Limit the amount of viewports tested for state changes only to the usable ones

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -969,7 +969,11 @@ 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 bool geometry_shaders_enabled =
+        regs.IsShaderConfigEnabled(static_cast<size_t>(Maxwell::ShaderProgram::Geometry));
+    const std::size_t viewport_count =
+        geometry_shaders_enabled ? Tegra::Engines::Maxwell3D::Regs::NumViewports : 1;
+    for (std::size_t i = 0; i < viewport_count; i++) {
         auto& viewport = current_state.viewports[i];
         const auto& src = regs.viewports[i];
         if (regs.viewport_transform_enabled) {
@@ -1157,7 +1161,11 @@ void RasterizerOpenGL::SyncLogicOpState() {
 
 void RasterizerOpenGL::SyncScissorTest(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 bool geometry_shaders_enabled =
+        regs.IsShaderConfigEnabled(static_cast<size_t>(Maxwell::ShaderProgram::Geometry));
+    const std::size_t viewport_count =
+        geometry_shaders_enabled ? Tegra::Engines::Maxwell3D::Regs::NumViewports : 1;
+    for (std::size_t i = 0; i < viewport_count; i++) {
         const auto& src = regs.scissor_test[i];
         auto& dst = current_state.viewports[i].scissor;
         dst.enabled = (src.enable != 0);