Add anisotropic filtering support to QSGTexture

This patch adds support to switch on anisotropic filtering on
QSGTexture and to QSGDefaultImageNode.
Not adding this support to QSGImageNode since it became public
in 5.8, and it does not allow additional virtual methods anymore.

Change-Id: Ibf1744845df2297f9129b1b5ce6a69d0a3b31c7c
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>

8 files changed, 94 insertions, 2 deletions

diff --git a/src/quick/scenegraph/util/qsgdefaultimagenode.cpp b/src/quick/scenegraph/util/qsgdefaultimagenode.cpp
index 63773887a0..7186ee4265 100644
--- a/src/quick/scenegraph/util/qsgdefaultimagenode.cpp
+++ b/src/quick/scenegraph/util/qsgdefaultimagenode.cpp
@@ -94,6 +94,21 @@ QSGTexture::Filtering QSGDefaultImageNode::mipmapFiltering() const
     return m_material.mipmapFiltering();
 }
 
+void QSGDefaultImageNode::setAnisotropyLevel(QSGTexture::AnisotropyLevel level)
+{
+    if (m_material.anisotropyLevel() == level)
+        return;
+
+    m_material.setAnisotropyLevel(level);
+    m_opaque_material.setAnisotropyLevel(level);
+    markDirty(DirtyMaterial);
+}
+
+QSGTexture::AnisotropyLevel QSGDefaultImageNode::anisotropyLevel() const
+{
+    return m_material.anisotropyLevel();
+}
+
 void QSGDefaultImageNode::setRect(const QRectF &r)
 {
     if (m_rect == r)
diff --git a/src/quick/scenegraph/util/qsgdefaultimagenode_p.h b/src/quick/scenegraph/util/qsgdefaultimagenode_p.h
index bb9ebec885..cb23e759d3 100644
--- a/src/quick/scenegraph/util/qsgdefaultimagenode_p.h
+++ b/src/quick/scenegraph/util/qsgdefaultimagenode_p.h
@@ -85,6 +85,10 @@ public:
     void setOwnsTexture(bool owns) override;
     bool ownsTexture() const override;
 
+    // QSGImageNode now being a public class does not allow any additional virtual methods. Placing these here, non-virtual.
+    void setAnisotropyLevel(QSGTexture::AnisotropyLevel level);
+    QSGTexture::AnisotropyLevel anisotropyLevel() const;
+
 private:
     QSGGeometry m_geometry;
     QSGOpaqueTextureMaterial m_opaque_material;
diff --git a/src/quick/scenegraph/util/qsgimagenode.h b/src/quick/scenegraph/util/qsgimagenode.h
index d25e732e4b..0e053c307f 100644
--- a/src/quick/scenegraph/util/qsgimagenode.h
+++ b/src/quick/scenegraph/util/qsgimagenode.h
@@ -67,6 +67,8 @@ public:
     virtual void setMipmapFiltering(QSGTexture::Filtering filtering) = 0;
     virtual QSGTexture::Filtering mipmapFiltering() const = 0;
 
+    // ### Qt6: Add anisotropy support here, and possibly a virtual hook or another mean to extend this class.
+
     enum TextureCoordinatesTransformFlag {
         NoTransform        = 0x00,
         MirrorHorizontally = 0x01,
diff --git a/src/quick/scenegraph/util/qsgtexture.cpp b/src/quick/scenegraph/util/qsgtexture.cpp
index 47248f2f37..bc59c49162 100644
--- a/src/quick/scenegraph/util/qsgtexture.cpp
+++ b/src/quick/scenegraph/util/qsgtexture.cpp
@@ -83,6 +83,9 @@ static const bool qsg_leak_check = !qEnvironmentVariableIsEmpty("QML_LEAK_CHECK"
 #define GL_BGRA 0x80E1
 #endif
 
+#ifndef GL_TEXTURE_MAX_ANISOTROPY_EXT
+#define GL_TEXTURE_MAX_ANISOTROPY_EXT 0x84FE
+#endif
 
 QT_BEGIN_NAMESPACE
 
@@ -97,10 +100,12 @@ inline static bool isPowerOfTwo(int x)
 QSGTexturePrivate::QSGTexturePrivate()
     : wrapChanged(false)
     , filteringChanged(false)
+    , anisotropyChanged(false)
     , horizontalWrap(QSGTexture::ClampToEdge)
     , verticalWrap(QSGTexture::ClampToEdge)
     , mipmapMode(QSGTexture::None)
     , filterMode(QSGTexture::Nearest)
+    , anisotropyLevel(QSGTexture::AnisotropyNone)
 {
 }
 
@@ -274,6 +279,23 @@ static void qt_debug_remove_texture(QSGTexture* texture)
 */
 
 /*!
+    \enum QSGTexture::AnisotropyLevel
+
+    Specifies the anisotropic filtering level to be used when
+    the texture is not screen aligned.
+
+    \value AnisotropyNone No anisotropic filtering.
+
+    \value Anisotropy2x 2x anisotropic filtering.
+
+    \value Anisotropy4x 4x anisotropic filtering.
+
+    \value Anisotropy8x 8x anisotropic filtering.
+
+    \value Anisotropy16x 16x anisotropic filtering.
+*/
+
+/*!
     \fn QSGTexture::QSGTexture(QSGTexturePrivate &dd)
     \internal
  */
@@ -472,6 +494,31 @@ QSGTexture::Filtering QSGTexture::filtering() const
     return (QSGTexture::Filtering) d_func()->filterMode;
 }
 
+/*!
+    Sets the level of anisotropic filtering to be used for the upcoming bind() call to \a level.
+    The default value is QSGTexture::AnisotropyNone, which means no anisotropic filtering is enabled.
+
+    \since 5.9
+ */
+void QSGTexture::setAnisotropyLevel(AnisotropyLevel level)
+{
+    Q_D(QSGTexture);
+    if (d->anisotropyLevel != (uint) level) {
+        d->anisotropyLevel = level;
+        d->anisotropyChanged = true;
+    }
+}
+
+/*!
+    Returns the anisotropy level in use for filtering this texture.
+
+    \since 5.9
+ */
+QSGTexture::AnisotropyLevel QSGTexture::anisotropyLevel() const
+{
+    return (QSGTexture::AnisotropyLevel) d_func()->anisotropyLevel;
+}
+
 
 
 /*!
@@ -548,6 +595,12 @@ void QSGTexture::updateBindOptions(bool force)
         d->filteringChanged = false;
     }
 
+    if (force || d->anisotropyChanged) {
+        d->anisotropyChanged = false;
+        if (QOpenGLContext::currentContext()->hasExtension(QByteArrayLiteral("GL_EXT_texture_filter_anisotropic")))
+            funcs->glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, float(1 << (d->anisotropyLevel)));
+    }
+
     if (force || d->wrapChanged) {
 #ifndef QT_NO_DEBUG
         if (d->horizontalWrap == Repeat || d->verticalWrap == Repeat) {
diff --git a/src/quick/scenegraph/util/qsgtexture.h b/src/quick/scenegraph/util/qsgtexture.h
index f0509b58ae..035acc02b1 100644
--- a/src/quick/scenegraph/util/qsgtexture.h
+++ b/src/quick/scenegraph/util/qsgtexture.h
@@ -67,6 +67,14 @@ public:
         Linear
     };
 
+    enum AnisotropyLevel {
+        AnisotropyNone,
+        Anisotropy2x,
+        Anisotropy4x,
+        Anisotropy8x,
+        Anisotropy16x
+    };
+
     virtual int textureId() const = 0;
     virtual QSize textureSize() const = 0;
     virtual bool hasAlphaChannel() const = 0;
@@ -87,6 +95,9 @@ public:
     void setFiltering(Filtering filter);
     QSGTexture::Filtering filtering() const;
 
+    void setAnisotropyLevel(AnisotropyLevel level);
+    QSGTexture::AnisotropyLevel anisotropyLevel() const;
+
     void setHorizontalWrapMode(WrapMode hwrap);
     QSGTexture::WrapMode horizontalWrapMode() const;
 
diff --git a/src/quick/scenegraph/util/qsgtexture_p.h b/src/quick/scenegraph/util/qsgtexture_p.h
index b6fcfc31c4..36f9b802ba 100644
--- a/src/quick/scenegraph/util/qsgtexture_p.h
+++ b/src/quick/scenegraph/util/qsgtexture_p.h
@@ -69,11 +69,13 @@ public:
 
     uint wrapChanged : 1;
     uint filteringChanged : 1;
+    uint anisotropyChanged : 1;
 
     uint horizontalWrap : 1;
     uint verticalWrap : 1;
     uint mipmapMode : 2;
     uint filterMode : 2;
+    uint anisotropyLevel: 3;
 };
 
 class Q_QUICK_PRIVATE_EXPORT QSGPlainTexture : public QSGTexture
diff --git a/src/quick/scenegraph/util/qsgtexturematerial.cpp b/src/quick/scenegraph/util/qsgtexturematerial.cpp
index 9326ea640d..c536445e82 100644
--- a/src/quick/scenegraph/util/qsgtexturematerial.cpp
+++ b/src/quick/scenegraph/util/qsgtexturematerial.cpp
@@ -110,6 +110,7 @@ void QSGOpaqueTextureMaterialShader::updateState(const RenderState &state, QSGMa
     Q_UNUSED(state)
 #endif
     t->setMipmapFiltering(tx->mipmapFiltering());
+    t->setAnisotropyLevel(tx->anisotropyLevel());
 
     if (oldTx == 0 || oldTx->texture()->textureId() != t->textureId())
         t->bind();
@@ -173,6 +174,7 @@ QSGOpaqueTextureMaterial::QSGOpaqueTextureMaterial()
     , m_mipmap_filtering(QSGTexture::None)
     , m_horizontal_wrap(QSGTexture::ClampToEdge)
     , m_vertical_wrap(QSGTexture::ClampToEdge)
+    , m_anisotropy_level(QSGTexture::AnisotropyNone)
 {
 }
 
diff --git a/src/quick/scenegraph/util/qsgtexturematerial.h b/src/quick/scenegraph/util/qsgtexturematerial.h
index dc87131773..87d8e5fd49 100644
--- a/src/quick/scenegraph/util/qsgtexturematerial.h
+++ b/src/quick/scenegraph/util/qsgtexturematerial.h
@@ -69,6 +69,9 @@ public:
     void setVerticalWrapMode(QSGTexture::WrapMode mode) { m_vertical_wrap = mode; }
     QSGTexture::WrapMode verticalWrapMode() const { return QSGTexture::WrapMode(m_vertical_wrap); }
 
+    void setAnisotropyLevel(QSGTexture::AnisotropyLevel level) { m_anisotropy_level = level; }
+    QSGTexture::AnisotropyLevel anisotropyLevel() const { return QSGTexture::AnisotropyLevel(m_anisotropy_level); }
+
 protected:
     QSGTexture *m_texture;
 
@@ -76,8 +79,8 @@ protected:
     uint m_mipmap_filtering: 2;
     uint m_horizontal_wrap : 1;
     uint m_vertical_wrap: 1;
-
-    uint m_reserved : 26;
+    uint m_anisotropy_level : 3;
+    uint m_reserved : 23;
 };