[Fix, Test] (MG_Backend/DirectGLES, MG_Util, CI): keep an explicit LOD constant under a new avoid flag - folding the bias uniform into it kills the ANGLE llvmpipe JIT

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.cpp

@@ -1343,6 +1343,8 @@ namespace MobileGL::MG_Util::BackendLoader {
             caps.IsAngleRenderer && caps.GLESRendererString.find("llvmpipe") != String::npos;
         caps.AvoidSamplerMipmapMinFilter =
             caps.IsAngleLlvmpipeRenderer && MG_Config::Features.AvoidSamplerMipmapMinFilter;
+        caps.AvoidExplicitLodBias =
+            caps.IsAngleLlvmpipeRenderer && MG_Config::Features.AvoidExplicitLodBias;
         MGLOG_I("    GL_EXT_disjoint_timer_query supported: %s",
                 caps.SupportsDisjointTimerQuery ? "true" : "false");
         MGLOG_I("    GL_KHR_parallel_shader_compile supported: %s",
@@ -1351,6 +1353,7 @@ namespace MobileGL::MG_Util::BackendLoader {
         MGLOG_I("    ANGLE llvmpipe renderer: %s", caps.IsAngleLlvmpipeRenderer ? "true" : "false");
         MGLOG_I("    Avoid sampler mipmap min filter: %s",
                 caps.AvoidSamplerMipmapMinFilter ? "true" : "false");
+        MGLOG_I("    Avoid explicit LOD bias: %s", caps.AvoidExplicitLodBias ? "true" : "false");
 
         return true;
     }

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.h

@@ -1156,6 +1156,9 @@ namespace MobileGL {
             // MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER feature toggle:
             // sampler min filters should drop their mipmap component.
             Bool AvoidSamplerMipmapMinFilter = false;
+            // IsAngleLlvmpipeRenderer combined with the MOBILEGL_AVOID_EXPLICIT_LOD_BIAS
+            // feature toggle: LOD-bias emulation should not touch explicit-LOD lookups.
+            Bool AvoidExplicitLodBias = false;
             // True when indirect draws leak the command's baseInstance word ("reserved,
             // must be zero" in unextended ES) into gl_InstanceID. Conforming ES drivers
             // keep gl_InstanceID zero-based; ANGLE's Vulkan backend hands the command