Tidy networkCurve shaders

Arrays for start/end position/angle, smaller centre position, dynamic
segment count based on max error, calculate distance in tessellation
evaluation, use start/end position directly to avoid rounding errors at
joins.

See https://schneide.blog/2025/05/21/calculating-the-number-of-segments-for-accurate-circle-rendering/

1 files changed, 5 insertions, 3 deletions

diff --git a/gfx/gl/shaders/networkCurve.geom b/gfx/gl/shaders/networkCurve.geom
index 1002fd4..4a5b3db 100644
--- a/gfx/gl/shaders/networkCurve.geom
+++ b/gfx/gl/shaders/networkCurve.geom
@@ -1,15 +1,17 @@
 #version 460 core
 
+layout(lines) in;
+layout(triangle_strip, max_vertices = 10) out;
+
 flat in ivec3 pos[];
 flat in mat2 rot[];
 flat in float tpos[];
+flat in float dist[];
 
-layout(lines) in;
-layout(triangle_strip, max_vertices = 10) out;
 include(`networkCommon.glsl')
 
 void
 main()
 {
-	doSeg(segDist(pos[0], pos[1]), pos[0], pos[1], tpos[0], tpos[1], rot[0], rot[1]);
+	doSeg(min(dist[0], dist[1]), pos[0], pos[1], tpos[0], tpos[1], rot[0], rot[1]);
 }