diff --git a/shader/lightmapCircle.frag b/shader/lightmapCircle.frag
index c29090cf5..7a6466b7e 100644
--- a/shader/lightmapCircle.frag
+++ b/shader/lightmapCircle.frag
@@ -1,12 +1,13 @@
 #version 430 core
 in vec2 cenPosT;
-in vec2 gParams;
+in float lum;
+
+in vec2 dField;
+
 out vec4 fColor;
 
 void main()
 {
-  vec2 pos = gl_FragCoord.xy;
-  float dist = min(1 , 2*distance(pos,cenPosT) / (gParams.x));
-  float c = gParams.y * pow(1-dist,2);
+  float c = pow (1 - min(1, dot(dField,dField)) , 2) * lum ;
   fColor = vec4(c,c,c,c);
 }
diff --git a/shader/lightmapCircle.geom b/shader/lightmapCircle.geom
index a32186b49..a8790706a 100644
--- a/shader/lightmapCircle.geom
+++ b/shader/lightmapCircle.geom
@@ -2,26 +2,31 @@
 layout (points) in;
 layout (triangle_strip, max_vertices = 4) out;
 in vec2 vParams [];
-out vec2 gParams;
+out float lum;
 out vec2 cenPosT;
+out vec2 dField;
 
 uniform vec2 winSize;
 uniform float zoom;
 
 void main()
 {
+  lum = vParams[0].y;
   vec3 cenPos = gl_in[0].gl_Position.xyz;
-  gParams = vec2( vParams[0].x * zoom * 2, vParams[0].y);
-  float gRad = gParams.x;
+  float gRad = vParams[0].x * zoom * 2;
 
   cenPosT = vec2 ( (cenPos.x + 1) * 0.5 * winSize.x , (cenPos.y + 1) * 0.5 * winSize.y);
 
+  dField = vec2 ( 1, 1);
   gl_Position = vec4 (cenPos.x + gRad/winSize.x, cenPos.y + gRad/winSize.y, -0.2 , 1);
   EmitVertex();
+  dField = vec2 (-1, 1);
   gl_Position = vec4 (cenPos.x - gRad/winSize.x, cenPos.y + gRad/winSize.y, -0.2 , 1);
   EmitVertex();
+  dField = vec2 ( 1,-1);
   gl_Position = vec4 (cenPos.x + gRad/winSize.x, cenPos.y - gRad/winSize.y, -0.2 , 1);
   EmitVertex();
+  dField = vec2 (-1,-1);
   gl_Position = vec4 (cenPos.x - gRad/winSize.x, cenPos.y - gRad/winSize.y, -0.2 , 1);
   EmitVertex();