gl_graphics_pipeline: Add downscale factor to shader uniforms

src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp

@@ -211,8 +211,7 @@ void EmitYDirection(EmitContext& ctx, IR::Inst& inst) {
 }
 
 void EmitResolutionDownFactor(EmitContext& ctx, IR::Inst& inst) {
-    UNIMPLEMENTED();
-    ctx.Add("MOV.F {}.x,1;", inst);
+    ctx.Add("MOV.F {}.x,program.env[0].x;", inst);
 }
 
 void EmitUndefU1(EmitContext& ctx, IR::Inst& inst) {

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);

src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp

@@ -446,8 +446,7 @@ void EmitYDirection(EmitContext& ctx, IR::Inst& inst) {
 }
 
 void EmitResolutionDownFactor(EmitContext& ctx, IR::Inst& inst) {
-    UNIMPLEMENTED();
-    ctx.AddF32("{}=1.0f;", inst);
+    ctx.AddF32("{}=down_factor;", inst);
 }
 
 void EmitLoadLocal(EmitContext& ctx, IR::Inst& inst, std::string_view word_offset) {

src/video_core/renderer_opengl/gl_graphics_pipeline.cpp

@@ -443,11 +443,24 @@ void GraphicsPipeline::ConfigureImpl(bool is_indexed) {
     if (!is_built.load(std::memory_order::relaxed)) {
         WaitForBuild();
     }
-    if (assembly_programs[0].handle != 0) {
+    const bool use_assembly{assembly_programs[0].handle != 0};
+    const bool is_rescaling{texture_cache.IsRescaling()};
+    const f32 config_down_factor{Settings::values.resolution_info.down_factor};
+    const f32 down_factor{is_rescaling ? config_down_factor : 1.0f};
+    if (use_assembly) {
         program_manager.BindAssemblyPrograms(assembly_programs, enabled_stages_mask);
     } else {
         program_manager.BindSourcePrograms(source_programs);
     }
+    for (size_t stage = 0; stage < source_programs.size(); ++stage) {
+        if (stage_infos[stage].uses_rescaling_uniform) {
+            if (use_assembly) {
+                glProgramEnvParameter4fARB(AssemblyStage(stage), 0, down_factor, 0.0f, 0.0f, 1.0f);
+            } else {
+                glProgramUniform1f(source_programs[stage].handle, 0, down_factor);
+            }
+        }
+    }
     const VideoCommon::ImageViewInOut* views_it{views.data()};
     GLsizei texture_binding = 0;
     GLsizei image_binding = 0;