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, 16 insertions, 0 deletions

diff --git a/examples/quick/shadereffects/content/shaders/outline.frag b/examples/quick/shadereffects/content/shaders/outline.frag
new file mode 100644
index 0000000000..9b46719873
--- /dev/null
+++ b/examples/quick/shadereffects/content/shaders/outline.frag
@@ -0,0 +1,16 @@
+uniform sampler2D source;
+uniform highp vec2 delta;
+uniform highp float qt_Opacity;
+
+varying highp vec2 qt_TexCoord0;
+
+void main() {
+    lowp vec4 tl = texture2D(source, qt_TexCoord0 - delta);
+    lowp vec4 tr = texture2D(source, qt_TexCoord0 + vec2(delta.x, -delta.y));
+    lowp vec4 bl = texture2D(source, qt_TexCoord0 - vec2(delta.x, -delta.y));
+    lowp vec4 br = texture2D(source, qt_TexCoord0 + delta);
+    mediump vec4 gx = (tl + bl) - (tr + br);
+    mediump vec4 gy = (tl + tr) - (bl + br);
+    gl_FragColor.xyz = vec3(0.);
+    gl_FragColor.w = clamp(dot(sqrt(gx * gx + gy * gy), vec4(1.)), 0., 1.) * qt_Opacity;
+}