Fix warning in stacklit.hlsl

com.unity.render-pipelines.high-definition/HDRP/Material/StackLit/StackLit.hlsl

 
     float _s_r0m, s_r12, m_rr; // we will need these outside the loop for further calculations
 
+    // HACK: If we don't use a local table and write the result directly in preLightData.vLayerEnergyCoeff
+    // we get a warning 'array reference cannot be used as an l-value; not natively addressable, forcing loop to unroll'
+    // Caution: be sure NB_VLAYERS == 3 and complete the code after
+    float3 localvLayerEnergyCoeff[NB_VLAYERS];
+
     // Iterate over the layers
     for(int i = 0; i < NB_VLAYERS; ++i)
     {
         _s_ri0 = (e_ri0 > 0.0) ? _s_ri0/e_ri0 : 0.0;
 
         // Store the coefficient and variance
-        preLightData.vLayerEnergyCoeff[i] = (m_r0i > 0.0) ? m_R0i : float3(0.0, 0.0, 0.0);
+        localvLayerEnergyCoeff[i] = (m_r0i > 0.0) ? m_R0i : float3(0.0, 0.0, 0.0);
         //preLightData.vLayerPerceptualRoughness[i] = (m_r0i > 0.0) ? LinearVarianceToPerceptualRoughness(_s_r0m) : 0.0;
 
         // Update energy
             ji0 *= j21;
         }
     }
+
+    // HACK: See note above why we need to do this
+    preLightData.vLayerEnergyCoeff[0] = localvLayerEnergyCoeff[0];
+    preLightData.vLayerEnergyCoeff[1] = localvLayerEnergyCoeff[1];
+    preLightData.vLayerEnergyCoeff[2] = localvLayerEnergyCoeff[2];
 
     //-------------------------------------------------------------
     // Post compute: