gl_graphics_pipeline: Add downscale factor to shader uniforms

src/shader_recompiler/backend/glsl/emit_context.cpp

@@ -393,6 +393,9 @@ EmitContext::EmitContext(IR::Program& program, Bindings& bindings, const Profile
             DefineGenericOutput(index, program.invocations);
         }
     }
+    if (info.uses_rescaling_uniform) {
+        header += "layout(location=0) uniform float down_factor;";
+    }
     DefineConstantBuffers(bindings);
     DefineStorageBuffers(bindings);
     SetupImages(bindings);