Add an effect for padding.

[movit] / padding_effect.frag

diff --git a/padding_effect.frag b/padding_effect.frag
new file mode 100644 (file)
index 0000000..344b34f
--- /dev/null
+++ b/padding_effect.frag
@@ -0,0 +1,30 @@
+uniform vec2 PREFIX(offset);
+uniform vec2 PREFIX(scale);
+uniform vec2 PREFIX(texcoord_min);
+uniform vec2 PREFIX(texcoord_max);
+
+vec4 FUNCNAME(vec2 tc) {
+       tc -= PREFIX(offset);
+       tc *= PREFIX(scale);
+
+#if 1
+       if (any(lessThan(tc, PREFIX(texcoord_min))) ||
+           any(greaterThan(tc, PREFIX(texcoord_max)))) {
+               return PREFIX(border_color);
+       }
+#endif
+       if (any(lessThan(tc, vec2(0.0))) ||
+           any(greaterThan(tc, vec2(1.0)))) {
+               return PREFIX(border_color);
+       } 
+#if 0
+       // In theory, maybe we should test on the outmost textel centers
+       // (e.g. (0.5/width, 0.5/height) for the top-left) instead of the
+       // texture border. However, since we only support integer padding
+       if (any(lessThan(tc, vec2(0.0))) || any(greaterThan(tc, vec2(1.0)))) {
+               return PREFIX(border_color);
+       }
+#endif
+
+       return INPUT(tc);
+}