From: Benjamin Otte <otte@redhat.com>
Date: Sun, 17 Sep 2023 04:26:16 +0000 (+0200)
Subject: gl: gradients should transition in unpremultiplied space
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gl: gradients should transition in unpremultiplied space

So make the gradient shaders do that.
---

diff --git a/gsk/gl/resources/conic_gradient.glsl b/gsk/gl/resources/conic_gradient.glsl
index f1d33cd6a7..eaa04aa3ad 100644
--- a/gsk/gl/resources/conic_gradient.glsl
+++ b/gsk/gl/resources/conic_gradient.glsl
@@ -75,10 +75,10 @@ void main() {
 
     if (offset < next_offset) {
       float f = (offset - curr_offset) / (next_offset - curr_offset);
-      vec4 curr_color = gsk_premultiply(get_color(i));
-      vec4 next_color = gsk_premultiply(get_color(i + 1));
+      vec4 curr_color = get_color(i);
+      vec4 next_color = get_color(i + 1);
       vec4 color = mix(curr_color, next_color, f);
-      gskSetScaledOutputColor(color, u_alpha);
+      gskSetScaledOutputColor(gsk_premultiply(color), u_alpha);
       return;
     }
   }
diff --git a/gsk/gl/resources/linear_gradient.glsl b/gsk/gl/resources/linear_gradient.glsl
index fa130be4cb..8a7a557f8e 100644
--- a/gsk/gl/resources/linear_gradient.glsl
+++ b/gsk/gl/resources/linear_gradient.glsl
@@ -97,10 +97,10 @@ void main() {
 
     if (offset < next_offset) {
       float f = (offset - curr_offset) / (next_offset - curr_offset);
-      vec4 curr_color = gsk_premultiply(get_color(i));
-      vec4 next_color = gsk_premultiply(get_color(i + 1));
+      vec4 curr_color = get_color(i);
+      vec4 next_color = get_color(i + 1);
       vec4 color = mix(curr_color, next_color, f);
-      gskSetScaledOutputColor(color, u_alpha);
+      gskSetScaledOutputColor(gsk_premultiply (color), u_alpha);
       return;
     }
   }
diff --git a/gsk/gl/resources/radial_gradient.glsl b/gsk/gl/resources/radial_gradient.glsl
index 59fad00290..d03ca96b8c 100644
--- a/gsk/gl/resources/radial_gradient.glsl
+++ b/gsk/gl/resources/radial_gradient.glsl
@@ -77,10 +77,10 @@ void main() {
 
     if (offset < next_offset) {
       float f = (offset - curr_offset) / (next_offset - curr_offset);
-      vec4 curr_color = gsk_premultiply(get_color(i));
-      vec4 next_color = gsk_premultiply(get_color(i + 1));
+      vec4 curr_color = get_color(i);
+      vec4 next_color = get_color(i + 1);
       vec4 color = mix(curr_color, next_color, f);
-      gskSetScaledOutputColor(color, u_alpha);
+      gskSetScaledOutputColor(gsk_premultiply(color), u_alpha);
       return;
     }
   }