Make sdr white point do a thing

Bug: 182312559
Test: SilkFX prototype changes

Change-Id: Ieca0e4c8e2229d14aac460945702d23759d208e9
diff --git a/libs/renderengine/gl/GLESRenderEngine.cpp b/libs/renderengine/gl/GLESRenderEngine.cpp
index d87315f..b5510d9 100644
--- a/libs/renderengine/gl/GLESRenderEngine.cpp
+++ b/libs/renderengine/gl/GLESRenderEngine.cpp
@@ -1233,8 +1233,10 @@
             }
         }
 
-        mState.maxMasteringLuminance = layer->source.buffer.maxMasteringLuminance;
-        mState.maxContentLuminance = layer->source.buffer.maxContentLuminance;
+        // Ensure luminance is at least 100 nits to avoid div-by-zero
+        const float maxLuminance = std::max(100.f, layer->source.buffer.maxLuminanceNits);
+        mState.maxMasteringLuminance = maxLuminance;
+        mState.maxContentLuminance = maxLuminance;
         mState.projectionMatrix = projectionMatrix * layer->geometry.positionTransform;
 
         const FloatRect bounds = layer->geometry.boundaries;