From 40044f21e1b05335bdf043a5362798027e1bbbfd Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Fri, 29 Jul 2022 11:08:59 +0000
Subject: [PATCH] effects: Honor transforms in OffscreenEffect

This ensures that transforms are honored with effects such as wobbly
windows.
---
 src/libkwineffects/kwineffects.cpp         | 20 +++++++++++++++
 src/libkwineffects/kwineffects.h           |  5 ++++
 src/libkwineffects/kwinoffscreeneffect.cpp |  3 ++-
 src/scenes/opengl/scene_opengl.cpp         | 29 +---------------------
 4 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/src/libkwineffects/kwineffects.cpp b/src/libkwineffects/kwineffects.cpp
index 648a01c7d0..56299aea9a 100644
--- a/src/libkwineffects/kwineffects.cpp
+++ b/src/libkwineffects/kwineffects.cpp
@@ -204,6 +204,26 @@ void PaintData::setRotationOrigin(const QVector3D &origin)
     d->rotationOrigin = origin;
 }
 
+QMatrix4x4 PaintData::toMatrix() const
+{
+    QMatrix4x4 ret;
+    if (d->translation != QVector3D(0, 0, 0)) {
+        ret.translate(d->translation);
+    }
+    if (d->scale != QVector3D(1, 1, 1)) {
+        ret.scale(d->scale);
+    }
+
+    if (d->rotationAngle != 0) {
+        ret.translate(d->rotationOrigin);
+        const QVector3D axis = d->rotationAxis;
+        ret.rotate(d->rotationAngle, axis.x(), axis.y(), axis.z());
+        ret.translate(-d->rotationOrigin);
+    }
+
+    return ret;
+}
+
 class WindowPaintDataPrivate
 {
 public:
diff --git a/src/libkwineffects/kwineffects.h b/src/libkwineffects/kwineffects.h
index 7e75870123..0d3dc19349 100644
--- a/src/libkwineffects/kwineffects.h
+++ b/src/libkwineffects/kwineffects.h
@@ -3092,6 +3092,11 @@ public:
      */
     QVector3D rotationAxis() const;
 
+    /**
+     * Returns the corresponding transform matrix.
+     */
+    QMatrix4x4 toMatrix() const;
+
 protected:
     PaintData();
     PaintData(const PaintData &other);
diff --git a/src/libkwineffects/kwinoffscreeneffect.cpp b/src/libkwineffects/kwinoffscreeneffect.cpp
index 5cf564e65e..731ebea58c 100644
--- a/src/libkwineffects/kwinoffscreeneffect.cpp
+++ b/src/libkwineffects/kwinoffscreeneffect.cpp
@@ -160,7 +160,8 @@ void OffscreenEffectPrivate::paint(EffectWindow *window, GLTexture *texture, con
 
     QMatrix4x4 mvp = data.screenProjectionMatrix();
     mvp.translate(window->x(), window->y());
-    shader->setUniform(GLShader::ModelViewProjectionMatrix, mvp);
+
+    shader->setUniform(GLShader::ModelViewProjectionMatrix, mvp * data.toMatrix());
     shader->setUniform(GLShader::ModulationConstant, QVector4D(rgb, rgb, rgb, a));
     shader->setUniform(GLShader::Saturation, data.saturation());
     shader->setUniform(GLShader::TextureWidth, texture->width());
diff --git a/src/scenes/opengl/scene_opengl.cpp b/src/scenes/opengl/scene_opengl.cpp
index f3d71222cd..d8cae6a000 100644
--- a/src/scenes/opengl/scene_opengl.cpp
+++ b/src/scenes/opengl/scene_opengl.cpp
@@ -409,33 +409,6 @@ QMatrix4x4 SceneOpenGL::modelViewProjectionMatrix(const WindowPaintData &data) c
     }
 }
 
-static QMatrix4x4 transformForPaintData(int mask, const WindowPaintData &data)
-{
-    // TODO: Switch to QTransform.
-    QMatrix4x4 matrix;
-
-    if (!(mask & Scene::PAINT_WINDOW_TRANSFORMED)) {
-        return matrix;
-    }
-
-    matrix.translate(data.translation());
-    const QVector3D scale = data.scale();
-    matrix.scale(scale.x(), scale.y(), scale.z());
-
-    if (data.rotationAngle() == 0.0) {
-        return matrix;
-    }
-
-    // Apply the rotation
-    // cannot use data.rotation.applyTo(&matrix) as QGraphicsRotation uses projectedRotate to map back to 2D
-    matrix.translate(data.rotationOrigin());
-    const QVector3D axis = data.rotationAxis();
-    matrix.rotate(data.rotationAngle(), axis.x(), axis.y(), axis.z());
-    matrix.translate(-data.rotationOrigin());
-
-    return matrix;
-}
-
 void SceneOpenGL::render(Item *item, int mask, const QRegion &region, const WindowPaintData &data)
 {
     if (region.isEmpty()) {
@@ -450,7 +423,7 @@ void SceneOpenGL::render(Item *item, int mask, const QRegion &region, const Wind
     renderContext.transformStack.push(QMatrix4x4());
     renderContext.opacityStack.push(data.opacity());
 
-    item->setTransform(transformForPaintData(mask, data));
+    item->setTransform(data.toMatrix());
 
     createRenderNode(item, &renderContext);