kwin: Add GLTexture::matrix()

This method returns a matrix that transforms normalized or un-normalized
texture coordinates, taking the texture target and y-inversion flag into
account.

eglonxbackend.cpp

@@ -376,6 +376,7 @@ bool EglTexture::loadTexture(const Pixmap &pix, const QSize &size, int depth)
     checkGLError("load texture");
     q->setYInverted(true);
     m_size = size;
+    updateMatrix();
     return true;
 }
 

glxbackend.cpp

@@ -612,6 +612,9 @@ bool GlxTexture::loadTexture(const Pixmap& pix, const QSize& size, int depth)
 #ifdef CHECK_GL_ERROR
     checkGLError("TextureLoad0");
 #endif
+
+    updateMatrix();
+
     unbind();
     return true;
 }

libkwineffects/kwingltexture.cpp

@@ -92,6 +92,8 @@ GLTexture::GLTexture(int width, int height)
         d->m_size = QSize(width, height);
         d->m_canUseMipmaps = true;
 
+        d->updateMatrix();
+
         glGenTextures(1, &d->m_texture);
         bind();
 #ifdef KWIN_HAVE_OPENGLES
@@ -204,6 +206,8 @@ bool GLTexture::load(const QImage& image, GLenum target)
     d->m_size = img.size();
     d->m_yInverted = true;
 
+    d->updateMatrix();
+
     img = d->convertToGLFormat(img);
 
     if (isNull()) {
@@ -526,6 +530,27 @@ QImage GLTexturePrivate::convertToGLFormat(const QImage& img) const
     return res;
 }
 
+void GLTexturePrivate::updateMatrix()
+{
+    m_matrix[NormalizedCoordinates].setToIdentity();
+    m_matrix[UnnormalizedCoordinates].setToIdentity();
+
+#ifndef KWIN_HAVE_OPENGLES
+    if (m_target == GL_TEXTURE_RECTANGLE_ARB)
+        m_matrix[NormalizedCoordinates].scale(m_size.width(), m_size.height());
+    else
+#endif
+        m_matrix[UnnormalizedCoordinates].scale(1.0 / m_size.width(), 1.0 / m_size.height());
+
+    if (!m_yInverted) {
+        m_matrix[NormalizedCoordinates].translate(0.0, 1.0);
+        m_matrix[NormalizedCoordinates].scale(1.0, -1.0);
+
+        m_matrix[UnnormalizedCoordinates].translate(0.0, m_size.height());
+        m_matrix[UnnormalizedCoordinates].scale(1.0, -1.0);
+    }
+}
+
 bool GLTexture::isYInverted() const
 {
     Q_D(const GLTexture);
@@ -536,6 +561,7 @@ void GLTexture::setYInverted(bool inverted)
 {
     Q_D(GLTexture);
     d->m_yInverted = inverted;
+    d->updateMatrix();
 }
 
 int GLTexture::width() const
@@ -550,6 +576,12 @@ int GLTexture::height() const
     return d->m_size.height();
 }
 
+QMatrix4x4 GLTexture::matrix(TextureCoordinateType type) const
+{
+    Q_D(const GLTexture);
+    return d->m_matrix[type];
+}
+
 bool GLTexture::NPOTTextureSupported()
 {
     return GLTexturePrivate::sNPOTTextureSupported;

libkwineffects/kwingltexture.h

@@ -28,6 +28,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QRegion>
 #include <QSharedPointer>
 #include <QExplicitlySharedDataPointer>
+#include <QtGui/QMatrix4x4>
 
 class QImage;
 class QPixmap;
@@ -41,6 +42,11 @@ namespace KWin
 class GLVertexBuffer;
 class GLTexturePrivate;
 
+enum TextureCoordinateType {
+    NormalizedCoordinates = 0,
+    UnnormalizedCoordinates
+};
+
 class KWIN_EXPORT GLTexture
 {
 public:
@@ -67,6 +73,14 @@ public:
      **/
     void setYInverted(bool inverted);
 
+    /**
+     * Returns a matrix that transforms texture coordinates of the given type,
+     * taking the texture target and the y-inversion flag into account.
+     *
+     * @since 4.11
+     */
+    QMatrix4x4 matrix(TextureCoordinateType type) const;
+
     virtual bool load(const QImage& image, GLenum target = GL_TEXTURE_2D);
     virtual bool load(const QPixmap& pixmap, GLenum target = GL_TEXTURE_2D);
     virtual bool load(const QString& fileName);

libkwineffects/kwingltexture_p.h

@@ -48,13 +48,16 @@ public:
 
     QImage convertToGLFormat(const QImage& img) const;
 
+    void updateMatrix();
+
     GLuint m_texture;
     GLenum m_target;
     GLenum m_filter;
     GLenum m_wrapMode;
     QSize m_size;
     QSizeF m_scale; // to un-normalize GL_TEXTURE_2D
-    bool m_yInverted; // texture has y inverted
+    QMatrix4x4 m_matrix[2];
+    bool m_yInverted; // texture is y-inverted
     bool m_canUseMipmaps;
     bool m_markedDirty;
     bool m_filterChanged;