Copy distance field shader changes to OpenGL runtime

Also fixes the OpenGL runtime to use alpha channel for the glyph texture
when using ES2.

Task-number: QT3DS-3343
Change-Id: Ia37c341802e504da21ebeaff6f3f1f5b50bd1bfe
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
 

1 files changed, 3 insertions, 4 deletions

diff --git a/src/Runtime/res/effectlib/distancefieldtext_core.frag b/src/Runtime/res/effectlib/distancefieldtext_core.frag
index 0f848bc1..bf60f874 100644
--- a/src/Runtime/res/effectlib/distancefieldtext_core.frag
+++ b/src/Runtime/res/effectlib/distancefieldtext_core.frag
@@ -5,10 +5,9 @@ out vec4 fragColor;
 uniform sampler2D _qt_texture;
 uniform vec4 color;
 
-in vec2 alphas;
-
 void main()
 {
-    fragColor = color * smoothstep(alphas.x, alphas.y,
-                                   texture(_qt_texture, sampleCoord).r);
+    float distance = texture(_qt_texture, sampleCoord).r;
+    float f = fwidth(distance);
+    fragColor = color * smoothstep(0.5 - f, 0.5, distance);
 }