shader: Fix disabled and unwritten attributes and varyings

src/shader_recompiler/backend/glsl/emit_glsl_context_get_set.cpp

@@ -179,8 +179,12 @@ void EmitGetAttribute(EmitContext& ctx, IR::Inst& inst, IR::Attribute attr,
     const char swizzle{"xyzw"[element]};
     if (IR::IsGeneric(attr)) {
         const u32 index{IR::GenericAttributeIndex(attr)};
-        if (!ctx.runtime_info.previous_stage_stores.Generic(index)) {
-            ctx.AddF32("{}=0.f;", inst, attr);
+        if (!ctx.runtime_info.previous_stage_stores.Generic(index, element)) {
+            if (element == 3) {
+                ctx.AddF32("{}=1.f;", inst, attr);
+            } else {
+                ctx.AddF32("{}=0.f;", inst, attr);
+            }
             return;
         }
         ctx.AddF32("{}=in_attr{}{}.{};", inst, index, InputVertexIndex(ctx, vertex), swizzle);

src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp

@@ -298,10 +298,14 @@ Id EmitGetAttribute(EmitContext& ctx, IR::Attribute attr, Id vertex) {
     if (IR::IsGeneric(attr)) {
         const u32 index{IR::GenericAttributeIndex(attr)};
         const std::optional<AttrInfo> type{AttrTypes(ctx, index)};
-        if (!type || !ctx.runtime_info.previous_stage_stores.Generic(index)) {
+        if (!type) {
             // Attribute is disabled
             return ctx.Const(0.0f);
         }
+        if (!ctx.runtime_info.previous_stage_stores.Generic(index, element)) {
+            // Varying component is not written
+            return ctx.Const(type && element == 3 ? 1.0f : 0.0f);
+        }
         const Id generic_id{ctx.input_generics.at(index)};
         const Id pointer{AttrPointer(ctx, type->pointer, vertex, generic_id, ctx.Const(element))};
         const Id value{ctx.OpLoad(type->id, pointer)};

src/video_core/renderer_opengl/renderer_opengl.cpp

@@ -140,6 +140,26 @@ RendererOpenGL::RendererOpenGL(Core::TelemetrySession& telemetry_session_,
     }
     AddTelemetryFields();
     InitOpenGLObjects();
+
+    // Initialize default attributes to match hardware's disabled attributes
+    GLint max_attribs{};
+    glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &max_attribs);
+    for (GLint attrib = 0; attrib < max_attribs; ++attrib) {
+        glVertexAttrib4f(attrib, 0.0f, 0.0f, 0.0f, 0.0f);
+    }
+    // Enable seamless cubemaps when per texture parameters are not available
+    if (!GLAD_GL_ARB_seamless_cubemap_per_texture && !GLAD_GL_AMD_seamless_cubemap_per_texture) {
+        glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
+    }
+    // Enable unified vertex attributes and query vertex buffer address when the driver supports it
+    if (device.HasVertexBufferUnifiedMemory()) {
+        glEnableClientState(GL_VERTEX_ATTRIB_ARRAY_UNIFIED_NV);
+        glEnableClientState(GL_ELEMENT_ARRAY_UNIFIED_NV);
+
+        glMakeNamedBufferResidentNV(vertex_buffer.handle, GL_READ_ONLY);
+        glGetNamedBufferParameterui64vNV(vertex_buffer.handle, GL_BUFFER_GPU_ADDRESS_NV,
+                                         &vertex_buffer_address);
+    }
 }
 
 RendererOpenGL::~RendererOpenGL() = default;
@@ -256,21 +276,6 @@ void RendererOpenGL::InitOpenGLObjects() {
 
     // Clear screen to black
     LoadColorToActiveGLTexture(0, 0, 0, 0, screen_info.texture);
-
-    // Enable seamless cubemaps when per texture parameters are not available
-    if (!GLAD_GL_ARB_seamless_cubemap_per_texture && !GLAD_GL_AMD_seamless_cubemap_per_texture) {
-        glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
-    }
-
-    // Enable unified vertex attributes and query vertex buffer address when the driver supports it
-    if (device.HasVertexBufferUnifiedMemory()) {
-        glEnableClientState(GL_VERTEX_ATTRIB_ARRAY_UNIFIED_NV);
-        glEnableClientState(GL_ELEMENT_ARRAY_UNIFIED_NV);
-
-        glMakeNamedBufferResidentNV(vertex_buffer.handle, GL_READ_ONLY);
-        glGetNamedBufferParameterui64vNV(vertex_buffer.handle, GL_BUFFER_GPU_ADDRESS_NV,
-                                         &vertex_buffer_address);
-    }
 }
 
 void RendererOpenGL::AddTelemetryFields() {