Impostors: fix view dependent blending

1 files changed, 5 insertions, 7 deletions

diff --git a/impostor.cginc b/impostor.cginc
index 1245a1c..bdb24e7 100644
--- a/impostor.cginc
+++ b/impostor.cginc
@@ -12,10 +12,8 @@ float _Cutoff;
 float _SphereRadius;
 float3 _ImpostorMainCameraPos;
 
-#ifndef IMPOSTOR_SHADOW_PASS
 float4 _Color;
 float _DebugMode;
-#endif
 
 float2 HemiOctEncode(float3 N) {
     N.y = max(N.y, 1e-4);
@@ -197,11 +195,11 @@ float4 frag(v2f i) : SV_Target {
 #endif
     float3 center = i.centerPos;
 
-    // For lattice lookup, we need the reverse view direction.
-    // Lattice points are indexed by outward direction (origin → lattice).
-    // We want lattice points whose inward direction (lattice → origin) matches the view ray.
-    // So we lookup using -viewDir to find lattice points pointing opposite to the ray.
-    float3 viewOS = normalize(mul((float3x3)unity_WorldToObject, -viewDir));
+    // For lattice lookup, use the camera-to-impostor-center direction (matches billboard orientation).
+    // Using the per-fragment view ray (camera→quad point) causes the selected lattice points/weights
+    // to vary across the billboard, which reads as "not smooth" while moving around the impostor.
+    float3 centerToCamWS = normalize(camPos - center);
+    float3 viewOS = normalize(mul((float3x3)unity_WorldToObject, centerToCamWS));
 
     // Get continuous grid position and find the 3 frames
     float gridRes = (float)_GridResolution;