Replaced normal computation.

Didn't solve the problem at hand though

shaders/lib/raymarching.glsl

@@ -8,13 +8,19 @@ vec2 RM_Map( in vec3 pos );
 vec3 RM_GetNormal(
 	in vec3 pos )
 {
-	vec2 v = vec2( .0005 , 0 );
-	return normalize( vec3(
-			RM_Map( pos + v.xyy ).x - RM_Map( pos - v.xyy ).x ,
-			RM_Map( pos + v.yxy ).x - RM_Map( pos - v.yxy ).x ,
-			RM_Map( pos + v.yyx ).x - RM_Map( pos - v.yyx ).x ) );
+	const vec2 e = vec2( 1 , -1 ) * .0001;
+	const vec4 f = vec4(
+		RM_Map( pos + e.xyy ).x ,
+		RM_Map( pos + e.yyx ).x ,
+		RM_Map( pos + e.yxy ).x ,
+		RM_Map( pos + e.xxx ).x );
+	return normalize( f.x * e.xyy
+			+ f.y * e.yyx
+			+ f.z * e.yxy
+			+ f.w * e.xxx );
 }
 
+
 // -----------------------------------------------------------------------------
 
 vec3 RM_Basic(

shaders/scene.f.glsl

@@ -18,7 +18,7 @@ T_PBRMaterial PBRMaterials[1] = {
 		// Albedo color
 		vec3( .8 , 1 , .8 ) ,
 		// Roughness , metallic , subsurface , anisotropy
-		.2 , .7 , .7 , .7 ,
+		.2 , .8 , .5 , .0 ,
 		// Specular strength / tint%
 		.5 , .5
 	}
@@ -49,10 +49,11 @@ vec2 RM_Map( vec3 pos )
 	vec3 q = pos;
 	HG_pMod2( q.xy , vec2( 8. ) );
 	HG_pR( q.xz , 1 );
-	return vec2( mix( HG_fBox( q , vec3( 1.5 ) ) ,
-				HG_fSphere( q , 1.5 ) ,
-				.35 ) ,
-			step( 0. , -HG_fSphere( pos , 3 ) ) );
+	return vec2( HG_fOpUnionColumns(
+			HG_fBox( q , vec3( 1.5 ) ) ,
+			HG_fSphere( q , 1.5 ) ,
+			1. , 8 ) ,
+		step( 0. , -HG_fSphere( pos , 3 ) ) );
 }