Implement lod bias for user materials

A lod bias can be applied to textures when dynamic resolution is
enabled. A proper lod bias is calculated and applied for quality levels
HIGH and ULTRA.

Lod Bias is implemented in glslang, which mean it's ignored when
glslang is not used, which currently happens with OpenGL backends with
optimization turned off (which includes filament LITE). This may be
fixed in the future.

libs/filamat/src/GLSLPostProcessor.cpp

@@ -30,6 +30,7 @@
 #include "sca/GLSLTools.h"
 
 #include <utils/Log.h>
+#include <filament/MaterialEnums.h>
 
 using namespace glslang;
 using namespace spirv_cross;
@@ -203,6 +204,12 @@ bool GLSLPostProcessor::process(const std::string& inputShader, Config const& co
         return false;
     }
 
+    // add texture lod bias
+    if (config.shaderType == filament::backend::FRAGMENT &&
+        config.domain == filament::MaterialDomain::SURFACE) {
+        GLSLTools::textureLodBias(tShader);
+    }
+
     program.addShader(&tShader);
     // Even though we only have a single shader stage, linking is still necessary to finalize
     // SPIR-V types