fix(shader): add dfWithID to sdf_test.wgsl for test compatibility

SDFTestEffect was failing with undefined dfWithID error. The raymarching.wgsl
include requires dfWithID even for single-pass effects. Added dummy implementation
that wraps df() for compatibility.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/workspaces/main/shaders/sdf_test.wgsl b/workspaces/main/shaders/sdf_test.wgsl
index 3c97613..71310f2 100644
--- a/workspaces/main/shaders/sdf_test.wgsl
+++ b/workspaces/main/shaders/sdf_test.wgsl
@@ -22,6 +22,15 @@ fn df(p: vec3<f32>) -> f32 {
     return min(d_sphere, d_box);
 }
 
+// Two-pass distance function (required by raymarching.wgsl)
+fn dfWithID(p: vec3<f32>) -> RayMarchResult {
+    var result: RayMarchResult;
+    result.distance = df(p);
+    result.distance_max = result.distance;
+    result.object_id = 0.0;
+    return result;
+}
+
 // Simple lighting
 fn shade(pos: vec3<f32>, rd: vec3<f32>) -> vec3<f32> {
     let n = normal(pos);