[effects] Use shader traits API for lookingglass

In the long run this effect needs to be modified. Rendering the complete
scene to an FBO is not the best approach.

effects/lookingglass/data/1.10/lookingglass.frag

@@ -4,15 +4,15 @@ uniform float u_zoom;
 uniform float u_radius;
 uniform vec2 u_textureSize;
 
-varying vec2 varyingTexCoords;
+varying vec2 texcoord0;
 
 #define PI 3.14159
 
 void main()
 {
-    vec2 d = u_cursor - varyingTexCoords;
+    vec2 d = u_cursor - texcoord0;
     float dist = sqrt(d.x*d.x + d.y*d.y);
-    vec2 texcoord = varyingTexCoords;
+    vec2 texcoord = texcoord0;
     if (dist < u_radius) {
         float disp = sin(dist / u_radius * PI) * (u_zoom - 1.0) * 20.0;
         texcoord += d / dist * disp;

effects/lookingglass/data/1.40/lookingglass.frag

@@ -5,7 +5,7 @@ uniform float u_zoom;
 uniform float u_radius;
 uniform vec2 u_textureSize;
 
-in vec2 varyingTexCoords;
+in vec2 texcoord0;
 
 out vec4 fragColor;
 
@@ -13,9 +13,9 @@ out vec4 fragColor;
 
 void main()
 {
-    vec2 d = u_cursor - varyingTexCoords;
+    vec2 d = u_cursor - texcoord0;
     float dist = sqrt(d.x*d.x + d.y*d.y);
-    vec2 texcoord = varyingTexCoords;
+    vec2 texcoord = texcoord0;
     if (dist < u_radius) {
         float disp = sin(dist / u_radius * PI) * (u_zoom - 1.0) * 20.0;
         texcoord += d / dist * disp;

effects/lookingglass/lookingglass.cpp

@@ -32,6 +32,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <KGlobalAccel>
 #include <KLocalizedString>
 #include <QVector2D>
+#include <QFile>
 
 #include <kmessagebox.h>
 
@@ -116,7 +117,12 @@ bool LookingGlassEffect::loadData()
     if (GLPlatform::instance()->glslVersion() >= coreVersionNumber)
         shadersDir = QStringLiteral("kwin/shaders/1.40/");
     const QString fragmentshader = QStandardPaths::locate(QStandardPaths::GenericDataLocation, shadersDir + QStringLiteral("lookingglass.frag"));
-    m_shader = ShaderManager::instance()->loadFragmentShader(ShaderManager::SimpleShader, fragmentshader);
+    QFile ff(fragmentshader);
+    if (!ff.open(QIODevice::ReadOnly)) {
+        qCCritical(KWINEFFECTS) << "Failed to read shader!";
+        return false;
+    }
+    m_shader = ShaderManager::instance()->generateCustomShader(ShaderTrait::MapTexture, QByteArray(), ff.readAll());
     if (m_shader->isValid()) {
         ShaderBinder binder(m_shader);
         m_shader->setUniform("u_textureSize", QVector2D(screenSize.width(), screenSize.height()));
@@ -228,10 +234,10 @@ void LookingGlassEffect::slotMouseChanged(const QPoint& pos, const QPoint& old,
     }
 }
 
-void LookingGlassEffect::postPaintScreen()
+void LookingGlassEffect::paintScreen(int mask, QRegion region, ScreenPaintData &data)
 {
     // Call the next effect.
-    effects->postPaintScreen();
+    effects->paintScreen(mask, region, data);
     if (m_valid && m_enabled) {
         // Disable render texture
         GLRenderTarget* target = GLRenderTarget::popRenderTarget();
@@ -245,6 +251,7 @@ void LookingGlassEffect::postPaintScreen()
         m_shader->setUniform("u_zoom", (float)zoom);
         m_shader->setUniform("u_radius", (float)radius);
         m_shader->setUniform("u_cursor", QVector2D(cursorPos().x(), cursorPos().y()));
+        m_shader->setUniform(GLShader::ModelViewProjectionMatrix, data.projectionMatrix());
         m_vbo->render(GL_TRIANGLES);
         m_texture->unbind();
     }

effects/lookingglass/lookingglass.h

@@ -46,7 +46,7 @@ public:
     virtual void reconfigure(ReconfigureFlags);
 
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
-    virtual void postPaintScreen();
+    void paintScreen(int mask, QRegion region, ScreenPaintData &data) override;
     virtual bool isActive() const;
 
     static bool supported();