1 files changed, 42 insertions, 0 deletions
diff --git a/source/blender/gpu/shaders/gpu_shader_icon_frag.glsl b/source/blender/gpu/shaders/gpu_shader_icon_frag.glsl
new file mode 100644
index 00000000000..4452349f23c
--- /dev/null
+++ b/source/blender/gpu/shaders/gpu_shader_icon_frag.glsl
@@ -0,0 +1,42 @@
+/**
+ * Draw the icons, leaving a semi-transparent rectangle on top of the icon.
+ *
+ * The top-left corner of the rectangle is rounded and drawned with anti-alias.
+ * The anti-alias is done by transitioning from the outer to the inner radius of
+ * the rounded corner, and the rectangle sides.
+ */
+
+void main()
+{
+  /* Top-left rounded corner parameters. */
+  const float circle_radius_outer = 0.1;
+  const float circle_radius_inner = 0.075;
+
+  /**
+   * Add a bit transparency to see a bit of the icon, without
+   * getting on the way of readability. */
+  const float mask_transparency = 0.25;
+
+  vec2 circle_center = vec2(circle_radius_outer - text_width, 0.5);
+  fragColor = texture(image, texCoord_interp) * color;
+
+  /* radius in icon space (1 is the icon width).  */
+  float radius = length(mask_coord_interp - circle_center);
+  float mask = smoothstep(circle_radius_inner, circle_radius_outer, radius);
+
+  bool lower_half = mask_coord_interp.y < circle_center.y;
+  bool right_half = mask_coord_interp.x > circle_center.x;
+
+  if (right_half && mask_coord_interp.y < circle_center.y + circle_radius_outer) {
+    mask = smoothstep(circle_center.y + circle_radius_inner,
+                      circle_center.y + circle_radius_outer,
+                      mask_coord_interp.y);
+  }
+  if (lower_half && mask_coord_interp.x > circle_center.x - circle_radius_outer) {
+    mask = smoothstep(circle_center.x - circle_radius_inner,
+                      circle_center.x - circle_radius_outer,
+                      mask_coord_interp.x);
+  }
+
+  fragColor = mix(vec4(0.0), fragColor, max(mask_transparency, mask));
+}