Migrate shadereffects example to be cross-backend

...while demonstrating best practices like file selectors.

Task-number: QTBUG-52914
Change-Id: Ibf7bca77b7b142f5ccb956e05efc5be974d53c79
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 15 insertions, 0 deletions

diff --git a/examples/quick/shadereffects/doc/src/shadereffects.qdoc b/examples/quick/shadereffects/doc/src/shadereffects.qdoc
index dc2a2681f5..7b1d68ebb5 100644
--- a/examples/quick/shadereffects/doc/src/shadereffects.qdoc
+++ b/examples/quick/shadereffects/doc/src/shadereffects.qdoc
@@ -51,6 +51,21 @@
     shader:
     \snippet shadereffects/shadereffects.qml fragment
 
+    In order to support multiple graphics APIs, not just OpenGL, the shader
+    source is not embedded into QML. Instead, file selectors are used to select
+    the correct variant at runtime. Based on the Qt Quick backend in use, Qt
+    will automatically select either \c{shaders/wobble.frag} with the GLSL
+    source code or \c{shaders/+hlsl/wobble.frag} with the HLSL source code.
+
+    \note For simplicity shader source code is used in all variants of the
+    files. However, with the Direct3D backend of Qt Quick pre-compiled shaders
+    are also supported. For example, try the following commands in the
+    \c{content/shaders/+hlsl} directory: \c{move wobble.frag wobble.frag.src}
+    followed by \c{fxc /E main /T ps_5_0 /Fo wobble.frag wobble.frag.src}. Now
+    \c wobble.frag contains Direct3D bytecode and that is what gets shipped
+    with the application instead of the shader source. Further changes are not
+    necessary, the application will function like before.
+
     You can use any custom property on the ShaderEffect in your shader. This
     makes animated shader code very easy:
     \snippet shadereffects/shadereffects.qml properties