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, 14 insertions, 0 deletions

diff --git a/examples/quick/shadereffects/content/shaders/shadow.frag b/examples/quick/shadereffects/content/shaders/shadow.frag
new file mode 100644
index 0000000000..8650ee4f4c
--- /dev/null
+++ b/examples/quick/shadereffects/content/shaders/shadow.frag
@@ -0,0 +1,14 @@
+uniform lowp float qt_Opacity;
+uniform highp vec2 offset;
+uniform sampler2D source;
+uniform sampler2D shadow;
+uniform highp float darkness;
+uniform highp vec2 delta;
+
+varying highp vec2 qt_TexCoord0;
+
+void main() {
+    lowp vec4 fg = texture2D(source, qt_TexCoord0);
+    lowp vec4 bg = texture2D(shadow, qt_TexCoord0 + delta);
+    gl_FragColor = (fg + vec4(0., 0., 0., darkness * bg.a) * (1. - fg.a)) * qt_Opacity;
+}