Add support for viewport_transfom_enable register

src/video_core/engines/maxwell_3d.h

@@ -879,7 +879,13 @@ public:
 
                 Cull cull;
 
-                INSERT_PADDING_WORDS(0x28);
+                u32 pixel_center_integer;
+
+                INSERT_PADDING_WORDS(0x1);
+
+                u32 viewport_transform_enabled;
+
+                INSERT_PADDING_WORDS(0x25);
 
                 struct {
                     u32 enable;
@@ -1188,6 +1194,8 @@ ASSERT_REG_POSITION(primitive_restart, 0x591);
 ASSERT_REG_POSITION(index_array, 0x5F2);
 ASSERT_REG_POSITION(instanced_arrays, 0x620);
 ASSERT_REG_POSITION(cull, 0x646);
+ASSERT_REG_POSITION(pixel_center_integer, 0x649);
+ASSERT_REG_POSITION(viewport_transform_enabled, 0x64B);
 ASSERT_REG_POSITION(logic_op, 0x671);
 ASSERT_REG_POSITION(clear_buffers, 0x674);
 ASSERT_REG_POSITION(color_mask, 0x680);

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -970,12 +970,20 @@ u32 RasterizerOpenGL::SetupTextures(Maxwell::ShaderStage stage, Shader& shader,
 void RasterizerOpenGL::SyncViewport(OpenGLState& current_state) {
     const auto& regs = Core::System::GetInstance().GPU().Maxwell3D().regs;
     for (std::size_t i = 0; i < Tegra::Engines::Maxwell3D::Regs::NumViewports; i++) {
-        const MathUtil::Rectangle<s32> viewport_rect{regs.viewport_transform[i].GetRect()};
         auto& viewport = current_state.viewports[i];
+        const auto& src = regs.viewports[i];
+        if (regs.viewport_transform_enabled) {
+            const MathUtil::Rectangle<s32> viewport_rect{regs.viewport_transform[i].GetRect()};
             viewport.x = viewport_rect.left;
             viewport.y = viewport_rect.bottom;
             viewport.width = viewport_rect.GetWidth();
             viewport.height = viewport_rect.GetHeight();
+        } else {
+            viewport.x = src.x;
+            viewport.y = src.y;
+            viewport.width = src.width;
+            viewport.height = src.height;
+        }
         viewport.depth_range_far = regs.viewports[i].depth_range_far;
         viewport.depth_range_near = regs.viewports[i].depth_range_near;
     }