scene: Don't touch texture sampling params in ItemRendererOpenGL

Items must be responsible for choosing texture sampling parameters.
Doing so in the ItemRendererOpenGL breaks the encapsulation.

src/backends/x11/standalone/x11_standalone_glx_backend.cpp

@@ -945,7 +945,8 @@ bool GlxPixmapTexturePrivate::create(SurfacePixmapX11 *texture)
     glGenTextures(1, &m_texture);
 
     q->setDirty();
-    q->setFilter(GL_NEAREST);
+    q->setFilter(GL_LINEAR);
+    q->setWrapMode(GL_CLAMP_TO_EDGE);
 
     glBindTexture(m_target, m_texture);
     glXBindTexImageEXT(m_backend->display(), m_glxPixmap, GLX_FRONT_LEFT_EXT, nullptr);

src/platformsupport/scenes/opengl/basiceglsurfacetexture_wayland.cpp

@@ -106,7 +106,7 @@ bool BasicEGLSurfaceTextureWayland::loadDmabufTexture(KWaylandServer::LinuxDmaBu
     m_texture->setSize(buffer->size());
     m_texture->create();
     m_texture->setWrapMode(GL_CLAMP_TO_EDGE);
-    m_texture->setFilter(GL_NEAREST);
+    m_texture->setFilter(GL_LINEAR);
     m_texture->bind();
     glEGLImageTargetTexture2DOES(GL_TEXTURE_2D, static_cast<GLeglImageOES>(image));
     m_texture->unbind();

src/scene/itemrenderer_opengl.cpp

@@ -353,8 +353,6 @@ void ItemRendererOpenGL::renderItem(const RenderTarget &renderTarget, const Rend
             opacity = renderNode.opacity;
         }
 
-        renderNode.texture->setFilter(GL_LINEAR);
-        renderNode.texture->setWrapMode(GL_CLAMP_TO_EDGE);
         renderNode.texture->bind();
 
         vbo->draw(scissorRegion, GL_TRIANGLES, renderNode.firstVertex,

src/scene/workspacescene_opengl.cpp

@@ -163,6 +163,8 @@ std::shared_ptr<GLTexture> DecorationShadowTextureCache::getTexture(ShadowTextur
     Data d;
     d.providers << provider;
     d.texture = std::make_shared<GLTexture>(shadow->decorationShadowImage());
+    d.texture->setFilter(GL_LINEAR);
+    d.texture->setWrapMode(GL_CLAMP_TO_EDGE);
     m_cache.insert(decoShadow.get(), d);
     return d.texture;
 }
@@ -251,6 +253,8 @@ void OpenGLShadowTextureProvider::update()
     }
 
     m_texture = std::make_shared<GLTexture>(image);
+    m_texture->setFilter(GL_LINEAR);
+    m_texture->setWrapMode(GL_CLAMP_TO_EDGE);
 
     if (m_texture->internalFormat() == GL_R8) {
         // Swizzle red to alpha and all other channels to zero
@@ -455,6 +459,7 @@ void SceneOpenGLDecorationRenderer::resizeTexture()
     if (!size.isEmpty()) {
         m_texture.reset(new GLTexture(GL_RGBA8, size.width(), size.height()));
         m_texture->setContentTransform(TextureTransform::MirrorY);
+        m_texture->setFilter(GL_LINEAR);
         m_texture->setWrapMode(GL_CLAMP_TO_EDGE);
         m_texture->clear();
     } else {