Partially working ellipse shader

shader/ellipse.geom

@@ -0,0 +1,45 @@
+#version 430 core
+layout (lines) in;
+layout (triangle_strip, max_vertices = 4) out;
+in vec4 vCol[];
+in float vRad[];
+out vec4 gColor;
+out float gRad;
+out vec2 gFocusA;
+out vec2 gFocusB;
+
+uniform vec2 winSize;
+uniform float zoom;
+
+void main()
+{
+  vec3 focusA = gl_in[0].gl_Position.xyz;
+  vec3 focusB = gl_in[1].gl_Position.xyz;
+  gColor = vCol[0];
+  gRad = vRad[0] * zoom * 2 ;
+
+  gFocusA = vec2 ( (focusA.x + 1) * 0.5 * winSize.x , (focusA.y + 1) * 0.5 * winSize.y);
+//  focusA = vec3 ( 0 , 0, focusA.z);
+  gFocusB = vec2 ( (focusB.x + 1) * 0.5 * winSize.x , (focusB.y + 1) * 0.5 * winSize.y);
+  float am = 0.5;
+
+  gl_Position = vec4 (focusA.x + gRad/winSize.x, focusA.y + gRad/winSize.y, focusA.z , 1);
+//  gl_Position = vec4 (focusA.x + am, focusA.y + am, -1 , 1);
+//  gl_Position = vec4 (focusA , 1);
+  EmitVertex();
+  gl_Position = vec4 (focusA.x - gRad/winSize.x, focusA.y + gRad/winSize.y, focusA.z , 1);
+//  gl_Position = vec4 (focusA.x - am, focusA.y + am, -1 , 1);
+//  gl_Position = vec4 (0 ,0.5 ,-1 , 1);
+//  gl_Position = vec4 (0 + gRad ,0 ,-1 , 1);
+  EmitVertex();
+  gl_Position = vec4 (focusA.x + gRad/winSize.x, focusA.y - gRad/winSize.y, focusA.z , 1);
+//  gl_Position = vec4 (focusA.x + am, focusA.y - am, -1 , 1);
+//  gl_Position = vec4 (0.5 ,0.5 ,-1 , 1);
+  EmitVertex();
+  gl_Position = vec4 (focusA.x - gRad/winSize.x, focusA.y - gRad/winSize.y, focusA.z , 1);
+//  gl_Position = vec4 (focusA.x - am, focusA.y - am, -1 , 1);
+//  gl_Position = vec4 (0.5 ,0 ,-1 , 1);
+  EmitVertex();
+
+  EndPrimitive();
+}