Support OpenGL core profile

[ChangeLog][Qt Graphical Effects] Added QtGraphicalEffects support for
OpenGL Core profile contexts.

Task-number: QTBUG-42107
Change-Id: I7111e2e6fb3a0b0391e76a17a8d091d288bfcc23
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/effects/shaders/gammaadjust.frag b/src/effects/shaders/gammaadjust.frag
new file mode 100644
index 0000000..f87492a
--- /dev/null
+++ b/src/effects/shaders/gammaadjust.frag
@@ -0,0 +1,10 @@
+varying highp vec2 qt_TexCoord0;
+uniform highp float qt_Opacity;
+uniform lowp sampler2D source;
+uniform highp float gamma;
+void main(void) {
+    highp vec4 originalColor = texture2D(source, qt_TexCoord0.st);
+    originalColor.rgb = originalColor.rgb / max(1.0/256.0, originalColor.a);
+    highp vec3 adjustedColor = pow(originalColor.rgb, vec3(gamma));
+    gl_FragColor = vec4(adjustedColor * originalColor.a, originalColor.a) * qt_Opacity;
+}