Issue with NoesisGUI + C++ OpenGL (Frame Buffer not Cleared / Overlapping Rendering
Posted: 19 Aug 2025, 11:26
Hi everyone,
I am currently integrating NoesisGUI into my C++ + OpenGL 2.x fixed-function pipeline project.
Most features are working fine, and in the vast majority of cases it runs normally, but I encountered a serious rendering issue when certain UI components extend beyond the screen edges.
From my experience, this affects my original OpenGL rendering in different ways:
xaml Code
C++ Code
My environment
Thanks in advance!
I am currently integrating NoesisGUI into my C++ + OpenGL 2.x fixed-function pipeline project.
Most features are working fine, and in the vast majority of cases it runs normally, but I encountered a serious rendering issue when certain UI components extend beyond the screen edges.
From my experience, this affects my original OpenGL rendering in different ways:
- When rendering NoesisGUI, the previous frame is not cleared, so semi-transparent elements get stacked until they look opaque. (see screenshot Fig.1, Fig.2)
- In some cases, my original OpenGL scene stops rendering and only NoesisGUI is rendered, again with the previous frame not being cleared (see Fig.3, Fig.4).
Code: Select all
<Page
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignWidth="1920"
d:DesignHeight="1080" xmlns:b="http://schemas.microsoft.com/xaml/behaviors">
<Page.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="ResourceDictionary.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Page.Resources>
<Grid x:Name="Master">
<Grid x:Name="MapMasterGrid">
<Viewbox x:Name="MapViewBox">
<Grid x:Name="MapGrid" Width="800" Height="600" ClipToBounds="True">
<Grid.RowDefinitions>
<RowDefinition Height="1*"/>
<RowDefinition Height="8*"/>
<RowDefinition Height="1*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="8*"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Grid Grid.Column="1" Grid.RowSpan="3">
<Grid.Background>
<SolidColorBrush Color="#00000000"/>
</Grid.Background>
<Grid x:Name="MapImageGird" RenderTransformOrigin="0.5,0.5" Width="512" Height="512" HorizontalAlignment="Center" VerticalAlignment="Center">
<Grid.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="{Binding Path=Value, ElementName=MapScaleSlider}" ScaleY="{Binding Path=Value, ElementName=MapScaleSlider}"/>
<SkewTransform/>
<RotateTransform Angle="-45"/>
<TranslateTransform/>
</TransformGroup>
</Grid.RenderTransform>
<Grid.Background>
<LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
<GradientStop Color="#FF000000" Offset="0"/>
<GradientStop Color="#FFFFFFFF" Offset="1"/>
</LinearGradientBrush>
</Grid.Background>
</Grid>
</Grid>
<StackPanel Grid.Column="2" Grid.Row="1">
<RepeatButton x:Name="MapPlus" Content="+" Width="30" Height="30"/>
<Slider x:Name="MapScaleSlider" Orientation="Vertical" Width="30" Maximum="1.5" Minimum="0.5" Value="0.75" Height="420"/>
<RepeatButton x:Name="MapDec" Width="30" Height="30" Content="-"/>
</StackPanel>
<Button x:Name="MapExitBtn" Style="{DynamicResource ExitButtonStyle}" VerticalAlignment="Center" Grid.Column="2" Margin="0" HorizontalAlignment="Center" Visibility="Collapsed"/>
</Grid>
</Viewbox>
</Grid>
</Grid>
</Page>
Code: Select all
enum class ViewType
{
Upper,
ToolTip,
HUD,
};
struct ViewData
{
Noesis::Ptr<Noesis::FrameworkElement> xaml;
Noesis::Ptr<Noesis::IView> view;
Noesis::Grid* backGrid;
bool isVisible;
bool isFirst;
};
std::map<ViewType, ViewData> g_views;
void NoesisGUIRender(ViewType viewType)
{
static uint64_t startTime = Noesis::HighResTimer::Ticks();
RECT rc;
::GetClientRect(g_hWnd, &rc);
uint32_t clientWidth = rc.right - rc.left;
uint32_t clientHeight = rc.bottom - rc.top;
uint64_t time = Noesis::HighResTimer::Ticks();
if (g_views[viewType].view != NULL && g_views[viewType].isVisible)
{
g_NoesisVM->UpdateEvent(viewType);
g_views[viewType].view->Update(Noesis::HighResTimer::Seconds(time - startTime));
g_views[viewType].view->GetRenderer()->UpdateRenderTree();
RenderView(g_views[viewType].view, g_context, clientWidth, clientHeight);
}
RestoreValues();
if (viewType != ViewType::ToolTip && g_views[ViewType::ToolTip].isVisible)
NoesisGUIRender(ViewType::ToolTip);
}
- C++ with OpenGL 2.1 fixed pipeline (legacy project, not using shaders yet)
NoesisGUI Version 3.2.7
Windows 10
NoesisGUI Renderer: OpenGL
- Do I need to explicitly clear some buffers before/after calling Noesis::GUI::Render()?
Is there a recommended way to handle clipping / scissoring when UI elements go outside the screen area?
Could this be related to my OpenGL state not being restored correctly after Noesis rendering?
Thanks in advance!