#5231: Avoid flickering during map load, caused by buffer swapping ev…

…en though no rendering is happening

libs/wxutil/GLWidget.cpp

@@ -15,7 +15,7 @@ const int ATTRIBS [] = {
 	0
 };
 
-GLWidget::GLWidget(wxWindow *parent, const std::function<void()>& renderCallback, const std::string& name) :
+GLWidget::GLWidget(wxWindow *parent, const std::function<bool()>& renderCallback, const std::string& name) :
 	wxGLCanvas(parent, wxID_ANY, ATTRIBS, wxDefaultPosition, wxDefaultSize,
                wxFULL_REPAINT_ON_RESIZE | wxWANTS_CHARS,
                wxString(name.c_str(), *wxConvCurrent)),
@@ -88,9 +88,12 @@ void GLWidget::OnPaint(wxPaintEvent& WXUNUSED(event))
 		SetCurrent(GlobalOpenGL().getwxGLContext());
 	}
 
-	_renderCallback();
-
-    SwapBuffers();
+	if (_renderCallback())
+	{
+		// Render callback returned true, so drawing took place 
+		// and we can swap the buffers
+		SwapBuffers();
+	}
 }
 
 } // namespace

libs/wxutil/GLWidget.h

@@ -20,14 +20,14 @@ class GLWidget :
 	bool _registered;
 
 	// The attached client method to invoke to render this view
-	std::function<void()> _renderCallback;
+	std::function<bool()> _renderCallback;
 
 	// Some widgets have their own openGL context, 
 	// If it  is non-NULL _privateContext will be used. 
 	wxGLContext* _privateContext;
 
 public:
-    GLWidget(wxWindow *parent, const std::function<void()>& renderCallback, const std::string& name);
+    GLWidget(wxWindow *parent, const std::function<bool()>& renderCallback, const std::string& name);
 
 	// Call this to enable/disable the private GL context of this widget
 	void SetHasPrivateContext(bool hasPrivateContext);

libs/wxutil/preview/GuiView.cpp

@@ -78,9 +78,9 @@ void GuiView::setGLViewPort()
 	debug::assertNoGlErrors();
 }
 
-void GuiView::draw()
+bool GuiView::draw()
 {
-	if (_gui == NULL) return;
+	if (!_gui) return false;
 
 	debug::assertNoGlErrors();
 
@@ -117,6 +117,8 @@ void GuiView::draw()
 	debug::assertNoGlErrors();
 
 	_renderer.render();
+
+	return true;
 }
 
 void GuiView::onSizeAllocate(wxSizeEvent& ev)

libs/wxutil/preview/GuiView.h

@@ -51,7 +51,7 @@ class GuiView :
 
 protected:
 	// Performs the actual GL setup and drawing
-	virtual void draw();
+	virtual bool draw();
 
 	// Calculates the visible area
 	virtual void setGLViewPort();

libs/wxutil/preview/RenderPreview.cpp

@@ -419,9 +419,9 @@ RenderStateFlags RenderPreview::getRenderFlagsWireframe()
            RENDER_PROGRAM;
 }
 
-void RenderPreview::drawPreview()
+bool RenderPreview::drawPreview()
 {
-    if (_renderingInProgress) return; // avoid double-entering this method
+    if (_renderingInProgress) return false; // avoid double-entering this method
 
     if (!_initialised)
     {
@@ -451,7 +451,7 @@ void RenderPreview::drawPreview()
 	{
 		// a return value of false means to cancel rendering
 		drawTime();
-		return;
+		return true; // swap buffers
 	}
 
     // Set up the camera
@@ -489,6 +489,8 @@ void RenderPreview::drawPreview()
 
     // Draw the render time
     drawTime();
+
+    return true;
 }
 
 void RenderPreview::renderWireFrame()

libs/wxutil/preview/RenderPreview.h

@@ -41,7 +41,7 @@ class RenderPreview :
 {
 private:
     void connectToolbarSignals();
-    void drawPreview();
+    bool drawPreview();
     void onGLScroll(wxMouseEvent& ev);
 	void onGLMouseClick(wxMouseEvent& ev);
     void onGLMouseRelease(wxMouseEvent& ev);

radiant/camera/CamWnd.cpp

@@ -780,14 +780,9 @@ void CamWnd::Cam_Draw()
     glBindTexture( GL_TEXTURE_2D, 0 );
 }
 
-void CamWnd::onRender()
+bool CamWnd::onRender()
 {
-    draw();
-}
-
-void CamWnd::draw()
-{
-    if (_drawing) return;
+    if (_drawing) return false;
 
     util::ScopedBoolLock lock(_drawing);
 
@@ -798,7 +793,11 @@ void CamWnd::draw()
         Cam_Draw();
 
         debug::assertNoGlErrors();
+
+        return true;
     }
+
+    return false;
 }
 
 void CamWnd::benchmark()

radiant/camera/CamWnd.h

@@ -95,7 +95,6 @@ class CamWnd :
     void queueDraw() override;
     void forceRedraw() override;
 
-    void draw();
     void update();
 
     // The callback when the scene gets changed
@@ -166,7 +165,7 @@ class CamWnd :
     void updateToolbarVisibility();
 
     void Cam_Draw();
-    void onRender();
+    bool onRender();
     void drawTime();
 
     CameraMouseToolEvent createMouseEvent(const Vector2& point, const Vector2& delta = Vector2(0, 0));

radiant/textool/TexTool.cpp

@@ -737,11 +737,11 @@ void TexTool::drawGrid()
 	}
 }
 
-void TexTool::onGLDraw()
+bool TexTool::onGLDraw()
 {
 	if (_updateNeeded)
 	{
-		return; // stop here, wait for the next idle event to refresh
+		return false; // stop here, wait for the next idle event to refresh
 	}
 
 	// Initialise the viewport
@@ -761,14 +761,15 @@ void TexTool::onGLDraw()
 	// Do nothing, if the shader name is empty
 	if (_shader == NULL || _shader->getName().empty())
 	{
-		return;
+		return true;
 	}
 
 	AABB& selAABB = getExtents();
 
 	// Is there a valid selection?
-	if (!selAABB.isValid()) {
-		return;
+	if (!selAABB.isValid())
+	{
+		return true;
 	}
 
 	AABB& texSpaceAABB = getVisibleTexSpace();
@@ -845,6 +846,8 @@ void TexTool::onGLDraw()
 		glEnd();
 		glDisable(GL_BLEND);
 	}
+
+	return true;
 }
 
 void TexTool::onGLResize(wxSizeEvent& ev)

radiant/textool/TexTool.h

@@ -184,7 +184,7 @@ class TexTool :
 	 */
 	Vector2 getTextureCoords(const double& x, const double& y);
 
-	void onGLDraw();
+	bool onGLDraw();
 	void onGLResize(wxSizeEvent& ev);
 
 	// The callbacks for capturing the mouse events

radiant/ui/common/ShaderSelector.cpp

@@ -250,12 +250,12 @@ void ShaderSelector::updateInfoTable()
 }
 
 // Callback to redraw the GL widget
-void ShaderSelector::onPreviewRender()
+bool ShaderSelector::onPreviewRender()
 {
 	// Get the viewport size from the GL widget
 	wxSize req = _glWidget->GetClientSize();
 
-	if (req.GetWidth() == 0 || req.GetHeight() == 0) return;
+	if (req.GetWidth() == 0 || req.GetHeight() == 0) return false;
 
 	glViewport(0, 0, req.GetWidth(), req.GetHeight());
 
@@ -325,6 +325,8 @@ void ShaderSelector::onPreviewRender()
 		glVertex2f(0.5*req.GetWidth() - hfWidth, 0.5*req.GetHeight() + hfHeight);
 		glEnd();
 	}
+
+	return true;
 }
 
 namespace

radiant/ui/common/ShaderSelector.h

@@ -156,7 +156,7 @@ class ShaderSelector :
 	void updateInfoTable();
 
 	// callbacks
-	void onPreviewRender();
+	bool onPreviewRender();
 	void _onSelChange(wxDataViewEvent& ev);
 };
 

radiant/ui/common/TexturePreviewCombo.cpp

@@ -99,12 +99,12 @@ void TexturePreviewCombo::_onContextMenu(wxDataViewEvent& ev)
 }
 
 // CALLBACKS
-void TexturePreviewCombo::_onRender()
+bool TexturePreviewCombo::_onRender()
 {
 	// Get the viewport size from the GL widget
 	wxSize req = _glWidget->GetClientSize();
 
-	if (req.GetWidth() == 0 || req.GetHeight() == 0) return;
+	if (req.GetWidth() == 0 || req.GetHeight() == 0) return false;
 
 	glPushAttrib(GL_ALL_ATTRIB_BITS);
 
@@ -167,6 +167,8 @@ void TexturePreviewCombo::_onRender()
 	}
 
 	glPopAttrib();
+
+	return true;
 }
 
 }

radiant/ui/common/TexturePreviewCombo.h

@@ -52,7 +52,7 @@ class TexturePreviewCombo :
 	void _onCopyTexName();
 
 	// render callback
-	void _onRender();
+	bool _onRender();
 
 	// Refresh info table utility function
 	void refreshInfoTable();

radiant/ui/texturebrowser/TextureBrowser.cpp

@@ -3,6 +3,7 @@
 #include "i18n.h"
 #include "ieventmanager.h"
 #include "itextstream.h"
+#include "imainframe.h"
 #include "iuimanager.h"
 #include "igroupdialog.h"
 #include "iradiant.h"
@@ -940,8 +941,13 @@ void TextureBrowser::onIdle(wxIdleEvent& ev)
     }
 }
 
-void TextureBrowser::onRender()
+bool TextureBrowser::onRender()
 {
+    if (!GlobalMainFrame().screenUpdatesEnabled())
+    {
+        return false;
+    }
+
 	debug::assertNoGlErrors();
 
     if (_updateNeeded)
@@ -952,6 +958,8 @@ void TextureBrowser::onRender()
     draw();
 
     debug::assertNoGlErrors();
+
+    return true;
 }
 
 } // namespace ui

radiant/ui/texturebrowser/TextureBrowser.h

@@ -226,7 +226,7 @@ class TextureBrowser :
 
 	// wx callbacks
     void onIdle(wxIdleEvent& ev);
-	void onRender();
+	bool onRender();
 	void onScrollChanged(wxScrollEvent& ev);
 	void onGLResize(wxSizeEvent& ev);
 	void onGLMouseScroll(wxMouseEvent& ev);

radiant/xyview/XYWnd.cpp

@@ -1540,14 +1540,19 @@ void XYWnd::onGLResize(wxSizeEvent& ev)
 	ev.Skip();
 }
 
-void XYWnd::onRender()
+bool XYWnd::onRender()
 {
 	if (GlobalMainFrame().screenUpdatesEnabled())
 	{
         util::ScopedBoolLock drawLock(_drawing);
 
 		draw();
+
+        return true;
 	}
+
+
+    return false; // nothing rendered
 }
 
 void XYWnd::onGLWindowScroll(wxMouseEvent& ev)

radiant/xyview/XYWnd.h

@@ -185,7 +185,7 @@ class XYWnd :
     void handleGLCapturedMouseMotion(const MouseToolPtr& tool, int x, int y, unsigned int state);
 
     // wxGLWidget-attached render method
-    void onRender();
+    bool onRender();
     void onGLResize(wxSizeEvent& ev);
     void onGLWindowScroll(wxMouseEvent& ev);