Improve ellipses

shader/ellipse.frag

@@ -1,25 +1,13 @@
 #version 430 core
 in vec4 gColor;
-in vec2 gFocusA;
-in vec2 gFocusB;
-in float gRad;
+in vec2 gBoundingBox;
 
 out vec4 fColor;
 //out float gl_FragDepth;
 
 void main()
 {
-  vec2 pos = gl_FragCoord.xy;
- // fColor = vec4( gColor.xyz , 0 );
- // fColor = vec4( gColor.xyz , 1 - step(distance(pos,cenPos.xy),gRad) );
- // fColor = vec4( gColor.xyz , distance(pos,cenPos.xy)/gRad );
-//  fColor = vec4( gColor.rgb, gColor.a * (1-step(gRad/2,distance(pos,cenPosT))) );
-  gl_FragDepth = max( gl_FragCoord.z 
-                    , step(gRad/2
-                          , distance(pos,gFocusA) + distance(gFocusA,gFocusB)
-                            //+ distance(pos,gFocusB)
-                          )
-                    );
+  if ( dot(gBoundingBox,gBoundingBox) > 1) { discard; }
   fColor = gColor;
 //  fColor = vec4 (1,1,1,1);
 }

shader/ellipse.geom

@@ -1,44 +1,33 @@
 #version 430 core
-layout (lines) in;
+layout (triangles) 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;
+out vec2 gBoundingBox;
 
 uniform vec2 winSize;
 uniform float zoom;
 
 void main()
 {
-  vec3 focusA = gl_in[0].gl_Position.xyz;
-  vec3 focusB = gl_in[1].gl_Position.xyz;
+  vec3 pa = gl_in[0].gl_Position.xyz;
+  vec3 pb = gl_in[1].gl_Position.xyz;
+  vec3 pc = gl_in[2].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);
+  gBoundingBox = vec2 (-1,1);
+  gl_Position = vec4 (pb, 1);
+  //gl_Position = vec4 (0.5,0,0, 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);
+  gBoundingBox = vec2 (1,1);
+  gl_Position = vec4 (pa, 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);
+  gBoundingBox = vec2 (-1,-1);
+  gl_Position = vec4 (pc, 1);
+//  gl_Position = vec4 (0.5,0.5,0, 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);
+  gBoundingBox = vec2 (1,-1);
+  gl_Position = vec4 (pa + pc - pb, 1);
   EmitVertex();
 
   EndPrimitive();

shader/ellipse.vert

@@ -1,9 +1,7 @@
 #version 430 core
 layout (location = 0) in vec3 position;
 layout (location = 1) in vec4 col;
-layout (location = 2) in float rad;
 out vec4 vCol;
-out float vRad;
 
 uniform vec2 winSize;
 uniform float zoom;
@@ -14,6 +12,5 @@ uniform mat4 worldMat;
 void main()
 {
   gl_Position = worldMat * vec4(position,1);
-  vRad = rad;
   vCol = col;
 }