectors

Author: tusharpm

src/backend/glsl_shaders/pie_gs.glsl

@@ -5,7 +5,7 @@ layout(triangle_strip, max_vertices = 64) out;
 const float Pi = 3.1415926535;
 const float radius = 0.75;
 const int PointsOnCircle = 42;
-const vec4 center = vec4(0.0, 0.0, 0.0, 1.0);
+const vec4 origin = vec4(0.0, 0.0, 0.0, 1.0);
 
 uniform mat4 viewMat;
 
@@ -25,13 +25,16 @@ void main()
     int Points = max(int(PointsOnCircle * pos.y), 1);
     float stepAngle = 2 * Pi * pos.y / Points;
 
+    float midAngle = 2 * Pi * (pos.x + pos.y / 2); 
+    vec4 center = vec4(origin.xy + 0.01 * vec2(cos(midAngle), sin(midAngle)), origin.zw);
+
     for (int i = 0; i <= Points; ++i) {
         if ((i & 1) == 0) {
             gl_Position = viewMat * center;
             EmitVertex();
         }
 
-        gl_Position = viewMat * vec4(center.xy + radius * vec2(cos(currAngle), sin(currAngle)), 0.0, 1.0);
+        gl_Position = viewMat * vec4(center.xy + radius * vec2(cos(currAngle), sin(currAngle)), center.zw);
         EmitVertex();
         currAngle += stepAngle;
     }