renderer_vulkan: adjust window origin and swizzle independently

src/video_core/renderer_vulkan/vk_rasterizer.cpp

@@ -75,14 +75,20 @@ VkViewport GetViewportState(const Device& device, const Maxwell& regs, size_t in
     const float width = conv(src.scale_x * 2.0f);
     float y = conv(src.translate_y - src.scale_y);
     float height = conv(src.scale_y * 2.0f);
-    bool y_negate = regs.window_origin.mode != Maxwell::WindowOrigin::Mode::UpperLeft;
 
-    if (!device.IsNvViewportSwizzleSupported()) {
-        y_negate = y_negate != (src.swizzle.y == Maxwell::ViewportSwizzle::NegativeY);
+    const bool lower_left = regs.window_origin.mode != Maxwell::WindowOrigin::Mode::UpperLeft;
+    const bool y_negate = !device.IsNvViewportSwizzleSupported() &&
+                          src.swizzle.y == Maxwell::ViewportSwizzle::NegativeY;
+
+    if (lower_left) {
+        // Flip by surface clip height
+        y += conv(static_cast<f32>(regs.surface_clip.height));
+        height = -height;
     }
 
     if (y_negate) {
-        y += conv(static_cast<f32>(regs.surface_clip.height));
+        // Flip by viewport height
+        y += height;
         height = -height;
     }