SuperTuxKart 1.5 upstream source (from official release tarball)

data/shaders/sp_text_billboard.frag

@@ -0,0 +1,15 @@
+in vec2 uv;
+in vec4 color;
+out vec4 o_diffuse_color;
+
+uniform sampler2D font_texture;
+
+void main()
+{
+    vec4 col = texture(font_texture, uv);
+    if (col.a < 0.5)
+    {
+        discard;
+    }
+    o_diffuse_color = vec4(col.xyz * color.xyz, 1.0);
+}