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, 12 insertions, 14 deletions

diff --git a/src/Runtime/res/effectlib/distancefieldtext_dropshadow_core.frag b/src/Runtime/res/effectlib/distancefieldtext_dropshadow_core.frag
index 4e46bd5f..51aae5a7 100644
--- a/src/Runtime/res/effectlib/distancefieldtext_dropshadow_core.frag
+++ b/src/Runtime/res/effectlib/distancefieldtext_dropshadow_core.frag
@@ -8,24 +8,22 @@ uniform sampler2D _qt_texture;
 uniform vec4 color;
 uniform vec4 shadowColor;
 
-in vec2 alphas;
-
 void main()
 {
-    float shadowAlpha = smoothstep(alphas.x,
-                                   alphas.y,
-                                   texture(_qt_texture,
-                                           clamp(shadowSampleCoord,
-                                                 normalizedTextureBounds.xy,
-                                                 normalizedTextureBounds.zw)).r);
+    float shadowDistance = texture(_qt_texture,
+                                   clamp(shadowSampleCoord,
+                                         normalizedTextureBounds.xy,
+                                         normalizedTextureBounds.zw)).r;
+    float shadowDistanceD = fwidth(shadowDistance);
+    float shadowAlpha = smoothstep(0.5 - shadowDistanceD, 0.5, shadowDistance);
     vec4 shadowPixel = color * shadowColor * shadowAlpha;
 
-    float textAlpha = smoothstep(alphas.x,
-                                 alphas.y,
-                                 texture(_qt_texture,
-                                         clamp(sampleCoord,
-                                               normalizedTextureBounds.xy,
-                                               normalizedTextureBounds.zw)).r);
+    float textDistance = texture(_qt_texture,
+                                 clamp(sampleCoord,
+                                       normalizedTextureBounds.xy,
+                                       normalizedTextureBounds.zw)).r;
+    float textDistanceD = fwidth(textDistance);
+    float textAlpha = smoothstep(0.5 - textDistanceD, 0.5, textDistance);
     vec4 textPixel = color * textAlpha;
 
     fragColor = mix(shadowPixel, textPixel, textPixel.a);