X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=padding_effect.frag;h=80b9633bb17e9f71fb5b6cce6c41a7ae6bad1838;hp=344b34fb4677faf419fb4c7036ec86a6a993bf53;hb=refs%2Fheads%2F1.3.x-release;hpb=eddc371976d7586176a74503ec9896159ececa43

diff --git a/padding_effect.frag b/padding_effect.frag
index 344b34f..80b9633 100644
--- a/padding_effect.frag
+++ b/padding_effect.frag
@@ -1,30 +1,25 @@
-uniform vec2 PREFIX(offset);
-uniform vec2 PREFIX(scale);
-uniform vec2 PREFIX(texcoord_min);
-uniform vec2 PREFIX(texcoord_max);
+// Implicit uniforms:
+// uniform vec2 PREFIX(offset);
+// uniform vec2 PREFIX(scale);
+//
+// uniform vec2 PREFIX(normalized_coords_to_texels);
+// uniform vec2 PREFIX(offset_bottomleft);
+// uniform vec2 PREFIX(offset_topright);
 
 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)))) {
+	vec2 tc_texels = tc * PREFIX(normalized_coords_to_texels);
+	vec2 coverage_bottomleft = clamp(tc_texels + PREFIX(offset_bottomleft), 0.0f, 1.0f);
+	vec2 coverare_topright = clamp(PREFIX(offset_topright) - tc_texels, 0.0f, 1.0f);
+	vec2 coverage_both = coverage_bottomleft * coverare_topright;
+	float coverage = coverage_both.x * coverage_both.y;
+
+	if (coverage <= 0.0f) {
+		// Short-circuit in case the underlying function is expensive to call.
 		return PREFIX(border_color);
+	} else {
+		return mix(PREFIX(border_color), INPUT(tc), coverage);
 	}
-#endif
-
-	return INPUT(tc);
 }