Improved shader (thanks BYP!)

client/webgl_shaders.js

@@ -197,23 +197,8 @@ const sdf_fs_src = `#version 300 es
             vec2 b = v_line.zw;
 
             vec2 pa = v_texcoord - a.xy, ba = b.xy - a.xy;
-            float h = dot(pa, ba) / dot(ba, ba);
-            /*
-            float dist = length(pa - ba * h) - v_thickness.y / 2.0;
-            */
-
-            float dist;
-            float r1 = v_thickness.x;
-            float r2 = v_thickness.y;
-
-            if (h < 0.0) {
-                dist = length(v_texcoord - a) - r1;
-            } else if (0.0 <= h && h < 1.0) {
-                vec2 Q = a + ba * h; 
-                dist = length(v_texcoord - Q) - (r1 + (r2 - r1) * length(Q - a) / length(ba));
-            } else {
-                dist = length(v_texcoord - b) - r2;
-            }
+            float h = clamp(dot(pa, ba) / dot(ba, ba), 0.0, 1.0);
+            float dist = length(v_texcoord - (a + ba * h)) - mix(v_thickness.x, v_thickness.y, h);
 
             float fade = 0.5 * length(fwidth(v_texcoord));
             float alpha = 1.0 - smoothstep(-fade, fade, dist);