reset custom cube shaders on screen change

the reset/setup invokes the viewport dimensions...

BUG: 323311
FIXED-IN: 4.11.1
REVIEW: 112133

kwin/effects/cube/cube.cpp

@@ -122,6 +122,7 @@ CubeEffect::CubeEffect()
     connect(effects, SIGNAL(tabBoxAdded(int)), this, SLOT(slotTabBoxAdded(int)));
     connect(effects, SIGNAL(tabBoxClosed()), this, SLOT(slotTabBoxClosed()));
     connect(effects, SIGNAL(tabBoxUpdated()), this, SLOT(slotTabBoxUpdated()));
+    connect(effects, SIGNAL(screenGeometryChanged(const QSize&)), this, SLOT(slotResetShaders()));
 
     reconfigure(ReconfigureAll);
 }
@@ -290,6 +291,14 @@ void CubeEffect::slotWallPaperLoaded()
     watcher->deleteLater();
 }
 
+void CubeEffect::slotResetShaders()
+{
+    ShaderManager::instance()->resetShader(m_capShader,         ShaderManager::GenericShader);
+    ShaderManager::instance()->resetShader(m_reflectionShader,  ShaderManager::GenericShader);
+    ShaderManager::instance()->resetShader(cylinderShader,      ShaderManager::GenericShader);
+    ShaderManager::instance()->resetShader(sphereShader,        ShaderManager::GenericShader);
+}
+
 bool CubeEffect::loadShader()
 {
     if (!(GLPlatform::instance()->supports(GLSL) &&

kwin/effects/cube/cube.h

@@ -139,6 +139,7 @@ private slots:
     void slotTabBoxClosed();
     void slotCubeCapLoaded();
     void slotWallPaperLoaded();
+    void slotResetShaders();
 private:
     enum RotationDirection {
         Left,

kwin/libkwineffects/kwinglutils.cpp

@@ -787,6 +787,16 @@ void ShaderManager::resetAllShaders()
     }
 }
 
+void ShaderManager::resetShader(GLShader *shader, ShaderType type)
+{
+    if (!(shader && shader->isValid()))
+        return;
+
+    pushShader(shader);
+    resetShader(type);
+    popShader();
+}
+
 
 void ShaderManager::pushShader(GLShader *shader)
 {

kwin/libkwineffects/kwinglutils.h

@@ -352,6 +352,12 @@ public:
      **/
     void resetAllShaders();
 
+    /**
+     * Resets ShaderType @p type uniforms of a custom shader
+     * @since 4.11.1
+     */
+    void resetShader(GLShader *shader, ShaderType type);
+
     /**
      * Creates a GLShader with a built-in vertex shader and a custom fragment shader.
      * @param vertex The generic vertex shader