QOpenGLTexture: Set wrap mode if NPOT textures are not fully supported

The OpenGL wrap mode defaults to GL_REPEAT although it is not supported for
non-power-of-two textures on hardware that only has limited support.

I.e. the following would create a texture with an invalid wrap mode:

    auto *t = new QOpenGLTexture(QOpenGLTexture::Target2D);
    t.setSize(123, 456);

This patch adds a check in QOpenGLWindow::setSize to see if it's called with a
non-power-of-two size on hardware without full support, and if so sets wrapMode
to ClampToEdge (which should work on devices with limited support).

Task-number: QTBUG-67418
Change-Id: I56e9f4383dbf5430c2bc5e4e9e585712b3603c13
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/gui/opengl/qopengltexture.cpp b/src/gui/opengl/qopengltexture.cpp
index b825b56d45..cea4b51a5c 100644
--- a/src/gui/opengl/qopengltexture.cpp
+++ b/src/gui/opengl/qopengltexture.cpp
@@ -2800,6 +2800,11 @@ QOpenGLTexture::TextureFormat QOpenGLTexture::format() const
     return d->format;
 }
 
+static bool isNpot(int width, int height = 1, int depth = 1)
+{
+    return width & (width-1) || height & (height-1) || depth & (depth-1);
+}
+
 /*!
     Sets the dimensions of this texture object to \a width,
     \a height, and \a depth. The default for each dimension is 1.
@@ -2807,6 +2812,10 @@ QOpenGLTexture::TextureFormat QOpenGLTexture::format() const
     implementation. Allocating storage for a texture less than the
     maximum size can still fail if your system is low on resources.
 
+    If a non-power-of-two \a width, \a height or \a depth is provided and your
+    OpenGL implementation doesn't have support for repeating non-power-of-two
+    textures, then the wrap mode is automatically set to ClampToEdge.
+
     \sa width(), height(), depth()
 */
 void QOpenGLTexture::setSize(int width, int height, int depth)
@@ -2819,6 +2828,9 @@ void QOpenGLTexture::setSize(int width, int height, int depth)
         return;
     }
 
+    if (isNpot(width, height, depth) && !hasFeature(Feature::NPOTTextureRepeat) && d->target != Target::TargetRectangle)
+        d->setWrapMode(WrapMode::ClampToEdge);
+
     switch (d->target) {
     case QOpenGLTexture::Target1D:
     case QOpenGLTexture::Target1DArray: