From ff5636c6f60ca1be67fb75dde72b02da1cc8c6b9 Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Sat, 21 May 2022 12:40:29 -0700
Subject: [PATCH] examples/gkurve: adjust frag shader to show barycentric
 coordinates

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 examples/gkurve/frag.wgsl | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/examples/gkurve/frag.wgsl b/examples/gkurve/frag.wgsl
index c3887ed2..fd2dfd0f 100755
--- a/examples/gkurve/frag.wgsl
+++ b/examples/gkurve/frag.wgsl
@@ -6,14 +6,13 @@ struct FragUniform {
 
 @stage(fragment) fn main( 
     @location(0) uv: vec2<f32>,
-    @interpolate(linear) @location(1) bary: vec3<f32>,
+    @interpolate(linear) @location(1) bary: vec2<f32>,
     @interpolate(flat) @location(2) triangle_index: u32,
 ) -> @location(0) vec4<f32> {
     // Example 1: Visualize barycentric coordinates:
-    // return vec4<f32>(bary.x, bary.y, bary.z, 1.0);
-    // return vec4<f32>(0.0, bary.x, 0.0, 1.0); // bottom-left of triangle
-    // return vec4<f32>(0.0, bary.y, 0.0, 1.0); // bottom-right of triangle
-    // return vec4<f32>(0.0, bary.z, 0.0, 1.0); // top of triangle
+    // return vec4<f32>(bary.x, bary.y, 0.0, 1.0);
+    // return vec4<f32>(0.0, bary.x, 0.0, 1.0); // [1.0 (bottom-left vertex), 0.0 (bottom-right vertex)]
+    // return vec4<f32>(0.0, bary.y, 0.0, 1.0); // [1.0 (bottom-left vertex), 1.0 (top-right face)]
 
     // Example 2: Render gkurve primitives
     var inversion = -1.0;
@@ -28,21 +27,19 @@ struct FragUniform {
         inversion = 1.0;
     }
 
-	// Gradients
-	let px = dpdx(bary.xy);
-	let py = dpdy(bary.xy);
+    // Gradients
+    let px = dpdx(bary.xy);
+    let py = dpdy(bary.xy);
 
-	// Chain rule
-	let fx = (2.0 * bary.x) * px.x - px.y;
-	let fy = (2.0 * bary.x) * py.x - py.y;
+    // Chain rule
+    let fx = (2.0 * bary.x) * px.x - px.y;
+    let fy = (2.0 * bary.x) * py.x - py.y;
 
-	// Signed distance
-	var dist = (bary.x * bary.x - bary.y) / sqrt(fx * fx + fy * fy);
-    // var dist = bary.z*bary.z - bary.y;
+    // Signed distance
+    var dist = (bary.x * bary.x - bary.y) / sqrt(fx * fx + fy * fy);
 
     dist *= inversion;
-    dist /= 128.0;
-    dist /= 1.75;
+    dist /= 300.0;
 
     // Border rendering.
     if (dist > 0.0 && dist <= 0.1) { return vec4<f32>(1.0, 0.0, 0.0, 1.0); }