From 15ac833f2c9b2a57f30c6ed1a2904571c3c63856 Mon Sep 17 00:00:00 2001
From: Onek8 <mail@1k8.org>
Date: Thu, 10 Jul 2025 00:09:21 +0000
Subject: [PATCH] Update leenkx/Shaders/std/constants.glsl

---
 leenkx/Shaders/std/constants.glsl | 57 +++++++++++++++++--------------
 1 file changed, 32 insertions(+), 25 deletions(-)

diff --git a/leenkx/Shaders/std/constants.glsl b/leenkx/Shaders/std/constants.glsl
index b9ccfdc..caf04dc 100644
--- a/leenkx/Shaders/std/constants.glsl
+++ b/leenkx/Shaders/std/constants.glsl
@@ -24,37 +24,44 @@ const int DIFFUSE_CONE_COUNT = 16;
 
 const float SHADOW_CONE_APERTURE = radians(15.0);
 
-const float DIFFUSE_CONE_APERTURE = radians(50.0);
+const float DIFFUSE_CONE_APERTURE = 0.872665; // 50 degrees in radians
 
-const vec3 DIFFUSE_CONE_DIRECTIONS[DIFFUSE_CONE_COUNT] = vec3[](
-    vec3(0.0, 0.0, 1.0), // center
+mat3 makeTangentBasis(const vec3 normal) {
+    // Create a tangent basis from normal vector
+    vec3 tangent;
+    vec3 bitangent;
 
-    vec3(0.0, 0.5, 0.866),
-    vec3(0.5, 0.0, 0.866),
-    vec3(0.0, -0.5, 0.866),
-    vec3(-0.5, 0.0, 0.866),
+    // Compute tangent (Frisvad's method)
+    if (abs(normal.z) < 0.999) {
+        tangent = normalize(cross(vec3(0, 1, 0), normal));
+    } else {
+        tangent = normalize(cross(normal, vec3(1, 0, 0)));
+    }
+    bitangent = cross(normal, tangent);
 
-    vec3(0.353, 0.353, 0.866),
-    vec3(0.353, -0.353, 0.866),
-    vec3(-0.353, -0.353, 0.866),
-    vec3(-0.353, 0.353, 0.866),
-
-    vec3(0.707, 0.0, 0.707),
-    vec3(0.0, 0.707, 0.707),
-    vec3(-0.707, 0.0, 0.707),
-    vec3(0.0, -0.707, 0.707),
-
-    vec3(0.5, 0.5, 0.707),
-    vec3(-0.5, 0.5, 0.707),
-    vec3(-0.5, -0.5, 0.707)
-);
-
-mat3 makeTangentBasis(vec3 normal) {
-    vec3 tangent = normalize(abs(normal.y) < 0.999 ? cross(normal, vec3(0, 1, 0)) : cross(normal, vec3(1, 0, 0)));
-    vec3 bitangent = cross(normal, tangent);
     return mat3(tangent, bitangent, normal);
 }
 
+// 16 optimized cone directions for hemisphere sampling (Z-up, normalized)
+const vec3 DIFFUSE_CONE_DIRECTIONS[16] = vec3[](
+    vec3(0.707107, 0.000000, 0.707107),  // Front
+    vec3(-0.707107, 0.000000, 0.707107), // Back
+    vec3(0.000000, 0.707107, 0.707107),  // Right
+    vec3(0.000000, -0.707107, 0.707107), // Left
+    vec3(0.500000, 0.500000, 0.707107),  // Front-right
+    vec3(-0.500000, 0.500000, 0.707107), // Back-right
+    vec3(0.500000, -0.500000, 0.707107), // Front-left
+    vec3(-0.500000, -0.500000, 0.707107),// Back-left
+    vec3(0.353553, 0.000000, 0.935414),  // Narrow front
+    vec3(-0.353553, 0.000000, 0.935414), // Narrow back
+    vec3(0.000000, 0.353553, 0.935414),  // Narrow right
+    vec3(0.000000, -0.353553, 0.935414), // Narrow left
+    vec3(0.270598, 0.270598, 0.923880),  // Narrow front-right
+    vec3(-0.270598, 0.270598, 0.923880), // Narrow back-right
+    vec3(0.270598, -0.270598, 0.923880), // Narrow front-left
+    vec3(-0.270598, -0.270598, 0.923880) // Narrow back-left
+);
+
 // TO DO - Disabled momentarily instead of changing formulas
 const float off_BayerMatrix8[8][8] =
 {